Fixing MathPowHalf on ARM.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index ac10793b46f56e7d088227233861c8e2aec06387..359b893b0aa81893d7a30e37c349260c47af09ca 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -3097,9 +3097,19 @@ void LCodeGen::DoMathSqrt(LUnaryMathOperation* instr) {
 void LCodeGen::DoMathPowHalf(LUnaryMathOperation* instr) {
   DoubleRegister input = ToDoubleRegister(instr->InputAt(0));
   DoubleRegister result = ToDoubleRegister(instr->result());
+
+  // Note that according to ECMA-262 15.8.2.13:
+  // Math.pow(-Infinity, 0.5) == Infinity
+  // Math.sqrt(-Infinity) == NaN
+  Label done;
+  __ VFPCompareAndSetFlags(input, -INFINITY);

[Sven Panne, 2011/12/06 08:23:12]

I think we should use V8_INFINITY here, although I don't fully understand the
rationale behind our #ifdef magic for this constant...

+  __ vneg(result, input, eq);
+  __ b(&done, eq);
+
   // Add +0 to convert -0 to +0.
   __ vadd(result, input, kDoubleRegZero);
   __ vsqrt(result, result);
+  __ bind(&done);
 }