Wrong folding of `select` into floating number ops

[bongjunj]

llvm-project/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

Lines 559 to 568 in ae618d3

	Value *NewSel = Builder.CreateSelect(SI.getCondition(), Swapped ? C : OOp,
	Swapped ? OOp : C, "", &SI);
	if (isa<FPMathOperator>(&SI))
	cast<Instruction>(NewSel)->setFastMathFlags(FMF);
	NewSel->takeName(TVI);
	BinaryOperator *BO =
	BinaryOperator::Create(TVI->getOpcode(), FalseVal, NewSel);
	BO->copyIRFlags(TVI);
	return BO;
	};

The compiler explorer's alive2 times out for this case.
But I post a proof that the optimization actually happens: https://alive2.llvm.org/ce/z/7MRSu5

This is the Alive2 report on my machine:

----------------------------------------
define float @fmul_by_self_if_0_oeq_zero_f32_fmul_nnan_ninf_nsz.2(float %x) {
#0:
  %#1 = fcmp ule float %x, 0.000000
  %scaled.x = fmul nnan ninf nsz float %x, %x
  %scaled.if.denormal = select nnan i1 %#1, float %x, float %scaled.x
  ret float %scaled.if.denormal
}
=>
define float @fmul_by_self_if_0_oeq_zero_f32_fmul_nnan_ninf_nsz.2(float %x) {
#0:
  %#1 = fcmp ule float %x, 0.000000
  %scaled.x = select nnan i1 %#1, float 1.000000, float %x
  %scaled.if.denormal = fmul nnan ninf nsz float %scaled.x, %x
  ret float %scaled.if.denormal
}
Transformation doesn't verify!

ERROR: Target is more poisonous than source

Example:
float %x = #xff800000 (-oo)

Source:
i1 %#1 = #x1 (1)
float %scaled.x = poison
float %scaled.if.denormal = #xff800000 (-oo)

Target:
i1 %#1 = #x1 (1)
float %scaled.x = #x3f800000 (1)
float %scaled.if.denormal = poison
Source value: #xff800000 (-oo)
Target value: poison

Summary:
  0 correct transformations
  1 incorrect transformations
  0 failed-to-prove transformations
  0 Alive2 errors