[llvm] [HashRecognize] Recognize trunc-to-i1 little-endian bit check (PR #213883)

[Vito Kortbeek via llvm-commits]

================
@@ -172,16 +173,24 @@ isSignificantBitCheckWellFormed(const RecurrenceInfo &ConditionalRecurrence,
   const Value *L;
   const APInt *R;
   Instruction *TV, *FV;
-  if (!match(SI, m_Select(m_ICmp(Pred, m_Value(L), m_APInt(R)),
----------------
vkortbeek-gf wrote:

I don't think that would help, but I might be missing something.

`m_SelectLike` would match `zext/sext(i1 %cond)` or `select`

But here we have:
```llvm
%cond = trunc i8 %x to i1
%next = select i1 %cond, i16 %with.poly, i16 %shift
```

Did you mean `m_ICmpLike`? That one seems to handle `trunc nuw X to i1`, equivalent to `icmp ne i8 %x, 0`, but we get a plain `trunc X to i1` equivalent to `icmp ne (and X, 1), 0`, so we miss the `nuw` flag.

Let me know if you had something else in mind.

https://github.com/llvm/llvm-project/pull/213883