[llvm] r257730 - [X86] Don't alter HasOpaqueSPAdjustment after we've relied on it

[Nadav Rotem via llvm-commits]

Yes. This is OK. 

> On Jan 14, 2016, at 9:47 AM, Hans Wennborg <hans at chromium.org> wrote:
> 
> I'd like to merge this to 3.8. Nadav, is this OK for you as code owner?
> 
> Thanks,
> Hans
> 
> On Wed, Jan 13, 2016 at 5:20 PM, David Majnemer via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>> Author: majnemer
>> Date: Wed Jan 13 19:20:03 2016
>> New Revision: 257730
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=257730&view=rev
>> Log:
>> [X86] Don't alter HasOpaqueSPAdjustment after we've relied on it
>> 
>> We rely on HasOpaqueSPAdjustment not changing after we've calculated
>> things based on it.  Things like whether or not we can use 'rep;movs' to
>> copy bytes around, that sort of thing.  If it changes, invariants in the
>> backend will quietly break.  This situation arose when we had a call to
>> memcpy *and* a COPY of the FLAGS register where we would attempt to
>> reference local variables using %esi, a register that was clobbered by
>> the 'rep;movs'.
>> 
>> This fixes PR26124.