systemverilog-plugin/third_party/yosys/simplify.cc

/*
 *  yosys -- Yosys Open SYnthesis Suite
 *
 *  Copyright (C) 2012  Claire Xenia Wolf <claire@yosyshq.com>
 *
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *  ---
 *
 *  This is the AST frontend library.
 *
 *  The AST frontend library is not a frontend on it's own but provides a
 *  generic abstract syntax tree (AST) abstraction for HDL code and can be
 *  used by HDL frontends. See "ast.h" for an overview of the API and the
 *  Verilog frontend for an usage example.
 *
 */

#include "kernel/log.h"
#include "libs/sha1/sha1.h"

#include "const2ast.h"

#include <sstream>
#include <stdarg.h>
#include <stdlib.h>
#include <math.h>

#include "simplify.h"

YOSYS_NAMESPACE_BEGIN
namespace VERILOG_FRONTEND
{
extern bool sv_mode;
}
YOSYS_NAMESPACE_END

namespace systemverilog_plugin
{

using namespace ::Yosys;
using namespace ::Yosys::AST_INTERNAL;

void annotateTypedEnums(Yosys::AST::AstNode *ast_node, Yosys::AST::AstNode *template_node)
{
	//check if enum
	if (template_node->attributes.count(ID::enum_type)) {
		//get reference to enum node:
		std::string enum_type = template_node->attributes[ID::enum_type]->str.c_str();
		//			log("enum_type=%s (count=%lu)\n", enum_type.c_str(), current_scope.count(enum_type));
		//			log("current scope:\n");
		//			for (auto &it : current_scope)
		//				log("  %s\n", it.first.c_str());
		log_assert(current_scope.count(enum_type) == 1);
		Yosys::AST::AstNode *enum_node = current_scope.at(enum_type);
		log_assert(enum_node->type == Yosys::AST::AST_ENUM);
		while (simplify(enum_node, true, false, false, 1, -1, false, true)) { }
		//get width from 1st enum item:
		log_assert(enum_node->children.size() >= 1);
		Yosys::AST::AstNode *enum_item0 = enum_node->children[0];
		log_assert(enum_item0->type == Yosys::AST::AST_ENUM_ITEM);
		int width;
		if (!enum_item0->range_valid)
			width = 1;
		else if (enum_item0->range_swapped)
			width = enum_item0->range_right - enum_item0->range_left + 1;
		else
			width = enum_item0->range_left - enum_item0->range_right + 1;
		log_assert(width > 0);
		//add declared enum items:
		for (auto enum_item : enum_node->children){
			log_assert(enum_item->type == Yosys::AST::AST_ENUM_ITEM);
			//get is_signed
			bool is_signed;
			if (enum_item->children.size() == 1){
				is_signed = false;
			} else if (enum_item->children.size() == 2){
				log_assert(enum_item->children[1]->type == Yosys::AST::AST_RANGE);
				is_signed = enum_item->children[1]->is_signed;
			} else {
				log_error("enum_item children size==%lu, expected 1 or 2 for %s (%s)\n",
						  enum_item->children.size(),
						  enum_item->str.c_str(), enum_node->str.c_str()
				);
			}
			//start building attribute string
			std::string enum_item_str = "\\enum_value_";
			//get enum item value
			if(enum_item->children[0]->type != Yosys::AST::AST_CONSTANT){
				log_error("expected const, got %s for %s (%s)\n",
						  type2str(enum_item->children[0]->type).c_str(),
						  enum_item->str.c_str(), enum_node->str.c_str()
						);
			}
			RTLIL::Const val = enum_item->children[0]->bitsAsConst(width, is_signed);
			enum_item_str.append(val.as_string());
			//set attribute for available val to enum item name mappings
			ast_node->attributes[enum_item_str.c_str()] = Yosys::AST::AstNode::mkconst_str(enum_item->str);
		}
	}
}

static bool name_has_dot(const std::string &name, std::string &struct_name)
{
	// check if plausible struct member name \sss.mmm
	std::string::size_type pos;
	if (name.substr(0, 1) == "\\" && (pos = name.find('.', 0)) != std::string::npos) {
		struct_name = name.substr(0, pos);
		return true;
	}
	return false;
}

static Yosys::AST::AstNode *make_range(int left, int right, bool is_signed = false)
{
	// generate a pre-validated range node for a fixed signal range.
	auto range = new Yosys::AST::AstNode(Yosys::AST::AST_RANGE);
	range->range_left = left;
	range->range_right = right;
	range->range_valid = true;
	range->children.push_back(Yosys::AST::AstNode::mkconst_int(left, true));
	range->children.push_back(Yosys::AST::AstNode::mkconst_int(right, true));
	range->is_signed = is_signed;
	return range;
}

static int range_width(Yosys::AST::AstNode *node, Yosys::AST::AstNode *rnode)
{
	log_assert(rnode->type==Yosys::AST::AST_RANGE);
	if (!rnode->range_valid) {
		log_file_error(node->filename, node->location.first_line, "Size must be constant in packed struct/union member %s\n", node->str.c_str());

	}
	// note: range swapping has already been checked for
	return rnode->range_left - rnode->range_right + 1;
}

[[noreturn]] static void struct_array_packing_error(Yosys::AST::AstNode *node)
{
	log_file_error(node->filename, node->location.first_line, "Unpacked array in packed struct/union member %s\n", node->str.c_str());
}

static void save_struct_range_dimensions(Yosys::AST::AstNode *node, Yosys::AST::AstNode *rnode)
{
	node->multirange_dimensions.push_back(rnode->range_right);
	node->multirange_dimensions.push_back(range_width(node, rnode));
	node->multirange_swapped.push_back(rnode->range_swapped);
}

static int get_struct_range_offset(Yosys::AST::AstNode *node, int dimension)
{
	return node->multirange_dimensions[2*dimension];
}

static int get_struct_range_width(Yosys::AST::AstNode *node, int dimension)
{
	return node->multirange_dimensions[2*dimension + 1];
}

static int size_packed_struct(Yosys::AST::AstNode *snode, int base_offset)
{
	// Struct members will be laid out in the structure contiguously from left to right.
	// Union members all have zero offset from the start of the union.
	// Determine total packed size and assign offsets.  Store these in the member node.
	bool is_union = (snode->type == Yosys::AST::AST_UNION);
	int offset = 0;
	int packed_width = -1;

	// embedded struct or union with range?
	auto it = std::remove_if(snode->children.begin(), snode->children.end(), [](Yosys::AST::AstNode *node) { return node->type == Yosys::AST::AST_RANGE; });
	std::vector<Yosys::AST::AstNode *> ranges(it, snode->children.end());
	snode->children.erase(it, snode->children.end());
	if (!ranges.empty()) {
		if (ranges.size() > 1) {
			log_file_error(ranges[1]->filename, ranges[1]->location.first_line,
						   "Currently support for custom-type with range is limited to single range\n");
		}
		for (auto range : ranges) {
			snode->multirange_dimensions.push_back(min(range->range_left, range->range_right));
			snode->multirange_dimensions.push_back(max(range->range_left, range->range_right) - min(range->range_left, range->range_right) + 1);
			snode->multirange_swapped.push_back(range->range_swapped);
		}
	}
	// examine members from last to first
	for (auto it = snode->children.rbegin(); it != snode->children.rend(); ++it) {
		auto node = *it;
		int width;
		if (node->type == Yosys::AST::AST_STRUCT || node->type == Yosys::AST::AST_UNION) {
			// embedded struct or union
			width = size_packed_struct(node, base_offset + offset);
			// set range of struct
			node->range_right = base_offset + offset;
			node->range_left = base_offset + offset + width - 1;
			node->range_valid = true;
		}
		else {
			log_assert(node->type == Yosys::AST::AST_STRUCT_ITEM);
			if (node->children.size() > 0 && node->children[0]->type == Yosys::AST::AST_RANGE) {
				// member width e.g. bit [7:0] a
				width = range_width(node, node->children[0]);
				if (node->children.size() == 2) {
					// Unpacked array. Note that this is a Yosys extension; only packed data types
					// and integer data types are allowed in packed structs / unions in SystemVerilog.
					if (node->children[1]->type == Yosys::AST::AST_RANGE) {
						// Unpacked array, e.g. bit [63:0] a [0:3]
						auto rnode = node->children[1];
						if (rnode->children.size() == 1) {
							// C-style array size, e.g. bit [63:0] a [4]
							node->multirange_dimensions.push_back(0);
							node->multirange_dimensions.push_back(rnode->range_left);
							node->multirange_swapped.push_back(true);
							width *= rnode->range_left;
						} else {
							save_struct_range_dimensions(node, rnode);
							width *= range_width(node, rnode);
						}
						save_struct_range_dimensions(node, node->children[0]);
					}
					else {
						// The Yosys extension for unpacked arrays in packed structs / unions
						// only supports memories, i.e. e.g. logic [7:0] a [256] - see above.
						struct_array_packing_error(node);
					}
				} else {
					// Vector
					save_struct_range_dimensions(node, node->children[0]);
				}
				// range nodes are now redundant
				for (Yosys::AST::AstNode *child : node->children)
					delete child;
				node->children.clear();
			}
			else if (node->children.size() > 0 && node->children[0]->type == Yosys::AST::AST_MULTIRANGE) {
				// Packed array, e.g. bit [3:0][63:0] a
				if (node->children.size() != 1) {
					// The Yosys extension for unpacked arrays in packed structs / unions
					// only supports memories, i.e. e.g. logic [7:0] a [256] - see above.
					struct_array_packing_error(node);
				}
				width = 1;
				for (auto rnode : node->children[0]->children) {
					save_struct_range_dimensions(node, rnode);
					width *= range_width(node, rnode);
				}
				// range nodes are now redundant
				for (Yosys::AST::AstNode *child : node->children)
					delete child;
				node->children.clear();
			}
			else if (node->range_left < 0) {
				// 1 bit signal: bit, logic or reg
				width = 1;
			}
			else {
				// already resolved and compacted
				width = node->range_left - node->range_right + 1;
			}
			if (is_union) {
				node->range_right = base_offset;
				node->range_left = base_offset + width - 1;
			}
			else {
				node->range_right = base_offset + offset;
				node->range_left = base_offset + offset + width - 1;
			}
			node->range_valid = true;
		}
		if (is_union) {
			// check that all members have the same size
			if (packed_width == -1) {
				// first member
				packed_width = width;
			}
			else {
				if (packed_width != width) {

					log_file_error(node->filename, node->location.first_line, "member %s of a packed union has %d bits, expecting %d\n", node->str.c_str(), width, packed_width);
				}
			}
		}
		else {
			offset += width;
		}
	}
	return (is_union ? packed_width : offset);
}

Yosys::AST::AstNode *get_struct_member(const Yosys::AST::AstNode *node)
{
	Yosys::AST::AstNode *member_node;
	if (node->attributes.count(ID::wiretype) && (member_node = node->attributes.at(ID::wiretype)) &&
	    (member_node->type == Yosys::AST::AST_STRUCT_ITEM || member_node->type == Yosys::AST::AST_STRUCT || member_node->type == Yosys::AST::AST_UNION))
	{
		return member_node;
	}
	return NULL;
}

static void add_members_to_scope(Yosys::AST::AstNode *snode, std::string name)
{
	// add all the members in a struct or union to local scope
	// in case later referenced in assignments
	log_assert(snode->type==Yosys::AST::AST_STRUCT || snode->type==Yosys::AST::AST_UNION);
	for (auto *node : snode->children) {
		auto member_name = name + "." + node->str;
		current_scope[member_name] = node;
		if (node->type != Yosys::AST::AST_STRUCT_ITEM) {
			// embedded struct or union
			add_members_to_scope(node, name + "." + node->str);
		}
	}
}

static int get_max_offset(Yosys::AST::AstNode *node)
{
	// get the width from the MS member in the struct
	// as members are laid out from left to right in the packed wire
	log_assert(node->type==Yosys::AST::AST_STRUCT || node->type==Yosys::AST::AST_UNION);
	while (node->type != Yosys::AST::AST_STRUCT_ITEM) {
		node = node->children[0];
	}
	return node->range_left;
}

static Yosys::AST::AstNode *make_packed_struct(Yosys::AST::AstNode *template_node, std::string &name)
{
	// create a wire for the packed struct
	auto wnode = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE);
	wnode->str = name;
	wnode->is_logic = true;
	wnode->range_valid = true;
	wnode->is_signed = template_node->is_signed;
	int offset = get_max_offset(template_node);
	auto range = make_range(offset, 0);
	wnode->children.push_back(range);
	// make sure this node is the one in scope for this name
	current_scope[name] = wnode;
	// add all the struct members to scope under the wire's name
	add_members_to_scope(template_node, name);
	return wnode;
}

// check if a node or its children contains an assignment to the given variable
static bool node_contains_assignment_to(const Yosys::AST::AstNode* node, const Yosys::AST::AstNode* var)
{
	if (node->type == Yosys::AST::AST_ASSIGN_EQ || node->type == Yosys::AST::AST_ASSIGN_LE) {
		// current node is iteslf an assignment
		log_assert(node->children.size() >= 2);
		const Yosys::AST::AstNode* lhs = node->children[0];
		if (lhs->type == Yosys::AST::AST_IDENTIFIER && lhs->str == var->str)
			return false;
	}
	for (const Yosys::AST::AstNode* child : node->children) {
		// if this child shadows the given variable
		if (child != var && child->str == var->str && child->type == Yosys::AST::AST_WIRE)
			break; // skip the remainder of this block/scope
		// depth-first short circuit
		if (!node_contains_assignment_to(child, var))
			return false;
	}
	return true;
}

static std::string prefix_id(const std::string &prefix, const std::string &str)
{
	log_assert(!prefix.empty() && (prefix.front() == '$' || prefix.front() == '\\'));
	log_assert(!str.empty() && (str.front() == '$' || str.front() == '\\'));
	log_assert(prefix.back() == '.');
	if (str.front() == '\\')
		return prefix + str.substr(1);
	return prefix + str;
}

// returns whether an expression contains an unbased unsized literal; does not
// check the literal exists in a self-determined context
static bool contains_unbased_unsized(const Yosys::AST::AstNode *node)
{
	if (node->type == Yosys::AST::AST_CONSTANT)
		return node->is_unsized;
	for (const Yosys::AST::AstNode *child : node->children)
		if (contains_unbased_unsized(child))
			return true;
	return false;
}

// adds a wire to the current module with the given name that matches the
// dimensions of the given wire reference
void add_wire_for_ref(const RTLIL::Wire *ref, const std::string &str)
{
	Yosys::AST::AstNode *left = Yosys::AST::AstNode::mkconst_int(ref->width - 1 + ref->start_offset, true);
	Yosys::AST::AstNode *right = Yosys::AST::AstNode::mkconst_int(ref->start_offset, true);
	if (ref->upto)
		std::swap(left, right);
	Yosys::AST::AstNode *range = new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, left, right);

	Yosys::AST::AstNode *wire = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, range);
	wire->is_signed = ref->is_signed;
	wire->is_logic = true;
	wire->str = str;

	current_ast_mod->children.push_back(wire);
	current_scope[str] = wire;
}

enum class IdentUsage {
	NotReferenced, // target variable is neither read or written in the block
	Assigned, // target variable is always assigned before use
	SyncRequired, // target variable may be used before it has been assigned
};

// determines whether a local variable a block is always assigned before it is
// used, meaning the nosync attribute can automatically be added to that
// variable
static IdentUsage always_asgn_before_use(const Yosys::AST::AstNode *node, const std::string &target)
{
	// This variable has been referenced before it has necessarily been assigned
	// a value in this procedure.
	if (node->type == Yosys::AST::AST_IDENTIFIER && node->str == target)
		return IdentUsage::SyncRequired;

	// For case statements (which are also used for if/else), we check each
	// possible branch. If the variable is assigned in all branches, then it is
	// assigned, and a sync isn't required. If it used before assignment in any
	// branch, then a sync is required.
	if (node->type == Yosys::AST::AST_CASE) {
		bool all_defined = true;
		bool any_used = false;
		bool has_default = false;
		for (const Yosys::AST::AstNode *child : node->children) {
			if (child->type == Yosys::AST::AST_COND && child->children.at(0)->type == Yosys::AST::AST_DEFAULT)
				has_default = true;
			IdentUsage nested = always_asgn_before_use(child, target);
			if (nested != IdentUsage::Assigned && child->type == Yosys::AST::AST_COND)
				all_defined = false;
			if (nested == IdentUsage::SyncRequired)
				any_used = true;
		}
		if (any_used)
			return IdentUsage::SyncRequired;
		else if (all_defined && has_default)
			return IdentUsage::Assigned;
		else
			return IdentUsage::NotReferenced;
	}

	// Check if this is an assignment to the target variable. For simplicity, we
	// don't analyze sub-ranges of the variable.
	if (node->type == Yosys::AST::AST_ASSIGN_EQ) {
		const Yosys::AST::AstNode *ident = node->children.at(0);
		if (ident->type == Yosys::AST::AST_IDENTIFIER && ident->str == target)
			return IdentUsage::Assigned;
	}

	for (const Yosys::AST::AstNode *child : node->children) {
		IdentUsage nested = always_asgn_before_use(child, target);
		if (nested != IdentUsage::NotReferenced)
			return nested;
	}
	return IdentUsage::NotReferenced;
}

static const std::string auto_nosync_prefix = "\\AutoNosync";

// mark a local variable in an always_comb block for automatic nosync
// consideration
static void mark_auto_nosync(Yosys::AST::AstNode *block, const Yosys::AST::AstNode *wire)
{
	log_assert(block->type == Yosys::AST::AST_BLOCK);
	log_assert(wire->type == Yosys::AST::AST_WIRE);
	block->attributes[auto_nosync_prefix + wire->str] = Yosys::AST::AstNode::mkconst_int(1,
			false);
}

// block names can be prefixed with an explicit scope during elaboration
static bool is_autonamed_block(const std::string &str) {
	size_t last_dot = str.rfind('.');
	// unprefixed names: autonamed if the first char is a dollar sign
	if (last_dot == std::string::npos)
		return str.at(0) == '$'; // e.g., `$fordecl_block$1`
	// prefixed names: autonamed if the final chunk begins with a dollar sign
	return str.rfind(".$") == last_dot; // e.g., `\foo.bar.$fordecl_block$1`
}

// check a procedural block for auto-nosync markings, remove them, and add
// nosync to local variables as necessary
static void check_auto_nosync(Yosys::AST::AstNode *node)
{
	std::vector<RTLIL::IdString> attrs_to_drop;
	for (const auto& elem : node->attributes) {
		// skip attributes that don't begin with the prefix
		if (elem.first.compare(0, auto_nosync_prefix.size(),
					auto_nosync_prefix.c_str()))
			continue;

		// delete and remove the attribute once we're done iterating
		attrs_to_drop.push_back(elem.first);

		// find the wire based on the attribute
		std::string wire_name = elem.first.substr(auto_nosync_prefix.size());
		auto it = current_scope.find(wire_name);
		if (it == current_scope.end())
			continue;

		// analyze the usage of the local variable in this block
		IdentUsage ident_usage = always_asgn_before_use(node, wire_name);
		if (ident_usage != IdentUsage::Assigned)
			continue;

		// mark the wire with `nosync`
		Yosys::AST::AstNode *wire = it->second;
		log_assert(wire->type == Yosys::AST::AST_WIRE);
		wire->attributes[ID::nosync] = node->mkconst_int(1, false);
	}

	// remove the attributes we've "consumed"
	for (const RTLIL::IdString &str : attrs_to_drop) {
		auto it = node->attributes.find(str);
		delete it->second;
		node->attributes.erase(it);
	}

	// check local variables in any nested blocks
	for (Yosys::AST::AstNode *child : node->children)
		check_auto_nosync(child);
}

static inline std::string encode_filename(const std::string &filename)
{    
    std::stringstream val; 
    if (!std::any_of(filename.begin(), filename.end(), [](char c) { 
        return static_cast<unsigned char>(c) < 33 || static_cast<unsigned char>(c) > 126; 
    })) return filename;
    for (unsigned char const c : filename) {
        if (c < 33 || c > 126) 
            val << stringf("$%02x", c);
        else 
            val << c;
    }    
    return val.str();
}

// convert the AST into a simpler AST that has all parameters substituted by their
// values, unrolled for-loops, expanded generate blocks, etc. when this function
// is done with an AST it can be converted into RTLIL using genRTLIL().
//
// this function also does all name resolving and sets the id2ast member of all
// nodes that link to a different node using names and lexical scoping.
bool simplify(Yosys::AST::AstNode *ast_node, bool const_fold, bool at_zero, bool in_lvalue, int stage, int width_hint, bool sign_hint, bool in_param)
{
	static int recursion_counter = 0;
	static bool deep_recursion_warning = false;

	if (recursion_counter++ == 1000 && deep_recursion_warning) {
		log_warning("Deep recursion in AST simplifier.\nDoes this design contain overly long or deeply nested expressions, or excessive recursion?\n");
		deep_recursion_warning = false;
	}

	static bool unevaluated_tern_branch = false;

	Yosys::AST::AstNode *newNode = NULL;
	bool did_something = false;

#if 0
	log("-------------\n");
	log("AST simplify[%d] depth %d at %s:%d on %s %p:\n", stage, recursion_counter, filename.c_str(), location.first_line, type2str(type).c_str(), this);
	log("const_fold=%d, at_zero=%d, in_lvalue=%d, stage=%d, width_hint=%d, sign_hint=%d, in_param=%d\n",
			int(const_fold), int(at_zero), int(in_lvalue), int(stage), int(width_hint), int(sign_hint), int(in_param));
	// dumpAst(NULL, "> ");
#endif

	if (stage == 0)
	{
		log_assert(ast_node->type == Yosys::AST::AST_MODULE || ast_node->type == Yosys::AST::AST_INTERFACE);

		deep_recursion_warning = true;
		while (simplify(ast_node, const_fold, at_zero, in_lvalue, 1, width_hint, sign_hint, in_param)) { }

		if (!flag_nomem2reg && !ast_node->get_bool_attribute(ID::nomem2reg))
		{
			dict<Yosys::AST::AstNode*, pool<std::string>> mem2reg_places;
			dict<Yosys::AST::AstNode*, uint32_t> mem2reg_candidates, dummy_proc_flags;
			uint32_t flags = flag_mem2reg ? Yosys::AST::AstNode::MEM2REG_FL_ALL : 0;
			ast_node->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, dummy_proc_flags, flags); // not sure if correct MAND

			pool<Yosys::AST::AstNode*> mem2reg_set;
			for (auto &it : mem2reg_candidates)
			{
				Yosys::AST::AstNode *mem = it.first;
				uint32_t memflags = it.second;
				bool this_nomeminit = flag_nomeminit;
				log_assert((memflags & ~0x00ffff00) == 0);

				if (mem->get_bool_attribute(ID::nomem2reg))
					continue;

				if (mem->get_bool_attribute(ID::nomeminit) || ast_node->get_bool_attribute(ID::nomeminit))
					this_nomeminit = true;

				if (memflags & Yosys::AST::AstNode::MEM2REG_FL_FORCED)
					goto silent_activate;

				if (memflags & Yosys::AST::AstNode::MEM2REG_FL_EQ2)
					goto verbose_activate;

				if (memflags & Yosys::AST::AstNode::MEM2REG_FL_SET_ASYNC)
					goto verbose_activate;

				if ((memflags & Yosys::AST::AstNode::MEM2REG_FL_SET_INIT) && (memflags & Yosys::AST::AstNode::MEM2REG_FL_SET_ELSE) && this_nomeminit)
					goto verbose_activate;

				if (memflags & Yosys::AST::AstNode::MEM2REG_FL_CMPLX_LHS)
					goto verbose_activate;

				if ((memflags & Yosys::AST::AstNode::MEM2REG_FL_CONST_LHS) && !(memflags & Yosys::AST::AstNode::MEM2REG_FL_VAR_LHS))
					goto verbose_activate;

