Refactor lookahead caching to hide cache key's.
Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>
diff --git a/libs/libvtrutil/src/vtr_cache.h b/libs/libvtrutil/src/vtr_cache.h
new file mode 100644
index 0000000..d1496d2
--- /dev/null
+++ b/libs/libvtrutil/src/vtr_cache.h
@@ -0,0 +1,44 @@
+#ifndef VTR_CACHE_H_
+#define VTR_CACHE_H_
+
+#include <memory>
+
+namespace vtr {
+
+// Simple cache
+template<typename CacheKey, typename CacheValue>
+class Cache {
+ public:
+ // Clear cache.
+ void clear() {
+ key_ = CacheKey();
+ value_.reset();
+ }
+
+ // Check if the cache is valid, and return the cached value if present and valid.
+ //
+ // Returns nullptr if the cache is invalid.
+ const CacheValue* get(const CacheKey& key) const {
+ if (key == key_ && value_) {
+ return value_.get();
+ } else {
+ return nullptr;
+ }
+ }
+
+ // Update the cache.
+ const CacheValue* set(const CacheKey& key, std::unique_ptr<CacheValue> value) {
+ key_ = key;
+ value_ = std::move(value);
+
+ return value_.get();
+ }
+
+ private:
+ CacheKey key_;
+ std::unique_ptr<CacheValue> value_;
+};
+
+} // namespace vtr
+
+#endif
diff --git a/vpr/src/base/vpr_context.h b/vpr/src/base/vpr_context.h
index d348c09..6ed3bca 100644
--- a/vpr/src/base/vpr_context.h
+++ b/vpr/src/base/vpr_context.h
@@ -284,12 +284,11 @@
std::string routing_id;
// Cache of router lookahead object.
- std::unique_ptr<RouterLookahead> cached_router_lookahead_;
-
- // Parameters used for cached router lookahead object.
- e_router_lookahead cached_router_lookahead_type_;
- std::string cached_lookahead_file_;
- std::vector<t_segment_inf> cached_segment_inf_;
+ //
+ // Cache key: (lookahead type, read lookahead (if any), segment definitions).
+ vtr::Cache<std::tuple<e_router_lookahead, std::string, std::vector<t_segment_inf>>,
+ RouterLookahead>
+ cached_router_lookahead_;
};
//This object encapsulates VPR's state. There is typically a single instance which is
diff --git a/vpr/src/base/vpr_types.h b/vpr/src/base/vpr_types.h
index 82cd0ae..01dca22 100644
--- a/vpr/src/base/vpr_types.h
+++ b/vpr/src/base/vpr_types.h
@@ -38,6 +38,7 @@
#include "vtr_vector.h"
#include "vtr_util.h"
#include "vtr_flat_map.h"
+#include "vtr_cache.h"
/*******************************************************************************
* Global data types and constants
diff --git a/vpr/src/route/router_lookahead.cpp b/vpr/src/route/router_lookahead.cpp
index 1de12c1..130b862 100644
--- a/vpr/src/route/router_lookahead.cpp
+++ b/vpr/src/route/router_lookahead.cpp
@@ -196,9 +196,7 @@
void invalidate_router_lookahead_cache() {
auto& router_ctx = g_vpr_ctx.mutable_routing();
- router_ctx.cached_router_lookahead_.reset();
- router_ctx.cached_lookahead_file_.clear();
- router_ctx.cached_segment_inf_.clear();
+ router_ctx.cached_router_lookahead_.clear();
}
const RouterLookahead* get_cached_router_lookahead(
@@ -208,23 +206,22 @@
const std::vector<t_segment_inf>& segment_inf) {
auto& router_ctx = g_vpr_ctx.routing();
+ auto cache_key = std::make_tuple(router_lookahead_type, read_lookahead, segment_inf);
+
// Check if cache is valid.
- if (
- router_ctx.cached_router_lookahead_ && read_lookahead == router_ctx.cached_lookahead_file_ && segment_inf == router_ctx.cached_segment_inf_) {
+ const RouterLookahead* router_lookahead = router_ctx.cached_router_lookahead_.get(cache_key);
+ if (router_lookahead) {
+ return router_lookahead;
} else {
// Cache is not valid, compute cached object.
auto& mut_router_ctx = g_vpr_ctx.mutable_routing();
- invalidate_router_lookahead_cache();
-
- mut_router_ctx.cached_router_lookahead_ = make_router_lookahead(
- router_lookahead_type,
- write_lookahead,
- read_lookahead,
- segment_inf);
- mut_router_ctx.cached_lookahead_file_ = read_lookahead;
- mut_router_ctx.cached_segment_inf_ = segment_inf;
+ return mut_router_ctx.cached_router_lookahead_.set(
+ cache_key,
+ make_router_lookahead(
+ router_lookahead_type,
+ write_lookahead,
+ read_lookahead,
+ segment_inf));
}
-
- return router_ctx.cached_router_lookahead_.get();
}
