On Tue, Apr 27, 2021 at 10:22 PM Jeff Law <jeffreya...@gmail.com> wrote:
>
> This change:
>
> d8e1f1d24179690fd9c0f63c27b12e030010d9ea is the first bad commit
> commit d8e1f1d24179690fd9c0f63c27b12e030010d9ea
> Author: Richard Biener <rguent...@suse.de>
> Date: Wed Apr 7 12:09:44 2021 +0200
>
> tree-optimization/99912 - schedule DSE before SRA
>
> For the testcase in the PR the main SRA pass is unable to do some
> important scalarizations because dead stores of addresses make
> the candiate variables disqualified. The following patch adds
> another DSE pass before SRA forming a DCE/DSE pair and moves the
> DSE pass that is currently closely after SRA up to after the
> next DCE pass, forming another DCE/DSE pair now residing after PRE.
>
> 2021-04-07 Richard Biener <rguent...@suse.de>
>
> PR tree-optimization/99912
> * passes.def (pass_all_optimizations): Add pass_dse before
> the first pass_dce, move the first pass_dse before the
> pass_dce following pass_pre.
>
> * gcc.dg/tree-ssa/ldist-33.c: Disable PRE and LIM.
> * gcc.dg/tree-ssa/pr96789.c: Adjust dump file scanned.
> * gcc.dg/tree-ssa/ssa-dse-28.c: Likewise.
> * gcc.dg/tree-ssa/ssa-dse-29.c: Likewise.
>
> Is breaking gcc.dg/Wrestrict-8.c on various targets (bfin-elf, lm32-elf,
> nds32le-elf, or1k-elf rx-elf). I haven't dug into it all except for
> quickly bisecting.
>
> http://3.14.90.209:8080/job/bfin-elf/
>
>
> If you want the full logs...
With a followup patch I see FAILs on x86_64-linux as well. The issue is
the testcase does things like
T (&a8_1[0], &a8_1[i], 5); /* { dg-warning "accessing 5 bytes at
offsets 0 and \\\[0, 8] overlaps between 2 and 5 bytes at offset
\\\[0, 3\\\]" } */
T (&a8_1[0], &a8_1[i], 6); /* { dg-warning "accessing 6 bytes at
offsets 0 and \\\[0, 8] overlaps between 4 and 6 bytes at offset
\\\[0, 2\\\]" } */
where T == memcpy. The first memcpy is dead and we can eliminate it
(but only when an intermediate memcpy lowered to load/store is there).
I'm changing the testcase to alias T to memcpy (..); foo (..); to place an
artificial use of the destination memory after the memcpy.
Richard.
>
> Jeff
>