				// log("Note: Not replacing memory %s with list of registers (flags=0x%08lx).\n", mem->str.c_str(), long(memflags));
				continue;

			verbose_activate:
				if (mem2reg_set.count(mem) == 0) {
					std::string message = stringf("Replacing memory %s with list of registers.", mem->str.c_str());
					bool first_element = true;
					for (auto &place : mem2reg_places[it.first]) {
						message += stringf("%s%s", first_element ? " See " : ", ", place.c_str());
						first_element = false;
					}
					log_warning("%s\n", message.c_str());
				}

			silent_activate:
				// log("Note: Replacing memory %s with list of registers (flags=0x%08lx).\n", mem->str.c_str(), long(memflags));
				mem2reg_set.insert(mem);
			}

			for (auto node : mem2reg_set)
			{
				int mem_width, mem_size, addr_bits;
				node->meminfo(mem_width, mem_size, addr_bits);

				int data_range_left = node->children[0]->range_left;
				int data_range_right = node->children[0]->range_right;

				if (node->children[0]->range_swapped)
					std::swap(data_range_left, data_range_right);

				for (int i = 0; i < mem_size; i++) {
					Yosys::AST::AstNode *reg = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE,
							node->mkconst_int(data_range_left, true), node->mkconst_int(data_range_right, true)));
					reg->str = stringf("%s[%d]", node->str.c_str(), i);
					reg->is_reg = true;
					reg->is_signed = node->is_signed;
					for (auto &it : node->attributes)
						if (it.first != ID::mem2reg)
							reg->attributes.emplace(it.first, it.second->clone());
					reg->filename = node->filename;
					reg->location = node->location;
					ast_node->children.push_back(reg);
					while (simplify(reg, true, false, false, 1, -1, false, false)) { } // <- not sure about reg being the first arg here...
				}
			}

			Yosys::AST::AstNode *async_block = NULL;
			while (ast_node->mem2reg_as_needed_pass2(mem2reg_set, ast_node, NULL, async_block)) { }

			vector<Yosys::AST::AstNode*> delnodes;
			ast_node->mem2reg_remove(mem2reg_set, delnodes);

			for (auto node : delnodes)
				delete node;
		}

		while (simplify(ast_node, const_fold, at_zero, in_lvalue, 2, width_hint, sign_hint, in_param)) { }
		recursion_counter--;
		return false;
	}

	Yosys::AST::current_filename = ast_node->filename;

	// we do not look inside a task or function
	// (but as soon as a task or function is instantiated we process the generated AST as usual)
	if (ast_node->type == Yosys::AST::AST_FUNCTION || ast_node->type == Yosys::AST::AST_TASK) {
		recursion_counter--;
		return false;
	}

	// deactivate all calls to non-synthesis system tasks
	// note that $display, $finish, and $stop are used for synthesis-time DRC so they're not in this list
	if ((ast_node->type == Yosys::AST::AST_FCALL || ast_node->type == Yosys::AST::AST_TCALL) && (ast_node->str == "$strobe" || ast_node->str == "$monitor" || ast_node->str == "$time" ||
			ast_node->str == "$dumpfile" || ast_node->str == "$dumpvars" || ast_node->str == "$dumpon" || ast_node->str == "$dumpoff" || ast_node->str == "$dumpall")) {
		log_file_warning(ast_node->filename, ast_node->location.first_line, "Ignoring call to system %s %s.\n", ast_node->type == Yosys::AST::AST_FCALL ? "function" : "task", ast_node->str.c_str());
		ast_node->delete_children();
		ast_node->str = std::string();
	}

	if ((ast_node->type == Yosys::AST::AST_TCALL) && (ast_node->str == "$display" || ast_node->str == "$write") && (!current_always || current_always->type != Yosys::AST::AST_INITIAL)) {
		log_file_warning(ast_node->filename, ast_node->location.first_line, "System task `%s' outside initial block is unsupported.\n", ast_node->str.c_str());
		ast_node->delete_children();
		ast_node->str = std::string();
	}

	// print messages if this a call to $display() or $write()
	// This code implements only a small subset of Verilog-2005 $display() format specifiers,
	// but should be good enough for most uses
	if ((ast_node->type == Yosys::AST::AST_TCALL) && ((ast_node->str == "$display") || (ast_node->str == "$write")))
	{
		int nargs = GetSize(ast_node->children);
		if (nargs < 1)
			log_file_error(ast_node->filename, ast_node->location.first_line, "System task `%s' got %d arguments, expected >= 1.\n",
					ast_node->str.c_str(), int(ast_node->children.size()));

		// First argument is the format string
		Yosys::AST::AstNode *node_string = ast_node->children[0];
		while (simplify(node_string, true, false, false, stage, width_hint, sign_hint, false)) { }
		if (node_string->type != Yosys::AST::AST_CONSTANT)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system task `%s' with non-constant 1st argument.\n", ast_node->str.c_str());
		std::string sformat = node_string->bitsAsConst().decode_string();
		std::string sout = ast_node->process_format_str(sformat, 1, stage, width_hint, sign_hint);
		// Finally, print the message (only include a \n for $display, not for $write)
		log("%s", sout.c_str());
		if (ast_node->str == "$display")
			log("\n");
		ast_node->delete_children();
		ast_node->str = std::string();
	}

	// activate const folding if this is anything that must be evaluated statically (ranges, parameters, attributes, etc.)
	if (ast_node->type == Yosys::AST::AST_WIRE || ast_node->type == Yosys::AST::AST_PARAMETER || ast_node->type == Yosys::AST::AST_LOCALPARAM || ast_node->type == Yosys::AST::AST_ENUM_ITEM || ast_node->type == Yosys::AST::AST_DEFPARAM || ast_node->type == Yosys::AST::AST_PARASET || ast_node->type == Yosys::AST::AST_RANGE || ast_node->type == Yosys::AST::AST_PREFIX || ast_node->type == Yosys::AST::AST_TYPEDEF)
		const_fold = true;
	if (ast_node->type == Yosys::AST::AST_IDENTIFIER && current_scope.count(ast_node->str) > 0 && (current_scope[ast_node->str]->type == Yosys::AST::AST_PARAMETER || current_scope[ast_node->str]->type == Yosys::AST::AST_LOCALPARAM || current_scope[ast_node->str]->type == Yosys::AST::AST_ENUM_ITEM))
		const_fold = true;

	// in certain cases a function must be evaluated constant. this is what in_param controls.
	if (ast_node->type == Yosys::AST::AST_PARAMETER || ast_node->type == Yosys::AST::AST_LOCALPARAM || ast_node->type == Yosys::AST::AST_DEFPARAM || ast_node->type == Yosys::AST::AST_PARASET || ast_node->type == Yosys::AST::AST_PREFIX)
		in_param = true;

	std::map<std::string, Yosys::AST::AstNode*> backup_scope;

	// create name resolution entries for all objects with names
	// also merge multiple declarations for the same wire (e.g. "output foobar; reg foobar;")
	if (ast_node->type == Yosys::AST::AST_MODULE || ast_node->type == Yosys::AST::AST_INTERFACE) {
		current_scope.clear();
		std::set<std::string> existing;
		int counter = 0;
		ast_node->label_genblks(existing, counter);
		std::map<std::string, Yosys::AST::AstNode*> this_wire_scope;
		for (size_t i = 0; i < ast_node->children.size(); i++) {
			Yosys::AST::AstNode *node = ast_node->children[i];

			if (node->type == Yosys::AST::AST_WIRE) {
				if (node->children.size() == 1 && node->children[0]->type == Yosys::AST::AST_RANGE) {
					for (auto c : node->children[0]->children) {
						if (!c->is_simple_const_expr()) {
							if (ast_node->attributes.count(ID::dynports))
								delete ast_node->attributes.at(ID::dynports);
							node->attributes[ID::dynports] = node->mkconst_int(1, true);
						}
					}
				}
				if (this_wire_scope.count(node->str) > 0) {
					Yosys::AST::AstNode *first_node = this_wire_scope[node->str];
					if (first_node->is_input && node->is_reg)
						goto wires_are_incompatible;
					if (!node->is_input && !node->is_output && node->is_reg && node->children.size() == 0)
						goto wires_are_compatible;
					if (first_node->children.size() == 0 && node->children.size() == 1 && node->children[0]->type == Yosys::AST::AST_RANGE) {
						Yosys::AST::AstNode *r = node->children[0];
						if (r->range_valid && r->range_left == 0 && r->range_right == 0) {
							delete r;
							node->children.pop_back();
						}
					}
					if (first_node->children.size() != node->children.size())
						goto wires_are_incompatible;
					for (size_t j = 0; j < node->children.size(); j++) {
						Yosys::AST::AstNode *n1 = first_node->children[j], *n2 = node->children[j];
						if (n1->type == Yosys::AST::AST_RANGE && n2->type == Yosys::AST::AST_RANGE && n1->range_valid && n2->range_valid) {
							if (n1->range_left != n2->range_left)
								goto wires_are_incompatible;
							if (n1->range_right != n2->range_right)
								goto wires_are_incompatible;
						} else if (*n1 != *n2)
							goto wires_are_incompatible;
					}
					if (first_node->range_left != node->range_left)
						goto wires_are_incompatible;
					if (first_node->range_right != node->range_right)
						goto wires_are_incompatible;
					if (first_node->port_id == 0 && (node->is_input || node->is_output))
						goto wires_are_incompatible;
				wires_are_compatible:
					if (node->is_input)
						first_node->is_input = true;
					if (node->is_output)
						first_node->is_output = true;
					if (node->is_reg)
						first_node->is_reg = true;
					if (node->is_logic)
						first_node->is_logic = true;
					if (node->is_signed)
						first_node->is_signed = true;
					for (auto &it : node->attributes) {
						if (first_node->attributes.count(it.first) > 0)
							delete first_node->attributes[it.first];
						first_node->attributes[it.first] = it.second->clone();
					}
					ast_node->children.erase(ast_node->children.begin()+(i--));
					did_something = true;
					delete node;
					continue;
				wires_are_incompatible:
					if (stage > 1)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Incompatible re-declaration of wire %s.\n", node->str.c_str());
					continue;
				}
				this_wire_scope[node->str] = node;
			}
			// these nodes appear at the top level in a module and can define names
			if (node->type == Yosys::AST::AST_PARAMETER || node->type == Yosys::AST::AST_LOCALPARAM || node->type == Yosys::AST::AST_WIRE || node->type == Yosys::AST::AST_AUTOWIRE || node->type == Yosys::AST::AST_GENVAR ||
					node->type == Yosys::AST::AST_MEMORY || node->type == Yosys::AST::AST_FUNCTION || node->type == Yosys::AST::AST_TASK || node->type == Yosys::AST::AST_DPI_FUNCTION || node->type == Yosys::AST::AST_CELL ||
					node->type == Yosys::AST::AST_TYPEDEF) {
				backup_scope[node->str] = current_scope[node->str];
				current_scope[node->str] = node;
			}
			if (node->type == Yosys::AST::AST_ENUM) {
				current_scope[node->str] = node;
				for (auto enode : node->children) {
					log_assert(enode->type==Yosys::AST::AST_ENUM_ITEM);
					if (current_scope.count(enode->str) == 0)
						current_scope[enode->str] = enode;
					else
						log_file_error(ast_node->filename, ast_node->location.first_line, "enum item %s already exists\n", enode->str.c_str());
				}
			}
		}
		for (size_t i = 0; i < ast_node->children.size(); i++) {
			Yosys::AST::AstNode *node = ast_node->children[i];
			if (node->type == Yosys::AST::AST_PARAMETER || node->type == Yosys::AST::AST_LOCALPARAM || node->type == Yosys::AST::AST_WIRE || node->type == Yosys::AST::AST_AUTOWIRE || node->type == Yosys::AST::AST_MEMORY || node->type == Yosys::AST::AST_TYPEDEF)
				while (simplify(node, true, false, false, 1, -1, false, node->type == Yosys::AST::AST_PARAMETER || node->type == Yosys::AST::AST_LOCALPARAM))
					did_something = true;
			if (node->type == Yosys::AST::AST_ENUM) {
				for (auto enode : node->children){
					log_assert(enode->type==Yosys::AST::AST_ENUM_ITEM);
					while (simplify(node, true, false, false, 1, -1, false, in_param))
						did_something = true;
				}
			}
		}

		for (Yosys::AST::AstNode *child : ast_node->children)
			if (child->type == Yosys::AST::AST_ALWAYS &&
					child->attributes.count(ID::always_comb))
				check_auto_nosync(child);
	}

	// create name resolution entries for all objects with names
	if (ast_node->type == Yosys::AST::AST_PACKAGE) {
		//add names to package scope
		for (size_t i = 0; i < ast_node->children.size(); i++) {
			Yosys::AST::AstNode *node = ast_node->children[i];
			// these nodes appear at the top level in a package and can define names
			if (node->type == Yosys::AST::AST_PARAMETER || node->type == Yosys::AST::AST_LOCALPARAM || node->type == Yosys::AST::AST_TYPEDEF || node->type == Yosys::AST::AST_FUNCTION || node->type == Yosys::AST::AST_TASK) {
				current_scope[node->str] = node;
			}
			if (node->type == Yosys::AST::AST_ENUM) {
				current_scope[node->str] = node;
				for (auto enode : node->children) {
					log_assert(enode->type==Yosys::AST::AST_ENUM_ITEM);
					if (current_scope.count(enode->str) == 0)
						current_scope[enode->str] = enode;
					else
						log_file_error(ast_node->filename, ast_node->location.first_line, "enum item %s already exists in package\n", enode->str.c_str());
				}
			}
		}
	}


	auto backup_current_block = current_block;
	auto backup_current_block_child = current_block_child;
	auto backup_current_top_block = current_top_block;
	auto backup_current_always = current_always;
	auto backup_current_always_clocked = current_always_clocked;

	if (ast_node->type == Yosys::AST::AST_ALWAYS || ast_node->type == Yosys::AST::AST_INITIAL)
	{
		if (current_always != nullptr)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Invalid nesting of always blocks and/or initializations.\n");

		current_always = ast_node;
		current_always_clocked = false;

		if (ast_node->type == Yosys::AST::AST_ALWAYS)
			for (auto child : ast_node->children) {
				if (child->type == Yosys::AST::AST_POSEDGE || child->type == Yosys::AST::AST_NEGEDGE)
					current_always_clocked = true;
				if (child->type == Yosys::AST::AST_EDGE && GetSize(child->children) == 1 &&
						child->children[0]->type == Yosys::AST::AST_IDENTIFIER && child->children[0]->str == "\\$global_clock")
					current_always_clocked = true;
			}
	}

	if (ast_node->type == Yosys::AST::AST_CELL) {
		bool lookup_suggested = false;

		for (Yosys::AST::AstNode *child : ast_node->children) {
			// simplify any parameters to constants
			if (child->type == Yosys::AST::AST_PARASET)
				while (simplify(child, true, false, false, 1, -1, false, true)) { }

			// look for patterns which _may_ indicate ambiguity requiring
			// resolution of the underlying module
			if (child->type == Yosys::AST::AST_ARGUMENT) {
				if (child->children.size() != 1)
					continue;
				const Yosys::AST::AstNode *value = child->children[0];
				if (value->type == Yosys::AST::AST_IDENTIFIER) {
					const Yosys::AST::AstNode *elem = value->id2ast;
					if (elem == nullptr) {
						if (current_scope.count(value->str))
							elem = current_scope.at(value->str);
						else
							continue;
					}
					if (elem->type == Yosys::AST::AST_MEMORY)
						// need to determine is the is a read or wire
						lookup_suggested = true;
					else if (elem->type == Yosys::AST::AST_WIRE && elem->is_signed && !value->children.empty())
						// this may be a fully sliced signed wire which needs
						// to be indirected to produce an unsigned connection
						lookup_suggested = true;
				}
				else if (contains_unbased_unsized(value))
					// unbased unsized literals extend to width of the context
					lookup_suggested = true;
			}
		}

		const RTLIL::Module *module = nullptr;
		if (lookup_suggested)
			module = ast_node->lookup_cell_module();
		if (module) {
			size_t port_counter = 0;
			for (Yosys::AST::AstNode *child : ast_node->children) {
				if (child->type != Yosys::AST::AST_ARGUMENT)
					continue;

				// determine the full name of port this argument is connected to
				RTLIL::IdString port_name;
				if (child->str.size())
					port_name = child->str;
				else {
					if (port_counter >= module->ports.size())
						log_file_error(ast_node->filename, ast_node->location.first_line,
								"Cell instance has more ports than the module!\n");
					port_name = module->ports[port_counter++];
				}

				// find the port's wire in the underlying module
				const RTLIL::Wire *ref = module->wire(port_name);
				if (ref == nullptr)
					log_file_error(ast_node->filename, ast_node->location.first_line,
							"Cell instance refers to port %s which does not exist in module %s!.\n",
							log_id(port_name), log_id(module->name));

				// select the argument, if present
				log_assert(child->children.size() <= 1);
				if (child->children.empty())
					continue;
				Yosys::AST::AstNode *arg = child->children[0];

				// plain identifiers never need indirection; this also prevents
				// adding infinite levels of indirection
				if (arg->type == Yosys::AST::AST_IDENTIFIER && arg->children.empty())
					continue;

				// only add indirection for standard inputs or outputs
				if (ref->port_input == ref->port_output)
					continue;

				did_something = true;

				// create the indirection wire
				std::stringstream sstr;
				sstr << "$indirect$" << ref->name.c_str() << "$" << encode_filename(ast_node->filename) << ":" << ast_node->location.first_line << "$" << (autoidx++);
				std::string tmp_str = sstr.str();
				add_wire_for_ref(ref, tmp_str);

				Yosys::AST::AstNode *asgn = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN);
				current_ast_mod->children.push_back(asgn);

				Yosys::AST::AstNode *ident = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
				ident->str = tmp_str;
				child->children[0] = ident->clone();

				if (ref->port_input && !ref->port_output) {
					asgn->children.push_back(ident);
					asgn->children.push_back(arg);
				} else {
					log_assert(!ref->port_input && ref->port_output);
					asgn->children.push_back(arg);
					asgn->children.push_back(ident);
				}
			}


		}
	}

	int backup_width_hint = width_hint;
	bool backup_sign_hint = sign_hint;

	bool detect_width_simple = false;
	bool child_0_is_self_determined = false;
	bool child_1_is_self_determined = false;
	bool child_2_is_self_determined = false;
	bool children_are_self_determined = false;
	bool reset_width_after_children = false;

	switch (ast_node->type)
	{
	case Yosys::AST::AST_ASSIGN_EQ:
	case Yosys::AST::AST_ASSIGN_LE:
	case Yosys::AST::AST_ASSIGN:
		while (!ast_node->children[0]->basic_prep && simplify(ast_node->children[0], false, false, true, stage, -1, false, in_param) == true)
			did_something = true;
		while (!ast_node->children[1]->basic_prep && simplify(ast_node->children[1], false, false, false, stage, -1, false, in_param) == true)
			did_something = true;
		ast_node->children[0]->detectSignWidth(backup_width_hint, backup_sign_hint);
		ast_node->children[1]->detectSignWidth(width_hint, sign_hint);
		width_hint = max(width_hint, backup_width_hint);
		child_0_is_self_determined = true;
		// test only once, before optimizations and memory mappings but after assignment LHS was mapped to an identifier
		if (ast_node->children[0]->id2ast && !ast_node->children[0]->was_checked) {
			if ((ast_node->type == Yosys::AST::AST_ASSIGN_LE || ast_node->type == Yosys::AST::AST_ASSIGN_EQ) && ast_node->children[0]->id2ast->is_logic)
				ast_node->children[0]->id2ast->is_reg = true; // if logic type is used in a block asignment
			if ((ast_node->type == Yosys::AST::AST_ASSIGN_LE || ast_node->type == Yosys::AST::AST_ASSIGN_EQ) && !ast_node->children[0]->id2ast->is_reg)
				log_warning("wire '%s' is assigned in a block at %s.\n", ast_node->children[0]->str.c_str(), ast_node->loc_string().c_str());
			if (ast_node->type == Yosys::AST::AST_ASSIGN && ast_node->children[0]->id2ast->is_reg) {
				bool is_rand_reg = false;
				if (ast_node->children[1]->type == Yosys::AST::AST_FCALL) {
					if (ast_node->children[1]->str == "\\$anyconst")
						is_rand_reg = true;
					if (ast_node->children[1]->str == "\\$anyseq")
						is_rand_reg = true;
					if (ast_node->children[1]->str == "\\$allconst")
						is_rand_reg = true;
					if (ast_node->children[1]->str == "\\$allseq")
						is_rand_reg = true;
				}
				if (!is_rand_reg)
					log_warning("reg '%s' is assigned in a continuous assignment at %s.\n", ast_node->children[0]->str.c_str(), ast_node->loc_string().c_str());
			}
			ast_node->children[0]->was_checked = true;
		}
		break;

	case Yosys::AST::AST_STRUCT:
	case Yosys::AST::AST_UNION:
		if (!ast_node->basic_prep) {
			for (auto *node : ast_node->children) {
				// resolve any ranges
				while (!node->basic_prep && simplify(node, true, false, false, stage, -1, false, false)) {
					did_something = true;
				}
			}
			// determine member offsets and widths
			size_packed_struct(ast_node, 0);

