[mlir] [llvm] [mlir] Add config for PDL (PR #69927)

[Mehdi Amini via llvm-commits]

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@@ -97,6 +98,7 @@ LogicalResult RewritePattern::match(Operation *op) const {
 /// Out-of-line vtable anchor.
 void RewritePattern::anchor() {}
 
+#if MLIR_ENABLE_PDL
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joker-eph wrote:

Can we extract the code in this file into a new .cpp and make it its own CMake library to manage enabling/disabling?

https://github.com/llvm/llvm-project/pull/69927