yosys-systemverilog: fix multirange with dot usage

Signed-off-by: Kamil Rakoczy <krakoczy@antmicro.com>

systemverilog-plugin/UhdmAst.cc

diff --git a/systemverilog-plugin/UhdmAst.cc b/systemverilog-plugin/UhdmAst.cc
index 06a50e3..64b2203 100644
--- a/systemverilog-plugin/UhdmAst.cc
+++ b/systemverilog-plugin/UhdmAst.cc
@@ -962,29 +962,47 @@
     }
     log_assert(struct_node);
     auto expanded = expand_dot(struct_node, dot);
-    if (node->children[0]->type == AST::AST_RANGE) {
-        int struct_size_int = get_max_offset_struct(struct_node) + 1;
-        log_assert(!wire_node->multirange_dimensions.empty());
-        int range = wire_node->multirange_dimensions.back() - 1;
-        if (!wire_node->attributes[UhdmAst::unpacked_ranges()]->children.empty() &&
-            wire_node->attributes[UhdmAst::unpacked_ranges()]->children.back()->range_left == range) {
-            expanded->children[1] = new AST::AstNode(
-              AST::AST_ADD, expanded->children[1],
-              new AST::AstNode(AST::AST_MUL, AST::AstNode::mkconst_int(struct_size_int, true, 32),
-                               new AST::AstNode(AST::AST_SUB, AST::AstNode::mkconst_int(range, true, 32), node->children[0]->children[0]->clone())));
-            expanded->children[0] = new AST::AstNode(
-              AST::AST_ADD, expanded->children[0],
-              new AST::AstNode(AST::AST_MUL, AST::AstNode::mkconst_int(struct_size_int, true, 32),
-                               new AST::AstNode(AST::AST_SUB, AST::AstNode::mkconst_int(range, true, 32), node->children[0]->children[0]->clone())));
-        } else {
-            expanded->children[1] = new AST::AstNode(
-              AST::AST_ADD, expanded->children[1],
-              new AST::AstNode(AST::AST_MUL, AST::AstNode::mkconst_int(struct_size_int, true, 32), node->children[0]->children[0]->clone()));
-            expanded->children[0] = new AST::AstNode(
-              AST::AST_ADD, expanded->children[0],
-              new AST::AstNode(AST::AST_MUL, AST::AstNode::mkconst_int(struct_size_int, true, 32), node->children[0]->children[0]->clone()));
+    std::vector<AST::AstNode *> struct_ranges;
+    for (auto c : node->children) {
+        if (c->type == AST::AST_RANGE) {
+            struct_ranges.push_back(c);
         }
     }
+    const auto wire_node_unpacked_ranges_size = wire_node->attributes[UhdmAst::unpacked_ranges()]->children.size();
+    // 'dot' notation can only be used on specific struct element
+    // '1' packed range is from wiretype and it is already expanded in 'expand_dot'
+    // TODO(krak): wire ranges are sometimes under wiretype node (e.g. in case of typedef)
+    // but wiretype ranges contains also struct range that is already expanded in 'expand_dot'
+    // we need to find a way to calculate size of wire ranges without struct range here to enable this assert
+    // const auto wire_node_packed_ranges_size = wire_node->attributes[UhdmAst::packed_ranges()]->children.size();
+    // const auto wire_node_ranges_size = wire_node_packed_ranges_size + wire_node_unpacked_ranges_size;
+    // log_assert(struct_ranges.size() == (wire_node_ranges_size - 1));
+
+    // Get size of single structure
+    int struct_size_int = get_max_offset_struct(struct_node) + 1;
+    // Get reverse iterator of wire dimensions
+    auto dimensions_it = wire_node->multirange_dimensions.rbegin();
+    unsigned long range_id = 0;
+    for (auto it = struct_ranges.rbegin(); it != struct_ranges.rend(); it++) {
+        // in 'dot' context, we need to select specific struct
+        // element, so assert that there is only 1 child (range with single const) in struct
+        log_assert((*it)->children.size() == 1);
+        bool is_unpacked_range = range_id < wire_node_unpacked_ranges_size;
+        // if unpacked range, select from back;
+        auto elem = is_unpacked_range
+                      ? new AST::AstNode(AST::AST_SUB, AST::AstNode::mkconst_int(*dimensions_it - 1, true, 32), (*it)->children[0]->clone())
+                      : (*it)->children[0]->clone();
+        // calculate which struct we selected
+        auto move_offset = new AST::AstNode(AST::AST_MUL, AST::AstNode::mkconst_int(struct_size_int, true, 32), elem);
+        // move our expanded dot to currently selected struct
+        expanded->children[0] = new AST::AstNode(AST::AST_ADD, move_offset->clone(), expanded->children[0]);
+        expanded->children[1] = new AST::AstNode(AST::AST_ADD, move_offset, expanded->children[1]);
+        // next range, multiply struct_size_int by whole dimension size
+        struct_size_int *= *dimensions_it;
+        // move iterator to next dimension width
+        dimensions_it += 2;
+        range_id++;
+    }
     return expanded;
 }