Specialize GenericUnaryStub so that it knows whether it needs to...

src/ia32/codegen-ia32.cc

 // Copyright 2010 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 7565 matching lines @@
           // Unary plus has no effect on int32 values.
           break;
         }
         default:
           UNREACHABLE();
           break;
       }
       frame_->Push(&value);
     } else {
       Load(node->expression());
-      bool overwrite =
+      bool can_overwrite =
           (node->expression()->AsBinaryOperation() != NULL &&
            node->expression()->AsBinaryOperation()->ResultOverwriteAllowed());
+      UnaryOverwriteMode overwrite =
+          can_overwrite ? UNARY_OVERWRITE : UNARY_NO_OVERWRITE;
+      bool no_negative_zero = node->expression()->no_negative_zero();
       switch (op) {
         case Token::NOT:
         case Token::DELETE:
         case Token::TYPEOF:
           UNREACHABLE();  // handled above
           break;
 
         case Token::SUB: {
-          GenericUnaryOpStub stub(Token::SUB, overwrite);
+          GenericUnaryOpStub stub(
+              Token::SUB,
+              overwrite,
+              no_negative_zero ? kIgnoreNegativeZero : kStrictNegativeZero);
           Result operand = frame_->Pop();
           Result answer = frame_->CallStub(&stub, &operand);
           answer.set_type_info(TypeInfo::Number());
           frame_->Push(&answer);
           break;
         }
         case Token::BIT_NOT: {
           // Smi check.
           JumpTarget smi_label;
           JumpTarget continue_label;
@@ skipping 3319 matching lines @@
 
 void GenericUnaryOpStub::Generate(MacroAssembler* masm) {
   Label slow, done;
 
   if (op_ == Token::SUB) {
     // Check whether the value is a smi.
     Label try_float;
     __ test(eax, Immediate(kSmiTagMask));
     __ j(not_zero, &try_float, not_taken);
 
-    // Go slow case if the value of the expression is zero
-    // to make sure that we switch between 0 and -0.
-    __ test(eax, Operand(eax));
-    __ j(zero, &slow, not_taken);
+    if (negative_zero_ == kStrictNegativeZero) {
+      // Go slow case if the value of the expression is zero
+      // to make sure that we switch between 0 and -0.
+      __ test(eax, Operand(eax));
+      __ j(zero, &slow, not_taken);
+    }
 
     // The value of the expression is a smi that is not zero.  Try
     // optimistic subtraction '0 - value'.
     Label undo;
     __ mov(edx, Operand(eax));
     __ Set(eax, Immediate(0));
     __ sub(eax, Operand(edx));
-    __ j(overflow, &undo, not_taken);
-
-    // If result is a smi we are done.
-    __ test(eax, Immediate(kSmiTagMask));
-    __ j(zero, &done, taken);
+    __ j(no_overflow, &done, taken);
 
     // Restore eax and go slow case.
     __ bind(&undo);
     __ mov(eax, Operand(edx));
     __ jmp(&slow);
 
     // Try floating point case.
     __ bind(&try_float);
     __ mov(edx, FieldOperand(eax, HeapObject::kMapOffset));
     __ cmp(edx, Factory::heap_number_map());
     __ j(not_equal, &slow);
-    if (overwrite_) {
+    if (overwrite_ == UNARY_OVERWRITE) {
       __ mov(edx, FieldOperand(eax, HeapNumber::kExponentOffset));
       __ xor_(edx, HeapNumber::kSignMask);  // Flip sign.
       __ mov(FieldOperand(eax, HeapNumber::kExponentOffset), edx);
     } else {
       __ mov(edx, Operand(eax));
       // edx: operand
       __ AllocateHeapNumber(eax, ebx, ecx, &undo);
       // eax: allocated 'empty' number
       __ mov(ecx, FieldOperand(edx, HeapNumber::kExponentOffset));
       __ xor_(ecx, HeapNumber::kSignMask);  // Flip sign.
@@ skipping 20 matching lines @@
     __ cmp(ecx, 0xc0000000);
     __ j(sign, &try_float, not_taken);
 
     // Tag the result as a smi and we're done.
     ASSERT(kSmiTagSize == 1);
     __ lea(eax, Operand(ecx, times_2, kSmiTag));
     __ jmp(&done);
 
     // Try to store the result in a heap number.
     __ bind(&try_float);
-    if (!overwrite_) {
+    if (overwrite_ == UNARY_NO_OVERWRITE) {
       // Allocate a fresh heap number, but don't overwrite eax until
       // we're sure we can do it without going through the slow case
       // that needs the value in eax.
       __ AllocateHeapNumber(ebx, edx, edi, &slow);
       __ mov(eax, Operand(ebx));
     }
     if (CpuFeatures::IsSupported(SSE2)) {
       CpuFeatures::Scope use_sse2(SSE2);
       __ cvtsi2sd(xmm0, Operand(ecx));
       __ movdbl(FieldOperand(eax, HeapNumber::kValueOffset), xmm0);
@@ skipping 2754 matching lines @@
   masm.GetCode(&desc);
   // Call the function from C++.
   return FUNCTION_CAST<MemCopyFunction>(buffer);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32