			// instance rather than just a type in a typedef or outer struct?
			if (!ast_node->str.empty() && ast_node->str[0] == '\\') {
				// instance so add a wire for the packed structure
				auto wnode = make_packed_struct(ast_node, ast_node->str);
				log_assert(current_ast_mod);
				current_ast_mod->children.push_back(wnode);
			}
			ast_node->basic_prep = true;
		}
		break;

	case Yosys::AST::AST_STRUCT_ITEM:
		break;

	case Yosys::AST::AST_ENUM:
		//log("\nENUM %s: %d child %d\n", ast_node->str.c_str(), ast_node->basic_prep, ast_node->children[0]->basic_prep);
		if (!ast_node->basic_prep) {
			for (auto item_node : ast_node->children) {
				while (!item_node->basic_prep && simplify(item_node, false, false, false, stage, -1, false, in_param))
					did_something = true;
			}
			// allocate values (called more than once)
			ast_node->allocateDefaultEnumValues();
		}
		break;

	case Yosys::AST::AST_PARAMETER:
	case Yosys::AST::AST_LOCALPARAM:
		// if parameter is implicit type which is the typename of a struct or union,
		// save information about struct in wiretype attribute
		if (ast_node->children[0]->type == Yosys::AST::AST_IDENTIFIER && current_scope.count(ast_node->children[0]->str) > 0) {
			auto item_node = current_scope[ast_node->children[0]->str];
			if (item_node->type == Yosys::AST::AST_STRUCT || item_node->type == Yosys::AST::AST_UNION) {
				ast_node->attributes[ID::wiretype] = item_node->clone();
				size_packed_struct(ast_node->attributes[ID::wiretype], 0);
				add_members_to_scope(ast_node->attributes[ID::wiretype], ast_node->str);
			}
		}
		while (!ast_node->children[0]->basic_prep && simplify(ast_node->children[0], false, false, false, stage, -1, false, true) == true)
			did_something = true;
		ast_node->children[0]->detectSignWidth(width_hint, sign_hint);
		if (ast_node->children.size() > 1 && ast_node->children[1]->type == Yosys::AST::AST_RANGE) {
			while (!ast_node->children[1]->basic_prep && simplify(ast_node->children[1], false, false, false, stage, -1, false, true) == true)
				did_something = true;
			if (!ast_node->children[1]->range_valid)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Non-constant width range on parameter decl.\n");
			width_hint = max(width_hint, ast_node->children[1]->range_left - ast_node->children[1]->range_right + 1);
		}
		break;
	case Yosys::AST::AST_ENUM_ITEM:
		while (!ast_node->children[0]->basic_prep && simplify(ast_node->children[0], false, false, false, stage, -1, false, in_param))
			did_something = true;
		ast_node->children[0]->detectSignWidth(width_hint, sign_hint);
		if (ast_node->children.size() > 1 && ast_node->children[1]->type == Yosys::AST::AST_RANGE) {
			while (!ast_node->children[1]->basic_prep && simplify(ast_node->children[1], false, false, false, stage, -1, false, in_param))
				did_something = true;
			if (!ast_node->children[1]->range_valid)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Non-constant width range on enum item decl.\n");
			width_hint = max(width_hint, ast_node->children[1]->range_left - ast_node->children[1]->range_right + 1);
		}
		break;

	case Yosys::AST::AST_TO_BITS:
	case Yosys::AST::AST_TO_SIGNED:
	case Yosys::AST::AST_TO_UNSIGNED:
	case Yosys::AST::AST_SELFSZ:
	case Yosys::AST::AST_CAST_SIZE:
	case Yosys::AST::AST_CONCAT:
	case Yosys::AST::AST_REPLICATE:
	case Yosys::AST::AST_REDUCE_AND:
	case Yosys::AST::AST_REDUCE_OR:
	case Yosys::AST::AST_REDUCE_XOR:
	case Yosys::AST::AST_REDUCE_XNOR:
	case Yosys::AST::AST_REDUCE_BOOL:
		detect_width_simple = true;
		children_are_self_determined = true;
		break;

	case Yosys::AST::AST_NEG:
	case Yosys::AST::AST_BIT_NOT:
	case Yosys::AST::AST_POS:
	case Yosys::AST::AST_BIT_AND:
	case Yosys::AST::AST_BIT_OR:
	case Yosys::AST::AST_BIT_XOR:
	case Yosys::AST::AST_BIT_XNOR:
	case Yosys::AST::AST_ADD:
	case Yosys::AST::AST_SUB:
	case Yosys::AST::AST_MUL:
	case Yosys::AST::AST_DIV:
	case Yosys::AST::AST_MOD:
		detect_width_simple = true;
		break;

	case Yosys::AST::AST_SHIFT_LEFT:
	case Yosys::AST::AST_SHIFT_RIGHT:
	case Yosys::AST::AST_SHIFT_SLEFT:
	case Yosys::AST::AST_SHIFT_SRIGHT:
	case Yosys::AST::AST_POW:
		detect_width_simple = true;
		child_1_is_self_determined = true;
		break;

	case Yosys::AST::AST_LT:
	case Yosys::AST::AST_LE:
	case Yosys::AST::AST_EQ:
	case Yosys::AST::AST_NE:
	case Yosys::AST::AST_EQX:
	case Yosys::AST::AST_NEX:
	case Yosys::AST::AST_GE:
	case Yosys::AST::AST_GT:
		width_hint = -1;
		sign_hint = true;
		for (auto child : ast_node->children) {
			while (!child->basic_prep && simplify(child, false, false, in_lvalue, stage, -1, false, in_param) == true)
				did_something = true;
			child->detectSignWidthWorker(width_hint, sign_hint);
		}
		reset_width_after_children = true;
		break;

	case Yosys::AST::AST_LOGIC_AND:
	case Yosys::AST::AST_LOGIC_OR:
	case Yosys::AST::AST_LOGIC_NOT:
		detect_width_simple = true;
		children_are_self_determined = true;
		break;

	case Yosys::AST::AST_TERNARY:
		child_0_is_self_determined = true;
		break;

	case Yosys::AST::AST_MEMRD:
		detect_width_simple = true;
		children_are_self_determined = true;
		break;

	case Yosys::AST::AST_FCALL:
	case Yosys::AST::AST_TCALL:
		children_are_self_determined = true;
		break;

	default:
		width_hint = -1;
		sign_hint = false;
	}

	if (detect_width_simple && width_hint < 0) {
		if (ast_node->type == Yosys::AST::AST_REPLICATE)
			while (simplify(ast_node->children[0], true, false, in_lvalue, stage, -1, false, true) == true)
				did_something = true;
		for (auto child : ast_node->children)
			while (!child->basic_prep && simplify(child, false, false, in_lvalue, stage, -1, false, in_param) == true)
				did_something = true;
		ast_node->detectSignWidth(width_hint, sign_hint);
	}

	if (ast_node->type == Yosys::AST::AST_FCALL && ast_node->str == "\\$past")
		ast_node->detectSignWidth(width_hint, sign_hint);

	if (ast_node->type == Yosys::AST::AST_TERNARY) {
		if (width_hint < 0) {
			while (!ast_node->children[0]->basic_prep && simplify(ast_node->children[0], true, false, in_lvalue, stage, -1, false, in_param))
				did_something = true;

			bool backup_unevaluated_tern_branch = unevaluated_tern_branch;
			Yosys::AST::AstNode *chosen = ast_node->get_tern_choice().first;

			unevaluated_tern_branch = backup_unevaluated_tern_branch || chosen == ast_node->children[2];
			while (!ast_node->children[1]->basic_prep && simplify(ast_node->children[1], false, false, in_lvalue, stage, -1, false, in_param))
				did_something = true;

			unevaluated_tern_branch = backup_unevaluated_tern_branch || chosen == ast_node->children[1];
			while (!ast_node->children[2]->basic_prep && simplify(ast_node->children[2], false, false, in_lvalue, stage, -1, false, in_param))
				did_something = true;

			unevaluated_tern_branch = backup_unevaluated_tern_branch;
			ast_node->detectSignWidth(width_hint, sign_hint);
		}
		int width_hint_left, width_hint_right;
		bool sign_hint_left, sign_hint_right;
		bool found_real_left, found_real_right;
		ast_node->children[1]->detectSignWidth(width_hint_left, sign_hint_left, &found_real_left);
		ast_node->children[2]->detectSignWidth(width_hint_right, sign_hint_right, &found_real_right);
		if (found_real_left || found_real_right) {
			child_1_is_self_determined = true;
			child_2_is_self_determined = true;
		}
	}

	if (ast_node->type == Yosys::AST::AST_CONDX && ast_node->children.size() > 0 && ast_node->children.at(0)->type == Yosys::AST::AST_CONSTANT) {
		for (auto &bit : ast_node->children.at(0)->bits)
			if (bit == State::Sz || bit == State::Sx)
				bit = State::Sa;
	}

	if (ast_node->type == Yosys::AST::AST_CONDZ && ast_node->children.size() > 0 && ast_node->children.at(0)->type == Yosys::AST::AST_CONSTANT) {
		for (auto &bit : ast_node->children.at(0)->bits)
			if (bit == State::Sz)
				bit = State::Sa;
	}

	if (const_fold && ast_node->type == Yosys::AST::AST_CASE)
	{
		ast_node->detectSignWidth(width_hint, sign_hint);
		while (simplify(ast_node->children[0], const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) { }
		if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT && ast_node->children[0]->bits_only_01()) {
			ast_node->children[0]->is_signed = sign_hint;
			RTLIL::Const case_expr = ast_node->children[0]->bitsAsConst(width_hint, sign_hint);
			std::vector<Yosys::AST::AstNode*> new_children;
			new_children.push_back(ast_node->children[0]);
			for (int i = 1; i < GetSize(ast_node->children); i++) {
				Yosys::AST::AstNode *child = ast_node->children[i];
				log_assert(child->type == Yosys::AST::AST_COND || child->type == Yosys::AST::AST_CONDX || child->type == Yosys::AST::AST_CONDZ);
				for (auto v : child->children) {
					if (v->type == Yosys::AST::AST_DEFAULT)
						goto keep_const_cond;
					if (v->type == Yosys::AST::AST_BLOCK)
						continue;
					while (simplify(v, const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) { }
					if (v->type == Yosys::AST::AST_CONSTANT && v->bits_only_01()) {
						RTLIL::Const case_item_expr = v->bitsAsConst(width_hint, sign_hint);
						RTLIL::Const match = const_eq(case_expr, case_item_expr, sign_hint, sign_hint, 1);
						log_assert(match.bits.size() == 1);
						if (match.bits.front() == RTLIL::State::S1) {
							while (i+1 < GetSize(ast_node->children))
								delete ast_node->children[++i];
							goto keep_const_cond;
						}
						continue;
					}
					goto keep_const_cond;
				}
				if (0)
			keep_const_cond:
					new_children.push_back(child);
				else
					delete child;
			}
			new_children.swap(ast_node->children);
		}
	}

	dict<std::string, pool<int>> backup_memwr_visible;
	dict<std::string, pool<int>> final_memwr_visible;

	if (ast_node->type == Yosys::AST::AST_CASE && stage == 2) {
		backup_memwr_visible = current_memwr_visible;
		final_memwr_visible = current_memwr_visible;
	}

	// simplify all children first
	// (iterate by index as e.g. auto wires can add new children in the process)
	for (size_t i = 0; i < ast_node->children.size(); i++) {
		bool did_something_here = true;
		bool backup_flag_autowire = flag_autowire;
		bool backup_unevaluated_tern_branch = unevaluated_tern_branch;
		if ((ast_node->type == Yosys::AST::AST_GENFOR || ast_node->type == Yosys::AST::AST_FOR) && i >= 3)
			break;
		if ((ast_node->type == Yosys::AST::AST_GENIF || ast_node->type == Yosys::AST::AST_GENCASE) && i >= 1)
			break;
		if (ast_node->type == Yosys::AST::AST_GENBLOCK)
			break;
		if (ast_node->type == Yosys::AST::AST_CELLARRAY && ast_node->children[i]->type == Yosys::AST::AST_CELL)
			continue;
		if (ast_node->type == Yosys::AST::AST_BLOCK && !ast_node->str.empty())
			break;
		if (ast_node->type == Yosys::AST::AST_PREFIX && i >= 1)
			break;
		if (ast_node->type == Yosys::AST::AST_DEFPARAM && i == 0)
			flag_autowire = true;
		if (ast_node->type == Yosys::AST::AST_TERNARY && i > 0 && !unevaluated_tern_branch) {
			Yosys::AST::AstNode *chosen = ast_node->get_tern_choice().first;
			unevaluated_tern_branch = chosen && chosen != ast_node->children[i];
		}
		while (did_something_here && i < ast_node->children.size()) {
			bool const_fold_here = const_fold, in_lvalue_here = in_lvalue;
			int width_hint_here = width_hint;
			bool sign_hint_here = sign_hint;
			bool in_param_here = in_param;
			if (i == 0 && (ast_node->type == Yosys::AST::AST_REPLICATE || ast_node->type == Yosys::AST::AST_WIRE))
				const_fold_here = true, in_param_here = true;
			if (i == 0 && (ast_node->type == Yosys::AST::AST_GENIF || ast_node->type == Yosys::AST::AST_GENCASE))
				in_param_here = true;
			if (i == 1 && (ast_node->type == Yosys::AST::AST_FOR || ast_node->type == Yosys::AST::AST_GENFOR))
				in_param_here = true;
			if (ast_node->type == Yosys::AST::AST_PARAMETER || ast_node->type == Yosys::AST::AST_LOCALPARAM)
				const_fold_here = true;
			if (i == 0 && (ast_node->type == Yosys::AST::AST_ASSIGN || ast_node->type == Yosys::AST::AST_ASSIGN_EQ || ast_node->type == Yosys::AST::AST_ASSIGN_LE))
				in_lvalue_here = true;
			if (ast_node->type == Yosys::AST::AST_BLOCK) {
				current_block = ast_node;
				current_block_child = ast_node->children[i];
			}
			if ((ast_node->type == Yosys::AST::AST_ALWAYS || ast_node->type == Yosys::AST::AST_INITIAL) && ast_node->children[i]->type == Yosys::AST::AST_BLOCK)
				current_top_block = ast_node->children[i];
			if (i == 0 && child_0_is_self_determined)
				width_hint_here = -1, sign_hint_here = false;
			if (i == 1 && child_1_is_self_determined)
				width_hint_here = -1, sign_hint_here = false;
			if (i == 2 && child_2_is_self_determined)
				width_hint_here = -1, sign_hint_here = false;
			if (children_are_self_determined)
				width_hint_here = -1, sign_hint_here = false;
			did_something_here = simplify(ast_node->children[i], const_fold_here, at_zero, in_lvalue_here, stage, width_hint_here, sign_hint_here, in_param_here);
			if (did_something_here)
				did_something = true;
		}
		if (stage == 2 && ast_node->children[i]->type == Yosys::AST::AST_INITIAL && current_ast_mod != ast_node) {
			current_ast_mod->children.push_back(ast_node->children[i]);
			ast_node->children.erase(ast_node->children.begin() + (i--));
			did_something = true;
		}
		flag_autowire = backup_flag_autowire;
		unevaluated_tern_branch = backup_unevaluated_tern_branch;
		if (stage == 2 && ast_node->type == Yosys::AST::AST_CASE) {
			for (auto &x : current_memwr_visible) {
				for (int y : x.second)
					final_memwr_visible[x.first].insert(y);
			}
			current_memwr_visible = backup_memwr_visible;
		}
	}
	for (auto &attr : ast_node->attributes) {
		while (simplify(attr.second, true, false, false, stage, -1, false, true))
			did_something = true;
	}
	if (ast_node->type == Yosys::AST::AST_CASE && stage == 2) {
		current_memwr_visible = final_memwr_visible;
	}
	if (ast_node->type == Yosys::AST::AST_ALWAYS && stage == 2) {
		current_memwr_visible.clear();
		current_memwr_count.clear();
	}

	if (reset_width_after_children) {
		width_hint = backup_width_hint;
		sign_hint = backup_sign_hint;
		if (width_hint < 0)
			ast_node->detectSignWidth(width_hint, sign_hint);
	}

	current_block = backup_current_block;
	current_block_child = backup_current_block_child;
	current_top_block = backup_current_top_block;
	current_always = backup_current_always;
	current_always_clocked = backup_current_always_clocked;

	for (auto it = backup_scope.begin(); it != backup_scope.end(); it++) {
		if (it->second == NULL)
			current_scope.erase(it->first);
		else
			current_scope[it->first] = it->second;
	}

	Yosys::AST::current_filename = ast_node->filename;

	if (ast_node->type == Yosys::AST::AST_MODULE || ast_node->type == Yosys::AST::AST_INTERFACE)
		current_scope.clear();

	// convert defparam nodes to cell parameters
	if (ast_node->type == Yosys::AST::AST_DEFPARAM && !ast_node->children.empty())
	{
		if (ast_node->children[0]->type != Yosys::AST::AST_IDENTIFIER)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Module name in defparam contains non-constant expressions!\n");

		string modname, paramname = ast_node->children[0]->str;

		size_t pos = paramname.rfind('.');

		while (pos != 0 && pos != std::string::npos)
		{
			modname = paramname.substr(0, pos);

			if (current_scope.count(modname))
				break;

			pos = paramname.rfind('.', pos - 1);
		}

		if (pos == std::string::npos)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Can't find object for defparam `%s`!\n", RTLIL::unescape_id(paramname).c_str());

		paramname = "\\" + paramname.substr(pos+1);

		if (current_scope.at(modname)->type != Yosys::AST::AST_CELL)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Defparam argument `%s . %s` does not match a cell!\n",
					RTLIL::unescape_id(modname).c_str(), RTLIL::unescape_id(paramname).c_str());

		Yosys::AST::AstNode *paraset = new Yosys::AST::AstNode(Yosys::AST::AST_PARASET, ast_node->children[1]->clone(), GetSize(ast_node->children) > 2 ? ast_node->children[2]->clone() : NULL);
		paraset->str = paramname;

		Yosys::AST::AstNode *cell = current_scope.at(modname);
		cell->children.insert(cell->children.begin() + 1, paraset);
		ast_node->delete_children();
	}

	// resolve typedefs
	if (ast_node->type == Yosys::AST::AST_TYPEDEF) {
		log_assert(ast_node->children.size() == 1);
		auto type_node = ast_node->children[0];
		log_assert(type_node->type == Yosys::AST::AST_WIRE || type_node->type == Yosys::AST::AST_MEMORY || type_node->type == Yosys::AST::AST_STRUCT || type_node->type == Yosys::AST::AST_UNION);
		while (simplify(type_node, const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) {
			did_something = true;
		}
		log_assert(!type_node->is_custom_type);
	}

	// resolve types of wires
	if (ast_node->type == Yosys::AST::AST_WIRE || ast_node->type == Yosys::AST::AST_MEMORY) {
		if (ast_node->is_custom_type) {
			log_assert(ast_node->children.size() >= 1);
			log_assert(ast_node->children[0]->type == Yosys::AST::AST_WIRETYPE);
			auto type_name = ast_node->children[0]->str;
			if (!current_scope.count(type_name)) {
				log_file_error(ast_node->filename, ast_node->location.first_line, "Unknown identifier `%s' used as type name\n", type_name.c_str());
			}
			Yosys::AST::AstNode *resolved_type_node = current_scope.at(type_name);
			if (resolved_type_node->type != Yosys::AST::AST_TYPEDEF)
				log_file_error(ast_node->filename, ast_node->location.first_line, "`%s' does not name a type\n", type_name.c_str());
			log_assert(resolved_type_node->children.size() == 1);
			Yosys::AST::AstNode *template_node = resolved_type_node->children[0];

			// Ensure typedef itself is fully simplified
			while (simplify(template_node, const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) {};

			if (template_node->type == Yosys::AST::AST_STRUCT || template_node->type == Yosys::AST::AST_UNION) {
				// replace with wire representing the packed structure
				newNode = make_packed_struct(template_node, ast_node->str);
				newNode->attributes[ID::wiretype] = ast_node->mkconst_str(resolved_type_node->str);
				// add original input/output attribute to resolved wire
				newNode->is_input = ast_node->is_input;
				newNode->is_output = ast_node->is_output;
				current_scope[ast_node->str] = ast_node;
				goto apply_newNode;
			}

			// Remove type reference
			delete ast_node->children[0];
			ast_node->children.erase(ast_node->children.begin());

			if (ast_node->type == Yosys::AST::AST_WIRE)
				ast_node->type = template_node->type;
			ast_node->is_reg = template_node->is_reg;
			ast_node->is_logic = template_node->is_logic;
			ast_node->is_signed = template_node->is_signed;
			ast_node->is_string = template_node->is_string;
			ast_node->is_custom_type = template_node->is_custom_type;

			ast_node->range_valid = template_node->range_valid;
			ast_node->range_swapped = template_node->range_swapped;
			ast_node->range_left = template_node->range_left;
			ast_node->range_right = template_node->range_right;

			ast_node->attributes[ID::wiretype] = ast_node->mkconst_str(resolved_type_node->str);

			// if an enum then add attributes to support simulator tracing
			annotateTypedEnums(ast_node, template_node);

			// Insert clones children from template at beginning
			for (int i  = 0; i < GetSize(template_node->children); i++)
				ast_node->children.insert(ast_node->children.begin() + i, template_node->children[i]->clone());

			if (ast_node->type == Yosys::AST::AST_MEMORY && GetSize(ast_node->children) == 1) {
				// Single-bit memories must have [0:0] range
				Yosys::AST::AstNode *rng = make_range(0, 0);
				ast_node->children.insert(ast_node->children.begin(), rng);
			}
			did_something = true;
		}
		log_assert(!ast_node->is_custom_type);
	}

	// resolve types of parameters
	if (ast_node->type == Yosys::AST::AST_LOCALPARAM || ast_node->type == Yosys::AST::AST_PARAMETER) {
		if (ast_node->is_custom_type) {
			log_assert(ast_node->children.size() == 2);
			log_assert(ast_node->children[1]->type == Yosys::AST::AST_WIRETYPE);
			auto type_name = ast_node->children[1]->str;
			if (!current_scope.count(type_name)) {
				log_file_error(ast_node->filename, ast_node->location.first_line, "Unknown identifier `%s' used as type name\n", type_name.c_str());
			}
			Yosys::AST::AstNode *resolved_type_node = current_scope.at(type_name);
			if (resolved_type_node->type != Yosys::AST::AST_TYPEDEF)
				log_file_error(ast_node->filename, ast_node->location.first_line, "`%s' does not name a type\n", type_name.c_str());
			log_assert(resolved_type_node->children.size() == 1);
			Yosys::AST::AstNode *template_node = resolved_type_node->children[0];

			// Ensure typedef itself is fully simplified
			while (simplify(template_node, const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) {};

			if (template_node->type == Yosys::AST::AST_STRUCT || template_node->type == Yosys::AST::AST_UNION) {
				// replace with wire representing the packed structure
				newNode = make_packed_struct(template_node, ast_node->str);
				newNode->attributes[ID::wiretype] = ast_node->mkconst_str(resolved_type_node->str);
				newNode->type = ast_node->type;
				current_scope[ast_node->str] = ast_node;
				// copy param value, it needs to be 1st value
				delete ast_node->children[1];
				ast_node->children.pop_back();
				newNode->children.insert(newNode->children.begin(), ast_node->children[0]->clone());
				goto apply_newNode;
			}
			delete ast_node->children[1];
			ast_node->children.pop_back();

			if (template_node->type == Yosys::AST::AST_MEMORY)
				log_file_error(ast_node->filename, ast_node->location.first_line, "unpacked array type `%s' cannot be used for a parameter\n", ast_node->children[1]->str.c_str());
			ast_node->is_signed = template_node->is_signed;
			ast_node->is_string = template_node->is_string;
			ast_node->is_custom_type = template_node->is_custom_type;

			ast_node->range_valid = template_node->range_valid;
			ast_node->range_swapped = template_node->range_swapped;
			ast_node->range_left = template_node->range_left;
			ast_node->range_right = template_node->range_right;
			ast_node->attributes[ID::wiretype] = ast_node->mkconst_str(resolved_type_node->str);
			for (auto template_child : template_node->children)
				ast_node->children.push_back(template_child->clone());
			did_something = true;
		}
		log_assert(!ast_node->is_custom_type);
	}

	// resolve constant prefixes
	if (ast_node->type == Yosys::AST::AST_PREFIX) {
		if (ast_node->children[0]->type != Yosys::AST::AST_CONSTANT) {
			// dumpAst(NULL, ">   ");
			log_file_error(ast_node->filename, ast_node->location.first_line, "Index in generate block prefix syntax is not constant!\n");
		}
		if (ast_node->children[1]->type == Yosys::AST::AST_PREFIX)
			simplify(ast_node->children[1], const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param);
		log_assert(ast_node->children[1]->type == Yosys::AST::AST_IDENTIFIER);
		newNode = ast_node->children[1]->clone();
		const char *second_part = ast_node->children[1]->str.c_str();
		if (second_part[0] == '\\')
			second_part++;
		newNode->str = stringf("%s[%d].%s", ast_node->str.c_str(), ast_node->children[0]->integer, second_part);
		goto apply_newNode;
	}

	// evaluate TO_BITS nodes
	if (ast_node->type == Yosys::AST::AST_TO_BITS) {
		if (ast_node->children[0]->type != Yosys::AST::AST_CONSTANT)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Left operand of to_bits expression is not constant!\n");
		if (ast_node->children[1]->type != Yosys::AST::AST_CONSTANT)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Right operand of to_bits expression is not constant!\n");
		RTLIL::Const new_value = ast_node->children[1]->bitsAsConst(ast_node->children[0]->bitsAsConst().as_int(), ast_node->children[1]->is_signed);
		newNode = Yosys::AST::AstNode::mkconst_bits(new_value.bits, ast_node->children[1]->is_signed);
		goto apply_newNode;
	}

