[Bug middle-end/70159] missed CSE optimization

["hiraditya at msn dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70159

AK <hiraditya at msn dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hiraditya at msn dot com

--- Comment #11 from AK <hiraditya at msn dot com> ---
Just as an update, the new gvn-hoist pass in llvm hoists the common
computations:

@cat test.c
float foo_p(float d, float min, float max, float a)
{
  float tmin;
  float tmax;

  float inv = 1.0f / d;
  if (inv >= 0) {
    tmin = (min - a) * inv;
    tmax = (max - a) * inv;
  } else {
    tmin = (max - a) * inv;
    tmax = (min - a) * inv;
  }

  return tmax + tmin;
}


clang -c -Ofast test.c -mllvm -print-after-all


*** IR Dump Before Early GVN Hoisting of Expressions ***
; Function Attrs: nounwind uwtable
define float @_Z5foo_pffff(float %d, float %min, float %max, float %a) #0 {
entry:
  %div = fdiv fast float 1.000000e+00, %d
  %cmp = fcmp fast oge float %div, 0.000000e+00
  br i1 %cmp, label %if.then, label %if.else

if.then:                                          ; preds = %entry
  %sub = fsub fast float %min, %a
  %mul = fmul fast float %sub, %div
  %sub1 = fsub fast float %max, %a
  %mul2 = fmul fast float %sub1, %div
  br label %if.end

if.else:                                          ; preds = %entry
  %sub3 = fsub fast float %max, %a
  %mul4 = fmul fast float %sub3, %div
  %sub5 = fsub fast float %min, %a
  %mul6 = fmul fast float %sub5, %div
  br label %if.end

if.end:                                           ; preds = %if.else, %if.then
  %tmax.0 = phi float [ %mul2, %if.then ], [ %mul6, %if.else ]
  %tmin.0 = phi float [ %mul, %if.then ], [ %mul4, %if.else ]
  %add = fadd fast float %tmax.0, %tmin.0
  ret float %add
}


*** IR Dump After Early GVN Hoisting of Expressions ***
; Function Attrs: nounwind uwtable
define float @_Z5foo_pffff(float %d, float %min, float %max, float %a) #0 {
entry:
  %div = fdiv fast float 1.000000e+00, %d
  %cmp = fcmp fast oge float %div, 0.000000e+00
  %sub = fsub fast float %min, %a
  %mul = fmul fast float %sub, %div
  %sub1 = fsub fast float %max, %a
  %mul2 = fmul fast float %sub1, %div
  br i1 %cmp, label %if.then, label %if.else

if.then:                                          ; preds = %entry
  br label %if.end

if.else:                                          ; preds = %entry
  br label %if.end

if.end:                                           ; preds = %if.else, %if.then
  %tmax.0 = phi float [ %mul2, %if.then ], [ %mul, %if.else ]
  %tmin.0 = phi float [ %mul, %if.then ], [ %mul2, %if.else ]
  %add = fadd fast float %tmax.0, %tmin.0
  ret float %add
}