[Bug tree-optimization/97873] New: Failure to optimize abs optimally (at least one useless instruction on x86)

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97873

            Bug ID: 97873
           Summary: Failure to optimize abs optimally (at least one
                    useless instruction on x86)
           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: ---

int abs(int x)
{
        return (x < 0) ? -x : x;
}

For x86 -O3, LLVM outputs this:

abs:
  mov eax, edi
  neg eax
  cmovl eax, edi
  ret

GCC outputs this:

abs:
  mov eax, edi
  neg eax
  cmp eax, edi
  cmovl eax, edi
  ret