X87: [turbofan] Turn Math.clz32 into an inlinable builtin.

port 3aa206b8 (r27329)

original commit message:

BUG=

Review URL: https://codereview.chromium.org/1022523005

Cr-Commit-Position: refs/heads/master@{#27429}

src/x87/lithium-codegen-x87.cc

@@ -4265,14 +4265,8 @@ void LCodeGen::DoMathLog(LMathLog* instr) {
 void LCodeGen::DoMathClz32(LMathClz32* instr) {
   Register input = ToRegister(instr->value());
   Register result = ToRegister(instr->result());
-  Label not_zero_input;
-  __ bsr(result, input);
 
-  __ j(not_zero, &not_zero_input);
-  __ Move(result, Immediate(63));  // 63^31 == 32
-
-  __ bind(&not_zero_input);
-  __ xor_(result, Immediate(31));  // for x in [0..31], 31^x == 31-x.
+  __ Lzcnt(result, input);
 }
 
 

src/x87/macro-assembler-x87.cc

@@ -2355,6 +2355,17 @@ void MacroAssembler::Move(const Operand& dst, const Immediate& x) {
 }
 
 
+void MacroAssembler::Lzcnt(Register dst, const Operand& src) {
+  // TODO(intel): Add support for LZCNT (with ABM/BMI1).
+  Label not_zero_src;
+  bsr(dst, src);
+  j(not_zero, &not_zero_src, Label::kNear);
+  Move(dst, Immediate(63));  // 63^31 == 32
+  bind(&not_zero_src);
+  xor_(dst, Immediate(31));  // for x in [0..31], 31^x == 31-x.
+}
+
+
 void MacroAssembler::SetCounter(StatsCounter* counter, int value) {
   if (FLAG_native_code_counters && counter->Enabled()) {
     mov(Operand::StaticVariable(ExternalReference(counter)), Immediate(value));

src/x87/macro-assembler-x87.h

@@ -776,6 +776,9 @@ class MacroAssembler: public Assembler {
   void Push(Register src) { push(src); }
   void Pop(Register dst) { pop(dst); }
 
+  void Lzcnt(Register dst, Register src) { Lzcnt(dst, Operand(src)); }
+  void Lzcnt(Register dst, const Operand& src);
+
   // Emit call to the code we are currently generating.
   void CallSelf() {
     Handle<Code> self(reinterpret_cast<Code**>(CodeObject().location()));