[SyzyASAN] Add support for LODS instruction.

[SyzyASAN] Add support for LODS instruction.

This is breaking on the current win-asan and LKGR continuous builders.

BUG=https://crbug.com/644608
R=sebmarchand@chromium.org

Committed: https://github.com/google/syzygy/commit/f10f8a119b48137b6f10fc1e85abd257cc32c1ab

[chrisha, 2016-09-08 17:08:16]

chrisha@chromium.org changed reviewers:
+ sebmarchand@chromium.org

[chrisha, 2016-09-08 17:08:17]

PTAL?

[Sébastien Marchand, 2016-09-08 17:14:06]

The CQ bit was checked by sebmarchand@chromium.org

[Sébastien Marchand, 2016-09-08 17:14:06]

lgtm

[commit-bot: I haz the power, 2016-09-08 17:14:09]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-08 17:43:05]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-09-08 17:43:06]

Internal error: failed to checkout. Please try again.

[Sigurður Ásgeirsson, 2016-09-08 18:36:33]

siggi@chromium.org changed reviewers:
+ siggi@chromium.org

[Sigurður Ásgeirsson, 2016-09-08 18:36:34]

Wow, what a PITA.
I don't understand where

REP LODS

would be useful - is that what's being generated, or just single LODS
instructions?

[chrisha, 2016-09-08 19:06:50]

On 2016/09/08 18:36:34, Sigurður Ásgeirsson wrote:
> Wow, what a PITA.
> I don't understand where
> 
> REP LODS
> 
> would be useful - is that what's being generated, or just single LODS
> instructions?

From the error message output by our tool, a REP LODS is being generated in
"gpu::gles2::GLES2DecoderImpl::HandleCompressedTexImage2D". I don't have the
disassembly in front of me. Intel x86 docs mention the following:

"For a block transfer of CX bytes, words or longs, precede a lods instruction
with a rep prefix; however, lods is used more typically within a loop construct
where further processing of the data moved into AL, AX, or EAX is usually
required."

So I guess it's not completely unused, but quite rare. Not sure what changed
recently to cause this to be built.

[chrisha, 2016-09-08 20:55:02]

Description was changed from

==========
[SyzyASAN] Add support for LODS instruction.

This is breaking on the current win-asan and LKGR continuous builders.

BUG=https://crbug.com/644608
==========

to

==========
[SyzyASAN] Add support for LODS instruction.

This is breaking on the current win-asan and LKGR continuous builders.

BUG=https://crbug.com/644608
R=sebmarchand@chromium.org

Committed:
https://github.com/google/syzygy/commit/f10f8a119b48137b6f10fc1e85abd257cc32c1ab
==========

[chrisha, 2016-09-08 20:55:03]

Committed patchset #1 (id:1) manually as
f10f8a119b48137b6f10fc1e85abd257cc32c1ab.