[Bug c++/115499] New: Missed optimization: Fold (a ^ (b || c)) && c to (a ^ 1) && c

[zhiwuyazhe154 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115499

            Bug ID: 115499
           Summary: Missed optimization: Fold (a ^ (b || c)) && c to (a ^
                    1) && c
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhiwuyazhe154 at gmail dot com
  Target Milestone: ---

godbolt example: https://godbolt.org/z/bjPnrTP7o

Code example: 
```
#include <algorithm>
unsigned long long int m, n;
void fn1(short a, unsigned long long int b, short c) {
    n = (a ^ (m || c)) && c;
}

void fn2(short a, unsigned long long int b, short c) {
    b = m;
    n = (a ^ (b || c)) && c;
}

void fn3(short a, unsigned long long int b, short c) {
    n = (a ^ (b || c)) && c;
}
```

In fact, these three functions are equivalent((a ^ 1) && c), but the processing
of the global variable m or the input parameter b by fn2 and fn3 leads to the
lack of arithmetic optimization.