Fix Math.pow(-0, 0.5) and Math.pow(-0, -0.5). These are not equal to sqrt(-0...

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 7933 matching lines @@
     // Test for -0.5.
     // Load xmm2 with -0.5.
     __ mov(answer.reg(), Immediate(0xBF000000));
     __ movd(xmm2, Operand(answer.reg()));
     __ cvtss2sd(xmm2, xmm2);
     // xmm2 now has -0.5.
     __ ucomisd(xmm2, xmm1);
     __ j(not_equal, &not_minus_half);
 
     // Calculates reciprocal of square root.
-    // Note that 1/sqrt(x) = sqrt(1/x))
-    __ divsd(xmm3, xmm0);
+    // sqrtsd returns -0 when input is -0.  ECMA spec requires +0.
+    __ xorpd(xmm1, xmm1);
+    __ addsd(xmm1, xmm0);
+    __ sqrtsd(xmm1, xmm1);
+    __ divsd(xmm3, xmm1);
     __ movsd(xmm1, xmm3);
-    __ sqrtsd(xmm1, xmm1);
     __ jmp(&allocate_return);
 
     // Test for 0.5.
     __ bind(&not_minus_half);
     // Load xmm2 with 0.5.
     // Since xmm3 is 1 and xmm2 is -0.5 this is simply xmm2 + xmm3.
     __ addsd(xmm2, xmm3);
     // xmm2 now has 0.5.
     __ ucomisd(xmm2, xmm1);
     call_runtime.Branch(not_equal);
     // Calculates square root.
-    __ movsd(xmm1, xmm0);
+    // sqrtsd returns -0 when input is -0.  ECMA spec requires +0.
+    __ xorpd(xmm1, xmm1);
+    __ addsd(xmm1, xmm0);
     __ sqrtsd(xmm1, xmm1);
 
     JumpTarget done;
     Label failure, success;
     __ bind(&allocate_return);
     // Make a copy of the frame to enable us to handle allocation
     // failure after the JumpTarget jump.
     VirtualFrame* clone = new VirtualFrame(frame());
     __ AllocateHeapNumber(answer.reg(), exponent.reg(),
                           base.reg(), &failure);
@@ skipping 2330 matching lines @@
   memcpy(chunk->GetStartAddress(), desc.buffer, desc.instr_size);
   CPU::FlushICache(chunk->GetStartAddress(), desc.instr_size);
   return FUNCTION_CAST<MemCopyFunction>(chunk->GetStartAddress());
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32