Harmony: optimize Math.clz32.

src/a64/lithium-codegen-a64.cc

Index: src/a64/lithium-codegen-a64.cc
diff --git a/src/a64/lithium-codegen-a64.cc b/src/a64/lithium-codegen-a64.cc
index 62a3b76cf2db79f18f76d58bc8205be2d6bf80fa..e46fe382647b6b640622807771ba17ad042f8592 100644
--- a/src/a64/lithium-codegen-a64.cc
+++ b/src/a64/lithium-codegen-a64.cc
@@ -3852,6 +3852,13 @@ void LCodeGen::DoMathLog(LMathLog* instr) {
 }
 
 
+void LCodeGen::DoMathClz32(LMathClz32* instr) {
+  Register input = ToRegister32(instr->value());
+  Register result = ToRegister(instr->result());
+  __ Clz(result, input);

[Sven Panne, 2014/02/19 13:24:08]

Hmmm, can we mix W and X registers in a single instruction? The intention seems
to be "count in 32bits and silently expand the result to 64bit", no clue if this
is possible.

+}
+
+
 void LCodeGen::DoMathPowHalf(LMathPowHalf* instr) {
   DoubleRegister input = ToDoubleRegister(instr->value());
   DoubleRegister result = ToDoubleRegister(instr->result());