[Bug c/111863] New: Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp"

[Bug c/111863] New: Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp"

[19373742 at buaa dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

            Bug ID: 111863
           Summary: Wrong code with "-O3 -fno-tree-ccp
                    -fno-tree-dominator-opts -fno-tree-vrp"
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: 19373742 at buaa dot edu.cn
  Target Milestone: ---

Created attachment 56138
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56138&action=edit
The preprocessed file

*******************************************************************************
OS and Platform:
Ubuntu 20.04.4 LTS
*******************************************************************************
gcc version:
$ gcc -v
Using built-in specs.
COLLECT_GCC=/home/cuisk/ctc/gcc-releases/gcc-14/bin/gcc
COLLECT_LTO_WRAPPER=/home/cuisk/ctc/gcc-releases/gcc-14/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ./configure --prefix=/home/cuisk/ctc/gcc-releases/gcc-14
--disable-multilib --enable-language=c,c++
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20231015 (experimental) (GCC) 
*******************************************************************************
Command Lines:
$ gcc -I ~/csmith/include/csmith-2.3.0/ -fsanitize=undefined a.c -o crt
$ ./crt
checksum = 2E494827

$ gcc -I ~/csmith/include/csmith-2.3.0/ -O3 -fno-tree-ccp
-fno-tree-dominator-opts -fno-tree-vrp a.c -o mis
$ ./mis
checksum = 326ED032

[Bug c/111863] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp"

[19373742 at buaa dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

--- Comment #1 from CTC <19373742 at buaa dot edu.cn> ---
Created attachment 56139
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56139&action=edit
The compiler output

[Bug c/111863] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp"

[19373742 at buaa dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

--- Comment #2 from CTC <19373742 at buaa dot edu.cn> ---
A reduced testcase:

$ cat a.c
#include <stdio.h>
int a;
volatile int *b = &a;
volatile int **c = &b;
static int d = 1;
static int e() {
  unsigned long f = 2;
  *b = 0 || 5;
  *b = ((**c & f) != d)%11;
  return 0;
}
int main() {
  e();
  printf("%d\n", a);
}

[Bug c/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp"

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |needs-bisection, wrong-code
            Summary|Wrong code with "-O3        |[14 Regression] Wrong code
                   |-fno-tree-ccp               |with "-O3 -fno-tree-ccp
                   |-fno-tree-dominator-opts    |-fno-tree-dominator-opts
                   |-fno-tree-vrp"              |-fno-tree-vrp"
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-10-18
             Status|UNCONFIRMED                 |NEW
      Known to work|                            |13.2.1
   Target Milestone|---                         |14.0

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.

[Bug c/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[14 Regression] Wrong code  |[14 Regression] Wrong code
                   |with "-O3 -fno-tree-ccp     |with "-O3 -fno-tree-ccp
                   |-fno-tree-dominator-opts    |-fno-tree-dominator-opts
                   |-fno-tree-vrp"              |-fno-tree-vrp" since
                   |                            |r14-1600
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |pinskia at gcc dot gnu.org
           Keywords|needs-bisection             |

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r14-1600-ge60593f3881c72a96a3fa4844d73e8a2cd14f670

[Bug middle-end/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Let me see where I made the mistake.
```
;; _11 = (int) _10;

(insn 10 9 11 (set (reg:CCZ 17 flags)
        (compare:CCZ (reg:SI 102 [ _7 ])
            (const_int 1 [0x1]))) "/app/example.cpp":10:24 -1
     (nil))

(insn 11 10 12 (set (reg:QI 109)
        (ne:QI (reg:CCZ 17 flags)
            (const_int 0 [0]))) "/app/example.cpp":10:24 -1
     (nil))
```
is definitely wrong.
It was in GCC 13:
```
(insn 10 9 11 (parallel [
            (set (reg:SI 92)
                (and:SI (reg:SI 86 [ _7 ])
                    (const_int 2 [0x2])))
            (clobber (reg:CC 17 flags))
        ]) "/app/example.cpp":10:24 -1
     (nil))

(insn 11 10 12 (set (reg:CCZ 17 flags)
        (compare:CCZ (reg:SI 92)
            (const_int 1 [0x1]))) "/app/example.cpp":10:24 -1
     (nil))

(insn 12 11 13 (set (reg:QI 94)
        (ne:QI (reg:CCZ 17 flags)
            (const_int 0 [0]))) "/app/example.cpp":10:24 -1
     (nil))
```

[Bug middle-end/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Oh I see the issue:
```
  _8 = _7 & 2;
  _10 = _8 != 1;

```

There needs to be a check that 1 here is the same as 2 or 0 ...

[Bug middle-end/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #6)
> Oh I see the issue:
> ```
>   _8 = _7 & 2;
>   _10 = _8 != 1;
> 
> ```
> 
> There needs to be a check that 1 here is the same as 2 or 0 ...

Wait I have that check:
      if (wi::popcount (nz) == 1
          && (integer_zerop (arg1)
              || wi::to_wide (arg1) == nz))

Why is that not working ...

[Bug middle-end/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Oh I see the issue now, I am changing arg0 even if we don't do the thing ...

[Bug middle-end/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 56141
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56141&action=edit
untested fix

This fixes the reuse of arg0 so we don't change it for the later on code.

[Bug middle-end/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 56142
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56142&action=edit
Reduced self-contained testcase

[Bug middle-end/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Andrew Pinski <pinskia@gcc.gnu.org>:

https://gcc.gnu.org/g:b20dbddcc41120144e700c4e3ef1ec396b1c56ab

commit r14-4729-gb20dbddcc41120144e700c4e3ef1ec396b1c56ab
Author: Andrew Pinski <pinskia@gmail.com>
Date:   Wed Oct 18 10:26:07 2023 -0700

    Fix expansion of `(a & 2) != 1`

    I had a thinko in r14-1600-ge60593f3881c72a96a3fa4844d73e8a2cd14f670
    where we would remove the `& CST` part if we ended up not calling
    expand_single_bit_test.
    This fixes the problem by introducing a new variable that will be used
    for calling expand_single_bit_test.
    As afar as I know this can only show up when disabling optimization
    passes as this above form would have been optimized away.

    Committed as obvious after a bootstrap/test on x86_64-linux-gnu.

            PR middle-end/111863

    gcc/ChangeLog:

            * expr.cc (do_store_flag): Don't over write arg0
            when stripping off `& POW2`.

    gcc/testsuite/ChangeLog:

            * gcc.c-torture/execute/pr111863-1.c: New test.

[Bug middle-end/111863] [14 Regression] Wrong code with "-O3 -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" since r14-1600

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111863

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed.