[turbofan]: Add a context relaxation Reducer

src/compiler/pipeline.cc

Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index 7ced8e67b261d83606059dbc4192dbdb6d4ada4a..3ee71db335b0d42e266dc27d9cc7f5761e3f9ae8 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -25,6 +25,7 @@
 #include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
 #include "src/compiler/js-builtin-reducer.h"
+#include "src/compiler/js-context-relaxation.h"
 #include "src/compiler/js-context-specialization.h"
 #include "src/compiler/js-generic-lowering.h"
 #include "src/compiler/js-inlining.h"
@@ -80,6 +81,7 @@ class PipelineData {
         javascript_(nullptr),
         jsgraph_(nullptr),
         js_type_feedback_(nullptr),
+        relaxed_context_(nullptr),
         schedule_(nullptr),
         instruction_zone_scope_(zone_pool_),
         instruction_zone_(instruction_zone_scope_.zone()),
@@ -191,6 +193,10 @@ class PipelineData {
   void set_js_type_feedback(JSTypeFeedbackTable* js_type_feedback) {
     js_type_feedback_ = js_type_feedback;
   }
+  Node* relaxed_context() const { return relaxed_context_; }
+  void set_relaxed_context(Node* relaxed_context) {
+    relaxed_context_ = relaxed_context;
+  }
 
   LoopAssignmentAnalysis* loop_assignment() const { return loop_assignment_; }
   void set_loop_assignment(LoopAssignmentAnalysis* loop_assignment) {
@@ -228,6 +234,7 @@ class PipelineData {
     jsgraph_ = nullptr;
     js_type_feedback_ = nullptr;
     schedule_ = nullptr;
+    relaxed_context_ = nullptr;
   }
 
   void DeleteInstructionZone() {
@@ -286,6 +293,7 @@ class PipelineData {
   JSOperatorBuilder* javascript_;
   JSGraph* jsgraph_;
   JSTypeFeedbackTable* js_type_feedback_;
+  Node* relaxed_context_;
   Schedule* schedule_;
 
   // All objects in the following group of fields are allocated in
@@ -379,6 +387,8 @@ class AstGraphBuilderWithPositions final : public AstGraphBuilder {
   AST_NODE_LIST(DEF_VISIT)
 #undef DEF_VISIT
 
+  using AstGraphBuilder::relaxed_context;
+
  private:
   SourcePositionTable* const source_positions_;
   SourcePosition const start_position_;
@@ -482,6 +492,7 @@ struct GraphBuilderPhase {
     if (!graph_builder.CreateGraph(constant_context, stack_check)) {
       data->set_compilation_failed();
     }
+    data->set_relaxed_context(graph_builder.relaxed_context());
   }
 };
 
@@ -690,6 +701,8 @@ struct GenericLoweringPhase {
 
   void Run(PipelineData* data, Zone* temp_zone) {
     JSGraphReducer graph_reducer(data->jsgraph(), temp_zone);
+    JSContextRelaxation relaxing(data->graph()->start(),
+                                 data->relaxed_context());
     DeadCodeElimination dead_code_elimination(&graph_reducer, data->graph(),
                                               data->common());
     CommonOperatorReducer common_reducer(&graph_reducer, data->graph(),
@@ -699,6 +712,7 @@ struct GenericLoweringPhase {
     SelectLowering select_lowering(data->jsgraph()->graph(),
                                    data->jsgraph()->common());
     TailCallOptimization tco(data->common(), data->graph());
+    AddReducer(data, &graph_reducer, &relaxing);
     AddReducer(data, &graph_reducer, &dead_code_elimination);
     AddReducer(data, &graph_reducer, &common_reducer);
     AddReducer(data, &graph_reducer, &generic_lowering);