[Bug middle-end/55152] New: MAX_EXPR(a,-a) is really ABS_EXPR(a)

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55152



             Bug #: 55152

           Summary: MAX_EXPR(a,-a) is really ABS_EXPR(a)

    Classification: Unclassified

           Product: gcc

           Version: 4.8.0

            Status: UNCONFIRMED

          Severity: normal

          Priority: P3

         Component: middle-end

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: gli...@gcc.gnu.org





I tried compiling this code with -Ofast, but *.optimized still only contained a

MAX_EXPR and not an ABS_EXPR (the back-end didn't find the optimization

either).



double f(double a){

  return (a>=-a)?a:-a;

}



It seems that some simple code in fold-const.c could help (fold is called from

the front-end for COND_EXPR), not sure if anything would call it if -a went

though a temporary variable though.