[Mlir-commits] [mlir] [mlir:doc] Clarify requirements on `RewritePatterns`. (PR #218351)

[Matthias Springer]

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@@ -73,15 +73,23 @@ public:
 
 #### Restrictions
 
+*   Patterns must transform verifiable IR into verifiable IR, i.e., the IR must
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matthias-springer wrote:

I've been advertising this as an "MLIR best practice", not a strict requirement. Technically, IR must be valid only between pass applications. There may be legitimate cases where this best practice does not apply, e.g. when converting function declarations and function calls with separate rewrite patterns.

https://github.com/llvm/llvm-project/pull/218351