Fix three bugs with handling negative zero in the optimizing compiler.

src/ia32/lithium-codegen-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 2738 matching lines @@
     EmitIntegerMathAbs(instr);
     __ bind(deferred->exit());
   }
 }
 
 
 void LCodeGen::DoMathFloor(LUnaryMathOperation* instr) {
   XMMRegister xmm_scratch = xmm0;
   Register output_reg = ToRegister(instr->result());
   XMMRegister input_reg = ToDoubleRegister(instr->value());
+  Label done;
+
+  // Deoptimize on negative numbers.
   __ xorps(xmm_scratch, xmm_scratch);  // Zero the register.
   __ ucomisd(input_reg, xmm_scratch);
+  DeoptimizeIf(below, instr->environment());
 
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
-    DeoptimizeIf(below_equal, instr->environment());
-  } else {
-    DeoptimizeIf(below, instr->environment());
+    // Check for negative zero.
+    Label positive_sign;
+    __ j(above, &positive_sign, Label::kNear);
+    __ movmskpd(output_reg, input_reg);
+    __ test(output_reg, Immediate(1));
+    DeoptimizeIf(not_zero, instr->environment());
+    __ Set(output_reg, Immediate(0));
+    __ jmp(&done, Label::kNear);
+    __ bind(&positive_sign);
   }
 
   // Use truncating instruction (OK because input is positive).
   __ cvttsd2si(output_reg, Operand(input_reg));
 
   // Overflow is signalled with minint.
   __ cmp(output_reg, 0x80000000u);
   DeoptimizeIf(equal, instr->environment());
+  __ bind(&done);
 }
 
 
 void LCodeGen::DoMathRound(LUnaryMathOperation* instr) {
   XMMRegister xmm_scratch = xmm0;
   Register output_reg = ToRegister(instr->result());
   XMMRegister input_reg = ToDoubleRegister(instr->value());
 
   Label below_half, done;
   // xmm_scratch = 0.5
@@ skipping 1615 matching lines @@
                                          env->deoptimization_index());
   __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32