[Bug middle-end/90663] [8/9 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[Bug middle-end/90663] [8/9 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|10.0                        |10.2.0, 11.0

--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
No progress in GCC 11.

[Bug middle-end/90663] [9 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|8.5                         |9.4

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 8 branch is being closed.

[Bug middle-end/90663] [9 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.4                         |9.5

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9.4 is being released, retargeting bugs to GCC 9.5.

[Bug middle-end/90663] [9/10/11/12 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |pinskia at gcc dot gnu.org
            Summary|[9 Regression] strcmp       |[9/10/11/12 Regression]
                   |(&a[i], a + i) not folded   |strcmp (&a[i], a + i) not
                   |for arrays and constant     |folded for arrays and
                   |index                       |constant index
             Status|NEW                         |ASSIGNED

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> Anyhow, I suggest to use get_addr_base_and_unit_offset in the gimple
> folder since there variable addresses will not appear literally but
> only in separate SSA defs.

We could also use ptr_difference_const now and see if the difference is zero.

Let me try that.

[Bug middle-end/90663] [10/11/12/13 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.5                         |10.4

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed

[Bug middle-end/90663] [10/11/12/13 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.4                        |10.5

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.

[Bug middle-end/90663] [10/11/12/13/14 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 55097
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55097&action=edit
Patch which I am testing

[Bug middle-end/90663] [10/11/12/13/14 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
           Assignee|pinskia at gcc dot gnu.org         |unassigned at gcc dot gnu.org

--- Comment #11 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #10)
> Created attachment 55097 [details]
> Patch which I am testing

Hmm, one failure
+FAIL: c-c++-common/Wrestrict.c  -Wc++-compat  memcpy (test for warnings, line
120)

GCC's code says:
      /* Avoid diagnosing exact overlap in calls to __builtin_memcpy.
         It's safe and may even be emitted by GCC itself (see bug
         32667).  */

Reduced testcase for the missing warning:
```
/* PR 35503 - Warn about restricted pointers
   { dg-do compile }
   { dg-options "-O2 -Wrestrict -ftrack-macro-expansion=0" } */

void sink (void*, ...);

/* Exercise memcpy with constant or known arguments.  */
void test_memcpy_cst (void *d, const void *s)
{
    struct {
      char a[7];
      char b[7];
      char c[7];
    } x;
    sink (&x);

    d = x.a + 7;
    s = x.b;
    __builtin_memcpy (d, s, 3);             /* { dg-warning "\\\[-Wrestrict"
"memcpy" } */
    sink (&x);
}

```

I am no longer working on this because I am not 100% sure if we want to still
warn here or not ...

[Bug middle-end/90663] [11/12/13/14 Regression] strcmp (&a[i], a + i) not folded for arrays and constant index

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90663

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.5                        |11.5

--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.