https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122797
Bug ID: 122797
Summary: [regression][bisected to 0f8bcacf6c46] Miscompilation
after strided accesses changes
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: kasper93 at gmail dot com
Target Milestone: ---
Created attachment 62876
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=62876&action=edit
cavasdsp.i
Hello,
I've noticed recent regression on the main branch in tree vectorization. After
commit 0f8bcacf6c4603cb7614aa23ef4a9568e46bddfa (vect: Reduce group size of
consecutive strided accesses.) some of FFmpeg tests are failing on both AMD64
and ARM64 builds (more on the later).
https://fate.ffmpeg.org/report.cgi?slot=amd64-gcc-snapshot&time=20251121190225
https://fate.ffmpeg.org/report.cgi?slot=arm64-gcc-snapshot&time=20251121185626
I bisected GCC to commit 0f8bcacf6c46, which introduces an issue with data
accesses and results in incorrect output. Multiple tests are affected, but as
an example, I'm attaching cavasdsp.i, which is miscompiled after the referenced
commit. I haven't investigated in detail which part of the generated code is
incorrect, so I'm leaving it to you to compare the assembly output before and
after the commit.
Thanks,
Kacper
