[llvm] r261039 - [X86] Fix a shrink-wrapping miscompile around __chkstk

[Hans Wennborg via llvm-commits]

Reid, what do you think about merging this to 3.8?

On Tue, Feb 16, 2016 at 4:17 PM, Reid Kleckner via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: rnk
> Date: Tue Feb 16 18:17:33 2016
> New Revision: 261039
>
> URL: http://llvm.org/viewvc/llvm-project?rev=261039&view=rev
> Log:
> [X86] Fix a shrink-wrapping miscompile around __chkstk
>
> __chkstk clobbers EAX. If EAX is live across the prologue, then we have
> to take extra steps to save it. We already had code to do this if EAX
> was a register parameter. This change adapts it to work when shrink
> wrapping is used.
>
> Modified:
>     llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
>     llvm/trunk/test/CodeGen/X86/shrink-wrap-chkstk.ll