InstCombine: incorrect sink of FP math through select changes NaN payload

[nunoplopes]

This optimization changes the NaN payload. It requires the nnan flag.

; test/Transforms/InstCombine/select-binop-foldable-floating-point.ll

define float @select_fadd(i1 %cond, float %A, float %B) {
  %C = fadd float %A, %B
  %D = select i1 %cond, float %C, float %A
  ret float %D
}
=>
define float @select_fadd(i1 %cond, float %A, float %B) {
  %C = select i1 %cond, float %B, float -0.000000
  %D = fadd float %C, %A
  ret float %D
}
Transformation doesn't verify!

ERROR: Value mismatch

Example:
i1 %cond = #x0 (0)
float %A = #x7f810000 (SNaN)
float %B = #x00000000 (+0.0)

Source:
float %C = #x7fc00000 (QNaN)
float %D = #x7f810000 (SNaN)

Target:
float %C = #x80000000 (-0.0)
float %D = #x7fc00000 (QNaN)
Source value: #x7f810000 (SNaN)
Target value: #x7fc00000 (QNaN)

[RKSimon]

@nunoplopes @michele-scandale OK to close this? I think #83200 handled it?

[nunoplopes]

Alive2 is not reporting any more issues related with this. Thanks!