[x86] Support immediate indices for StoreWriteBarrier.

src/compiler/ia32/code-generator-ia32.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/ia32/assembler-ia32.h"
@@ skipping 772 matching lines @@
     }
     case kIA32Push:
       if (HasImmediateInput(instr, 0)) {
         __ push(i.InputImmediate(0));
       } else {
         __ push(i.InputOperand(0));
       }
       break;
     case kIA32StoreWriteBarrier: {
       Register object = i.InputRegister(0);
-      Register index = i.InputRegister(1);
       Register value = i.InputRegister(2);
-      __ mov(Operand(object, index, times_1, 0), value);
-      __ lea(index, Operand(object, index, times_1, 0));
       SaveFPRegsMode mode =
           frame()->DidAllocateDoubleRegisters() ? kSaveFPRegs : kDontSaveFPRegs;
-      __ RecordWrite(object, index, value, mode);
+      if (HasImmediateInput(instr, 1)) {
+        int index = i.InputInt32(1);
+        Register scratch = i.TempRegister(1);
+        __ mov(Operand(object, index), value);
+        __ RecordWriteContextSlot(object, index, value, scratch, mode);
+      } else {
+        Register index = i.InputRegister(1);
+        __ mov(Operand(object, index, times_1, 0), value);
+        __ lea(index, Operand(object, index, times_1, 0));
+        __ RecordWrite(object, index, value, mode);
+      }
       break;
     }
     case kCheckedLoadInt8:
       ASSEMBLE_CHECKED_LOAD_INTEGER(movsx_b);
       break;
     case kCheckedLoadUint8:
       ASSEMBLE_CHECKED_LOAD_INTEGER(movzx_b);
       break;
     case kCheckedLoadInt16:
       ASSEMBLE_CHECKED_LOAD_INTEGER(movsx_w);
@@ skipping 627 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8