[hydrogen] don't bailout assignments to consts

src/x64/lithium-codegen-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2051 matching lines @@
   CallCode(ic, RelocInfo::CODE_TARGET_CONTEXT, instr);
 }
 
 
 void LCodeGen::DoLoadContextSlot(LLoadContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
   __ movq(result, ContextOperand(context, instr->slot_index()));
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ CompareRoot(result, Heap::kTheHoleValueRootIndex);
-    DeoptimizeIf(equal, instr->environment());
+    if (instr->hydrogen()->DeoptimizesOnHole()) {
+      DeoptimizeIf(equal, instr->environment());
+    } else {
+      Label is_not_hole;
+      __ j(not_equal, &is_not_hole, Label::kNear);
+
+      __ movq(result, factory()->undefined_value(), RelocInfo::NONE);
+
+      __ bind(&is_not_hole);
+    }
   }
 }
 
 
 void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register value = ToRegister(instr->value());
+
   Operand target = ContextOperand(context, instr->slot_index());
+
+  Label skip_assignment;
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ CompareRoot(target, Heap::kTheHoleValueRootIndex);
-    DeoptimizeIf(equal, instr->environment());
+    if (instr->hydrogen()->DeoptimizesOnHole()) {
+      DeoptimizeIf(equal, instr->environment());
+    } else {
+      __ j(not_equal, &skip_assignment, Label::kNear);
+    }
   }
   __ movq(target, value);
+
   if (instr->hydrogen()->NeedsWriteBarrier()) {
     HType type = instr->hydrogen()->value()->type();
     SmiCheck check_needed =
         type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     int offset = Context::SlotOffset(instr->slot_index());
     Register scratch = ToRegister(instr->TempAt(0));
     __ RecordWriteContextSlot(context,
                               offset,
                               value,
                               scratch,
                               kSaveFPRegs,
                               EMIT_REMEMBERED_SET,
                               check_needed);
   }
+
+  __ bind(&skip_assignment);
 }
 
 
 void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
   Register object = ToRegister(instr->InputAt(0));
   Register result = ToRegister(instr->result());
   if (instr->hydrogen()->is_in_object()) {
     __ movq(result, FieldOperand(object, instr->hydrogen()->offset()));
   } else {
     __ movq(result, FieldOperand(object, JSObject::kPropertiesOffset));
@@ skipping 2207 matching lines @@
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64