[Mlir-commits] [mlir] [mlir][docs] Add poison example to canonicalization section (PR #192782)

[Matthias Springer]

https://github.com/matthias-springer created https://github.com/llvm/llvm-project/pull/192782

Mention that folding to `ub.poison` is a common canonicalization.


>From bbf0a6dd858586ba9a3be67766349a4ba932d0d9 Mon Sep 17 00:00:00 2001
From: Matthias Springer <me at m-sp.org>
Date: Sat, 18 Apr 2026 09:47:21 +0000
Subject: [PATCH] [mlir][docs] Add poison example to canonicalization section

---
 mlir/docs/Canonicalization.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mlir/docs/Canonicalization.md b/mlir/docs/Canonicalization.md
index 6f48e60c94962..6fbcf09c51df3 100644
--- a/mlir/docs/Canonicalization.md
+++ b/mlir/docs/Canonicalization.md
@@ -96,6 +96,8 @@ canonicalizations include:
   rewriting `tensor.insert_slice(%src, tensor.cast(%dst))` (where the cast
   converts from `tensor<5xf32>` to `tensor<?xf32>`) as
   `tensor.cast(tensor.insert_slice(%src, %dst))`.
+* Replacing poisoned results with `ub.poison`. E.g., replacing
+  `arith.divsi(%c5, %c2, exact)` with `ub.poison`.
 
 
 Note: Some canonicalizations do not apply when they would lead to IR size