Some improvements in register usage in lithium compilation of LoadKeyed/StoreKeyed operations.

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 1826 matching lines @@
     HLoadExternalArrayPointer* instr) {
   LOperand* input = UseRegisterAtStart(instr->value());
   return DefineAsRegister(new(zone()) LLoadExternalArrayPointer(input));
 }
 
 
 LInstruction* LChunkBuilder::DoLoadKeyed(HLoadKeyed* instr) {
   ASSERT(instr->key()->representation().IsInteger32() ||
          instr->key()->representation().IsTagged());
   ElementsKind elements_kind = instr->elements_kind();
-  bool clobbers_key = instr->key()->representation().IsTagged();
+  bool clobbers_key = ArrayOpClobbersKey<HLoadKeyed>(instr);
   LOperand* key = clobbers_key
       ? UseTempRegister(instr->key())
       : UseRegisterOrConstantAtStart(instr->key());
-  LLoadKeyed* result = NULL;
+  LOperand* elements = UseRegisterAtStart(instr->elements());
+  LLoadKeyed* result = new(zone()) LLoadKeyed(elements, key);
 
-  if (!instr->is_external()) {
-    LOperand* obj = UseRegisterAtStart(instr->elements());
-    result = new(zone()) LLoadKeyed(obj, key);
-  } else {
+#ifdef DEBUG
+  if (instr->is_external()) {
     ASSERT(
         (instr->representation().IsInteger32() &&
          (elements_kind != EXTERNAL_FLOAT_ELEMENTS) &&
          (elements_kind != EXTERNAL_DOUBLE_ELEMENTS)) ||
         (instr->representation().IsDouble() &&
          ((elements_kind == EXTERNAL_FLOAT_ELEMENTS) ||
           (elements_kind == EXTERNAL_DOUBLE_ELEMENTS))));
-    LOperand* external_pointer = UseRegister(instr->elements());
-    result = new(zone()) LLoadKeyed(external_pointer, key);
   }
+#endif
 
   DefineAsRegister(result);
   bool can_deoptimize = instr->RequiresHoleCheck() ||
       (elements_kind == EXTERNAL_UNSIGNED_INT_ELEMENTS);
   // An unsigned int array load might overflow and cause a deopt, make sure it
   // has an environment.
   return can_deoptimize ? AssignEnvironment(result) : result;
 }
 
 
 LInstruction* LChunkBuilder::DoLoadKeyedGeneric(HLoadKeyedGeneric* instr) {
   LOperand* object = UseFixed(instr->object(), rdx);
   LOperand* key = UseFixed(instr->key(), rax);
 
   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();
+  bool clobbers_key = ArrayOpClobbersKey<HStoreKeyed>(instr);
   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)
+  LOperand* val = needs_write_barrier
       ? UseTempRegister(instr->value())
       : UseRegisterAtStart(instr->value());
-  LStoreKeyed* result = NULL;
+  LOperand* elements = UseRegisterAtStart(instr->elements());
 
+#ifdef DEBUG
   if (!instr->is_external()) {
     ASSERT(instr->elements()->representation().IsTagged());
-
-    LOperand* object = NULL;
-    if (instr->value()->representation().IsDouble()) {
-      object = UseRegisterAtStart(instr->elements());
-    } else {
-      ASSERT(instr->value()->representation().IsTagged());
-      object = UseTempRegister(instr->elements());
-    }
-
-    result = new(zone()) LStoreKeyed(object, key, val);
   } else {
+    ElementsKind elements_kind = instr->elements_kind();
     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());
+  }
+#endif
 
-    LOperand* external_pointer = UseRegister(instr->elements());
-    result = new(zone()) LStoreKeyed(external_pointer, key, val);
-  }
-
+  LStoreKeyed* result = new(zone()) LStoreKeyed(elements, key, val);
   ASSERT(result != NULL);
   return result;
 }
 
 
 LInstruction* LChunkBuilder::DoStoreKeyedGeneric(HStoreKeyedGeneric* instr) {
   LOperand* object = UseFixed(instr->object(), rdx);
   LOperand* key = UseFixed(instr->key(), rcx);
   LOperand* value = UseFixed(instr->value(), rax);
 
@@ skipping 322 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