Avoid assigning esp (or ebp for framepointer-using frames) in Om1.

Avoid assigning esp (or ebp for framepointer-using frames) in Om1.

For ebp, exclude as needed. For esp, don't mark it as
an int register.

Not sure exactly how to do a targeted test for this Om1
register allocator. The Om1 regalloc seems to start w/ a
fresh whitelist after each instruction, so it may assign
the same register (e.g., eax), as an earlier instruction.
Without pre-colored registers, I'm not sure how to force it
to allocate something other than the first few registers.
I do have a test case that has a ton of pre-colored
registers, (e.g., cmpxchg8b), but that is a different CL:
https://codereview.chromium.org/362463002/

Encountered for:
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3882
R=stichnot@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=9559899

[Jim Stichnoth, 2014-07-02 23:03:36]

lgtm

https://codereview.chromium.org/369573005/diff/1/src/IceTargetLoweringX8632.cpp
File src/IceTargetLoweringX8632.cpp (right):

https://codereview.chromium.org/369573005/diff/1/src/IceTargetLoweringX8632.c...
src/IceTargetLoweringX8632.cpp:2525: RegSetMask RegExclude = RegSet_None |
RegSet_StackPointer;
Could probably just use
  RegSetMask RegExclude = RegSet_StackPointer;

[Jim Stichnoth, 2014-07-02 23:23:44]

https://codereview.chromium.org/369573005/diff/1/src/IceTargetLoweringX8632.cpp
File src/IceTargetLoweringX8632.cpp (right):

https://codereview.chromium.org/369573005/diff/1/src/IceTargetLoweringX8632.c...
src/IceTargetLoweringX8632.cpp:2525: RegSetMask RegExclude = RegSet_None |
RegSet_StackPointer;
On 2014/07/02 23:03:36, stichnot wrote:
> Could probably just use
>   RegSetMask RegExclude = RegSet_StackPointer;

Actually, it would be even better to use RegSet_None, except that for some
reason Reg_esp is marked as isInt in IceInstX8632.def.  I don't know if there
would be any problems setting isInt to 0, but I think the existing lit tests and
cross tests would flag any problems.

[jvoung (off chromium), 2014-07-02 23:43:39]

https://codereview.chromium.org/369573005/diff/1/src/IceTargetLoweringX8632.cpp
File src/IceTargetLoweringX8632.cpp (right):

https://codereview.chromium.org/369573005/diff/1/src/IceTargetLoweringX8632.c...
src/IceTargetLoweringX8632.cpp:2525: RegSetMask RegExclude = RegSet_None |
RegSet_StackPointer;
On 2014/07/02 23:23:44, stichnot wrote:
> On 2014/07/02 23:03:36, stichnot wrote:
> > Could probably just use
> >   RegSetMask RegExclude = RegSet_StackPointer;
> 
> Actually, it would be even better to use RegSet_None, except that for some
> reason Reg_esp is marked as isInt in IceInstX8632.def.  I don't know if there
> would be any problems setting isInt to 0, but I think the existing lit tests
and
> cross tests would flag any problems.


Okay so the idea is mark esp as a non-int register and the calls to
getRegisterSetForType() will never return it.

I tried it out, and at least the existing lit tests/crosstests are okay with
it... but let's chat about it next week, you're on vacation!

[jvoung (off chromium), 2014-07-09 16:24:08]

Okay sticking with marking esp as not an int reg (patch set 3)

[jvoung (off chromium), 2014-07-09 16:54:37]

Committed patchset #3 manually as r9559899 (presubmit successful).