[x86] Improve code generation for context materialization.

src/compiler/x64/code-generator-x64.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/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/scopes.h"
@@ skipping 1291 matching lines @@
           __ Move(dst,
                   isolate()->factory()->NewNumber(src.ToFloat32(), TENURED));
           break;
         case Constant::kFloat64:
           __ Move(dst,
                   isolate()->factory()->NewNumber(src.ToFloat64(), TENURED));
           break;
         case Constant::kExternalReference:
           __ Move(dst, src.ToExternalReference());
           break;
-        case Constant::kHeapObject:
-          __ Move(dst, src.ToHeapObject());
+        case Constant::kHeapObject: {
+          Handle<HeapObject> src_object = src.ToHeapObject();
+          if (info()->IsOptimizing() &&
+              src_object.is_identical_to(info()->context())) {
+            // Loading the context from the frame is way cheaper than
+            // materializing the actual context heap object address.
+            __ movp(dst, Operand(rbp, StandardFrameConstants::kContextOffset));
+          } else {
+            __ Move(dst, src_object);
+          }
           break;
+        }
         case Constant::kRpoNumber:
           UNREACHABLE();  // TODO(dcarney): load of labels on x64.
           break;
       }
       if (destination->IsStackSlot()) {
         __ movq(g.ToOperand(destination), kScratchRegister);
       }
     } else if (src.type() == Constant::kFloat32) {
       // TODO(turbofan): Can we do better here?
       uint32_t src_const = bit_cast<uint32_t>(src.ToFloat32());
@@ skipping 110 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8