[llvm] [GlobalIsel] Canonicalize G_FCMP (PR #108891)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

Maybe there is a misunderstanding.

I have a vreg s128 and ask for a GIConstant. Then I either get a std::nullopt or a wrapper around an APint with 128 bit. Even if between the vreg and the G_CONSTANT are some copies, exts, and trunc. With lookthrough we interpret the IR and get the correct result because IR is always well-formed.


I have a vreg 10xs64 and ask for a GIConstant. Then I either get std::nullopt or there is a G_BUILD_VECTOR directly on the vreg or behind some copies.

https://github.com/llvm/llvm-project/pull/108891