[Bug tree-optimization/96245] New: Failure to optimize arithmetic pattern in switch

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96245

            Bug ID: 96245
           Summary: Failure to optimize arithmetic pattern in switch
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gabravier at gmail dot com
  Target Milestone: ---

void f(int x)
{
    switch (x)
    {
        case 0:
            putchar('0');
            break;
        case 1:
            putchar('1');
            break;
        case 2:
            putchar('2');
            break;
        case 3:
            putchar('3');
            break;
        case 4:
            putchar('4');
            break;
        case 5:
            putchar('5');
            break;
        case 6:
            putchar('6');
            break;
        case 7:
            putchar('7');
            break;
        case 8:
            putchar('8');
            break;
        case 9:
            putchar('9');
            break;
    }
}

This can be optimized to `if ((unsigned)x < 10) putchar('0' + x);`. This
transformation is done by LLVM, but not by GCC.