[Bug target/120360] New: Horrible code generation for trivial decrement with test

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120360

            Bug ID: 120360
           Summary: Horrible code generation for trivial decrement with
                    test
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org, torva...@linux-foundation.org
  Target Milestone: ---
            Target: x86_64-*-*, i?86-*-*

This is like PR 49095 but a little more complex.

Take:
```
typedef signed int type;

int g(void);
int f(type *b)
{
  type a = *b;
  *b = a - 24;
  if (a == 24)
    return g();
  return 0;
}

int f1(type *b)
{
  type a = *b;
  *b = a - 24;
  if (*b == 0)
    return g();
  return 0;
}
```

f1 is currently solved by PR 49095 but f is not. I noticed this while moving
around some single_use for a match pattern.