[PATCH] sccvn: Consider def BB in rpo_vn_valueize [PR98464]

[Richard Biener]

On December 31, 2020 8:02:37 AM GMT+01:00, "Kewen.Lin" <linkw@linux.ibm.com> wrote:
>Hi,
>
>As PR98464 shows, this patch is to make rpo_vn_valueize
>consider the definition basic block of name, to sync
>with what we do in function eliminate_stmt.
>
>Bootstrapped/regtested on powerpc64le-linux-gnu P9.
>
>Full SPEC2017 build/run passed on P9.

Note it is incorrect to query availability at the context of a value, so the patch isn't correct. I'll have a look after I return from vacation. 

Richard. 

>BR,
>Kewen
>
>gcc/ChangeLog:
>
>	PR tree-optimization/98464
>	* tree-ssa-sccvn.c (rpo_vn_valueize): Use the def basic block
>	to keep consistent with eliminate_stmt.
>
>gcc/testsuite/ChangeLog:
>
>	PR tree-optimization/98464
>	* g++.dg/tree-ssa/pr98464.C: New test.
>
>---