[builtins] Introduce proper Float64Exp operator.

src/crankshaft/ia32/lithium-codegen-ia32.cc

Index: src/crankshaft/ia32/lithium-codegen-ia32.cc
diff --git a/src/crankshaft/ia32/lithium-codegen-ia32.cc b/src/crankshaft/ia32/lithium-codegen-ia32.cc
index cdd96a0826f6f28ea989c42278113b1614c92372..48a7f3f13558bb0cc33b1c19afdd4389f2121bca 100644
--- a/src/crankshaft/ia32/lithium-codegen-ia32.cc
+++ b/src/crankshaft/ia32/lithium-codegen-ia32.cc
@@ -3425,11 +3425,16 @@ void LCodeGen::DoMathClz32(LMathClz32* instr) {
 void LCodeGen::DoMathExp(LMathExp* instr) {
   XMMRegister input = ToDoubleRegister(instr->value());
   XMMRegister result = ToDoubleRegister(instr->result());
-  XMMRegister temp0 = double_scratch0();
-  Register temp1 = ToRegister(instr->temp1());
-  Register temp2 = ToRegister(instr->temp2());
-
-  MathExpGenerator::EmitMathExp(masm(), input, result, temp0, temp1, temp2);
+  // Pass one double as argument on the stack.
+  __ PrepareCallCFunction(2, eax);
+  __ movsd(Operand(esp, 0 * kDoubleSize), input);
+  __ CallCFunction(ExternalReference::ieee754_exp_function(isolate()), 2);
+  // Return value is in st(0) on ia32.
+  // Store it into the result register.
+  __ sub(esp, Immediate(kDoubleSize));
+  __ fstp_d(Operand(esp, 0));
+  __ movsd(result, Operand(esp, 0));
+  __ add(esp, Immediate(kDoubleSize));
 }
 
 void LCodeGen::PrepareForTailCall(const ParameterCount& actual,