[x86] Support immediate indices for StoreWriteBarrier.

src/compiler/x64/instruction-selector-x64.cc

 // Copyright 2014 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 <algorithm>
 
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 136 matching lines @@
 
 void InstructionSelector::VisitStore(Node* node) {
   X64OperandGenerator g(this);
   Node* base = node->InputAt(0);
   Node* index = node->InputAt(1);
   Node* value = node->InputAt(2);
 
   StoreRepresentation store_rep = OpParameter<StoreRepresentation>(node);
   MachineType rep = RepresentationOf(store_rep.machine_type());
   if (store_rep.write_barrier_kind() == kFullWriteBarrier) {
-    DCHECK(rep == kRepTagged);
+    DCHECK_EQ(kRepTagged, rep);
     // TODO(dcarney): refactor RecordWrite function to take temp registers
     //                and pass them here instead of using fixed regs
-    // TODO(dcarney): handle immediate indices.
-    InstructionOperand temps[] = {g.TempRegister(rcx), g.TempRegister(rdx)};
-    Emit(kX64StoreWriteBarrier, g.NoOutput(), g.UseFixed(base, rbx),
-         g.UseFixed(index, rcx), g.UseFixed(value, rdx), arraysize(temps),
-         temps);
+    if (g.CanBeImmediate(index)) {
+      InstructionOperand temps[] = {g.TempRegister(rcx), g.TempRegister()};
+      Emit(kX64StoreWriteBarrier, g.NoOutput(), g.UseFixed(base, rbx),
+           g.UseImmediate(index), g.UseFixed(value, rcx), arraysize(temps),
+           temps);
+    } else {
+      InstructionOperand temps[] = {g.TempRegister(rcx), g.TempRegister(rdx)};
+      Emit(kX64StoreWriteBarrier, g.NoOutput(), g.UseFixed(base, rbx),
+           g.UseFixed(index, rcx), g.UseFixed(value, rdx), arraysize(temps),
+           temps);
+    }
     return;
   }
   DCHECK_EQ(kNoWriteBarrier, store_rep.write_barrier_kind());
+
   ArchOpcode opcode;
   switch (rep) {
     case kRepFloat32:
       opcode = kX64Movss;
       break;
     case kRepFloat64:
       opcode = kX64Movsd;
       break;
     case kRepBit:  // Fall through.
     case kRepWord8:
@@ skipping 1352 matching lines @@
   if (CpuFeatures::IsSupported(SSE4_1)) {
     flags |= MachineOperatorBuilder::kFloat64RoundDown |
              MachineOperatorBuilder::kFloat64RoundTruncate;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8