[Bug middle-end/111541] New: missing optimization x & ~c | (y | c) -> x | (y | c)

[Bug middle-end/111541] New: missing optimization x & ~c | (y | c) -> x | (y | c)

[vanyacpp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111541

            Bug ID: 111541
           Summary: missing optimization x & ~c | (y | c) -> x | (y | c)
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vanyacpp at gmail dot com
  Target Milestone: ---

On this function clang generates shorter code:

unsigned foo(unsigned x, unsigned y, unsigned c)
{
    return x & ~c | (y | c);
}

Clang notices that the expression can be simplified to x | (y | c). It would be
great if GCC can do the same.

https://gcc.godbolt.org/z/dMo4nEjrs

This issue is symmetric to the one described in PR 98710. The idea behind this
simplification is the following: when we are working with bitsets, "|" can be
read as adding bits and "&~" as removing. Therefore the expression "x & ~c | (y
| c)" can be read as removing "c" from "x" and then adding "y | c".

So the simplification

x & ~c | (y | c) -> x | (y | c)

means there is no need to remove "c" if later we add something containing "c".

[Bug middle-end/111541] missing optimization x & ~c | (y | c) -> x | (y | c)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111541

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement

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

Note this also should be optimized:
```
_Bool foo1(_Bool x, _Bool y, unsigned a)
{
  _Bool c = a != 0;
    return x & !c | (y | c);
}
```

Down to:
```
_Bool foo1_(_Bool x, _Bool y, unsigned a)
{
  _Bool c = a != 0;
  return x | (y | c);
}
```

[Bug middle-end/111541] missing optimization x & ~c | (y | c) -> x | (y | c)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111541

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-09-22
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
.