	// annotate constant ranges
	if (ast_node->type == Yosys::AST::AST_RANGE) {
		bool old_range_valid = ast_node->range_valid;
		ast_node->range_valid = false;
		ast_node->range_swapped = false;
		ast_node->range_left = -1;
		ast_node->range_right = 0;
		log_assert(ast_node->children.size() >= 1);
		if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT) {
			ast_node->range_valid = true;
			ast_node->range_left = ast_node->children[0]->integer;
			if (ast_node->children.size() == 1)
				ast_node->range_right = ast_node->range_left;
		}
		if (ast_node->children.size() >= 2) {
			if (ast_node->children[1]->type == Yosys::AST::AST_CONSTANT)
				ast_node->range_right = ast_node->children[1]->integer;
			else
				ast_node->range_valid = false;
		}
		if (old_range_valid != ast_node->range_valid)
			did_something = true;
		if (ast_node->range_valid && ast_node->range_right > ast_node->range_left) {
			int tmp = ast_node->range_right;
			ast_node->range_right = ast_node->range_left;
			ast_node->range_left = tmp;
			ast_node->range_swapped = true;
		}
	}

	// annotate wires with their ranges
	if (ast_node->type == Yosys::AST::AST_WIRE) {
		if (ast_node->children.size() > 0) {
			if (ast_node->children[0]->range_valid) {
				if (!ast_node->range_valid)
					did_something = true;
				ast_node->range_valid = true;
				ast_node->range_swapped = ast_node->children[0]->range_swapped;
				ast_node->range_left = ast_node->children[0]->range_left;
				ast_node->range_right = ast_node->children[0]->range_right;
				bool force_upto = false, force_downto = false;
				if (ast_node->attributes.count(ID::force_upto)) {
					Yosys::AST::AstNode *val = ast_node->attributes[ID::force_upto];
					if (val->type != Yosys::AST::AST_CONSTANT)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Attribute `force_upto' with non-constant value!\n");
					force_upto = val->asAttrConst().as_bool();
				}
				if (ast_node->attributes.count(ID::force_downto)) {
					Yosys::AST::AstNode *val = ast_node->attributes[ID::force_downto];
					if (val->type != Yosys::AST::AST_CONSTANT)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Attribute `force_downto' with non-constant value!\n");
					force_downto = val->asAttrConst().as_bool();
				}
				if (force_upto && force_downto)
					log_file_error(ast_node->filename, ast_node->location.first_line, "Attributes `force_downto' and `force_upto' cannot be both set!\n");
				if ((force_upto && !ast_node->range_swapped) || (force_downto && ast_node->range_swapped)) {
					std::swap(ast_node->range_left, ast_node->range_right);
					ast_node->range_swapped = force_upto;
				}
			}
		} else {
			if (!ast_node->range_valid)
				did_something = true;
			ast_node->range_valid = true;
			ast_node->range_swapped = false;
			ast_node->range_left = 0;
			ast_node->range_right = 0;
		}
	}

	// resolve multiranges on memory decl
	if (ast_node->type == Yosys::AST::AST_MEMORY && ast_node->children.size() > 1 && ast_node->children[1]->type == Yosys::AST::AST_MULTIRANGE)
	{
		int total_size = 1;
		ast_node->multirange_dimensions.clear();
		ast_node->multirange_swapped.clear();
		for (auto range : ast_node->children[1]->children) {
			if (!range->range_valid)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Non-constant range on memory decl.\n");
			ast_node->multirange_dimensions.push_back(min(range->range_left, range->range_right));
			ast_node->multirange_dimensions.push_back(max(range->range_left, range->range_right) - min(range->range_left, range->range_right) + 1);
			ast_node->multirange_swapped.push_back(range->range_swapped);
			total_size *= ast_node->multirange_dimensions.back();
		}
		delete ast_node->children[1];
		ast_node->children[1] = new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(0, true), ast_node->mkconst_int(total_size-1, true));
		did_something = true;
	}

	// resolve multiranges on memory access
	if (ast_node->type == Yosys::AST::AST_IDENTIFIER && ast_node->id2ast && ast_node->id2ast->type == Yosys::AST::AST_MEMORY && ast_node->children.size() > 0 && ast_node->children[0]->type == Yosys::AST::AST_MULTIRANGE)
	{
		Yosys::AST::AstNode *index_expr = nullptr;

		ast_node->integer = ast_node->children[0]->children.size(); // save original number of dimensions for $size() etc.
		for (int i = 0; 2*i < GetSize(ast_node->id2ast->multirange_dimensions); i++)
		{
			if (GetSize(ast_node->children[0]->children) <= i)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Insufficient number of array indices for %s.\n", log_id(ast_node->str));

			Yosys::AST::AstNode *new_index_expr = ast_node->children[0]->children[i]->children.at(0)->clone();

			if (ast_node->id2ast->multirange_dimensions[2*i])
				new_index_expr = new Yosys::AST::AstNode(Yosys::AST::AST_SUB, new_index_expr, ast_node->mkconst_int(ast_node->id2ast->multirange_dimensions[2*i], true));

			if (i == 0)
				index_expr = new_index_expr;
			else
				index_expr = new Yosys::AST::AstNode(Yosys::AST::AST_ADD, new Yosys::AST::AstNode(Yosys::AST::AST_MUL, index_expr, ast_node->mkconst_int(ast_node->id2ast->multirange_dimensions[2*i+1], true)), new_index_expr);
		}

		for (int i = GetSize(ast_node->id2ast->multirange_dimensions)/2; i < GetSize(ast_node->children[0]->children); i++)
			ast_node->children.push_back(ast_node->children[0]->children[i]->clone());

		delete ast_node->children[0];
		if (index_expr == nullptr)
			ast_node->children.erase(ast_node->children.begin());
		else
			ast_node->children[0] = new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, index_expr);

		did_something = true;
	}

	// trim/extend parameters
	if (ast_node->type == Yosys::AST::AST_PARAMETER || ast_node->type == Yosys::AST::AST_LOCALPARAM || ast_node->type == Yosys::AST::AST_ENUM_ITEM) {
		if (ast_node->children.size() > 1 && ast_node->children[1]->type == Yosys::AST::AST_RANGE) {
			if (!ast_node->children[1]->range_valid)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Non-constant width range on parameter decl.\n");
			int width = std::abs(ast_node->children[1]->range_left - ast_node->children[1]->range_right) + 1;
			if (ast_node->children[0]->type == Yosys::AST::AST_REALVALUE) {
				RTLIL::Const constvalue = ast_node->children[0]->realAsConst(width);
				log_file_warning(ast_node->filename, ast_node->location.first_line, "converting real value %e to binary %s.\n",
						ast_node->children[0]->realvalue, log_signal(constvalue));
				delete ast_node->children[0];
				ast_node->children[0] = Yosys::AST::AstNode::mkconst_bits(constvalue.bits, sign_hint);
				did_something = true;
			}
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT) {
				if (width != int(ast_node->children[0]->bits.size())) {
					RTLIL::SigSpec sig(ast_node->children[0]->bits);
					sig.extend_u0(width, ast_node->children[0]->is_signed);
					Yosys::AST::AstNode *old_child_0 = ast_node->children[0];
					ast_node->children[0] = Yosys::AST::AstNode::mkconst_bits(sig.as_const().bits, ast_node->is_signed);
					delete old_child_0;
				}
				ast_node->children[0]->is_signed = ast_node->is_signed;
			}
			ast_node->range_valid = true;
			ast_node->range_swapped = ast_node->children[1]->range_swapped;
			ast_node->range_left = ast_node->children[1]->range_left;
			ast_node->range_right = ast_node->children[1]->range_right;
		} else
		if (ast_node->children.size() > 1 && ast_node->children[1]->type == Yosys::AST::AST_REALVALUE && ast_node->children[0]->type == Yosys::AST::AST_CONSTANT) {
			double as_realvalue = ast_node->children[0]->asReal(sign_hint);
			delete ast_node->children[0];
			ast_node->children[0] = new Yosys::AST::AstNode(Yosys::AST::AST_REALVALUE);
			ast_node->children[0]->realvalue = as_realvalue;
			did_something = true;
		}
	}

	if (ast_node->type == Yosys::AST::AST_IDENTIFIER && !ast_node->basic_prep) {
		// check if a plausible struct member sss.mmmm
		std::string sname;
		if (name_has_dot(ast_node->str, sname)) {
			if (current_scope.count(ast_node->str) > 0) {
				auto item_node = current_scope[ast_node->str];
				if (item_node->type == Yosys::AST::AST_STRUCT_ITEM || item_node->type == Yosys::AST::AST_STRUCT || item_node->type == Yosys::AST::AST_UNION) {
					// structure member, rewrite ast_node node to reference the packed struct wire
					auto range = Yosys::AST::make_struct_member_range(ast_node, item_node);
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER, range);
					newNode->str = sname;
					// save type and original number of dimensions for $size() etc.
					newNode->attributes[ID::wiretype] = item_node->clone();
					if (!item_node->multirange_dimensions.empty() && ast_node->children.size() > 0) {
						if (ast_node->children[0]->type == Yosys::AST::AST_RANGE)
							newNode->integer = 1;
						else if (ast_node->children[0]->type == Yosys::AST::AST_MULTIRANGE)
							newNode->integer = ast_node->children[0]->children.size();
					}
					newNode->basic_prep = true;
					if (item_node->is_signed)
						newNode = new Yosys::AST::AstNode(Yosys::AST::AST_TO_SIGNED, newNode);
					goto apply_newNode;
				}
			}
		}
	}
	// annotate identifiers using scope resolution and create auto-wires as needed
	if (ast_node->type == Yosys::AST::AST_IDENTIFIER) {
		if (current_scope.count(ast_node->str) == 0) {
			Yosys::AST::AstNode *current_scope_ast = (current_ast_mod == nullptr) ? current_ast : current_ast_mod;
			ast_node->str = ast_node->try_pop_module_prefix();
			for (auto node : current_scope_ast->children) {
				//log("looking at mod scope child %s\n", type2str(node->type).c_str());
				switch (node->type) {
				case Yosys::AST::AST_PARAMETER:
				case Yosys::AST::AST_LOCALPARAM:
				case Yosys::AST::AST_WIRE:
				case Yosys::AST::AST_AUTOWIRE:
				case Yosys::AST::AST_GENVAR:
				case Yosys::AST::AST_MEMORY:
				case Yosys::AST::AST_FUNCTION:
				case Yosys::AST::AST_TASK:
				case Yosys::AST::AST_DPI_FUNCTION:
					//log("found child %s, %s\n", type2str(node->type).c_str(), node->str.c_str());
					if (ast_node->str == node->str) {
						//log("add %s, type %s to scope\n", ast_node->str.c_str(), type2str(node->type).c_str());
						current_scope[node->str] = node;
					}
					break;
				case Yosys::AST::AST_ENUM:
					current_scope[node->str] = node;
					for (auto enum_node : node->children) {
						log_assert(enum_node->type==Yosys::AST::AST_ENUM_ITEM);
						if (ast_node->str == enum_node->str) {
							//log("\nadding enum item %s to scope\n", ast_node->str.c_str());
							current_scope[ast_node->str] = enum_node;
						}
					}
					break;
				default:
					break;
				}
			}
		}
		if (current_scope.count(ast_node->str) == 0) {
			if (current_ast_mod == nullptr) {
				log_file_error(ast_node->filename, ast_node->location.first_line, "Identifier `%s' is implicitly declared outside of a module.\n", ast_node->str.c_str());
			} else if (flag_autowire || ast_node->str == "\\$global_clock") {
				Yosys::AST::AstNode *auto_wire = new Yosys::AST::AstNode(Yosys::AST::AST_AUTOWIRE);
				auto_wire->str = ast_node->str;
				current_ast_mod->children.push_back(auto_wire);
				current_scope[ast_node->str] = auto_wire;
				did_something = true;
			} else {
				log_file_error(ast_node->filename, ast_node->location.first_line, "Identifier `%s' is implicitly declared and `default_nettype is set to none.\n", ast_node->str.c_str());
			}
		}
		if (ast_node->id2ast != current_scope[ast_node->str]) {
			ast_node->id2ast = current_scope[ast_node->str];
			did_something = true;
		}
	}

	// split memory access with bit select to individual statements
	if (ast_node->type == Yosys::AST::AST_IDENTIFIER && ast_node->children.size() == 2 && ast_node->children[0]->type == Yosys::AST::AST_RANGE && ast_node->children[1]->type == Yosys::AST::AST_RANGE && !in_lvalue && stage == 2)
	{
		if (ast_node->id2ast == NULL || ast_node->id2ast->type != Yosys::AST::AST_MEMORY || ast_node->children[0]->children.size() != 1)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Invalid bit-select on memory access!\n");

		int mem_width, mem_size, addr_bits;
		ast_node->id2ast->meminfo(mem_width, mem_size, addr_bits);

		int data_range_left = ast_node->id2ast->children[0]->range_left;
		int data_range_right = ast_node->id2ast->children[0]->range_right;

		if (ast_node->id2ast->children[0]->range_swapped)
			std::swap(data_range_left, data_range_right);

		std::stringstream sstr;
		sstr << "$mem2bits$" << ast_node->str << "$" << encode_filename(ast_node->filename) << ":" << ast_node->location.first_line << "$" << (autoidx++);
		std::string wire_id = sstr.str();

		Yosys::AST::AstNode *wire = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(data_range_left, true), ast_node->mkconst_int(data_range_right, true)));
		wire->str = wire_id;
		if (current_block)
			wire->attributes[ID::nosync] = ast_node->mkconst_int(1, false);
		current_ast_mod->children.push_back(wire);
		while (simplify(wire, true, false, false, 1, -1, false, false)) { }

		Yosys::AST::AstNode *data = ast_node->clone();
		delete data->children[1];
		data->children.pop_back();

		Yosys::AST::AstNode *assign = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), data);
		assign->children[0]->str = wire_id;
		assign->children[0]->was_checked = true;

		if (current_block)
		{
			size_t assign_idx = 0;
			while (assign_idx < current_block->children.size() && current_block->children[assign_idx] != current_block_child)
				assign_idx++;
			log_assert(assign_idx < current_block->children.size());
			current_block->children.insert(current_block->children.begin()+assign_idx, assign);
			wire->is_reg = true;
		}
		else
		{
			Yosys::AST::AstNode *proc = new Yosys::AST::AstNode(Yosys::AST::AST_ALWAYS, new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK));
			proc->children[0]->children.push_back(assign);
			current_ast_mod->children.push_back(proc);
		}

		newNode = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER, ast_node->children[1]->clone());
		newNode->str = wire_id;
		newNode->integer = ast_node->integer; // save original number of dimensions for $size() etc.
		newNode->id2ast = wire;
		goto apply_newNode;
	}

	if (ast_node->type == Yosys::AST::AST_WHILE)
		log_file_error(ast_node->filename, ast_node->location.first_line, "While loops are only allowed in constant functions!\n");

	if (ast_node->type == Yosys::AST::AST_REPEAT)
	{
		Yosys::AST::AstNode *count = ast_node->children[0];
		Yosys::AST::AstNode *body = ast_node->children[1];

		// eval count expression
		while (simplify(count, true, false, false, stage, 32, true, false)) { }

		if (count->type != Yosys::AST::AST_CONSTANT)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Repeat loops outside must have constant repeat counts!\n");

		// convert to a block with the body repeated n times
		ast_node->type = Yosys::AST::AST_BLOCK;
		ast_node->children.clear();
		for (int i = 0; i < count->bitsAsConst().as_int(); i++)
			ast_node->children.insert(ast_node->children.begin(), body->clone());

		delete count;
		delete body;
		did_something = true;
	}

	// unroll for loops and generate-for blocks
	if ((ast_node->type == Yosys::AST::AST_GENFOR || ast_node->type == Yosys::AST::AST_FOR) && ast_node->children.size() != 0)
	{
		Yosys::AST::AstNode *init_ast = ast_node->children[0];
		Yosys::AST::AstNode *while_ast = ast_node->children[1];
		Yosys::AST::AstNode *next_ast = ast_node->children[2];
		Yosys::AST::AstNode *body_ast = ast_node->children[3];

		while (body_ast->type == Yosys::AST::AST_GENBLOCK && body_ast->str.empty() &&
				body_ast->children.size() == 1 && body_ast->children.at(0)->type == Yosys::AST::AST_GENBLOCK)
			body_ast = body_ast->children.at(0);

		const char* loop_type_str = "procedural";
		const char* var_type_str = "register";
		Yosys::AST::AstNodeType var_type = Yosys::AST::AST_WIRE;
		if (ast_node->type == Yosys::AST::AST_GENFOR) {
			loop_type_str = "generate";
			var_type_str = "genvar";
			var_type = Yosys::AST::AST_GENVAR;
		}

		if (init_ast->type != Yosys::AST::AST_ASSIGN_EQ)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Unsupported 1st expression of %s for-loop!\n", loop_type_str);
		if (next_ast->type != Yosys::AST::AST_ASSIGN_EQ)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Unsupported 3rd expression of %s for-loop!\n", loop_type_str);

		if (init_ast->children[0]->id2ast == NULL || init_ast->children[0]->id2ast->type != var_type)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Left hand side of 1st expression of %s for-loop is not a %s!\n", loop_type_str, var_type_str);
		if (next_ast->children[0]->id2ast == NULL || next_ast->children[0]->id2ast->type != var_type)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Left hand side of 3rd expression of %s for-loop is not a %s!\n", loop_type_str, var_type_str);

		if (init_ast->children[0]->id2ast != next_ast->children[0]->id2ast)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Incompatible left-hand sides in 1st and 3rd expression of %s for-loop!\n", loop_type_str);

		// eval 1st expression
		Yosys::AST::AstNode *varbuf = init_ast->children[1]->clone();
		{
			int expr_width_hint = -1;
			bool expr_sign_hint = true;
			varbuf->detectSignWidth(expr_width_hint, expr_sign_hint);
			while (simplify(varbuf, true, false, false, stage, 32, true, false)) { }
		}

		if (varbuf->type != Yosys::AST::AST_CONSTANT)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Right hand side of 1st expression of %s for-loop is not constant!\n", loop_type_str);

		auto resolved = current_scope.at(init_ast->children[0]->str);
		if (resolved->range_valid) {
			int const_size = varbuf->range_left - varbuf->range_right;
			int resolved_size = resolved->range_left - resolved->range_right;
			if (const_size < resolved_size) {
				for (int i = const_size; i < resolved_size; i++)
					varbuf->bits.push_back(resolved->is_signed ? varbuf->bits.back() : State::S0);
				varbuf->range_left = resolved->range_left;
				varbuf->range_right = resolved->range_right;
				varbuf->range_swapped = resolved->range_swapped;
				varbuf->range_valid = resolved->range_valid;
			}
		}

		varbuf = new Yosys::AST::AstNode(Yosys::AST::AST_LOCALPARAM, varbuf);
		varbuf->str = init_ast->children[0]->str;

		Yosys::AST::AstNode *backup_scope_varbuf = current_scope[varbuf->str];
		current_scope[varbuf->str] = varbuf;

		size_t current_block_idx = 0;
		if (ast_node->type == Yosys::AST::AST_FOR) {
			while (current_block_idx < current_block->children.size() &&
					current_block->children[current_block_idx] != current_block_child)
				current_block_idx++;
		}

		while (1)
		{
			// eval 2nd expression
			Yosys::AST::AstNode *buf = while_ast->clone();
			{
				int expr_width_hint = -1;
				bool expr_sign_hint = true;
				buf->detectSignWidth(expr_width_hint, expr_sign_hint);
				while (simplify(buf, true, false, false, stage, expr_width_hint, expr_sign_hint, false)) { }
			}

			if (buf->type != Yosys::AST::AST_CONSTANT)
				log_file_error(ast_node->filename, ast_node->location.first_line, "2nd expression of %s for-loop is not constant!\n", loop_type_str);

			if (buf->integer == 0) {
				delete buf;
				break;
			}
			delete buf;

			// expand body
			int index = varbuf->children[0]->integer;
			log_assert(body_ast->type == Yosys::AST::AST_GENBLOCK || body_ast->type == Yosys::AST::AST_BLOCK);
			log_assert(!body_ast->str.empty());
			buf = body_ast->clone();

			std::stringstream sstr;
			sstr << buf->str << "[" << index << "].";
			std::string prefix = sstr.str();

			// create a scoped localparam for the current value of the loop variable
			Yosys::AST::AstNode *local_index = varbuf->clone();
			size_t pos = local_index->str.rfind('.');
			if (pos != std::string::npos) // remove outer prefix
				local_index->str = "\\" + local_index->str.substr(pos + 1);
			local_index->str = prefix_id(prefix, local_index->str);
			current_scope[local_index->str] = local_index;
			current_ast_mod->children.push_back(local_index);

			buf->expand_genblock(prefix);

			if (ast_node->type == Yosys::AST::AST_GENFOR) {
				for (size_t i = 0; i < buf->children.size(); i++) {
					simplify(buf->children[i], const_fold, false, false, stage, -1, false, false);
					current_ast_mod->children.push_back(buf->children[i]);
				}
			} else {
				for (size_t i = 0; i < buf->children.size(); i++)
					current_block->children.insert(current_block->children.begin() + current_block_idx++, buf->children[i]);
			}
			buf->children.clear();
			delete buf;

			// eval 3rd expression
			buf = next_ast->children[1]->clone();
			{
				int expr_width_hint = -1;
				bool expr_sign_hint = true;
				buf->detectSignWidth(expr_width_hint, expr_sign_hint);
				while (simplify(buf, true, false, false, stage, expr_width_hint, expr_sign_hint, true)) { }
			}

			if (buf->type != Yosys::AST::AST_CONSTANT)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Right hand side of 3rd expression of %s for-loop is not constant (%s)!\n", loop_type_str, type2str(buf->type).c_str());

			delete varbuf->children[0];
			varbuf->children[0] = buf;
		}

		if (ast_node->type == Yosys::AST::AST_FOR) {
			Yosys::AST::AstNode *buf = next_ast->clone();
			delete buf->children[1];
			buf->children[1] = varbuf->children[0]->clone();
			current_block->children.insert(current_block->children.begin() + current_block_idx++, buf);
		}

		current_scope[varbuf->str] = backup_scope_varbuf;
		delete varbuf;
		ast_node->delete_children();
		did_something = true;
	}

	// check for local objects in unnamed block
	if (ast_node->type == Yosys::AST::AST_BLOCK && ast_node->str.empty())
	{
		for (size_t i = 0; i < ast_node->children.size(); i++)
			if (ast_node->children[i]->type == Yosys::AST::AST_WIRE || ast_node->children[i]->type == Yosys::AST::AST_MEMORY || ast_node->children[i]->type == Yosys::AST::AST_PARAMETER || ast_node->children[i]->type == Yosys::AST::AST_LOCALPARAM || ast_node->children[i]->type == Yosys::AST::AST_TYPEDEF)
			{
				log_assert(!VERILOG_FRONTEND::sv_mode);
				log_file_error(ast_node->children[i]->filename, ast_node->children[i]->location.first_line, "Local declaration in unnamed block is only supported in SystemVerilog mode!\n");
			}
	}

	// transform block with name
	if (ast_node->type == Yosys::AST::AST_BLOCK && !ast_node->str.empty())
	{
		ast_node->expand_genblock(ast_node->str + ".");

		// if ast_node is an autonamed block is in an always_comb
		if (current_always && current_always->attributes.count(ID::always_comb)
				&& is_autonamed_block(ast_node->str))
			// track local variables in ast_node block so we can consider adding
			// nosync once the block has been fully elaborated
			for (Yosys::AST::AstNode *child : ast_node->children)
				if (child->type == Yosys::AST::AST_WIRE &&
						!child->attributes.count(ID::nosync))
					mark_auto_nosync(ast_node, child);

		std::vector<Yosys::AST::AstNode*> new_children;
		for (size_t i = 0; i < ast_node->children.size(); i++)
			if (ast_node->children[i]->type == Yosys::AST::AST_WIRE || ast_node->children[i]->type == Yosys::AST::AST_MEMORY || ast_node->children[i]->type == Yosys::AST::AST_PARAMETER || ast_node->children[i]->type == Yosys::AST::AST_LOCALPARAM || ast_node->children[i]->type == Yosys::AST::AST_TYPEDEF) {
				simplify(ast_node->children[i], false, false, false, stage, -1, false, false);
				current_ast_mod->children.push_back(ast_node->children[i]);
				current_scope[ast_node->children[i]->str] = ast_node->children[i];
			} else
				new_children.push_back(ast_node->children[i]);

		ast_node->children.swap(new_children);
		did_something = true;
		ast_node->str.clear();
	}

