[crankshaft] Get rid of the StoreFrameContext instruction.

src/crankshaft/hydrogen.cc

 // Copyright 2013 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/crankshaft/hydrogen.h"
 
 #include <sstream>
 
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast-numbering.h"
@@ skipping 4681 matching lines @@
         } else {
           function = New<HThisFunction>();
         }
         AddInstruction(function);
         // Allocate a block context and store it to the stack frame.
         HValue* scope_info = Add<HConstant>(scope->GetScopeInfo(isolate()));
         Add<HPushArguments>(scope_info, function);
         HInstruction* inner_context = Add<HCallRuntime>(
             Runtime::FunctionForId(Runtime::kPushBlockContext), 2);
         inner_context->SetFlag(HValue::kHasNoObservableSideEffects);
-        HInstruction* instr = Add<HStoreFrameContext>(inner_context);
         set_scope(scope);
         environment()->BindContext(inner_context);
-        if (instr->HasObservableSideEffects()) {
-          AddSimulate(stmt->EntryId(), REMOVABLE_SIMULATE);

[Benedikt Meurer, 2016/03/30 07:07:56]

Please also remove this BailoutId from the Statement if it's never used.

-        }
       }
       VisitDeclarations(scope->declarations());
       AddSimulate(stmt->DeclsId(), REMOVABLE_SIMULATE);
     }
     CHECK_BAILOUT(VisitStatements(stmt->statements()));
   }
   set_scope(outer_scope);
   if (scope != NULL && current_block() != NULL &&
       scope->ContextLocalCount() > 0) {
     HValue* inner_context = environment()->context();
     HValue* outer_context = Add<HLoadNamedField>(
         inner_context, nullptr,
         HObjectAccess::ForContextSlot(Context::PREVIOUS_INDEX));
 
-    HInstruction* instr = Add<HStoreFrameContext>(outer_context);
     environment()->BindContext(outer_context);
-    if (instr->HasObservableSideEffects()) {
-      AddSimulate(stmt->ExitId(), REMOVABLE_SIMULATE);

[Benedikt Meurer, 2016/03/30 07:07:56]

Please also remove this BailoutId from the Statement if it's never used.

-    }
   }
   HBasicBlock* break_block = break_info.break_block();
   if (break_block != NULL) {
     if (current_block() != NULL) Goto(break_block);
     break_block->SetJoinId(stmt->ExitId());
     set_current_block(break_block);
   }
 }
 
 
@@ skipping 119 matching lines @@
   HValue* context = environment()->context();
   Drop(drop_extra);
   int context_pop_count = inner_scope->ContextChainLength(outer_scope);
   if (context_pop_count > 0) {
     while (context_pop_count-- > 0) {
       HInstruction* context_instruction = Add<HLoadNamedField>(
           context, nullptr,
           HObjectAccess::ForContextSlot(Context::PREVIOUS_INDEX));
       context = context_instruction;
     }
-    HInstruction* instr = Add<HStoreFrameContext>(context);
-    if (instr->HasObservableSideEffects()) {
-      AddSimulate(stmt->target()->EntryId(), REMOVABLE_SIMULATE);
-    }
     environment()->BindContext(context);
   }
 
   Goto(continue_block);
   set_current_block(NULL);
 }
 
 
 void HOptimizedGraphBuilder::VisitBreakStatement(BreakStatement* stmt) {
   DCHECK(!HasStackOverflow());
@@ skipping 13 matching lines @@
   HValue* context = environment()->context();
   Drop(drop_extra);
   int context_pop_count = inner_scope->ContextChainLength(outer_scope);
   if (context_pop_count > 0) {
     while (context_pop_count-- > 0) {
       HInstruction* context_instruction = Add<HLoadNamedField>(
           context, nullptr,
           HObjectAccess::ForContextSlot(Context::PREVIOUS_INDEX));
       context = context_instruction;
     }
-    HInstruction* instr = Add<HStoreFrameContext>(context);
-    if (instr->HasObservableSideEffects()) {
-      AddSimulate(stmt->target()->ExitId(), REMOVABLE_SIMULATE);
-    }
     environment()->BindContext(context);
   }
   Goto(break_block);
   set_current_block(NULL);
 }
 
 
 void HOptimizedGraphBuilder::VisitReturnStatement(ReturnStatement* stmt) {
   DCHECK(!HasStackOverflow());
   DCHECK(current_block() != NULL);
@@ skipping 8670 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8