Prevent deopt on double value assignment to typed arrays

src/ia32/lithium-ia32.cc

 // Copyright 2011 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 1666 matching lines @@
   if (from.IsTagged()) {
     if (to.IsDouble()) {
       LOperand* value = UseRegister(instr->value());
       LNumberUntagD* res = new LNumberUntagD(value);
       return AssignEnvironment(DefineAsRegister(res));
     } else {
       ASSERT(to.IsInteger32());
       LOperand* value = UseRegister(instr->value());
       bool needs_check = !instr->value()->type().IsSmi();
       if (needs_check) {
+        bool truncating = instr->CanTruncateToInt32();
         LOperand* xmm_temp =
-            (instr->CanTruncateToInt32() && CpuFeatures::IsSupported(SSE3))
+            (truncating && CpuFeatures::IsSupported(SSE3))
             ? NULL
             : FixedTemp(xmm1);
         LTaggedToI* res = new LTaggedToI(value, xmm_temp);
         return AssignEnvironment(DefineSameAsFirst(res));
       } else {
         return DefineSameAsFirst(new LSmiUntag(value, needs_check));
       }
     }
   } else if (from.IsDouble()) {
     if (to.IsTagged()) {
       LOperand* value = UseRegister(instr->value());
       LOperand* temp = TempRegister();
 
       // Make sure that temp and result_temp are different registers.
       LUnallocated* result_temp = TempRegister();
       LNumberTagD* result = new LNumberTagD(value, temp);
       return AssignPointerMap(Define(result, result_temp));
     } else {
       ASSERT(to.IsInteger32());
-      bool needs_temp = instr->CanTruncateToInt32() &&
-          !CpuFeatures::IsSupported(SSE3);
+      bool truncating = instr->CanTruncateToInt32();
+      bool needs_temp = truncating && !CpuFeatures::IsSupported(SSE3);
       LOperand* value = needs_temp ?
           UseTempRegister(instr->value()) : UseRegister(instr->value());
       LOperand* temp = needs_temp ? TempRegister() : NULL;
       return AssignEnvironment(DefineAsRegister(new LDoubleToI(value, temp)));
     }
   } else if (from.IsInteger32()) {
     if (to.IsTagged()) {
       HValue* val = instr->value();
       LOperand* value = UseRegister(val);
       if (val->HasRange() && val->range()->IsInSmiRange()) {
@@ skipping 66 matching lines @@
     LOperand* reg = UseFixed(value, eax);
     // Register allocator doesn't (yet) support allocation of double
     // temps. Reserve xmm1 explicitly.
     LOperand* temp = FixedTemp(xmm1);
     LClampTToUint8* result = new LClampTToUint8(reg, temp);
     return AssignEnvironment(DefineFixed(result, eax));
   }
 }
 
 
+LInstruction* LChunkBuilder::DoToInt32(HToInt32* instr) {
+  HValue* value = instr->value();
+  Representation input_rep = value->representation();
+  if (input_rep.IsDouble()) {
+    LOperand* reg = UseRegister(value);
+    // Register allocator doesn't (yet) support allocation of double
+    // temps. Reserve xmm1 explicitly.
+    LOperand* xmm_temp =

[Kevin Millikin (Chromium), 2011/05/26 07:53:37]

Some of this code can be lifted out of the if (the allocation of xmm_temp
before, and possibly AssignEnvironment after depending on your taste.

[danno, 2011/06/01 13:14:41]

Done.

+        CpuFeatures::IsSupported(SSE3)
+        ? NULL
+        : FixedTemp(xmm1);
+    return AssignEnvironment(
+        DefineAsRegister(new LDoubleToI(reg, xmm_temp)));
+  } else if (input_rep.IsInteger32()) {
+    // Canonicalization should already have removed the hydrogen instruction in
+    // this case, since it is a noop.
+    UNREACHABLE();
+    return NULL;
+  } else {
+    ASSERT(input_rep.IsTagged());
+    LOperand* reg = UseRegister(value);
+    // Register allocator doesn't (yet) support allocation of double
+    // temps. Reserve xmm1 explicitly.
+    LOperand* xmm_temp =
+        CpuFeatures::IsSupported(SSE3)
+        ? NULL
+        : FixedTemp(xmm1);
+    return AssignEnvironment(
+        DefineSameAsFirst(new LTaggedToI(reg, xmm_temp)));
+  }
+}
+
+
 LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
   return new LReturn(UseFixed(instr->value(), eax));
 }
 
 
 LInstruction* LChunkBuilder::DoConstant(HConstant* instr) {
   Representation r = instr->representation();
   if (r.IsInteger32()) {
     return DefineAsRegister(new LConstantI);
   } else if (r.IsDouble()) {
@@ skipping 446 matching lines @@
   LOperand* key = UseOrConstantAtStart(instr->key());
   LOperand* object = UseOrConstantAtStart(instr->object());
   LIn* result = new LIn(key, object);
   return MarkAsCall(DefineFixed(result, eax), instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32