[v8-dev] ARM: Improve Lithium register constraints.

src/arm/codegen-arm.cc

Index: src/arm/codegen-arm.cc
diff --git a/src/arm/codegen-arm.cc b/src/arm/codegen-arm.cc
index 1bcf3e3a605b051571dc9c51912264c65b90e14e..5bc12887ab99c4a1bdb0a5cc934811da3b48cb46 100644
--- a/src/arm/codegen-arm.cc
+++ b/src/arm/codegen-arm.cc
@@ -774,6 +774,7 @@ void MathExpGenerator::EmitMathExp(MacroAssembler* masm,
   ASSERT(!temp1.is(temp3));
   ASSERT(!temp2.is(temp3));
   ASSERT(ExternalReference::math_exp_constants(0).address() != NULL);
+  // Register input isn't modified. All other registers are clobbered.

[danno, 2013/08/20 14:53:20]

nit: You already have a comment in the header about register usage, and this
one's position doesn't make it necessarily intuitive to update if things change.
I would discard this one and just keep the one in the header.

[vincent.belliard.fr, 2013/08/22 12:35:48]

I will discard it in the next release.

 
   Label done;
 
@@ -798,8 +799,8 @@ void MathExpGenerator::EmitMathExp(MacroAssembler* masm,
   __ vmul(double_scratch1, double_scratch1, double_scratch2);
   __ vsub(double_scratch1, double_scratch1, input);
   __ vsub(result, result, double_scratch1);
-  __ vmul(input, double_scratch1, double_scratch1);
-  __ vmul(result, result, input);
+  __ vmul(double_scratch2, double_scratch1, double_scratch1);
+  __ vmul(result, result, double_scratch2);
   __ mov(temp1, Operand(temp2, LSR, 11));
   __ vldr(double_scratch2, ExpConstant(7, temp3));
   __ vmul(result, result, double_scratch2);
@@ -817,8 +818,8 @@ void MathExpGenerator::EmitMathExp(MacroAssembler* masm,
   __ add(temp3, temp3, Operand(kPointerSize));
   __ ldr(temp2, MemOperand(temp3, temp2, LSL, 3));
   __ orr(temp1, temp1, temp2);
-  __ vmov(input, ip, temp1);
-  __ vmul(result, result, input);
+  __ vmov(double_scratch1, ip, temp1);
+  __ vmul(result, result, double_scratch1);
   __ bind(&done);
 }