[InstCombine] Missed fold: icmp(fptosi(x), c) -> fcmp(x,c)

[zhengyang92]

define i1 @src(float %x) {
entry:
    %n0 = fptosi float %x to i32
    %r = icmp eq i32 %n0, -1000000000
    ret i1 %r
}
define i1 @tgt(float %x) {
entry:
    %r = fcmp oeq float %x, -1.000000e+09
    ret i1 %r
}

Alive proof: https://alive2.llvm.org/ce/z/Zkm4CJ