	// simplify unconditional generate block
	if (ast_node->type == Yosys::AST::AST_GENBLOCK && ast_node->children.size() != 0)
	{
		if (!ast_node->str.empty()) {
			ast_node->expand_genblock(ast_node->str + ".");
		}

		for (size_t i = 0; i < ast_node->children.size(); i++) {
			simplify(ast_node->children[i], const_fold, false, false, stage, -1, false, false);
			current_ast_mod->children.push_back(ast_node->children[i]);
		}

		ast_node->children.clear();
		did_something = true;
	}

	// simplify generate-if blocks
	if (ast_node->type == Yosys::AST::AST_GENIF && ast_node->children.size() != 0)
	{
		Yosys::AST::AstNode *buf = ast_node->children[0]->clone();
		while (simplify(buf, true, false, false, stage, width_hint, sign_hint, false)) { }
		if (buf->type != Yosys::AST::AST_CONSTANT) {
			// for (auto f : log_files)
			// 	dumpAst(f, "verilog-ast> ");
			log_file_error(ast_node->filename, ast_node->location.first_line, "Condition for generate if is not constant!\n");
		}
		if (buf->asBool() != 0) {
			delete buf;
			buf = ast_node->children[1]->clone();
		} else {
			delete buf;
			buf = ast_node->children.size() > 2 ? ast_node->children[2]->clone() : NULL;
		}

		if (buf)
		{
			if (buf->type != Yosys::AST::AST_GENBLOCK)
				buf = new Yosys::AST::AstNode(Yosys::AST::AST_GENBLOCK, buf);

			if (!buf->str.empty()) {
				buf->expand_genblock(buf->str + ".");
			}

			for (size_t i = 0; i < buf->children.size(); i++) {
				simplify(buf->children[i], const_fold, false, false, stage, -1, false, false);
				current_ast_mod->children.push_back(buf->children[i]);
			}

			buf->children.clear();
			delete buf;
		}

		ast_node->delete_children();
		did_something = true;
	}

	// simplify generate-case blocks
	if (ast_node->type == Yosys::AST::AST_GENCASE && ast_node->children.size() != 0)
	{
		Yosys::AST::AstNode *buf = ast_node->children[0]->clone();
		while (simplify(buf, true, false, false, stage, width_hint, sign_hint, false)) { }
		if (buf->type != Yosys::AST::AST_CONSTANT) {
			// for (auto f : log_files)
			// 	dumpAst(f, "verilog-ast> ");
			log_file_error(ast_node->filename, ast_node->location.first_line, "Condition for generate case is not constant!\n");
		}

		bool ref_signed = buf->is_signed;
		RTLIL::Const ref_value = buf->bitsAsConst();
		delete buf;

		Yosys::AST::AstNode *selected_case = NULL;
		for (size_t i = 1; i < ast_node->children.size(); i++)
		{
			log_assert(ast_node->children.at(i)->type == Yosys::AST::AST_COND || ast_node->children.at(i)->type == Yosys::AST::AST_CONDX || ast_node->children.at(i)->type == Yosys::AST::AST_CONDZ);

			Yosys::AST::AstNode *this_genblock = NULL;
			for (auto child : ast_node->children.at(i)->children) {
				log_assert(this_genblock == NULL);
				if (child->type == Yosys::AST::AST_GENBLOCK)
					this_genblock = child;
			}

			for (auto child : ast_node->children.at(i)->children)
			{
				if (child->type == Yosys::AST::AST_DEFAULT) {
					if (selected_case == NULL)
						selected_case = this_genblock;
					continue;
				}
				if (child->type == Yosys::AST::AST_GENBLOCK)
					continue;

				buf = child->clone();
				while (simplify(buf, true, false, false, stage, width_hint, sign_hint, true)) { }
				if (buf->type != Yosys::AST::AST_CONSTANT) {
					// for (auto f : log_files)
					// 	dumpAst(f, "verilog-ast> ");
					log_file_error(ast_node->filename, ast_node->location.first_line, "Expression in generate case is not constant!\n");
				}

				bool is_selected = RTLIL::const_eq(ref_value, buf->bitsAsConst(), ref_signed && buf->is_signed, ref_signed && buf->is_signed, 1).as_bool();
				delete buf;

				if (is_selected) {
					selected_case = this_genblock;
					i = ast_node->children.size();
					break;
				}
			}
		}

		if (selected_case != NULL)
		{
			log_assert(selected_case->type == Yosys::AST::AST_GENBLOCK);
			buf = selected_case->clone();

			if (!buf->str.empty()) {
				buf->expand_genblock(buf->str + ".");
			}

			for (size_t i = 0; i < buf->children.size(); i++) {
				simplify(buf->children[i], const_fold, false, false, stage, -1, false, false);
				current_ast_mod->children.push_back(buf->children[i]);
			}

			buf->children.clear();
			delete buf;
		}

		ast_node->delete_children();
		did_something = true;
	}

	// unroll cell arrays
	if (ast_node->type == Yosys::AST::AST_CELLARRAY)
	{
		if (!ast_node->children.at(0)->range_valid)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Non-constant array range on cell array.\n");

		newNode = new Yosys::AST::AstNode(Yosys::AST::AST_GENBLOCK);
		int num = max(ast_node->children.at(0)->range_left, ast_node->children.at(0)->range_right) - min(ast_node->children.at(0)->range_left, ast_node->children.at(0)->range_right) + 1;

		for (int i = 0; i < num; i++) {
			int idx = ast_node->children.at(0)->range_left > ast_node->children.at(0)->range_right ? ast_node->children.at(0)->range_right + i : ast_node->children.at(0)->range_right - i;
			Yosys::AST::AstNode *new_cell = ast_node->children.at(1)->clone();
			newNode->children.push_back(new_cell);
			new_cell->str += stringf("[%d]", idx);
			if (new_cell->type == Yosys::AST::AST_PRIMITIVE) {
				log_file_error(ast_node->filename, ast_node->location.first_line, "Cell arrays of primitives are currently not supported.\n");
			} else {
				log_assert(new_cell->children.at(0)->type == Yosys::AST::AST_CELLTYPE);
				new_cell->children.at(0)->str = stringf("$array:%d:%d:%s", i, num, new_cell->children.at(0)->str.c_str());
			}
		}

		goto apply_newNode;
	}

	// replace primitives with assignments
	if (ast_node->type == Yosys::AST::AST_PRIMITIVE)
	{
		if (ast_node->children.size() < 2)
			log_file_error(ast_node->filename, ast_node->location.first_line, "Insufficient number of arguments for primitive `%s'!\n", ast_node->str.c_str());

		std::vector<Yosys::AST::AstNode*> children_list;
		for (auto child : ast_node->children) {
			log_assert(child->type == Yosys::AST::AST_ARGUMENT);
			log_assert(child->children.size() == 1);
			children_list.push_back(child->children[0]);
			child->children.clear();
			delete child;
		}
		ast_node->children.clear();

		if (ast_node->str == "bufif0" || ast_node->str == "bufif1" || ast_node->str == "notif0" || ast_node->str == "notif1")
		{
			if (children_list.size() != 3)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Invalid number of arguments for primitive `%s'!\n", ast_node->str.c_str());

			std::vector<RTLIL::State> z_const(1, RTLIL::State::Sz);

			Yosys::AST::AstNode *mux_input = children_list.at(1);
			if (ast_node->str == "notif0" || ast_node->str == "notif1") {
				mux_input = new Yosys::AST::AstNode(Yosys::AST::AST_BIT_NOT, mux_input);
			}
			Yosys::AST::AstNode *node = new Yosys::AST::AstNode(Yosys::AST::AST_TERNARY, children_list.at(2));
			if (ast_node->str == "bufif0") {
				node->children.push_back(Yosys::AST::AstNode::mkconst_bits(z_const, false));
				node->children.push_back(mux_input);
			} else {
				node->children.push_back(mux_input);
				node->children.push_back(Yosys::AST::AstNode::mkconst_bits(z_const, false));
			}

			ast_node->str.clear();
			ast_node->type = Yosys::AST::AST_ASSIGN;
			ast_node->children.push_back(children_list.at(0));
			ast_node->children.back()->was_checked = true;
			ast_node->children.push_back(node);
			did_something = true;
		}
		else if (ast_node->str == "buf" || ast_node->str == "not")
		{
			Yosys::AST::AstNode *input = children_list.back();
			if (ast_node->str == "not")
				input = new Yosys::AST::AstNode(Yosys::AST::AST_BIT_NOT, input);

			newNode = new Yosys::AST::AstNode(Yosys::AST::AST_GENBLOCK);
			for (auto it = children_list.begin(); it != std::prev(children_list.end()); it++) {
				newNode->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN, *it, input->clone()));
				newNode->children.back()->was_checked = true;
			}
			delete input;

			did_something = true;
		}
		else
		{
			Yosys::AST::AstNodeType op_type = Yosys::AST::AST_NONE;
			bool invert_results = false;

			if (ast_node->str == "and")
				op_type = Yosys::AST::AST_BIT_AND;
			if (ast_node->str == "nand")
				op_type = Yosys::AST::AST_BIT_AND, invert_results = true;
			if (ast_node->str == "or")
				op_type = Yosys::AST::AST_BIT_OR;
			if (ast_node->str == "nor")
				op_type = Yosys::AST::AST_BIT_OR, invert_results = true;
			if (ast_node->str == "xor")
				op_type = Yosys::AST::AST_BIT_XOR;
			if (ast_node->str == "xnor")
				op_type = Yosys::AST::AST_BIT_XOR, invert_results = true;
			log_assert(op_type != Yosys::AST::AST_NONE);

			Yosys::AST::AstNode *node = children_list[1];
			if (op_type != Yosys::AST::AST_POS)
				for (size_t i = 2; i < children_list.size(); i++) {
					node = new Yosys::AST::AstNode(op_type, node, children_list[i]);
					node->location = ast_node->location;
				}
			if (invert_results)
				node = new Yosys::AST::AstNode(Yosys::AST::AST_BIT_NOT, node);

			ast_node->str.clear();
			ast_node->type = Yosys::AST::AST_ASSIGN;
			ast_node->children.push_back(children_list[0]);
			ast_node->children.back()->was_checked = true;
			ast_node->children.push_back(node);
			did_something = true;
		}
	}

	// replace dynamic ranges in left-hand side expressions (e.g. "foo[bar] <= 1'b1;") with
	// either a big case block that selects the correct single-bit assignment, or mask and
	// shift operations.
	if (ast_node->type == Yosys::AST::AST_ASSIGN_EQ || ast_node->type == Yosys::AST::AST_ASSIGN_LE)
	{
		if (ast_node->children[0]->type != Yosys::AST::AST_IDENTIFIER || ast_node->children[0]->children.size() == 0)
			goto skip_dynamic_range_lvalue_expansion;
		if (ast_node->children[0]->children[0]->range_valid || did_something)
			goto skip_dynamic_range_lvalue_expansion;
		if (ast_node->children[0]->id2ast == NULL || ast_node->children[0]->id2ast->type != Yosys::AST::AST_WIRE)
			goto skip_dynamic_range_lvalue_expansion;
		if (!ast_node->children[0]->id2ast->range_valid)
			goto skip_dynamic_range_lvalue_expansion;

		int source_width = ast_node->children[0]->id2ast->range_left - ast_node->children[0]->id2ast->range_right + 1;
		int source_offset = ast_node->children[0]->id2ast->range_right;
		int result_width = 1;
		Yosys::AST::AstNode *member_node = systemverilog_plugin::get_struct_member(ast_node->children[0]);
		if (member_node) {
			// Clamp chunk to range of member within struct/union.
			log_assert(!source_offset && !ast_node->children[0]->id2ast->range_swapped);
			source_width = member_node->range_left - member_node->range_right + 1;
		}

		Yosys::AST::AstNode *shift_expr = NULL;
		Yosys::AST::AstNode *range = ast_node->children[0]->children[0];

		if (range->children.size() == 1) {
			shift_expr = range->children[0]->clone();
		} else {
			shift_expr = range->children[1]->clone();
			Yosys::AST::AstNode *left_at_zero_ast = range->children[0]->clone();
			Yosys::AST::AstNode *right_at_zero_ast = range->children[1]->clone();
			while (simplify(left_at_zero_ast, true, true, false, stage, -1, false, false)) { }
			while (simplify(right_at_zero_ast, true, true, false, stage, -1, false, false)) { }
			if (left_at_zero_ast->type != Yosys::AST::AST_CONSTANT || right_at_zero_ast->type != Yosys::AST::AST_CONSTANT)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Unsupported expression on dynamic range select on signal `%s'!\n", ast_node->str.c_str());
			result_width = abs(int(left_at_zero_ast->integer - right_at_zero_ast->integer)) + 1;
			delete left_at_zero_ast;
			delete right_at_zero_ast;
		}

		bool use_case_method = false;

		if (ast_node->children[0]->id2ast->attributes.count(ID::nowrshmsk)) {
			Yosys::AST::AstNode *node = ast_node->children[0]->id2ast->attributes.at(ID::nowrshmsk);
			while (simplify(node, true, false, false, stage, -1, false, false)) { }
			if (node->type != Yosys::AST::AST_CONSTANT)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Non-constant value for `nowrshmsk' attribute on `%s'!\n", ast_node->children[0]->id2ast->str.c_str());
			if (node->asAttrConst().as_bool())
				use_case_method = true;
		}

		if (!use_case_method && current_always->detect_latch(ast_node->children[0]->str))
			use_case_method = true;

		if (use_case_method)
		{
			// big case block

			did_something = true;
			newNode = new Yosys::AST::AstNode(Yosys::AST::AST_CASE, shift_expr);
			for (int i = 0; i < source_width; i++) {
				int start_bit = source_offset + i;
				int end_bit = std::min(start_bit+result_width,source_width) - 1;
				Yosys::AST::AstNode *cond = new Yosys::AST::AstNode(Yosys::AST::AST_COND, ast_node->mkconst_int(start_bit, true));
				Yosys::AST::AstNode *lvalue = ast_node->children[0]->clone();
				lvalue->delete_children();
				if (member_node)
					lvalue->attributes[ID::wiretype] = member_node->clone();
				lvalue->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_RANGE,
						ast_node->mkconst_int(end_bit, true), ast_node->mkconst_int(start_bit, true)));
				cond->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK, new Yosys::AST::AstNode(ast_node->type, lvalue, ast_node->children[1]->clone())));
				newNode->children.push_back(cond);
			}
		}
		else
		{
			// mask and shift operations, disabled for now

			Yosys::AST::AstNode *wire_mask = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(source_width-1, true), ast_node->mkconst_int(0, true)));
			wire_mask->str = stringf("$bitselwrite$mask$%s:%d$%d", encode_filename(ast_node->filename).c_str(), ast_node->location.first_line, autoidx++);
			wire_mask->attributes[ID::nosync] = ast_node->mkconst_int(1, false);
			wire_mask->is_logic = true;
			while (simplify(wire_mask, true, false, false, 1, -1, false, false)) { }
			current_ast_mod->children.push_back(wire_mask);

			Yosys::AST::AstNode *wire_data = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(source_width-1, true), ast_node->mkconst_int(0, true)));
			wire_data->str = stringf("$bitselwrite$data$%s:%d$%d", encode_filename(ast_node->filename).c_str(), ast_node->location.first_line, autoidx++);
			wire_data->attributes[ID::nosync] = ast_node->mkconst_int(1, false);
			wire_data->is_logic = true;
			while (simplify(wire_data, true, false, false, 1, -1, false, false)) { }
			current_ast_mod->children.push_back(wire_data);

			int shamt_width_hint = -1;
			bool shamt_sign_hint = true;
			shift_expr->detectSignWidth(shamt_width_hint, shamt_sign_hint);

			Yosys::AST::AstNode *wire_sel = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(shamt_width_hint-1, true), ast_node->mkconst_int(0, true)));
			wire_sel->str = stringf("$bitselwrite$sel$%s:%d$%d", encode_filename(ast_node->filename).c_str(), ast_node->location.first_line, autoidx++);
			wire_sel->attributes[ID::nosync] = ast_node->mkconst_int(1, false);
			wire_sel->is_logic = true;
			wire_sel->is_signed = shamt_sign_hint;
			while (simplify(wire_sel, true, false, false, 1, -1, false, false)) { }
			current_ast_mod->children.push_back(wire_sel);

			did_something = true;
			newNode = new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK);

			Yosys::AST::AstNode *lvalue = ast_node->children[0]->clone();
			lvalue->delete_children();
			if (member_node)
				lvalue->attributes[ID::wiretype] = member_node->clone();

			Yosys::AST::AstNode *ref_mask = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
			ref_mask->str = wire_mask->str;
			ref_mask->id2ast = wire_mask;
			ref_mask->was_checked = true;

			Yosys::AST::AstNode *ref_data = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
			ref_data->str = wire_data->str;
			ref_data->id2ast = wire_data;
			ref_data->was_checked = true;

			Yosys::AST::AstNode *ref_sel = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
			ref_sel->str = wire_sel->str;
			ref_sel->id2ast = wire_sel;
			ref_sel->was_checked = true;

			Yosys::AST::AstNode *old_data = lvalue->clone();
			if (ast_node->type == Yosys::AST::AST_ASSIGN_LE)
				old_data->lookahead = true;

			Yosys::AST::AstNode *s = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, ref_sel->clone(), shift_expr);
			newNode->children.push_back(s);

			Yosys::AST::AstNode *shamt = ref_sel;

			// convert to signed while preserving the sign and value
			shamt = new Yosys::AST::AstNode(Yosys::AST::AST_CAST_SIZE, ast_node->mkconst_int(shamt_width_hint + 1, true), shamt);
			shamt = new Yosys::AST::AstNode(Yosys::AST::AST_TO_SIGNED, shamt);

			// offset the shift amount by the lower bound of the dimension
			int start_bit = source_offset;
			shamt = new Yosys::AST::AstNode(Yosys::AST::AST_SUB, shamt, ast_node->mkconst_int(start_bit, true));

			// reflect the shift amount if the dimension is swapped
			if (ast_node->children[0]->id2ast->range_swapped)
				shamt = new Yosys::AST::AstNode(Yosys::AST::AST_SUB, ast_node->mkconst_int(source_width - result_width, true), shamt);

			// AST_SHIFT uses negative amounts for shifting left
			shamt = new Yosys::AST::AstNode(Yosys::AST::AST_NEG, shamt);

			Yosys::AST::AstNode *t;

			t = Yosys::AST::AstNode::mkconst_bits(std::vector<RTLIL::State>(result_width, State::S1), false);
			t = new Yosys::AST::AstNode(Yosys::AST::AST_SHIFT, t, shamt->clone());
			t = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, ref_mask->clone(), t);
			newNode->children.push_back(t);

			t = new Yosys::AST::AstNode(Yosys::AST::AST_BIT_AND, Yosys::AST::AstNode::mkconst_bits(std::vector<RTLIL::State>(result_width, State::S1), false), ast_node->children[1]->clone());
			t = new Yosys::AST::AstNode(Yosys::AST::AST_SHIFT, t, shamt);
			t = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, ref_data->clone(), t);
			newNode->children.push_back(t);

			t = new Yosys::AST::AstNode(Yosys::AST::AST_BIT_AND, old_data, new Yosys::AST::AstNode(Yosys::AST::AST_BIT_NOT, ref_mask));
			t = new Yosys::AST::AstNode(Yosys::AST::AST_BIT_OR, t, ref_data);
			t = new Yosys::AST::AstNode(ast_node->type, lvalue, t);
			newNode->children.push_back(t);
		}

		goto apply_newNode;
	}
skip_dynamic_range_lvalue_expansion:;

	if (stage > 1 && (ast_node->type == Yosys::AST::AST_ASSERT || ast_node->type == Yosys::AST::AST_ASSUME || ast_node->type == Yosys::AST::AST_LIVE || ast_node->type == Yosys::AST::AST_FAIR || ast_node->type == Yosys::AST::AST_COVER) && current_block != NULL)
	{
		std::stringstream sstr;
		sstr << "$formal$" << encode_filename(ast_node->filename) << ":" << ast_node->location.first_line << "$" << (autoidx++);
		std::string id_check = sstr.str() + "_CHECK", id_en = sstr.str() + "_EN";

		Yosys::AST::AstNode *wire_check = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE);
		wire_check->str = id_check;
		wire_check->was_checked = true;
		current_ast_mod->children.push_back(wire_check);
		current_scope[wire_check->str] = wire_check;
		while (simplify(wire_check, true, false, false, 1, -1, false, false)) { }

		Yosys::AST::AstNode *wire_en = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE);
		wire_en->str = id_en;
		wire_en->was_checked = true;
		current_ast_mod->children.push_back(wire_en);
		if (current_always_clocked) {
			current_ast_mod->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_INITIAL, new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK, new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_LE, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), ast_node->mkconst_int(0, false, 1)))));
			current_ast_mod->children.back()->children[0]->children[0]->children[0]->str = id_en;
			current_ast_mod->children.back()->children[0]->children[0]->children[0]->was_checked = true;
		}
		current_scope[wire_en->str] = wire_en;
		while (simplify(wire_en, true, false, false, 1, -1, false, false)) { }

		Yosys::AST::AstNode *check_defval;
		if (ast_node->type == Yosys::AST::AST_LIVE || ast_node->type == Yosys::AST::AST_FAIR) {
			check_defval = new Yosys::AST::AstNode(Yosys::AST::AST_REDUCE_BOOL, ast_node->children[0]->clone());
		} else {
			std::vector<RTLIL::State> x_bit;
			x_bit.push_back(RTLIL::State::Sx);
			check_defval = Yosys::AST::AstNode::mkconst_bits(x_bit, false);
		}

		Yosys::AST::AstNode *assign_check = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_LE, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), check_defval);
		assign_check->children[0]->str = id_check;
		assign_check->children[0]->was_checked = true;

		Yosys::AST::AstNode *assign_en = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_LE, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), ast_node->mkconst_int(0, false, 1));
		assign_en->children[0]->str = id_en;
		assign_en->children[0]->was_checked = true;

		Yosys::AST::AstNode *default_signals = new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK);
		default_signals->children.push_back(assign_check);
		default_signals->children.push_back(assign_en);
		current_top_block->children.insert(current_top_block->children.begin(), default_signals);

		if (ast_node->type == Yosys::AST::AST_LIVE || ast_node->type == Yosys::AST::AST_FAIR) {
			assign_check = nullptr;
		} else {
			assign_check = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_LE, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), new Yosys::AST::AstNode(Yosys::AST::AST_REDUCE_BOOL, ast_node->children[0]->clone()));
			assign_check->children[0]->str = id_check;
			assign_check->children[0]->was_checked = true;
		}

		if (current_always == nullptr || current_always->type != Yosys::AST::AST_INITIAL) {
			assign_en = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_LE, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), ast_node->mkconst_int(1, false, 1));
		} else {
			assign_en = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_LE, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), new Yosys::AST::AstNode(Yosys::AST::AST_FCALL));
			assign_en->children[1]->str = "\\$initstate";
		}
		assign_en->children[0]->str = id_en;
		assign_en->children[0]->was_checked = true;

		newNode = new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK);
		if (assign_check != nullptr)
			newNode->children.push_back(assign_check);
		newNode->children.push_back(assign_en);

