Reduce strength of ModI for power-of-2 divisor.

Reduce strength of ModI for power-of-2 divisor.

This is ia32 only. I will port it to other platforms if this looks good to you.

Committed: http://code.google.com/p/v8/source/detail?r=7158

[Kevin Millikin (Chromium), 2011-03-11 11:59:43]

I think it's fine.

http://codereview.chromium.org/6665006/diff/1/src/hydrogen-instructions.h
File src/hydrogen-instructions.h (right):

http://codereview.chromium.org/6665006/diff/1/src/hydrogen-instructions.h#new...
src/hydrogen-instructions.h:2573: int32_t value =
HConstant::cast(right())->HasInteger32Value();
HConstant::cast(right()->Integer32Value();

http://codereview.chromium.org/6665006/diff/1/src/ia32/lithium-codegen-ia32.cc
File src/ia32/lithium-codegen-ia32.cc (right):

http://codereview.chromium.org/6665006/diff/1/src/ia32/lithium-codegen-ia32.c...
src/ia32/lithium-codegen-ia32.cc:797: __ and_ (dividend, divisor - 1);
No space after and_ here and below.

[Vyacheslav Egorov (Chromium), 2011-03-14 14:30:51]

I have fixed issues with ia32 implementation and ported it to ARM/x64.

Please take another look.

http://codereview.chromium.org/6665006/diff/1/src/hydrogen-instructions.h
File src/hydrogen-instructions.h (right):

http://codereview.chromium.org/6665006/diff/1/src/hydrogen-instructions.h#new...
src/hydrogen-instructions.h:2573: int32_t value =
HConstant::cast(right())->HasInteger32Value();
On 2011/03/11 11:59:43, Kevin Millikin wrote:
> HConstant::cast(right()->Integer32Value();

Done.

http://codereview.chromium.org/6665006/diff/1/src/ia32/lithium-codegen-ia32.cc
File src/ia32/lithium-codegen-ia32.cc (right):

http://codereview.chromium.org/6665006/diff/1/src/ia32/lithium-codegen-ia32.c...
src/ia32/lithium-codegen-ia32.cc:797: __ and_ (dividend, divisor - 1);
On 2011/03/11 11:59:43, Kevin Millikin wrote:
> No space after and_ here and below.

Done.

[Kevin Millikin (Chromium), 2011-03-14 14:35:07]

I just looked at the new code.  LGTM, comment applies to x64 as well.

http://codereview.chromium.org/6665006/diff/6001/src/arm/lithium-codegen-arm.cc
File src/arm/lithium-codegen-arm.cc (right):

http://codereview.chromium.org/6665006/diff/6001/src/arm/lithium-codegen-arm....
src/arm/lithium-codegen-arm.cc:799: if
(HMod::cast(instr->hydrogen())->HasPowerOf2Divisor()) {
The HMod::cast should not be necessary here (and just below).