[Bug target/80706] [7/8 Regression] peephole2 uses uninitialized stack variables on i686

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80706

--- Comment #15 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Jakub Jelinek from comment #13)
> Created attachment 41340 [details]
> gcc8-pr80706.patch
> 
> I came up with this (in addition to #c7).  This removes one of the two
> useless stores in the original pr71245-1.c testcase and restores the above
> pr71245-1.c modification to what it used to look before (well, even better,
> as it reserves smaller stack).

The committed patch fixes unwanted matching by introducing specialized SSE
load/store patterns. I don't think it is worth complicating sync.md any
further, the stack slot is shared, and the patched compiler generates exactly
the same assembly as before.