[Bug tree-optimization/113964] [11/12/13/14/15 Regression] repeat copy of struct

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113964

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|repeat copy of struct       |[11/12/13/14/15 Regression]
                   |                            |repeat copy of struct
      Known to fail|                            |4.6.4, 4.7.1, 4.9.0, 5.1.0
      Known to work|                            |4.1.2, 4.4.7, 4.5.3
   Last reconfirmed|                            |2024-02-17
   Target Milestone|---                         |11.5
           Keywords|                            |missed-optimization
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. There is no DSE before esra .... And ESRA goes wrong because of
that.


Before ESRA we have:
```

  _1 = e.f0.f4;
  _2 = (unsigned char) _1;
  e.f3 = _2;
  e.f0 = g_50;
  g_16 = MEM[(const struct S1 &)&e];
```

And SRA thinks it should do:
```
Created a replacement for e offset: 0, size: 8: e$f3D.4642
Created a replacement for e offset: 192, size: 32: e$f0$f4D.4643
```

But the store to e.f3 is dead due to the store to e.f0.

I suspect this should be defered until GCC 15 and maybe we should try to reorg
the optimization pipeline there ...