[InstSimplify] fold fcmp using isKnownNeverInfinity + isKnownNeverNaN
Follow-up to D84035 / rG7393d7574c09.
This sidesteps a question of FMF/poison on fcmp raised in PR46077:
http://bugs.llvm.org/PR46077
https://alive2.llvm.org/ce/z/TCsyzD
define i1 @src(float %x) {
%0:
%x42 = fadd nnan ninf float %x, 42.000000
%r = fcmp ueq float %x42, inf
ret i1 %r
}
=>
define i1 @tgt(float %x) {
%0:
ret i1 0
}
Transformation seems to be correct!
https://alive2.llvm.org/ce/z/FQaH7a
define i1 @src(i8 %x) {
%0:
%cast = uitofp i8 %x to float
%r = fcmp one float inf, %cast
ret i1 %r
}
=>
define i1 @tgt(i8 %x) {
%0:
ret i1 1
}
Transformation seems to be correct!