[turbofan] Allow unique or multiple control path states

Templetize ControlPathState on whether multiple states are allowed for the same node. Instantiate BranchElimination to allow a single state
per node, and WasmGCOperatorReducer to allow multiple.
This fixes a performance regression caused by crrev.com/c/3717994.

Bug: chromium:1339826
Change-Id: Id52d643daad618f45c3d8509f2a661e177609a0c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3754941
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81772}

src/compiler/branch-elimination.cc

@@ -52,10 +52,6 @@ Reduction BranchElimination::Reduce(Node* node) {
   }
 }
 
-namespace {
-using ControlPathConditions = ControlPathState<BranchCondition>;
-}
-
 void BranchElimination::SimplifyBranchCondition(Node* branch) {
   // Try to use a phi as a branch condition if the control flow from the branch
   // is known from previous branches. For example, in the graph below, the

src/compiler/branch-elimination.h

@@ -40,8 +40,8 @@ struct BranchCondition {
 };
 
 class V8_EXPORT_PRIVATE BranchElimination final
-    : public NON_EXPORTED_BASE(
-          AdvancedReducerWithControlPathState<BranchCondition>) {
+    : public NON_EXPORTED_BASE(AdvancedReducerWithControlPathState)<
+          BranchCondition, kUniqueInstance> {
  public:
   enum Phase {
     kEARLY,
@@ -56,6 +56,9 @@ class V8_EXPORT_PRIVATE BranchElimination final
   Reduction Reduce(Node* node) final;
 
  private:
+  using ControlPathConditions =
+      ControlPathState<BranchCondition, kUniqueInstance>;
+
   Reduction ReduceBranch(Node* node);
   Reduction ReduceDeoptimizeConditional(Node* node);
   Reduction ReduceIf(Node* node, bool is_true_branch);
@@ -65,10 +68,10 @@ class V8_EXPORT_PRIVATE BranchElimination final
   Reduction ReduceStart(Node* node);
   Reduction ReduceOtherControl(Node* node);
   void SimplifyBranchCondition(Node* branch);
-  Reduction UpdateStatesHelper(
-      Node* node, ControlPathState<BranchCondition> prev_conditions,
-      Node* current_condition, Node* current_branch, bool is_true_branch,
-      bool in_new_block) {
+  Reduction UpdateStatesHelper(Node* node,
+                               ControlPathConditions prev_conditions,
+                               Node* current_condition, Node* current_branch,
+                               bool is_true_branch, bool in_new_block) {
     return UpdateStates(
         node, prev_conditions, current_condition,
         BranchCondition(current_condition, current_branch, is_true_branch),

src/compiler/wasm-gc-operator-reducer.h

@@ -40,7 +40,8 @@ struct NodeWithType {
 // arguments. Although types have been assigned to nodes already, this class
 // also tracks additional type information along control paths.
 class WasmGCOperatorReducer final
-    : public AdvancedReducerWithControlPathState<NodeWithType> {
+    : public AdvancedReducerWithControlPathState<NodeWithType,
+                                                 kMultipleInstances> {
  public:
   WasmGCOperatorReducer(Editor* editor, Zone* temp_zone_, MachineGraph* mcgraph,
                         const wasm::WasmModule* module);
@@ -50,7 +51,7 @@ class WasmGCOperatorReducer final
   Reduction Reduce(Node* node) final;
 
  private:
-  using ControlPathTypes = ControlPathState<NodeWithType>;
+  using ControlPathTypes = ControlPathState<NodeWithType, kMultipleInstances>;
 
   Reduction ReduceAssertNotNull(Node* node);
   Reduction ReduceCheckNull(Node* node);