I have had a closer look again: We really need to split this CL into smaller
pieces, otherwise we'll either have a hard time in case we break some corner
case with this change or we'll have to revert everything and you'll have to
start over again.
https://codereview.chromium.org/23156006/diff/1/src/globals.h
File src/globals.h (right):
https://codereview.chromium.org/23156006/diff/1/src/globals.h#newcode170
src/globals.h:170: #define V8_BETTER_OPERAND_ON_RIGHT
On 2013/08/22 12:35:48, vincent.belliard.fr wrote:
Once again, the code has been made for IA32 where operands only used
once are
better at left because operations clobber the left value.
With ARM, we have 3 operands operations so there is no advantage to
put used
once operands on the left.
The XXXMemOperand functions could have been defined with the
MemOperand on the
left instead of on the right. However, it would have been not
consistent with
other macro assembler functions.
The choice of left operand is arbitrary (but this is good for IA32).
We only put
this define to be able to make the better choice for a CPU.
It was difficult to find a good name for the define (and we can't use
the
ARCH_ARM define directly in hydrogen-instructions.h). If you have some
suggestions we can change the name.
I still don't see why this macro is needed at all. As you say, ARM has 3
operand instructions, so it doesn't matter and we could as well have the
better operand on the left there as well. What am I missing?
https://codereview.chromium.org/23156006/
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