		Yosys::AST::AstNode *assertnode = new Yosys::AST::AstNode(ast_node->type);
		assertnode->location = ast_node->location;
		assertnode->str = ast_node->str;
		assertnode->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER));
		assertnode->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER));
		assertnode->children[0]->str = id_check;
		assertnode->children[1]->str = id_en;
		assertnode->attributes.swap(ast_node->attributes);
		current_ast_mod->children.push_back(assertnode);

		goto apply_newNode;
	}

	if (stage > 1 && (ast_node->type == Yosys::AST::AST_ASSERT || ast_node->type == Yosys::AST::AST_ASSUME || ast_node->type == Yosys::AST::AST_LIVE || ast_node->type == Yosys::AST::AST_FAIR || ast_node->type == Yosys::AST::AST_COVER) && ast_node->children.size() == 1)
	{
		ast_node->children.push_back(ast_node->mkconst_int(1, false, 1));
		did_something = true;
	}

	// found right-hand side identifier for memory -> replace with memory read port
	if (stage > 1 && ast_node->type == Yosys::AST::AST_IDENTIFIER && ast_node->id2ast != NULL && ast_node->id2ast->type == Yosys::AST::AST_MEMORY && !in_lvalue &&
			ast_node->children.size() == 1 && ast_node->children[0]->type == Yosys::AST::AST_RANGE && ast_node->children[0]->children.size() == 1) {
		newNode = new Yosys::AST::AstNode(Yosys::AST::AST_MEMRD, ast_node->children[0]->children[0]->clone());
		newNode->str = ast_node->str;
		newNode->id2ast = ast_node->id2ast;
		goto apply_newNode;
	}

	// assignment with nontrivial member in left-hand concat expression -> split assignment
	if ((ast_node->type == Yosys::AST::AST_ASSIGN_EQ || ast_node->type == Yosys::AST::AST_ASSIGN_LE) && ast_node->children[0]->type == Yosys::AST::AST_CONCAT && width_hint > 0)
	{
		bool found_nontrivial_member = false;

		for (auto child : ast_node->children[0]->children) {
			if (child->type == Yosys::AST::AST_IDENTIFIER && child->id2ast != NULL && child->id2ast->type == Yosys::AST::AST_MEMORY)
				found_nontrivial_member = true;
		}

		if (found_nontrivial_member)
		{
			newNode = new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK);

			Yosys::AST::AstNode *wire_tmp = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(width_hint-1, true), ast_node->mkconst_int(0, true)));
			wire_tmp->str = stringf("$splitcmplxassign$%s:%d$%d", encode_filename(ast_node->filename).c_str(), ast_node->location.first_line, autoidx++);
			current_ast_mod->children.push_back(wire_tmp);
			current_scope[wire_tmp->str] = wire_tmp;
			wire_tmp->attributes[ID::nosync] = ast_node->mkconst_int(1, false);
			while (simplify(wire_tmp, true, false, false, 1, -1, false, false)) { }
			wire_tmp->is_logic = true;

			Yosys::AST::AstNode *wire_tmp_id = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
			wire_tmp_id->str = wire_tmp->str;

			newNode->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, wire_tmp_id, ast_node->children[1]->clone()));
			newNode->children.back()->was_checked = true;

			int cursor = 0;
			for (auto child : ast_node->children[0]->children)
			{
				int child_width_hint = -1;
				bool child_sign_hint = true;
				child->detectSignWidth(child_width_hint, child_sign_hint);

				Yosys::AST::AstNode *rhs = wire_tmp_id->clone();
				rhs->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(cursor+child_width_hint-1, true), ast_node->mkconst_int(cursor, true)));
				newNode->children.push_back(new Yosys::AST::AstNode(ast_node->type, child->clone(), rhs));

				cursor += child_width_hint;
			}

			goto apply_newNode;
		}
	}

	// assignment with memory in left-hand side expression -> replace with memory write port
	if (stage > 1 && (ast_node->type == Yosys::AST::AST_ASSIGN_EQ || ast_node->type == Yosys::AST::AST_ASSIGN_LE) && ast_node->children[0]->type == Yosys::AST::AST_IDENTIFIER &&
			ast_node->children[0]->id2ast && ast_node->children[0]->id2ast->type == Yosys::AST::AST_MEMORY && ast_node->children[0]->id2ast->children.size() >= 2 &&
			ast_node->children[0]->id2ast->children[0]->range_valid && ast_node->children[0]->id2ast->children[1]->range_valid &&
			(ast_node->children[0]->children.size() == 1 || ast_node->children[0]->children.size() == 2) && ast_node->children[0]->children[0]->type == Yosys::AST::AST_RANGE)
	{
		std::stringstream sstr;
		sstr << "$memwr$" << ast_node->children[0]->str << "$" << encode_filename(ast_node->filename) << ":" << ast_node->location.first_line << "$" << (autoidx++);
		std::string id_addr = sstr.str() + "_ADDR", id_data = sstr.str() + "_DATA", id_en = sstr.str() + "_EN";

		int mem_width, mem_size, addr_bits;
		bool mem_signed = ast_node->children[0]->id2ast->is_signed;
		ast_node->children[0]->id2ast->meminfo(mem_width, mem_size, addr_bits);

		newNode = new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK);
		Yosys::AST::AstNode *defNode = new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK);

		int data_range_left = ast_node->children[0]->id2ast->children[0]->range_left;
		int data_range_right = ast_node->children[0]->id2ast->children[0]->range_right;
		int mem_data_range_offset = std::min(data_range_left, data_range_right);

		int addr_width_hint = -1;
		bool addr_sign_hint = true;
		ast_node->children[0]->children[0]->children[0]->detectSignWidthWorker(addr_width_hint, addr_sign_hint);
		addr_bits = std::max(addr_bits, addr_width_hint);

		std::vector<RTLIL::State> x_bits_addr, x_bits_data, set_bits_en;
		for (int i = 0; i < addr_bits; i++)
			x_bits_addr.push_back(RTLIL::State::Sx);
		for (int i = 0; i < mem_width; i++)
			x_bits_data.push_back(RTLIL::State::Sx);
		for (int i = 0; i < mem_width; i++)
			set_bits_en.push_back(RTLIL::State::S1);

		Yosys::AST::AstNode *node_addr = nullptr;
		if (ast_node->children[0]->children[0]->children[0]->isConst()) {
			node_addr = ast_node->children[0]->children[0]->children[0]->clone();
		} else {
			Yosys::AST::AstNode *wire_addr = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(addr_bits-1, true), ast_node->mkconst_int(0, true)));
			wire_addr->str = id_addr;
			wire_addr->was_checked = true;
			current_ast_mod->children.push_back(wire_addr);
			current_scope[wire_addr->str] = wire_addr;
			while (simplify(wire_addr, true, false, false, 1, -1, false, false)) { }

			Yosys::AST::AstNode *assign_addr = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), Yosys::AST::AstNode::mkconst_bits(x_bits_addr, false));
			assign_addr->children[0]->str = id_addr;
			assign_addr->children[0]->was_checked = true;
			defNode->children.push_back(assign_addr);

			assign_addr = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), ast_node->children[0]->children[0]->children[0]->clone());
			assign_addr->children[0]->str = id_addr;
			assign_addr->children[0]->was_checked = true;
			newNode->children.push_back(assign_addr);

			node_addr = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
			node_addr->str = id_addr;
		}

		Yosys::AST::AstNode *node_data = nullptr;
		if (ast_node->children[0]->children.size() == 1 && ast_node->children[1]->isConst()) {
			node_data = ast_node->children[1]->clone();
		} else {
			Yosys::AST::AstNode *wire_data = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(mem_width-1, true), ast_node->mkconst_int(0, true)));
			wire_data->str = id_data;
			wire_data->was_checked = true;
			wire_data->is_signed = mem_signed;
			current_ast_mod->children.push_back(wire_data);
			current_scope[wire_data->str] = wire_data;
			while (simplify(wire_data, true, false, false, 1, -1, false, false)) { }

			Yosys::AST::AstNode *assign_data = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), Yosys::AST::AstNode::mkconst_bits(x_bits_data, false));
			assign_data->children[0]->str = id_data;
			assign_data->children[0]->was_checked = true;
			defNode->children.push_back(assign_data);

			node_data = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
			node_data->str = id_data;
		}

		Yosys::AST::AstNode *wire_en = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE, ast_node->mkconst_int(mem_width-1, true), ast_node->mkconst_int(0, true)));
		wire_en->str = id_en;
		wire_en->was_checked = true;
		current_ast_mod->children.push_back(wire_en);
		current_scope[wire_en->str] = wire_en;
		while (simplify(wire_en, true, false, false, 1, -1, false, false)) { }

		Yosys::AST::AstNode *assign_en_first = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), ast_node->mkconst_int(0, false, mem_width));
		assign_en_first->children[0]->str = id_en;
		assign_en_first->children[0]->was_checked = true;
		defNode->children.push_back(assign_en_first);

		Yosys::AST::AstNode *node_en = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
		node_en->str = id_en;

		if (!defNode->children.empty())
			current_top_block->children.insert(current_top_block->children.begin(), defNode);
		else
			delete defNode;

		Yosys::AST::AstNode *assign_data = nullptr;
		Yosys::AST::AstNode *assign_en = nullptr;
		if (ast_node->children[0]->children.size() == 2)
		{
			if (ast_node->children[0]->children[1]->range_valid)
			{
				int offset = ast_node->children[0]->children[1]->range_right;
				int width = ast_node->children[0]->children[1]->range_left - offset + 1;
				offset -= mem_data_range_offset;

				std::vector<RTLIL::State> padding_x(offset, RTLIL::State::Sx);

				assign_data = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER),
						new Yosys::AST::AstNode(Yosys::AST::AST_CONCAT, Yosys::AST::AstNode::mkconst_bits(padding_x, false), ast_node->children[1]->clone()));
				assign_data->children[0]->str = id_data;
				assign_data->children[0]->was_checked = true;

				for (int i = 0; i < mem_width; i++)
					set_bits_en[i] = offset <= i && i < offset+width ? RTLIL::State::S1 : RTLIL::State::S0;
				assign_en = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), Yosys::AST::AstNode::mkconst_bits(set_bits_en, false));
				assign_en->children[0]->str = id_en;
				assign_en->children[0]->was_checked = true;
			}
			else
			{
				Yosys::AST::AstNode *the_range = ast_node->children[0]->children[1];
				Yosys::AST::AstNode *left_at_zero_ast = the_range->children[0]->clone();
				Yosys::AST::AstNode *right_at_zero_ast = the_range->children.size() >= 2 ? the_range->children[1]->clone() : left_at_zero_ast->clone();
				Yosys::AST::AstNode *offset_ast = right_at_zero_ast->clone();

				if (mem_data_range_offset)
					offset_ast = new Yosys::AST::AstNode(Yosys::AST::AST_SUB, offset_ast, ast_node->mkconst_int(mem_data_range_offset, true));

				while (simplify(left_at_zero_ast, true, true, false, 1, -1, false, false)) { }
				while (simplify(right_at_zero_ast, true, true, false, 1, -1, false, false)) { }
				if (left_at_zero_ast->type != Yosys::AST::AST_CONSTANT || right_at_zero_ast->type != Yosys::AST::AST_CONSTANT)
					log_file_error(ast_node->filename, ast_node->location.first_line, "Unsupported expression on dynamic range select on signal `%s'!\n", ast_node->str.c_str());
				int width = abs(int(left_at_zero_ast->integer - right_at_zero_ast->integer)) + 1;

				assign_data = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER),
						new Yosys::AST::AstNode(Yosys::AST::AST_SHIFT_LEFT, ast_node->children[1]->clone(), offset_ast->clone()));
				assign_data->children[0]->str = id_data;
				assign_data->children[0]->was_checked = true;

				for (int i = 0; i < mem_width; i++)
					set_bits_en[i] = i < width ? RTLIL::State::S1 : RTLIL::State::S0;
				assign_en = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER),
						new Yosys::AST::AstNode(Yosys::AST::AST_SHIFT_LEFT, Yosys::AST::AstNode::mkconst_bits(set_bits_en, false), offset_ast->clone()));
				assign_en->children[0]->str = id_en;
				assign_en->children[0]->was_checked = true;

				delete left_at_zero_ast;
				delete right_at_zero_ast;
				delete offset_ast;
			}
		}
		else
		{
			if (!(ast_node->children[0]->children.size() == 1 && ast_node->children[1]->isConst())) {
				assign_data = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), ast_node->children[1]->clone());
				assign_data->children[0]->str = id_data;
				assign_data->children[0]->was_checked = true;
			}

			assign_en = new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER), Yosys::AST::AstNode::mkconst_bits(set_bits_en, false));
			assign_en->children[0]->str = id_en;
			assign_en->children[0]->was_checked = true;
		}
		if (assign_data)
			newNode->children.push_back(assign_data);
		if (assign_en)
			newNode->children.push_back(assign_en);

		Yosys::AST::AstNode *wrnode;
		if (current_always->type == Yosys::AST::AST_INITIAL)
			wrnode = new Yosys::AST::AstNode(Yosys::AST::AST_MEMINIT, node_addr, node_data, node_en, ast_node->mkconst_int(1, false));
		else
			wrnode = new Yosys::AST::AstNode(Yosys::AST::AST_MEMWR, node_addr, node_data, node_en);
		wrnode->str = ast_node->children[0]->str;
		wrnode->id2ast = ast_node->children[0]->id2ast;
		wrnode->location = ast_node->location;
		if (wrnode->type == Yosys::AST::AST_MEMWR) {
			int portid = current_memwr_count[wrnode->str]++;
			wrnode->children.push_back(ast_node->mkconst_int(portid, false));
			std::vector<RTLIL::State> priority_mask;
			for (int i = 0; i < portid; i++) {
				bool has_prio = current_memwr_visible[wrnode->str].count(i);
				priority_mask.push_back(State(has_prio));
			}
			wrnode->children.push_back(Yosys::AST::AstNode::mkconst_bits(priority_mask, false));
			current_memwr_visible[wrnode->str].insert(portid);
			current_always->children.push_back(wrnode);
		} else {
			current_ast_mod->children.push_back(wrnode);
		}

		if (newNode->children.empty()) {
			delete newNode;
			newNode = new Yosys::AST::AstNode();
		}
		goto apply_newNode;
	}

	// replace function and task calls with the code from the function or task
	if ((ast_node->type == Yosys::AST::AST_FCALL || ast_node->type == Yosys::AST::AST_TCALL) && !ast_node->str.empty())
	{
		if (ast_node->type == Yosys::AST::AST_FCALL)
		{
			if (ast_node->str == "\\$initstate")
			{
				int myidx = autoidx++;

				Yosys::AST::AstNode *wire = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE);
				wire->str = stringf("$initstate$%d_wire", myidx);
				current_ast_mod->children.push_back(wire);
				while (simplify(wire, true, false, false, 1, -1, false, false)) { }

				Yosys::AST::AstNode *cell = new Yosys::AST::AstNode(Yosys::AST::AST_CELL, new Yosys::AST::AstNode(Yosys::AST::AST_CELLTYPE), new Yosys::AST::AstNode(Yosys::AST::AST_ARGUMENT, new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER)));
				cell->str = stringf("$initstate$%d", myidx);
				cell->children[0]->str = "$initstate";
				cell->children[1]->str = "\\Y";
				cell->children[1]->children[0]->str = wire->str;
				cell->children[1]->children[0]->id2ast = wire;
				current_ast_mod->children.push_back(cell);
				while (simplify(cell, true, false, false, 1, -1, false, false)) { }

				newNode = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
				newNode->str = wire->str;
				newNode->id2ast = wire;
				goto apply_newNode;
			}

			if (ast_node->str == "\\$past")
			{
				if (width_hint < 0)
					goto replace_fcall_later;

				int num_steps = 1;

				if (GetSize(ast_node->children) != 1 && GetSize(ast_node->children) != 2)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 1 or 2.\n",
							RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));

				if (!current_always_clocked)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s is only allowed in clocked blocks.\n",
							RTLIL::unescape_id(ast_node->str).c_str());

				if (GetSize(ast_node->children) == 2)
				{
					Yosys::AST::AstNode *buf = ast_node->children[1]->clone();
					while (simplify(buf, true, false, false, stage, -1, false, false)) { }
					if (buf->type != Yosys::AST::AST_CONSTANT)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant value.\n", ast_node->str.c_str());

					num_steps = buf->asInt(true);
					delete buf;
				}

				Yosys::AST::AstNode *block = nullptr;

				for (auto child : current_always->children)
					if (child->type == Yosys::AST::AST_BLOCK)
						block = child;

				log_assert(block != nullptr);

				if (num_steps == 0) {
					newNode = ast_node->children[0]->clone();
					goto apply_newNode;
				}

				int myidx = autoidx++;
				Yosys::AST::AstNode *outreg = nullptr;

				for (int i = 0; i < num_steps; i++)
				{
					Yosys::AST::AstNode *reg = new Yosys::AST::AstNode(Yosys::AST::AST_WIRE, new Yosys::AST::AstNode(Yosys::AST::AST_RANGE,
							ast_node->mkconst_int(width_hint-1, true), ast_node->mkconst_int(0, true)));

					reg->str = stringf("$past$%s:%d$%d$%d", encode_filename(ast_node->filename).c_str(), ast_node->location.first_line, myidx, i);
					reg->is_reg = true;
					reg->is_signed = sign_hint;

					current_ast_mod->children.push_back(reg);

					while (simplify(reg, true, false, false, 1, -1, false, false)) { }

					Yosys::AST::AstNode *regid = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
					regid->str = reg->str;
					regid->id2ast = reg;
					regid->was_checked = true;

					Yosys::AST::AstNode *rhs = nullptr;

					if (outreg == nullptr) {
						rhs = ast_node->children.at(0)->clone();
					} else {
						rhs = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
						rhs->str = outreg->str;
						rhs->id2ast = outreg;
					}

					block->children.push_back(new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_LE, regid, rhs));
					outreg = reg;
				}

				newNode = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
				newNode->str = outreg->str;
				newNode->id2ast = outreg;
				goto apply_newNode;
			}

			if (ast_node->str == "\\$stable" || ast_node->str == "\\$rose" || ast_node->str == "\\$fell" || ast_node->str == "\\$changed")
			{
				if (GetSize(ast_node->children) != 1)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 1.\n",
							RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));

				if (!current_always_clocked)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s is only allowed in clocked blocks.\n",
							RTLIL::unescape_id(ast_node->str).c_str());

				Yosys::AST::AstNode *present = ast_node->children.at(0)->clone();
				Yosys::AST::AstNode *past = ast_node->clone();
				past->str = "\\$past";

				if (ast_node->str == "\\$stable")
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_EQ, past, present);

				else if (ast_node->str == "\\$changed")
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_NE, past, present);

				else if (ast_node->str == "\\$rose")
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_LOGIC_AND,
							new Yosys::AST::AstNode(Yosys::AST::AST_LOGIC_NOT, new Yosys::AST::AstNode(Yosys::AST::AST_BIT_AND, past, ast_node->mkconst_int(1,false))),
							new Yosys::AST::AstNode(Yosys::AST::AST_BIT_AND, present, ast_node->mkconst_int(1,false)));

				else if (ast_node->str == "\\$fell")
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_LOGIC_AND,
							new Yosys::AST::AstNode(Yosys::AST::AST_BIT_AND, past, ast_node->mkconst_int(1,false)),
							new Yosys::AST::AstNode(Yosys::AST::AST_LOGIC_NOT, new Yosys::AST::AstNode(Yosys::AST::AST_BIT_AND, present, ast_node->mkconst_int(1,false))));

				else
					log_abort();

				goto apply_newNode;
			}

			// $anyconst and $anyseq are mapped in genRTLIL()
			if (ast_node->str == "\\$anyconst" || ast_node->str == "\\$anyseq" || ast_node->str == "\\$allconst" || ast_node->str == "\\$allseq") {
				recursion_counter--;
				return false;
			}

			if (ast_node->str == "\\$clog2")
			{
				if (ast_node->children.size() != 1)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 1.\n",
							RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));

				Yosys::AST::AstNode *buf = ast_node->children[0]->clone();
				while (simplify(buf, true, false, false, stage, width_hint, sign_hint, false)) { }
				if (buf->type != Yosys::AST::AST_CONSTANT)
					log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant value.\n", ast_node->str.c_str());

				RTLIL::Const arg_value = buf->bitsAsConst();
				if (arg_value.as_bool())
					arg_value = const_sub(arg_value, 1, false, false, GetSize(arg_value));
				delete buf;

				uint32_t result = 0;
				for (size_t i = 0; i < arg_value.bits.size(); i++)
					if (arg_value.bits.at(i) == RTLIL::State::S1)
						result = i + 1;

				newNode = ast_node->mkconst_int(result, true);
				goto apply_newNode;
			}

			if (ast_node->str == "\\$size" || ast_node->str == "\\$bits" || ast_node->str == "\\$high" || ast_node->str == "\\$low" || ast_node->str == "\\$left" || ast_node->str == "\\$right")
			{
				int dim = 1;
				if (ast_node->str == "\\$bits") {
					if (ast_node->children.size() != 1)
						log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 1.\n",
								RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));
				} else {
					if (ast_node->children.size() != 1 && ast_node->children.size() != 2)
						log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 1 or 2.\n",
							RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));
					if (ast_node->children.size() == 2) {
						Yosys::AST::AstNode *buf = ast_node->children[1]->clone();
						// Evaluate constant expression
						while (simplify(buf, true, false, false, stage, width_hint, sign_hint, false)) { }
						dim = buf->asInt(false);
						delete buf;
					}
				}
				Yosys::AST::AstNode *buf = ast_node->children[0]->clone();
				int mem_depth = 1;
				int result, high = 0, low = 0, left = 0, right = 0, width = 1; // defaults for a simple wire
				Yosys::AST::AstNode *id_ast = NULL;

				// Is this needed?
				//while (simplify(buf, true, false, false, stage, width_hint, sign_hint, false)) { }
				buf->detectSignWidth(width_hint, sign_hint);

				if (buf->type == Yosys::AST::AST_IDENTIFIER) {
					id_ast = buf->id2ast;
					if (id_ast == NULL && current_scope.count(buf->str))
						id_ast = current_scope.at(buf->str);
					if (!id_ast)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to resolve identifier %s for width detection!\n", buf->str.c_str());

					// Check for item in packed struct / union
					Yosys::AST::AstNode *item_node = systemverilog_plugin::get_struct_member(buf);
					if (id_ast->type == Yosys::AST::AST_WIRE && item_node) {
						// The dimension of the original array expression is saved in the 'integer' field
						dim += buf->integer;
						if (item_node->multirange_dimensions.empty()) {
							if (dim != 1)
								log_file_error(ast_node->filename, ast_node->location.first_line, "Dimension %d out of range in `%s', as it only has one dimension!\n", dim, item_node->str.c_str());
							left  = high = item_node->range_left;
							right = low  = item_node->range_right;
						} else {
							int dims = GetSize(item_node->multirange_dimensions)/2;
							if (dim < 1 || dim > dims)
								log_file_error(ast_node->filename, ast_node->location.first_line, "Dimension %d out of range in `%s', as it only has dimensions 1..%d!\n", dim, item_node->str.c_str(), dims);
							right = low  = get_struct_range_offset(item_node, dim - 1);
							left  = high = low + get_struct_range_width(item_node, dim - 1) - 1;
							if (item_node->multirange_swapped[dim - 1]) {
								std::swap(left, right);
							}
							for (int i = dim; i < dims; i++) {
							    mem_depth *= get_struct_range_width(item_node, i);
							}
						}
					}
					// Otherwise, we have 4 cases:
					// wire x;                ==> AST_WIRE, no AST_RANGE children
					// wire [1:0]x;           ==> AST_WIRE, AST_RANGE children
					// wire [1:0]x[1:0];      ==> AST_MEMORY, two AST_RANGE children (1st for packed, 2nd for unpacked)
					// wire [1:0]x[1:0][1:0]; ==> AST_MEMORY, one AST_RANGE child (0) for packed, then AST_MULTIRANGE child (1) for unpacked
					// (updated: actually by the time we are here, AST_MULTIRANGE is converted into one big AST_RANGE)
					// case 0 handled by default
					else if ((id_ast->type == Yosys::AST::AST_WIRE || id_ast->type == Yosys::AST::AST_MEMORY) && id_ast->children.size() > 0) {
						// handle packed array left/right for case 1, and cases 2/3 when requesting the last dimension (packed side)
						Yosys::AST::AstNode *wire_range = id_ast->children[0];
						left = wire_range->children[0]->integer;
						right = wire_range->children[1]->integer;
						high = max(left, right);
						low  = min(left, right);
					}
					if (id_ast->type == Yosys::AST::AST_MEMORY) {
						// a slice of our identifier means we advance to the next dimension, e.g. $size(a[3])
						if (buf->children.size() > 0) {
							// something is hanging below this identifier
							if (buf->children[0]->type == Yosys::AST::AST_RANGE && buf->integer == 0)
								// if integer == 0, ast_node node was originally created as Yosys::AST::AST_RANGE so it's dimension is 1
								dim++;
							// more than one range, e.g. $size(a[3][2])
							else // created an Yosys::AST::AST_MULTIRANGE, converted to Yosys::AST::AST_RANGE, but original dimension saved in 'integer' field
								dim += buf->integer; // increment by multirange size
						}

