Revert of [builtins] Introduce proper Float64Exp operator.

src/x64/codegen-x64.cc

Index: src/x64/codegen-x64.cc
diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index 911f3cb64aa10d229629b8611a8a57974ffd79d8..6731e9eba86a5fe2e4826e9b21eba8249076fb9b 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -30,6 +30,38 @@
 
 
 #define __ masm.
+
+
+UnaryMathFunctionWithIsolate CreateExpFunction(Isolate* isolate) {
+  size_t actual_size;
+  byte* buffer =
+      static_cast<byte*>(base::OS::Allocate(1 * KB, &actual_size, true));
+  if (buffer == nullptr) return nullptr;
+  ExternalReference::InitializeMathExpData();
+
+  MacroAssembler masm(isolate, buffer, static_cast<int>(actual_size),
+                      CodeObjectRequired::kNo);
+  // xmm0: raw double input.
+  XMMRegister input = xmm0;
+  XMMRegister result = xmm1;
+  __ pushq(rax);
+  __ pushq(rbx);
+
+  MathExpGenerator::EmitMathExp(&masm, input, result, xmm2, rax, rbx);
+
+  __ popq(rbx);
+  __ popq(rax);
+  __ Movsd(xmm0, result);
+  __ Ret();
+
+  CodeDesc desc;
+  masm.GetCode(&desc);
+  DCHECK(!RelocInfo::RequiresRelocation(desc));
+
+  Assembler::FlushICache(isolate, buffer, actual_size);
+  base::OS::ProtectCode(buffer, actual_size);
+  return FUNCTION_CAST<UnaryMathFunctionWithIsolate>(buffer);
+}
 
 
 UnaryMathFunctionWithIsolate CreateSqrtFunction(Isolate* isolate) {
@@ -467,6 +499,59 @@
   __ bind(&done);
 }
 
+
+void MathExpGenerator::EmitMathExp(MacroAssembler* masm,
+                                   XMMRegister input,
+                                   XMMRegister result,
+                                   XMMRegister double_scratch,
+                                   Register temp1,
+                                   Register temp2) {
+  DCHECK(!input.is(result));
+  DCHECK(!input.is(double_scratch));
+  DCHECK(!result.is(double_scratch));
+  DCHECK(!temp1.is(temp2));
+  DCHECK(ExternalReference::math_exp_constants(0).address() != NULL);
+  DCHECK(!masm->serializer_enabled());  // External references not serializable.
+
+  Label done;
+
+  __ Move(kScratchRegister, ExternalReference::math_exp_constants(0));
+  __ Movsd(double_scratch, Operand(kScratchRegister, 0 * kDoubleSize));
+  __ Xorpd(result, result);
+  __ Ucomisd(double_scratch, input);
+  __ j(above_equal, &done);
+  __ Ucomisd(input, Operand(kScratchRegister, 1 * kDoubleSize));
+  __ Movsd(result, Operand(kScratchRegister, 2 * kDoubleSize));
+  __ j(above_equal, &done);
+  __ Movsd(double_scratch, Operand(kScratchRegister, 3 * kDoubleSize));
+  __ Movsd(result, Operand(kScratchRegister, 4 * kDoubleSize));
+  __ Mulsd(double_scratch, input);
+  __ Addsd(double_scratch, result);
+  __ Movq(temp2, double_scratch);
+  __ Subsd(double_scratch, result);
+  __ Movsd(result, Operand(kScratchRegister, 6 * kDoubleSize));
+  __ leaq(temp1, Operand(temp2, 0x1ff800));
+  __ andq(temp2, Immediate(0x7ff));
+  __ shrq(temp1, Immediate(11));
+  __ Mulsd(double_scratch, Operand(kScratchRegister, 5 * kDoubleSize));
+  __ Move(kScratchRegister, ExternalReference::math_exp_log_table());
+  __ shlq(temp1, Immediate(52));
+  __ orq(temp1, Operand(kScratchRegister, temp2, times_8, 0));
+  __ Move(kScratchRegister, ExternalReference::math_exp_constants(0));
+  __ Subsd(double_scratch, input);
+  __ Movsd(input, double_scratch);
+  __ Subsd(result, double_scratch);
+  __ Mulsd(input, double_scratch);
+  __ Mulsd(result, input);
+  __ Movq(input, temp1);
+  __ Mulsd(result, Operand(kScratchRegister, 7 * kDoubleSize));
+  __ Subsd(result, double_scratch);
+  __ Addsd(result, Operand(kScratchRegister, 8 * kDoubleSize));
+  __ Mulsd(result, input);
+
+  __ bind(&done);
+}
+
 #undef __