[Bug middle-end/90248] [8/9/10 Regression] larger than 0 compare fails with -ffinite-math-only -funsafe-math-optimizations

[ch3root at openwall dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90248

Alexander Cherepanov <ch3root at openwall dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |ch3root at openwall dot com

--- Comment #13 from Alexander Cherepanov <ch3root at openwall dot com> ---
(In reply to Andrew Pinski from comment #7)
> I copied an optimization from LLVM so I
> think they also mess up a similar way (though differently).
I looked into reporting this problem to llvm but I don't see it there. In the
current llvm sources I can only find this:
https://github.com/llvm/llvm-project/blob/master/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp#L2348

  // If needed, negate the value that will be the sign argument of the
copysign:
  // (bitcast X) <  0 ? -TC :  TC --> copysign(TC,  X)
  // (bitcast X) <  0 ?  TC : -TC --> copysign(TC, -X)
  // (bitcast X) >= 0 ? -TC :  TC --> copysign(TC, -X)
  // (bitcast X) >= 0 ?  TC : -TC --> copysign(TC,  X)

AIUI `bitcast` here means a bitcast to an integer type. For example, this:

----------------------------------------------------------------------
union u { double d; long l; };

double f(double x)
{
    return (union u){x}.l >= 0 ? 2.3 : -2.3;
}
----------------------------------------------------------------------

is optimized into this:

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; Function Attrs: nounwind readnone uwtable
define dso_local double @f(double %0) local_unnamed_addr #0 {
  %2 = tail call double @llvm.copysign.f64(double 2.300000e+00, double %0)
  ret double %2
}
----------------------------------------------------------------------

Did I miss something?