						// We got here only if the argument is a memory
						// Otherwise $size() and $bits() return the expression width
						Yosys::AST::AstNode *mem_range = id_ast->children[1];
						if (ast_node->str == "\\$bits") {
							if (mem_range->type == Yosys::AST::AST_RANGE) {
								if (!mem_range->range_valid)
									log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to detect width of memory access `%s'!\n", buf->str.c_str());
								mem_depth = mem_range->range_left - mem_range->range_right + 1;
							} else
								log_file_error(ast_node->filename, ast_node->location.first_line, "Unknown memory depth AST type in `%s'!\n", buf->str.c_str());
						} else {
							// $size(), $left(), $right(), $high(), $low()
							int dims = 1;
							if (mem_range->type == Yosys::AST::AST_RANGE) {
								if (id_ast->multirange_dimensions.empty()) {
									if (!mem_range->range_valid)
										log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to detect width of memory access `%s'!\n", buf->str.c_str());
									if (dim == 1) {
										left  = mem_range->range_right;
										right = mem_range->range_left;
										high = max(left, right);
										low  = min(left, right);
									}
								} else {
									dims = GetSize(id_ast->multirange_dimensions)/2;
									if (dim <= dims) {
										width_hint = id_ast->multirange_dimensions[2*dim-1];
										high = id_ast->multirange_dimensions[2*dim-2] + id_ast->multirange_dimensions[2*dim-1] - 1;
										low  = id_ast->multirange_dimensions[2*dim-2];
										if (id_ast->multirange_swapped[dim-1]) {
											left = low;
											right = high;
										} else {
											right = low;
											left = high;
										}
									} else if ((dim > dims+1) || (dim < 0))
										log_file_error(ast_node->filename, ast_node->location.first_line, "Dimension %d out of range in `%s', as it only has dimensions 1..%d!\n", dim, buf->str.c_str(), dims+1);
								}
							} else {
								log_file_error(ast_node->filename, ast_node->location.first_line, "Unknown memory depth AST type in `%s'!\n", buf->str.c_str());
							}
						}
					}
					width = high - low + 1;
				} else {
					width = width_hint;
				}
				delete buf;
				if (ast_node->str == "\\$high")
					result = high;
				else if (ast_node->str == "\\$low")
					result = low;
				else if (ast_node->str == "\\$left")
					result = left;
				else if (ast_node->str == "\\$right")
					result = right;
				else if (ast_node->str == "\\$size")
					result = width;
				else { // ast_node->str == "\\$bits"
					result = width * mem_depth;
				}
				newNode = ast_node->mkconst_int(result, true);
				goto apply_newNode;
			}

			if (ast_node->str == "\\$ln" || ast_node->str == "\\$log10" || ast_node->str == "\\$exp" || ast_node->str == "\\$sqrt" || ast_node->str == "\\$pow" ||
					ast_node->str == "\\$floor" || ast_node->str == "\\$ceil" || ast_node->str == "\\$sin" || ast_node->str == "\\$cos" || ast_node->str == "\\$tan" ||
					ast_node->str == "\\$asin" || ast_node->str == "\\$acos" || ast_node->str == "\\$atan" || ast_node->str == "\\$atan2" || ast_node->str == "\\$hypot" ||
					ast_node->str == "\\$sinh" || ast_node->str == "\\$cosh" || ast_node->str == "\\$tanh" || ast_node->str == "\\$asinh" || ast_node->str == "\\$acosh" || ast_node->str == "\\$atanh" ||
					ast_node->str == "\\$rtoi" || ast_node->str == "\\$itor")
			{
				bool func_with_two_arguments = ast_node->str == "\\$pow" || ast_node->str == "\\$atan2" || ast_node->str == "\\$hypot";
				double x = 0, y = 0;

				if (func_with_two_arguments) {
					if (ast_node->children.size() != 2)
						log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 2.\n",
								RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));
				} else {
					if (ast_node->children.size() != 1)
						log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 1.\n",
								RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));
				}

				if (ast_node->children.size() >= 1) {
					while (simplify(ast_node->children[0], true, false, false, stage, width_hint, sign_hint, false)) { }
					if (!ast_node->children[0]->isConst())
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant argument.\n",
								RTLIL::unescape_id(ast_node->str).c_str());
					int child_width_hint = width_hint;
					bool child_sign_hint = sign_hint;
					ast_node->children[0]->detectSignWidth(child_width_hint, child_sign_hint);
					x = ast_node->children[0]->asReal(child_sign_hint);
				}

				if (ast_node->children.size() >= 2) {
					while (simplify(ast_node->children[1], true, false, false, stage, width_hint, sign_hint, false)) { }
					if (!ast_node->children[1]->isConst())
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant argument.\n",
								RTLIL::unescape_id(ast_node->str).c_str());
					int child_width_hint = width_hint;
					bool child_sign_hint = sign_hint;
					ast_node->children[1]->detectSignWidth(child_width_hint, child_sign_hint);
					y = ast_node->children[1]->asReal(child_sign_hint);
				}

				if (ast_node->str == "\\$rtoi") {
					newNode = ast_node->mkconst_int(x, true);
				} else {
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_REALVALUE);
					if (ast_node->str == "\\$ln")         newNode->realvalue = ::log(x);
					else if (ast_node->str == "\\$log10") newNode->realvalue = ::log10(x);
					else if (ast_node->str == "\\$exp")   newNode->realvalue = ::exp(x);
					else if (ast_node->str == "\\$sqrt")  newNode->realvalue = ::sqrt(x);
					else if (ast_node->str == "\\$pow")   newNode->realvalue = ::pow(x, y);
					else if (ast_node->str == "\\$floor") newNode->realvalue = ::floor(x);
					else if (ast_node->str == "\\$ceil")  newNode->realvalue = ::ceil(x);
					else if (ast_node->str == "\\$sin")   newNode->realvalue = ::sin(x);
					else if (ast_node->str == "\\$cos")   newNode->realvalue = ::cos(x);
					else if (ast_node->str == "\\$tan")   newNode->realvalue = ::tan(x);
					else if (ast_node->str == "\\$asin")  newNode->realvalue = ::asin(x);
					else if (ast_node->str == "\\$acos")  newNode->realvalue = ::acos(x);
					else if (ast_node->str == "\\$atan")  newNode->realvalue = ::atan(x);
					else if (ast_node->str == "\\$atan2") newNode->realvalue = ::atan2(x, y);
					else if (ast_node->str == "\\$hypot") newNode->realvalue = ::hypot(x, y);
					else if (ast_node->str == "\\$sinh")  newNode->realvalue = ::sinh(x);
					else if (ast_node->str == "\\$cosh")  newNode->realvalue = ::cosh(x);
					else if (ast_node->str == "\\$tanh")  newNode->realvalue = ::tanh(x);
					else if (ast_node->str == "\\$asinh") newNode->realvalue = ::asinh(x);
					else if (ast_node->str == "\\$acosh") newNode->realvalue = ::acosh(x);
					else if (ast_node->str == "\\$atanh") newNode->realvalue = ::atanh(x);
					else if (ast_node->str == "\\$itor")  newNode->realvalue = x;
					else log_abort();
				}
				goto apply_newNode;
			}

			if (ast_node->str == "\\$sformatf") {
				Yosys::AST::AstNode *node_string = ast_node->children[0];
				while (simplify(node_string, true, false, false, stage, width_hint, sign_hint, false)) { }
				if (node_string->type != Yosys::AST::AST_CONSTANT)
					log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant 1st argument.\n", ast_node->str.c_str());
				std::string sformat = node_string->bitsAsConst().decode_string();
				std::string sout = ast_node->process_format_str(sformat, 1, stage, width_hint, sign_hint);
				newNode = ast_node->mkconst_str(sout);
				goto apply_newNode;
			}

			if (ast_node->str == "\\$countbits") {
				if (ast_node->children.size() < 2)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected at least 2.\n",
							RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));

				std::vector<RTLIL::State> control_bits;

				// Determine which bits to count
				for (size_t i = 1; i < ast_node->children.size(); i++) {
					Yosys::AST::AstNode *node = ast_node->children[i];
					while (simplify(node, true, false, false, stage, -1, false, false)) { }
					if (node->type != Yosys::AST::AST_CONSTANT)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant control bit argument.\n", ast_node->str.c_str());
					if (node->bits.size() != 1)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with control bit width != 1.\n", ast_node->str.c_str());
					control_bits.push_back(node->bits[0]);
				}

				// Detect width of exp (first argument of $countbits)
				int  exp_width = -1;
				bool exp_sign  = false;
				Yosys::AST::AstNode *exp = ast_node->children[0];
				exp->detectSignWidth(exp_width, exp_sign, NULL);

				newNode = ast_node->mkconst_int(0, false);

				for (int i = 0; i < exp_width; i++) {
					// Generate nodes for:  exp << i >> ($size(exp) - 1)
					//                          ^^   ^^
					Yosys::AST::AstNode *lsh_node = new Yosys::AST::AstNode(Yosys::AST::AST_SHIFT_LEFT, exp->clone(), Yosys::AST::AstNode::mkconst_int(i, false));
					Yosys::AST::AstNode *rsh_node = new Yosys::AST::AstNode(Yosys::AST::AST_SHIFT_RIGHT, lsh_node, Yosys::AST::AstNode::mkconst_int(exp_width - 1, false));

					Yosys::AST::AstNode *or_node = nullptr;

					for (RTLIL::State control_bit : control_bits) {
						// Generate node for:  (exp << i >> ($size(exp) - 1)) === control_bit
						//                                                    ^^^
						Yosys::AST::AstNode *eq_node = new Yosys::AST::AstNode(Yosys::AST::AST_EQX, rsh_node->clone(), Yosys::AST::AstNode::mkconst_bits({control_bit}, false));

						// Or the result for each checked bit value
						if (or_node)
							or_node = new Yosys::AST::AstNode(Yosys::AST::AST_LOGIC_OR, or_node, eq_node);
						else
							or_node = eq_node;
					}

					// We should have at least one element in control_bits,
					// because we checked for the number of arguments above
					log_assert(or_node != nullptr);

					delete rsh_node;

					// Generate node for adding with result of previous bit
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_ADD, newNode, or_node);
				}

				goto apply_newNode;
			}

			if (ast_node->str == "\\$countones" || ast_node->str == "\\$isunknown" || ast_node->str == "\\$onehot" || ast_node->str == "\\$onehot0") {
				if (ast_node->children.size() != 1)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 1.\n",
							RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));

				Yosys::AST::AstNode *countbits = ast_node->clone();
				countbits->str = "\\$countbits";

				if (ast_node->str == "\\$countones") {
					countbits->children.push_back(Yosys::AST::AstNode::mkconst_bits({RTLIL::State::S1}, false));
					newNode = countbits;
				} else if (ast_node->str == "\\$isunknown") {
					countbits->children.push_back(Yosys::AST::AstNode::mkconst_bits({RTLIL::Sx}, false));
					countbits->children.push_back(Yosys::AST::AstNode::mkconst_bits({RTLIL::Sz}, false));
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_GT, countbits, Yosys::AST::AstNode::mkconst_int(0, false));
				} else if (ast_node->str == "\\$onehot") {
					countbits->children.push_back(Yosys::AST::AstNode::mkconst_bits({RTLIL::State::S1}, false));
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_EQ, countbits, Yosys::AST::AstNode::mkconst_int(1, false));
				} else if (ast_node->str == "\\$onehot0") {
					countbits->children.push_back(Yosys::AST::AstNode::mkconst_bits({RTLIL::State::S1}, false));
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_LE, countbits, Yosys::AST::AstNode::mkconst_int(1, false));
				} else {
					log_abort();
				}

				goto apply_newNode;
			}

			if (current_scope.count(ast_node->str) != 0 && current_scope[ast_node->str]->type == Yosys::AST::AST_DPI_FUNCTION)
			{
				Yosys::AST::AstNode *dpi_decl = current_scope[ast_node->str];

				std::string rtype, fname;
				std::vector<std::string> argtypes;
				std::vector<Yosys::AST::AstNode*> args;

				rtype = RTLIL::unescape_id(dpi_decl->children.at(0)->str);
				fname = RTLIL::unescape_id(dpi_decl->children.at(1)->str);

				for (int i = 2; i < GetSize(dpi_decl->children); i++)
				{
					if (i-2 >= GetSize(ast_node->children))
						log_file_error(ast_node->filename, ast_node->location.first_line, "Insufficient number of arguments in DPI function call.\n");

					argtypes.push_back(RTLIL::unescape_id(dpi_decl->children.at(i)->str));
					args.push_back(ast_node->children.at(i-2)->clone());
					while (simplify(args.back(), true, false, false, stage, -1, false, true)) { }

					if (args.back()->type != Yosys::AST::AST_CONSTANT && args.back()->type != Yosys::AST::AST_REALVALUE)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate DPI function with non-constant argument.\n");
				}

				newNode = dpi_call(rtype, fname, argtypes, args);

				for (auto arg : args)
					delete arg;

				goto apply_newNode;
			}

			if (current_scope.count(ast_node->str) == 0)
				ast_node->str = ast_node->try_pop_module_prefix();
			if (current_scope.count(ast_node->str) == 0 || current_scope[ast_node->str]->type != Yosys::AST::AST_FUNCTION)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Can't resolve function name `%s'.\n", ast_node->str.c_str());
		}

		if (ast_node->type == Yosys::AST::AST_TCALL)
		{
			if (ast_node->str == "$finish" || ast_node->str == "$stop")
			{
				if (!current_always || current_always->type != Yosys::AST::AST_INITIAL)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System task `%s' outside initial block is unsupported.\n", ast_node->str.c_str());

				log_file_error(ast_node->filename, ast_node->location.first_line, "System task `%s' executed.\n", ast_node->str.c_str());
			}

			if (ast_node->str == "\\$readmemh" || ast_node->str == "\\$readmemb")
			{
				if (GetSize(ast_node->children) < 2 || GetSize(ast_node->children) > 4)
					log_file_error(ast_node->filename, ast_node->location.first_line, "System function %s got %d arguments, expected 2-4.\n",
							RTLIL::unescape_id(ast_node->str).c_str(), int(ast_node->children.size()));

				Yosys::AST::AstNode *node_filename = ast_node->children[0]->clone();
				while (simplify(node_filename, true, false, false, stage, width_hint, sign_hint, false)) { }
				if (node_filename->type != Yosys::AST::AST_CONSTANT)
					log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant 1st argument.\n", ast_node->str.c_str());

				Yosys::AST::AstNode *node_memory = ast_node->children[1]->clone();
				while (simplify(node_memory, true, false, false, stage, width_hint, sign_hint, false)) { }
				if (node_memory->type != Yosys::AST::AST_IDENTIFIER || node_memory->id2ast == nullptr || node_memory->id2ast->type != Yosys::AST::AST_MEMORY)
					log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-memory 2nd argument.\n", ast_node->str.c_str());

				int start_addr = -1, finish_addr = -1;

				if (GetSize(ast_node->children) > 2) {
					Yosys::AST::AstNode *node_addr = ast_node->children[2]->clone();
					while (simplify(node_addr, true, false, false, stage, width_hint, sign_hint, false)) { }
					if (node_addr->type != Yosys::AST::AST_CONSTANT)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant 3rd argument.\n", ast_node->str.c_str());
					start_addr = int(node_addr->asInt(false));
				}

				if (GetSize(ast_node->children) > 3) {
					Yosys::AST::AstNode *node_addr = ast_node->children[3]->clone();
					while (simplify(node_addr, true, false, false, stage, width_hint, sign_hint, false)) { }
					if (node_addr->type != Yosys::AST::AST_CONSTANT)
						log_file_error(ast_node->filename, ast_node->location.first_line, "Failed to evaluate system function `%s' with non-constant 4th argument.\n", ast_node->str.c_str());
					finish_addr = int(node_addr->asInt(false));
				}

				bool unconditional_init = false;
				if (current_always->type == Yosys::AST::AST_INITIAL) {
					pool<Yosys::AST::AstNode*> queue;
					log_assert(current_always->children[0]->type == Yosys::AST::AST_BLOCK);
					queue.insert(current_always->children[0]);
					while (!unconditional_init && !queue.empty()) {
						pool<Yosys::AST::AstNode*> next_queue;
						for (auto n : queue)
						for (auto c : n->children) {
							if (c == ast_node)
								unconditional_init = true;
							next_queue.insert(c);
						}
						next_queue.swap(queue);
					}
				}

				newNode = ast_node->readmem(ast_node->str == "\\$readmemh", node_filename->bitsAsConst().decode_string(), node_memory->id2ast, start_addr, finish_addr, unconditional_init);
				delete node_filename;
				delete node_memory;
				goto apply_newNode;
			}

			if (current_scope.count(ast_node->str) == 0)
				ast_node->str = ast_node->try_pop_module_prefix();
			if (current_scope.count(ast_node->str) == 0 || current_scope[ast_node->str]->type != Yosys::AST::AST_TASK)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Can't resolve task name `%s'.\n", ast_node->str.c_str());
		}


		std::stringstream sstr;
		sstr << ast_node->str << "$func$" << encode_filename(ast_node->filename) << ":" << ast_node->location.first_line << "$" << (autoidx++) << '.';
		std::string prefix = sstr.str();

		Yosys::AST::AstNode *decl = current_scope[ast_node->str];
		if (unevaluated_tern_branch && decl->is_recursive_function())
			goto replace_fcall_later;
		decl = decl->clone();
		decl->replace_result_wire_name_in_function(ast_node->str, "$result"); // enables recursion
		decl->expand_genblock(prefix);

		if (decl->type == Yosys::AST::AST_FUNCTION && !decl->attributes.count(ID::via_celltype))
		{
			bool require_const_eval = decl->has_const_only_constructs();
			bool all_args_const = true;
			for (auto child : ast_node->children) {
				while (simplify(child, true, false, false, 1, -1, false, true)) { }
				if (child->type != Yosys::AST::AST_CONSTANT && child->type != Yosys::AST::AST_REALVALUE)
					all_args_const = false;
			}

			if (all_args_const) {
				Yosys::AST::AstNode *func_workspace = decl->clone();
				func_workspace->str = prefix_id(prefix, "$result");
				newNode = func_workspace->eval_const_function(ast_node, in_param || require_const_eval);
				delete func_workspace;
				if (newNode) {
					delete decl;
					goto apply_newNode;
				}
			}

			if (in_param)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Non-constant function call in constant expression.\n");
			if (require_const_eval)
				log_file_error(ast_node->filename, ast_node->location.first_line, "Function %s can only be called with constant arguments.\n", ast_node->str.c_str());
		}

		size_t arg_count = 0;
		dict<std::string, Yosys::AST::AstNode*> wire_cache;
		vector<Yosys::AST::AstNode*> new_stmts;
		vector<Yosys::AST::AstNode*> output_assignments;

		if (current_block == NULL)
		{
			log_assert(ast_node->type == Yosys::AST::AST_FCALL);

			Yosys::AST::AstNode *wire = NULL;
			std::string res_name = prefix_id(prefix, "$result");
			for (auto child : decl->children)
				if (child->type == Yosys::AST::AST_WIRE && child->str == res_name)
					wire = child->clone();
			log_assert(wire != NULL);

			wire->port_id = 0;
			wire->is_input = false;
			wire->is_output = false;

			current_scope[wire->str] = wire;
			current_ast_mod->children.push_back(wire);
			while (simplify(wire, true, false, false, 1, -1, false, false)) { }

			Yosys::AST::AstNode *lvalue = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
			lvalue->str = wire->str;

			Yosys::AST::AstNode *always = new Yosys::AST::AstNode(Yosys::AST::AST_ALWAYS, new Yosys::AST::AstNode(Yosys::AST::AST_BLOCK,
					new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, lvalue, ast_node->clone())));
			always->children[0]->children[0]->was_checked = true;

			current_ast_mod->children.push_back(always);

			goto replace_fcall_with_id;
		}

		if (decl->attributes.count(ID::via_celltype))
		{
			std::string celltype = decl->attributes.at(ID::via_celltype)->asAttrConst().decode_string();
			std::string outport = ast_node->str;

			if (celltype.find(' ') != std::string::npos) {
				int pos = celltype.find(' ');
				outport = RTLIL::escape_id(celltype.substr(pos+1));
				celltype = RTLIL::escape_id(celltype.substr(0, pos));
			} else
				celltype = RTLIL::escape_id(celltype);

			Yosys::AST::AstNode *cell = new Yosys::AST::AstNode(Yosys::AST::AST_CELL, new Yosys::AST::AstNode(Yosys::AST::AST_CELLTYPE));
			cell->str = prefix.substr(0, GetSize(prefix)-1);
			cell->children[0]->str = celltype;

			for (auto attr : decl->attributes)
				if (attr.first.str().rfind("\\via_celltype_defparam_", 0) == 0)
				{
					Yosys::AST::AstNode *cell_arg = new Yosys::AST::AstNode(Yosys::AST::AST_PARASET, attr.second->clone());
					cell_arg->str = RTLIL::escape_id(attr.first.substr(strlen("\\via_celltype_defparam_")));
					cell->children.push_back(cell_arg);
				}

			for (auto child : decl->children)
				if (child->type == Yosys::AST::AST_WIRE && (child->is_input || child->is_output || (ast_node->type == Yosys::AST::AST_FCALL && child->str == ast_node->str)))
				{
					Yosys::AST::AstNode *wire = child->clone();
					wire->port_id = 0;
					wire->is_input = false;
					wire->is_output = false;
					current_ast_mod->children.push_back(wire);
					while (simplify(wire, true, false, false, 1, -1, false, false)) { }

					Yosys::AST::AstNode *wire_id = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
					wire_id->str = wire->str;

					if ((child->is_input || child->is_output) && arg_count < ast_node->children.size())
					{
						Yosys::AST::AstNode *arg = ast_node->children[arg_count++]->clone();
						Yosys::AST::AstNode *assign = child->is_input ?
								new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, wire_id->clone(), arg) :
								new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, arg, wire_id->clone());
						assign->children[0]->was_checked = true;

						for (auto it = current_block->children.begin(); it != current_block->children.end(); it++) {
							if (*it != current_block_child)
								continue;
							current_block->children.insert(it, assign);
							break;
						}
					}

