[Bug tree-optimization/91249] New: Missed optimization: division and multiplying ops in ffast-math mode

[zamazan4ik at tut dot by]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91249

            Bug ID: 91249
           Summary: Missed optimization: division and multiplying ops in
                    ffast-math mode
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zamazan4ik at tut dot by
  Target Milestone: ---

For this code:

float foo(float x, float y)
{
    return x * y/y;
}


gcc(trunk,9,8,7,6,5) with '-O3 -ffast-math' produces this:


foo(float, float):
        mulss   xmm0, xmm1
        divss   xmm0, xmm1
        ret


clang(trunk) with '-O3 -ffast-math' produces this:


foo(float, float):                               # @foo(float, float)
        ret


Notes: playground on godbolt - https://godbolt.org/z/Qjr3OD