[turbofan] Implement proper caching of heap constants in the JSGraph.

src/compiler/js-graph.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/code-stubs.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/typer.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-Node* JSGraph::ImmovableHeapConstant(Handle<HeapObject> value) {
-  // TODO(bmeurer): Flatten cons strings here before we canonicalize them?
-  return graph()->NewNode(common()->HeapConstant(value));
-}
-
-
 #define CACHED(name, expr) \
   cached_nodes_[name] ? cached_nodes_[name] : (cached_nodes_[name] = (expr))
 
 
 Node* JSGraph::CEntryStubConstant(int result_size) {
   if (result_size == 1) {
     return CACHED(kCEntryStubConstant,
-                  ImmovableHeapConstant(CEntryStub(isolate(), 1).GetCode()));
+                  HeapConstant(CEntryStub(isolate(), 1).GetCode()));
   }
-  return ImmovableHeapConstant(CEntryStub(isolate(), result_size).GetCode());
+  return HeapConstant(CEntryStub(isolate(), result_size).GetCode());
 }
 
 
 Node* JSGraph::EmptyFixedArrayConstant() {
   return CACHED(kEmptyFixedArrayConstant,
-                ImmovableHeapConstant(factory()->empty_fixed_array()));
+                HeapConstant(factory()->empty_fixed_array()));
 }
 
 
 Node* JSGraph::UndefinedConstant() {
-  return CACHED(kUndefinedConstant,
-                ImmovableHeapConstant(factory()->undefined_value()));
+  return CACHED(kUndefinedConstant, HeapConstant(factory()->undefined_value()));
 }
 
 
 Node* JSGraph::TheHoleConstant() {
-  return CACHED(kTheHoleConstant,
-                ImmovableHeapConstant(factory()->the_hole_value()));
+  return CACHED(kTheHoleConstant, HeapConstant(factory()->the_hole_value()));
 }
 
 
 Node* JSGraph::TrueConstant() {
-  return CACHED(kTrueConstant, ImmovableHeapConstant(factory()->true_value()));
+  return CACHED(kTrueConstant, HeapConstant(factory()->true_value()));
 }
 
 
 Node* JSGraph::FalseConstant() {
-  return CACHED(kFalseConstant,
-                ImmovableHeapConstant(factory()->false_value()));
+  return CACHED(kFalseConstant, HeapConstant(factory()->false_value()));
 }
 
 
 Node* JSGraph::NullConstant() {
-  return CACHED(kNullConstant, ImmovableHeapConstant(factory()->null_value()));
+  return CACHED(kNullConstant, HeapConstant(factory()->null_value()));
 }
 
 
 Node* JSGraph::ZeroConstant() {
   return CACHED(kZeroConstant, NumberConstant(0.0));
 }
 
 
 Node* JSGraph::OneConstant() {
   return CACHED(kOneConstant, NumberConstant(1.0));
 }
 
 
 Node* JSGraph::NaNConstant() {
   return CACHED(kNaNConstant,
                 NumberConstant(std::numeric_limits<double>::quiet_NaN()));
 }
 
 
 Node* JSGraph::HeapConstant(Handle<HeapObject> value) {
-  // TODO(turbofan): canonicalize heap constants using <magic approach>.
-  // TODO(titzer): We could also match against the addresses of immortable
-  // immovables here, even without access to the heap, thus always
-  // canonicalizing references to them.
-  return ImmovableHeapConstant(value);
+  // TODO(bmeurer): Flatten cons strings here before we canonicalize them?
+  Node** loc = cache_.FindHeapConstant(value);
+  if (*loc == nullptr) {
+    *loc = graph()->NewNode(common()->HeapConstant(value));
+  }
+  return *loc;
 }
 
 
 Node* JSGraph::Constant(Handle<Object> value) {
   // Dereference the handle to determine if a number constant or other
   // canonicalized node can be used.
   if (value->IsNumber()) {
     return Constant(value->Number());
   } else if (value->IsUndefined()) {
     return UndefinedConstant();
@@ skipping 109 matching lines @@
   for (size_t i = 0; i < arraysize(cached_nodes_); i++) {
     if (Node* node = cached_nodes_[i]) {
       if (!node->IsDead()) nodes->push_back(node);
     }
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8