Fix performance regression in DXT5Decoder.js.

src/x64/lithium-x64.cc

 // Copyright 2012 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 1869 matching lines @@
 
   LLoadKeyedGeneric* result = new(zone()) LLoadKeyedGeneric(object, key);
   return MarkAsCall(DefineFixed(result, rax), instr);
 }
 
 
 LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
   ElementsKind elements_kind = instr->elements_kind();
   bool needs_write_barrier = instr->NeedsWriteBarrier();
   bool clobbers_key = instr->key()->representation().IsTagged();
-  LOperand* key = (clobbers_key || needs_write_barrier)
-      ? UseTempRegister(instr->key())
-      : UseRegisterOrConstantAtStart(instr->key());
-  bool val_is_temp_register =
-      elements_kind == EXTERNAL_PIXEL_ELEMENTS ||
-      elements_kind == EXTERNAL_FLOAT_ELEMENTS;
-  LOperand* val = (needs_write_barrier || val_is_temp_register)
-      ? UseTempRegister(instr->value())
-      : UseRegisterAtStart(instr->value());
   LStoreKeyed* result = NULL;
 
   if (!instr->is_external()) {
     ASSERT(instr->elements()->representation().IsTagged());
 
     LOperand* object = NULL;
+    LOperand* key = NULL;
+    LOperand* val = NULL;
     if (instr->value()->representation().IsDouble()) {
       object = UseRegisterAtStart(instr->elements());
+      val = UseTempRegister(instr->value());
+      key = clobbers_key ? UseTempRegister(instr->key())
+          : UseRegisterOrConstantAtStart(instr->key());
     } else {
       ASSERT(instr->value()->representation().IsTagged());
       object = UseTempRegister(instr->elements());
+      val = needs_write_barrier ? UseTempRegister(instr->value())
+          : UseRegisterAtStart(instr->value());
+      key = (clobbers_key || needs_write_barrier)
+          ? UseTempRegister(instr->key())
+          : UseRegisterOrConstantAtStart(instr->key());
     }
 
     result = new(zone()) LStoreKeyed(object, key, val);
   } else {
     ASSERT(
         (instr->value()->representation().IsInteger32() &&
          (elements_kind != EXTERNAL_FLOAT_ELEMENTS) &&
          (elements_kind != EXTERNAL_DOUBLE_ELEMENTS)) ||
         (instr->value()->representation().IsDouble() &&
          ((elements_kind == EXTERNAL_FLOAT_ELEMENTS) ||
           (elements_kind == EXTERNAL_DOUBLE_ELEMENTS))));
     ASSERT(instr->elements()->representation().IsExternal());
-
+    bool val_is_temp_register =
+        elements_kind == EXTERNAL_PIXEL_ELEMENTS ||
+        elements_kind == EXTERNAL_FLOAT_ELEMENTS;
+    LOperand* val = val_is_temp_register ? UseTempRegister(instr->value())
+        : UseRegister(instr->value());
+    LOperand* key = clobbers_key ? UseTempRegister(instr->key())
+        : UseRegisterOrConstantAtStart(instr->key());
     LOperand* external_pointer = UseRegister(instr->elements());
     result = new(zone()) LStoreKeyed(external_pointer, key, val);
   }
 
   ASSERT(result != NULL);
   return result;
 }
 
 
 LInstruction* LChunkBuilder::DoStoreKeyedGeneric(HStoreKeyedGeneric* instr) {
@@ skipping 326 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64