[Mlir-commits] [mlir] [mlir][Vector] add vector.insert canonicalization pattern for vectors created from ub.poison (PR #142944)

[Yang Bai]

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@@ -3191,6 +3227,109 @@ class InsertSplatToSplat final : public OpRewritePattern<InsertOp> {
   }
 };
 
+// Pattern to optimize a chain of constant insertions into a poison vector.
+//
+// This pattern identifies chains of vector.insert operations that:
+// 1. Start from an ub.poison operation.
+// 2. Insert only constant values at static positions.
+// 3. Completely initialize all elements in the resulting vector.
+//
+// When these conditions are met, the entire chain can be replaced with a
+// single arith.constant operation containing a dense elements attribute.
+//
+// Example transformation:
+//   %poison = ub.poison : vector<2xi32>
+//   %0 = vector.insert %c1, %poison[0] : i32 into vector<2xi32>
+//   %1 = vector.insert %c2, %0[1] : i32 into vector<2xi32>
+// ->
+//   %result = arith.constant dense<[1, 2]> : vector<2xi32>
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yangtetris wrote:

Got it! Thanks.

https://github.com/llvm/llvm-project/pull/142944