Optionally use 31-bits SMI value for 64-bit system

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 699 matching lines @@
   }
 
   ASSERT(instr->representation().IsSmiOrInteger32());
   ASSERT(instr->left()->representation().Equals(instr->representation()));
   ASSERT(instr->right()->representation().Equals(instr->representation()));
   LOperand* left = UseRegisterAtStart(instr->left());
 
   HValue* right_value = instr->right();
   LOperand* right = NULL;
   int constant_value = 0;
+  bool does_deopt = false;
   if (right_value->IsConstant()) {
     HConstant* constant = HConstant::cast(right_value);
     right = chunk_->DefineConstantOperand(constant);
     constant_value = constant->Integer32Value() & 0x1f;
+    if (SmiValuesAre31Bits() && instr->representation().IsSmi() &&
+        constant_value > 0) {
+      // Left shifts can deoptimize if we shift by > 0 and the result cannot be
+      // truncated to smi.
+      for (HUseIterator it(instr->uses()); !it.Done(); it.Advance()) {
+        if (!it.value()->CheckFlag(HValue::kTruncatingToSmi)) {
+          does_deopt = true;
+          break;
+        }
+      }
+    }
   } else {
     right = UseFixed(right_value, rcx);
   }
 
   // Shift operations can only deoptimize if we do a logical shift by 0 and
   // the result cannot be truncated to int32.
-  bool does_deopt = false;
   if (op == Token::SHR && constant_value == 0) {
     if (FLAG_opt_safe_uint32_operations) {
       does_deopt = !instr->CheckFlag(HInstruction::kUint32);
     } else {
       for (HUseIterator it(instr->uses()); !it.Done(); it.Advance()) {
         if (!it.value()->CheckFlag(HValue::kTruncatingToInt32)) {
           does_deopt = true;
           break;
         }
       }
@@ skipping 1107 matching lines @@
     if (to.IsTagged()) {
       HValue* val = instr->value();
       LOperand* value = UseRegister(val);
       if (val->CheckFlag(HInstruction::kUint32)) {
         LOperand* temp = FixedTemp(xmm1);
         LNumberTagU* result = new(zone()) LNumberTagU(value, temp);
         return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
       } else if (val->HasRange() && val->range()->IsInSmiRange()) {
         return DefineSameAsFirst(new(zone()) LSmiTag(value));
       } else {
-        LNumberTagI* result = new(zone()) LNumberTagI(value);
+        LOperand* temp = (SmiValuesAre31Bits()) ? FixedTemp(xmm1) : NULL;
+        LNumberTagI* result = new(zone()) LNumberTagI(value, temp);
         return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
       }
     } else if (to.IsSmi()) {
       HValue* val = instr->value();
       LOperand* value = UseRegister(val);
       LInstruction* result =
           DefineAsRegister(new(zone()) LInteger32ToSmi(value));
       if (val->HasRange() && val->range()->IsInSmiRange()) {
         return result;
       }
@@ skipping 212 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoLoadExternalArrayPointer(
     HLoadExternalArrayPointer* instr) {
   LOperand* input = UseRegisterAtStart(instr->value());
   return DefineAsRegister(new(zone()) LLoadExternalArrayPointer(input));
 }
 
 
 LInstruction* LChunkBuilder::DoLoadKeyed(HLoadKeyed* instr) {
-  ASSERT(instr->key()->representation().IsInteger32());
+  ASSERT((SmiValuesAre32Bits() &&
+          instr->key()->representation().IsInteger32()) ||
+         (SmiValuesAre31Bits() &&
+          instr->key()->representation().IsSmiOrInteger32()));
   ElementsKind elements_kind = instr->elements_kind();
-  LOperand* key = UseRegisterOrConstantAtStart(instr->key());
+  bool clobbers_key = instr->key()->representation().IsSmi();
+  LOperand* key = clobbers_key
+      ? UseTempRegister(instr->key())
+      : UseRegisterOrConstantAtStart(instr->key());
   LLoadKeyed* result = NULL;
 
   if (!instr->is_external()) {
     LOperand* obj = UseRegisterAtStart(instr->elements());
     result = new(zone()) LLoadKeyed(obj, key);
   } else {
     ASSERT(
         (instr->representation().IsInteger32() &&
          (elements_kind != EXTERNAL_FLOAT_ELEMENTS) &&
          (elements_kind != EXTERNAL_DOUBLE_ELEMENTS)) ||
@@ skipping 17 matching lines @@
   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 clobbers_key = instr->key()->representation().IsSmi();
 
   if (!instr->is_external()) {
     ASSERT(instr->elements()->representation().IsTagged());
     bool needs_write_barrier = instr->NeedsWriteBarrier();
     LOperand* object = NULL;
     LOperand* key = NULL;
     LOperand* val = NULL;
 
     if (instr->value()->representation().IsDouble()) {
       object = UseRegisterAtStart(instr->elements());
       val = UseTempRegister(instr->value());
-      key = UseRegisterOrConstantAtStart(instr->key());
+      key = clobbers_key ? UseTempRegister(instr->key())
+          : UseRegisterOrConstantAtStart(instr->key());
     } else {
       ASSERT(instr->value()->representation().IsSmiOrTagged());
       object = UseTempRegister(instr->elements());
       if (needs_write_barrier) {
         val = UseTempRegister(instr->value());
         key = UseTempRegister(instr->key());
       } else {
         val = UseRegisterOrConstantAtStart(instr->value());
-        key = UseRegisterOrConstantAtStart(instr->key());
+        key = clobbers_key ? UseTempRegister(instr->key())
+            : UseRegisterOrConstantAtStart(instr->key());
       }
     }
 
     return new(zone()) LStoreKeyed(object, key, val);
   }
 
   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 = UseRegisterOrConstantAtStart(instr->key());
+  LOperand* key = clobbers_key ? UseTempRegister(instr->key())
+      : UseRegisterOrConstantAtStart(instr->key());
   LOperand* external_pointer = UseRegister(instr->elements());
   return new(zone()) LStoreKeyed(external_pointer, key, val);
 }
 
 
 LInstruction* LChunkBuilder::DoStoreKeyedGeneric(HStoreKeyedGeneric* instr) {
   LOperand* object = UseFixed(instr->object(), rdx);
   LOperand* key = UseFixed(instr->key(), rcx);
   LOperand* value = UseFixed(instr->value(), rax);
 
@@ skipping 345 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