[Bug target/109780] [12/13/14/15 Regression] csmith: runtime crash with -O2 -march=znver1

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109780

--- Comment #35 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Uroš Bizjak from comment #34)
> The problematic code is expanded from:
> 
> ;; Generating RTL for gimple basic block 5
> 
> ;; __builtin_memset (&k, 0, 40);
> 
> (insn 21 20 22 (parallel [
>             (set (reg:DI 107)
>                 (plus:DI (reg/f:DI 93 virtual-stack-vars)
>                     (const_int -48 [0xffffffffffffffd0])))
>             (clobber (reg:CC 17 flags))
>         ]) "pr109780.c":11:12 -1
>      (nil))

It is not a good idea to CSE address that refers to virtual stack vars to a
temporary. This defeats stack/frame pointer detection, mentioned in Comment
#33, and consequently fails to increase stack alignment.