[wasm] Use vector for states in Int64Lowering

Using a map to store node states in Int64Lowering has proven slow.
Therefore, we change the data structure to a vector indexed by node ids.

Bug: v8:12166, chromium:1271179
Change-Id: I13b78091fe1a6a13c26afd706d3839b0c04390f4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3291308Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77971}

src/compiler/int64-lowering.cc

@@ -31,7 +31,7 @@ Int64Lowering::Int64Lowering(
       machine_(machine),
       common_(common),
       simplified_(simplified),
-      state_(),
+      state_(graph->NodeCount(), State::kUnvisited),
       stack_(zone),
       replacements_(nullptr),
       signature_(signature),
@@ -48,21 +48,19 @@ void Int64Lowering::LowerGraph() {
     return;
   }
   stack_.push_back({graph()->end(), 0});
-  state_[graph()->end()] = State::kOnStack;
+  state_[graph()->end()->id()] = State::kOnStack;
 
   while (!stack_.empty()) {
     NodeState& top = stack_.back();
     if (top.input_index == top.node->InputCount()) {
       // All inputs of top have already been lowered, now lower top.
       stack_.pop_back();
-      state_[top.node] = State::kVisited;
+      state_[top.node->id()] = State::kVisited;
       LowerNode(top.node);
     } else {
       // Push the next input onto the stack.
       Node* input = top.node->InputAt(top.input_index++);
-      static_assert(State() == State::kUnvisited,
-                    "Default value for State has to be kUnvisited");
-      if (state_[input] == State::kUnvisited) {
+      if (state_[input->id()] == State::kUnvisited) {
         if (input->opcode() == IrOpcode::kPhi) {
           // To break cycles with phi nodes we push phis on a separate stack so
           // that they are processed after all other nodes.
@@ -74,7 +72,7 @@ void Int64Lowering::LowerGraph() {
         } else {
           stack_.push_back({input, 0});
         }
-        state_[input] = State::kOnStack;
+        state_[input->id()] = State::kOnStack;
       }
     }
   }

src/compiler/int64-lowering.h

@@ -93,7 +93,7 @@ class V8_EXPORT_PRIVATE Int64Lowering {
   MachineOperatorBuilder* machine_;
   CommonOperatorBuilder* common_;
   SimplifiedOperatorBuilder* simplified_;
-  std::unordered_map<Node*, State> state_;
+  std::vector<State> state_;
   ZoneDeque<NodeState> stack_;
   Replacement* replacements_;
   Signature<MachineRepresentation>* signature_;