PPC/s390: [builtins] Introduce proper Float64Exp operator.

src/crankshaft/ppc/lithium-ppc.cc

Index: src/crankshaft/ppc/lithium-ppc.cc
diff --git a/src/crankshaft/ppc/lithium-ppc.cc b/src/crankshaft/ppc/lithium-ppc.cc
index df2948369e4ccb604d905b4183bc96288513ba82..e092908135707ca9cc321bbe4efb4a3719f66402 100644
--- a/src/crankshaft/ppc/lithium-ppc.cc
+++ b/src/crankshaft/ppc/lithium-ppc.cc
@@ -1161,12 +1161,8 @@ LInstruction* LChunkBuilder::DoMathClz32(HUnaryMathOperation* instr) {
 LInstruction* LChunkBuilder::DoMathExp(HUnaryMathOperation* instr) {
   DCHECK(instr->representation().IsDouble());
   DCHECK(instr->value()->representation().IsDouble());
-  LOperand* input = UseRegister(instr->value());
-  LOperand* temp1 = TempRegister();
-  LOperand* temp2 = TempRegister();
-  LOperand* double_temp = TempDoubleRegister();
-  LMathExp* result = new (zone()) LMathExp(input, double_temp, temp1, temp2);
-  return DefineAsRegister(result);
+  LOperand* input = UseFixedDouble(instr->value(), d1);
+  return MarkAsCall(DefineFixedDouble(new (zone()) LMathExp(input), d1), instr);
 }