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From: "stammark at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/108177] MVE predicated stores to same address get
 optimized away
Date: Thu, 06 Apr 2023 17:32:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108177

--- Comment #5 from Stam Markianos-Wright <stammark at gcc dot gnu.org> ---
With the fix to MVE auto_inc having gone in as
ddc9b5ee13cd686c8674f92d46045563c06a23ea I have found that this fix keeps t=
he
auto-inc on these predicated stores broken.

It seems to fail in auto_inc_dec at this condition:

```
  /* Make sure this reg appears only once in this insn.  */
  if (count_occurrences (PATTERN (mem_insn.insn), mem_insn.reg0, 1) !=3D 1)
    {
      if (dump_file)
        fprintf (dump_file, "mem count failure\n");
      return false;
    }
```
(which makes sense with the pattern now having the MEM appear twice)


I guess this is not urgent since this is only a performance impact on one
instruction. Also if the change needs to be in the auto-inc pass instead of=
 the
backend, then likely something for GCC14, but I thought this would be a good
place to record this ;)

Does anyone have any ideas on this? Or I wonder what the AVX case does for =
this=