[InstCombine] Commuted pattern is not handled

[dtcxzyw]

https://godbolt.org/z/3qoK61hdf

define float @test17_unary_fneg(float %a, float %b, float %z) {
  %d = fmul fast float %z, 4.000000e+01
  %c = fneg fast float %d
  %e = fmul fast float %a, %c
  %f = fneg fast float %e
  ret float %f
}

define float @test17_unary_fneg1(float %a, float %b, float %z) {
  %d = fmul fast float %z, 4.000000e+01
  %c = fneg fast float %d
  %e = fmul fast float %c, %a
  %f = fneg fast float %e
  ret float %f
}

define float @test17_unary_fneg(float %a, float %b, float %z) {
  %1 = fmul fast float %z, 4.000000e+01
  %f = fmul fast float %a, %1
  ret float %f
}

define float @test17_unary_fneg1(float %a, float %b, float %z) {
  %c = fmul fast float %z, -4.000000e+01
  %1 = fneg fast float %a
  %f = fmul fast float %c, %1
  ret float %f
}