					Yosys::AST::AstNode *cell_arg = new Yosys::AST::AstNode(Yosys::AST::AST_ARGUMENT, wire_id);
					cell_arg->str = child->str == ast_node->str ? outport : child->str;
					cell->children.push_back(cell_arg);
				}

			current_ast_mod->children.push_back(cell);
			goto replace_fcall_with_id;
		}

		for (auto child : decl->children)
			if (child->type == Yosys::AST::AST_WIRE || child->type == Yosys::AST::AST_MEMORY || child->type == Yosys::AST::AST_PARAMETER || child->type == Yosys::AST::AST_LOCALPARAM || child->type == Yosys::AST::AST_ENUM_ITEM)
			{
				Yosys::AST::AstNode *wire = nullptr;

				if (wire_cache.count(child->str))
				{
					wire = wire_cache.at(child->str);
					bool contains_value = wire->type == Yosys::AST::AST_LOCALPARAM;
					if (wire->children.size() == contains_value) {
						for (auto c : child->children)
							wire->children.push_back(c->clone());
					} else if (!child->children.empty()) {
						while (simplify(child, true, false, false, stage, -1, false, false)) { }
						if (GetSize(child->children) == GetSize(wire->children) - contains_value) {
							for (int i = 0; i < GetSize(child->children); i++)
								if (*child->children.at(i) != *wire->children.at(i + contains_value))
									goto tcall_incompatible_wires;
						} else {
					tcall_incompatible_wires:
							log_file_error(ast_node->filename, ast_node->location.first_line, "Incompatible re-declaration of wire %s.\n", child->str.c_str());
						}
					}
				}
				else
				{
					wire = child->clone();
					wire->port_id = 0;
					wire->is_input = false;
					wire->is_output = false;
					wire->is_reg = true;
					wire->attributes[ID::nosync] = Yosys::AST::AstNode::mkconst_int(1, false);
					if (child->type == Yosys::AST::AST_ENUM_ITEM)
						wire->attributes[ID::enum_base_type] = child->attributes[ID::enum_base_type];

					wire_cache[child->str] = wire;

					current_scope[wire->str] = wire;
					current_ast_mod->children.push_back(wire);
				}

				while (simplify(wire, true, false, false, 1, -1, false, false)) { }

				if ((child->is_input || child->is_output) && arg_count < ast_node->children.size())
				{
					Yosys::AST::AstNode *arg = ast_node->children[arg_count++]->clone();
					// convert purely constant arguments into localparams
					if (child->is_input && child->type == Yosys::AST::AST_WIRE && arg->type == Yosys::AST::AST_CONSTANT && node_contains_assignment_to(decl, child)) {
						wire->type = Yosys::AST::AST_LOCALPARAM;
						if (wire->attributes.count(ID::nosync))
							delete wire->attributes.at(ID::nosync);
						wire->attributes.erase(ID::nosync);
						wire->children.insert(wire->children.begin(), arg->clone());
						// args without a range implicitly have width 1
						if (wire->children.back()->type != Yosys::AST::AST_RANGE) {
							// check if this wire is redeclared with an explicit size
							bool uses_explicit_size = false;
							for (const Yosys::AST::AstNode *other_child : decl->children)
								if (other_child->type == Yosys::AST::AST_WIRE && child->str == other_child->str
										&& !other_child->children.empty()
										&& other_child->children.back()->type == Yosys::AST::AST_RANGE) {
									uses_explicit_size = true;
									break;
								}
							if (!uses_explicit_size) {
								Yosys::AST::AstNode* range = new Yosys::AST::AstNode();
								range->type = Yosys::AST::AST_RANGE;
								wire->children.push_back(range);
								range->children.push_back(Yosys::AST::AstNode::mkconst_int(0, true));
								range->children.push_back(Yosys::AST::AstNode::mkconst_int(0, true));
							}
						}
						// updates the sizing
						while (simplify(wire, true, false, false, 1, -1, false, false)) { }
						delete arg;
						continue;
					}
					Yosys::AST::AstNode *wire_id = new Yosys::AST::AstNode(Yosys::AST::AST_IDENTIFIER);
					wire_id->str = wire->str;
					Yosys::AST::AstNode *assign = child->is_input ?
							new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, wire_id, arg) :
							new Yosys::AST::AstNode(Yosys::AST::AST_ASSIGN_EQ, arg, wire_id);
					assign->children[0]->was_checked = true;
					if (child->is_input)
						new_stmts.push_back(assign);
					else
						output_assignments.push_back(assign);
				}
			}

		for (auto child : decl->children)
			if (child->type != Yosys::AST::AST_WIRE && child->type != Yosys::AST::AST_MEMORY && child->type != Yosys::AST::AST_PARAMETER && child->type != Yosys::AST::AST_LOCALPARAM)
				new_stmts.push_back(child->clone());

		new_stmts.insert(new_stmts.end(), output_assignments.begin(), output_assignments.end());

		for (auto it = current_block->children.begin(); ; it++) {
			log_assert(it != current_block->children.end());
			if (*it == current_block_child) {
				current_block->children.insert(it, new_stmts.begin(), new_stmts.end());
				break;
			}
		}

	replace_fcall_with_id:
		delete decl;
		if (ast_node->type == Yosys::AST::AST_FCALL) {
			ast_node->delete_children();
			ast_node->type = Yosys::AST::AST_IDENTIFIER;
			ast_node->str = prefix_id(prefix, "$result");
		}
		if (ast_node->type == Yosys::AST::AST_TCALL)
			ast_node->str = "";
		did_something = true;
	}

replace_fcall_later:;

	// perform const folding when activated
	if (const_fold)
	{
		bool string_op;
		std::vector<RTLIL::State> tmp_bits;
		RTLIL::Const (*const_func)(const RTLIL::Const&, const RTLIL::Const&, bool, bool, ys_size_type);
		RTLIL::Const dummy_arg;

		switch (ast_node->type)
		{
		case Yosys::AST::AST_IDENTIFIER:
			if (current_scope.count(ast_node->str) > 0 && (current_scope[ast_node->str]->type == Yosys::AST::AST_PARAMETER || current_scope[ast_node->str]->type == Yosys::AST::AST_LOCALPARAM || current_scope[ast_node->str]->type == Yosys::AST::AST_ENUM_ITEM)) {
				if (current_scope[ast_node->str]->children[0]->type == Yosys::AST::AST_CONSTANT) {
					if (ast_node->children.size() != 0 && ast_node->children[0]->type == Yosys::AST::AST_RANGE && ast_node->children[0]->range_valid) {
						std::vector<RTLIL::State> data;
						bool param_upto = current_scope[ast_node->str]->range_valid && current_scope[ast_node->str]->range_swapped;
						int param_offset = current_scope[ast_node->str]->range_valid ? current_scope[ast_node->str]->range_right : 0;
						int param_width = current_scope[ast_node->str]->range_valid ? current_scope[ast_node->str]->range_left - current_scope[ast_node->str]->range_right + 1 :
								GetSize(current_scope[ast_node->str]->children[0]->bits);
						int tmp_range_left = ast_node->children[0]->range_left, tmp_range_right = ast_node->children[0]->range_right;
						if (param_upto) {
							tmp_range_left = (param_width + 2*param_offset) - ast_node->children[0]->range_right - 1;
							tmp_range_right = (param_width + 2*param_offset) - ast_node->children[0]->range_left - 1;
						}
						Yosys::AST::AstNode *member_node = systemverilog_plugin::get_struct_member(ast_node);
						int chunk_offset = member_node ? member_node->range_right : 0;
						log_assert(!(chunk_offset && param_upto));
						for (int i = tmp_range_right; i <= tmp_range_left; i++) {
							int index = i - param_offset;
							if (0 <= index && index < param_width)
								data.push_back(current_scope[ast_node->str]->children[0]->bits[chunk_offset + index]);
							else
								data.push_back(RTLIL::State::Sx);
						}
						newNode = Yosys::AST::AstNode::mkconst_bits(data, false);
					} else
					if (ast_node->children.size() == 0)
						newNode = current_scope[ast_node->str]->children[0]->clone();
				} else
				if (current_scope[ast_node->str]->children[0]->isConst())
					newNode = current_scope[ast_node->str]->children[0]->clone();
			}
			else if (at_zero && current_scope.count(ast_node->str) > 0) {
				Yosys::AST::AstNode *node = current_scope[ast_node->str];
				if (node->type == Yosys::AST::AST_WIRE || node->type == Yosys::AST::AST_AUTOWIRE || node->type == Yosys::AST::AST_MEMORY)
					newNode = node->mkconst_int(0, sign_hint, width_hint);
			}
			break;
		case Yosys::AST::AST_MEMRD:
			if (at_zero) {
				newNode = Yosys::AST::AstNode::mkconst_int(0, sign_hint, width_hint);
			}
			break;
		case Yosys::AST::AST_BIT_NOT:
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = RTLIL::const_not(ast_node->children[0]->bitsAsConst(width_hint, sign_hint), dummy_arg, sign_hint, false, width_hint);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, sign_hint);
			}
			break;
		case Yosys::AST::AST_TO_SIGNED:
		case Yosys::AST::AST_TO_UNSIGNED:
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = ast_node->children[0]->bitsAsConst(width_hint, sign_hint);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, ast_node->type == Yosys::AST::AST_TO_SIGNED);
			}
			break;
		if (0) { case Yosys::AST::AST_BIT_AND:  const_func = RTLIL::const_and;  }
		if (0) { case Yosys::AST::AST_BIT_OR:   const_func = RTLIL::const_or;   }
		if (0) { case Yosys::AST::AST_BIT_XOR:  const_func = RTLIL::const_xor;  }
		if (0) { case Yosys::AST::AST_BIT_XNOR: const_func = RTLIL::const_xnor; }
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT && ast_node->children[1]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = const_func(ast_node->children[0]->bitsAsConst(width_hint, sign_hint),
						ast_node->children[1]->bitsAsConst(width_hint, sign_hint), sign_hint, sign_hint, width_hint);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, sign_hint);
			}
			break;
		if (0) { case Yosys::AST::AST_REDUCE_AND:  const_func = RTLIL::const_reduce_and;  }
		if (0) { case Yosys::AST::AST_REDUCE_OR:   const_func = RTLIL::const_reduce_or;   }
		if (0) { case Yosys::AST::AST_REDUCE_XOR:  const_func = RTLIL::const_reduce_xor;  }
		if (0) { case Yosys::AST::AST_REDUCE_XNOR: const_func = RTLIL::const_reduce_xnor; }
		if (0) { case Yosys::AST::AST_REDUCE_BOOL: const_func = RTLIL::const_reduce_bool; }
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = const_func(RTLIL::Const(ast_node->children[0]->bits), dummy_arg, false, false, -1);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, false);
			}
			break;
		case Yosys::AST::AST_LOGIC_NOT:
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = RTLIL::const_logic_not(RTLIL::Const(ast_node->children[0]->bits), dummy_arg, ast_node->children[0]->is_signed, false, -1);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, false);
			} else
			if (ast_node->children[0]->isConst()) {
				newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(sign_hint) == 0, false, 1);
			}
			break;
		if (0) { case Yosys::AST::AST_LOGIC_AND: const_func = RTLIL::const_logic_and; }
		if (0) { case Yosys::AST::AST_LOGIC_OR:  const_func = RTLIL::const_logic_or;  }
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT && ast_node->children[1]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = const_func(RTLIL::Const(ast_node->children[0]->bits), RTLIL::Const(ast_node->children[1]->bits),
						ast_node->children[0]->is_signed, ast_node->children[1]->is_signed, -1);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, false);
			} else
			if (ast_node->children[0]->isConst() && ast_node->children[1]->isConst()) {
				if (ast_node->type == Yosys::AST::AST_LOGIC_AND)
					newNode = Yosys::AST::AstNode::mkconst_int((ast_node->children[0]->asReal(sign_hint) != 0) && (ast_node->children[1]->asReal(sign_hint) != 0), false, 1);
				else
					newNode = Yosys::AST::AstNode::mkconst_int((ast_node->children[0]->asReal(sign_hint) != 0) || (ast_node->children[1]->asReal(sign_hint) != 0), false, 1);
			}
			break;
		if (0) { case Yosys::AST::AST_SHIFT_LEFT:   const_func = RTLIL::const_shl;  }
		if (0) { case Yosys::AST::AST_SHIFT_RIGHT:  const_func = RTLIL::const_shr;  }
		if (0) { case Yosys::AST::AST_SHIFT_SLEFT:  const_func = RTLIL::const_sshl; }
		if (0) { case Yosys::AST::AST_SHIFT_SRIGHT: const_func = RTLIL::const_sshr; }
		if (0) { case Yosys::AST::AST_POW:          const_func = RTLIL::const_pow; }
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT && ast_node->children[1]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = const_func(ast_node->children[0]->bitsAsConst(width_hint, sign_hint),
						RTLIL::Const(ast_node->children[1]->bits), sign_hint, ast_node->type == Yosys::AST::AST_POW ? ast_node->children[1]->is_signed : false, width_hint);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, sign_hint);
			} else
			if (ast_node->type == Yosys::AST::AST_POW && ast_node->children[0]->isConst() && ast_node->children[1]->isConst()) {
				newNode = new Yosys::AST::AstNode(Yosys::AST::AST_REALVALUE);
				newNode->realvalue = pow(ast_node->children[0]->asReal(sign_hint), ast_node->children[1]->asReal(sign_hint));
			}
			break;
		if (0) { case Yosys::AST::AST_LT:  const_func = RTLIL::const_lt; }
		if (0) { case Yosys::AST::AST_LE:  const_func = RTLIL::const_le; }
		if (0) { case Yosys::AST::AST_EQ:  const_func = RTLIL::const_eq; }
		if (0) { case Yosys::AST::AST_NE:  const_func = RTLIL::const_ne; }
		if (0) { case Yosys::AST::AST_EQX: const_func = RTLIL::const_eqx; }
		if (0) { case Yosys::AST::AST_NEX: const_func = RTLIL::const_nex; }
		if (0) { case Yosys::AST::AST_GE:  const_func = RTLIL::const_ge; }
		if (0) { case Yosys::AST::AST_GT:  const_func = RTLIL::const_gt; }
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT && ast_node->children[1]->type == Yosys::AST::AST_CONSTANT) {
				int cmp_width = max(ast_node->children[0]->bits.size(), ast_node->children[1]->bits.size());
				bool cmp_signed = ast_node->children[0]->is_signed && ast_node->children[1]->is_signed;
				RTLIL::Const y = const_func(ast_node->children[0]->bitsAsConst(cmp_width, cmp_signed),
						ast_node->children[1]->bitsAsConst(cmp_width, cmp_signed), cmp_signed, cmp_signed, 1);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, false);
			} else
			if (ast_node->children[0]->isConst() && ast_node->children[1]->isConst()) {
				bool cmp_signed = (ast_node->children[0]->type == Yosys::AST::AST_REALVALUE || ast_node->children[0]->is_signed) && (ast_node->children[1]->type == Yosys::AST::AST_REALVALUE || ast_node->children[1]->is_signed);
				switch (ast_node->type) {
				case Yosys::AST::AST_LT:  newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(cmp_signed) <  ast_node->children[1]->asReal(cmp_signed), false, 1); break;
				case Yosys::AST::AST_LE:  newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(cmp_signed) <= ast_node->children[1]->asReal(cmp_signed), false, 1); break;
				case Yosys::AST::AST_EQ:  newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(cmp_signed) == ast_node->children[1]->asReal(cmp_signed), false, 1); break;
				case Yosys::AST::AST_NE:  newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(cmp_signed) != ast_node->children[1]->asReal(cmp_signed), false, 1); break;
				case Yosys::AST::AST_EQX: newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(cmp_signed) == ast_node->children[1]->asReal(cmp_signed), false, 1); break;
				case Yosys::AST::AST_NEX: newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(cmp_signed) != ast_node->children[1]->asReal(cmp_signed), false, 1); break;
				case Yosys::AST::AST_GE:  newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(cmp_signed) >= ast_node->children[1]->asReal(cmp_signed), false, 1); break;
				case Yosys::AST::AST_GT:  newNode = Yosys::AST::AstNode::mkconst_int(ast_node->children[0]->asReal(cmp_signed) >  ast_node->children[1]->asReal(cmp_signed), false, 1); break;
				default: log_abort();
				}
			}
			break;
		if (0) { case Yosys::AST::AST_ADD: const_func = RTLIL::const_add; }
		if (0) { case Yosys::AST::AST_SUB: const_func = RTLIL::const_sub; }
		if (0) { case Yosys::AST::AST_MUL: const_func = RTLIL::const_mul; }
		if (0) { case Yosys::AST::AST_DIV: const_func = RTLIL::const_div; }
		if (0) { case Yosys::AST::AST_MOD: const_func = RTLIL::const_mod; }
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT && ast_node->children[1]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = const_func(ast_node->children[0]->bitsAsConst(width_hint, sign_hint),
						ast_node->children[1]->bitsAsConst(width_hint, sign_hint), sign_hint, sign_hint, width_hint);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, sign_hint);
			} else
			if (ast_node->children[0]->isConst() && ast_node->children[1]->isConst()) {
				newNode = new Yosys::AST::AstNode(Yosys::AST::AST_REALVALUE);
				switch (ast_node->type) {
				case Yosys::AST::AST_ADD: newNode->realvalue = ast_node->children[0]->asReal(sign_hint) + ast_node->children[1]->asReal(sign_hint); break;
				case Yosys::AST::AST_SUB: newNode->realvalue = ast_node->children[0]->asReal(sign_hint) - ast_node->children[1]->asReal(sign_hint); break;
				case Yosys::AST::AST_MUL: newNode->realvalue = ast_node->children[0]->asReal(sign_hint) * ast_node->children[1]->asReal(sign_hint); break;
				case Yosys::AST::AST_DIV: newNode->realvalue = ast_node->children[0]->asReal(sign_hint) / ast_node->children[1]->asReal(sign_hint); break;
				case Yosys::AST::AST_MOD: newNode->realvalue = fmod(ast_node->children[0]->asReal(sign_hint), ast_node->children[1]->asReal(sign_hint)); break;
				default: log_abort();
				}
			}
			break;
		if (0) { case Yosys::AST::AST_SELFSZ: const_func = RTLIL::const_pos; }
		if (0) { case Yosys::AST::AST_POS: const_func = RTLIL::const_pos; }
		if (0) { case Yosys::AST::AST_NEG: const_func = RTLIL::const_neg; }
			if (ast_node->children[0]->type == Yosys::AST::AST_CONSTANT) {
				RTLIL::Const y = const_func(ast_node->children[0]->bitsAsConst(width_hint, sign_hint), dummy_arg, sign_hint, false, width_hint);
				newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, sign_hint);
			} else
			if (ast_node->children[0]->isConst()) {
				newNode = new Yosys::AST::AstNode(Yosys::AST::AST_REALVALUE);
				if (ast_node->type == Yosys::AST::AST_NEG)
					newNode->realvalue = -ast_node->children[0]->asReal(sign_hint);
				else
					newNode->realvalue = +ast_node->children[0]->asReal(sign_hint);
			}
			break;
		case Yosys::AST::AST_TERNARY:
			if (ast_node->children[0]->isConst())
			{
				auto pair = ast_node->get_tern_choice();
				Yosys::AST::AstNode *choice = pair.first;
				Yosys::AST::AstNode *not_choice = pair.second;

				if (choice != NULL) {
					if (choice->type == Yosys::AST::AST_CONSTANT) {
						int other_width_hint = width_hint;
						bool other_sign_hint = sign_hint, other_real = false;
						not_choice->detectSignWidth(other_width_hint, other_sign_hint, &other_real);
						if (other_real) {
							newNode = new Yosys::AST::AstNode(Yosys::AST::AST_REALVALUE);
							choice->detectSignWidth(width_hint, sign_hint);
							newNode->realvalue = choice->asReal(sign_hint);
						} else {
							RTLIL::Const y = choice->bitsAsConst(width_hint, sign_hint);
							if (choice->is_string && y.bits.size() % 8 == 0 && sign_hint == false)
								newNode = Yosys::AST::AstNode::mkconst_str(y.bits);
							else
								newNode = Yosys::AST::AstNode::mkconst_bits(y.bits, sign_hint);
						}
					} else
					if (choice->isConst()) {
						newNode = choice->clone();
					}
				} else if (ast_node->children[1]->type == Yosys::AST::AST_CONSTANT && ast_node->children[2]->type == Yosys::AST::AST_CONSTANT) {
					RTLIL::Const a = ast_node->children[1]->bitsAsConst(width_hint, sign_hint);
					RTLIL::Const b = ast_node->children[2]->bitsAsConst(width_hint, sign_hint);
					log_assert(a.bits.size() == b.bits.size());
					for (size_t i = 0; i < a.bits.size(); i++)
						if (a.bits[i] != b.bits[i])
							a.bits[i] = RTLIL::State::Sx;
					newNode = Yosys::AST::AstNode::mkconst_bits(a.bits, sign_hint);
				} else if (ast_node->children[1]->isConst() && ast_node->children[2]->isConst()) {
					newNode = new Yosys::AST::AstNode(Yosys::AST::AST_REALVALUE);
					if (ast_node->children[1]->asReal(sign_hint) == ast_node->children[2]->asReal(sign_hint))
						newNode->realvalue = ast_node->children[1]->asReal(sign_hint);
					else
						// IEEE Std 1800-2012 Sec. 11.4.11 states that the entry in Table 7-1 for
						// the data type in question should be returned if the ?: is ambiguous. The
						// value in Table 7-1 for the 'real' type is 0.0.
						newNode->realvalue = 0.0;
				}
			}
			break;
		case Yosys::AST::AST_CAST_SIZE:
			if (ast_node->children.at(0)->type == Yosys::AST::AST_CONSTANT && ast_node->children.at(1)->type == Yosys::AST::AST_CONSTANT) {
				int width = ast_node->children[0]->bitsAsConst().as_int();
				RTLIL::Const val;
				if (ast_node->children[1]->is_unsized)
					val = ast_node->children[1]->bitsAsUnsizedConst(width);
				else
					val = ast_node->children[1]->bitsAsConst(width);
				newNode = Yosys::AST::AstNode::mkconst_bits(val.bits, ast_node->children[1]->is_signed);
			}
			break;
		case Yosys::AST::AST_CONCAT:
			string_op = !ast_node->children.empty();
			for (auto it = ast_node->children.begin(); it != ast_node->children.end(); it++) {
				if ((*it)->type != Yosys::AST::AST_CONSTANT)
					goto not_const;
				if (!(*it)->is_string)
					string_op = false;
				tmp_bits.insert(tmp_bits.end(), (*it)->bits.begin(), (*it)->bits.end());
			}
			newNode = string_op ? Yosys::AST::AstNode::mkconst_str(tmp_bits) : Yosys::AST::AstNode::mkconst_bits(tmp_bits, false);
			break;
		case Yosys::AST::AST_REPLICATE:
			if (ast_node->children.at(0)->type != Yosys::AST::AST_CONSTANT || ast_node->children.at(1)->type != Yosys::AST::AST_CONSTANT)
				goto not_const;
			for (int i = 0; i < ast_node->children[0]->bitsAsConst().as_int(); i++)
				tmp_bits.insert(tmp_bits.end(), ast_node->children.at(1)->bits.begin(), ast_node->children.at(1)->bits.end());
			newNode = ast_node->children.at(1)->is_string ? Yosys::AST::AstNode::mkconst_str(tmp_bits) : Yosys::AST::AstNode::mkconst_bits(tmp_bits, false);
			break;
		default:
		not_const:
			break;
		}
	}

	// if any of the above set 'newNode' -> use 'newNode' as template to update 'ast_node'
	if (newNode) {
apply_newNode:
		// fprintf(stderr, "----\n");
		// dumpAst(stderr, "- ");
		// newNode->dumpAst(stderr, "+ ");
		log_assert(newNode != NULL);
		newNode->filename = ast_node->filename;
		newNode->location = ast_node->location;
		newNode->cloneInto(ast_node);
		delete newNode;
		did_something = true;
	}

	if (!did_something)
		ast_node->basic_prep = true;

	recursion_counter--;
	return did_something;
}

} // namespace systemverilog_plugin