ARM64: Add overflow checking support for multiplications by constant powers of 2.

ARM64: Add overflow checking support for multiplications by constant powers of 2.

R=ulan@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=20246

[ulan, 2014-03-25 08:26:35]

lgtm

https://codereview.chromium.org/210253002/diff/1/src/arm64/lithium-arm64.cc
File src/arm64/lithium-arm64.cc (right):

https://codereview.chromium.org/210253002/diff/1/src/arm64/lithium-arm64.cc#n...
src/arm64/lithium-arm64.cc:1914: !((constant >= -1) && (constant <= 2));
Since (constant >= -1) && (constant <= 2) used twice consider giving it a name
like small_constant to improve readability.

[Alexandre Rames, 2014-03-25 10:31:44]

https://codereview.chromium.org/210253002/diff/1/src/arm64/lithium-arm64.cc
File src/arm64/lithium-arm64.cc (right):

https://codereview.chromium.org/210253002/diff/1/src/arm64/lithium-arm64.cc#n...
src/arm64/lithium-arm64.cc:1914: !((constant >= -1) && (constant <= 2));
On 2014/03/25 08:26:35, ulan wrote:
> Since (constant >= -1) && (constant <= 2) used twice consider giving it a name
> like small_constant to improve readability.

Will do before landing.

[Alexandre Rames, 2014-03-25 13:35:26]

Committed patchset #1 manually as r20246 (presubmit successful).

[ulan, 2014-03-25 15:44:40]

On 2014/03/25 13:35:26, Alexandre Rames wrote:
> Committed patchset #1 manually as r20246 (presubmit successful).

Looks like this regressed mjsunit/mul-exhaustive-part4 in no-snapshot debug
build:
--- stdout ---
============ Stress 1/2 ============
============ Stress 2/2 ============
v8/test/mjsunit/mjsunit.js:178: Failure: expected <2147483648> found
<-2147483648>

[Alexandre Rames, 2014-03-25 19:36:24]

Updated the patch to fix the failure observed in mjsunit/mul-exhaustive-part4.
Checked that optdebug tests pass both with and without snapshot.

[ulan, 2014-03-26 09:00:28]

On 2014/03/25 19:36:24, Alexandre Rames wrote:
> Updated the patch to fix the failure observed in mjsunit/mul-exhaustive-part4.
> Checked that optdebug tests pass both with and without snapshot.

Could you upload this in a new CL with description "Reland ..."?