[Bug tree-optimization/112738] New: forwprop4 introduces invalid wide signed Boolean values

[Bug tree-optimization/112738] New: forwprop4 introduces invalid wide signed Boolean values

[kristerw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112738

            Bug ID: 112738
           Summary: forwprop4 introduces invalid wide signed Boolean
                    values
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kristerw at gcc dot gnu.org
  Target Milestone: ---

The forwprop4 pass introduces an invalid wide Boolean when compiling the
following function with -O3 for X86_64:

  int *a, b, c, d;
  void
  foo (void)
  {
    for (; d <= 0; d++)
      b &= ((a || d) ^ c) == 1;
  }

What is happening is that forwprop4 changes the IR

  _38 = (signed int) _16;
  _59 = -_38;
  _65 = (<signed-boolean:32>) _59;

to the incorrect

  _55 = (<signed-boolean:32>) _16;
  _65 = -_55;

[Bug tree-optimization/112738] [14 Regression] forwprop4 introduces invalid wide signed Boolean values

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112738

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
            Summary|forwprop4 introduces        |[14 Regression] forwprop4
                   |invalid wide signed Boolean |introduces invalid wide
                   |values                      |signed Boolean values
           Assignee|unassigned at gcc dot gnu.org      |pinskia at gcc dot gnu.org
   Target Milestone|---                         |14.0
   Last reconfirmed|                            |2023-11-27
           Keywords|                            |wrong-code
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Mine.


```
/* (nop_outer_cast)-(inner_cast)var -> -(outer_cast)(var)
   if var is smaller in precision.
   This is always safe for both doing the negative in signed or unsigned
   as the value for undefined will not show up.  */
(simplify
 (convert (negate:s@1 (convert:s @0)))
 (if (INTEGRAL_TYPE_P (type)
      && tree_nop_conversion_p (type, TREE_TYPE (@1))
      && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0)))
    (negate (convert @0))))
```

This needs a check for !BOOLEAN_TYPE here I think. boolean is the special case
...

[Bug tree-optimization/112738] [14 Regression] forwprop4 introduces invalid wide signed Boolean values

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112738

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is what I will be testing:
```
/* (nop_outer_cast)-(inner_cast)var -> -(outer_cast)(var)
   if var is smaller in precision.
   This is always safe for both doing the negative in signed or unsigned
   as the value for undefined will not show up.
   Note the outer cast cannot be a boolean type as the only valid values
   are 0,-1/1 (depending on the signedness of the boolean) and the negative
   is there to get the correct value.  */
(simplify
 (convert (negate:s@1 (convert:s @0)))
 (if (INTEGRAL_TYPE_P (type)
      && tree_nop_conversion_p (type, TREE_TYPE (@1))
      && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0))
      && TREE_CODE (type) != BOOLEAN_TYPE)
    (negate (convert @0))))
```
It even records on why boolean check is needed.

[Bug tree-optimization/112738] [14 Regression] forwprop4 introduces invalid wide signed Boolean values

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112738

--- Comment #3 from GCC 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:68ffaf839883253e0f288862ff20b8005c92df4e

commit r14-5938-g68ffaf839883253e0f288862ff20b8005c92df4e
Author: Andrew Pinski <quic_apinski@quicinc.com>
Date:   Mon Nov 27 16:41:25 2023 -0800

    MATCH: Fix invalid signed boolean type usage

    This fixes the incorrect assumption that was done in
r14-3721-ge6bcf839894783,
    that being able to doing the negative after the conversion would be a valid
thing
    but really it is not valid for boolean types.

    Bootstrapped and tested on x86_64-linux-gnu.

    gcc/ChangeLog:

            PR tree-optimization/112738
            * match.pd (`(nop_convert)-(convert)a`): Reject
            when the outer type is boolean.

    Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

[Bug tree-optimization/112738] [14 Regression] forwprop4 introduces invalid wide signed Boolean values

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112738

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

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

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed.