[Mlir-commits] [mlir] [mlir][spirv] Support poison index when converting vector.insert/extract (PR #125560)

[Jakub Kuderski]

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@@ -154,14 +174,26 @@ struct VectorExtractOpConvert final
     }
 
     if (std::optional<int64_t> id =
-            getConstantIntValue(extractOp.getMixedPosition()[0]))
-      rewriter.replaceOpWithNewOp<spirv::CompositeExtractOp>(
-          extractOp, dstType, adaptor.getVector(),
-          rewriter.getI32ArrayAttr(id.value()));
-    else
+            getConstantIntValue(extractOp.getMixedPosition()[0])) {
+      // TODO: It would be better to apply the ub.poison folding for this case
+      //       unconditionally, and have a specific SPIR-V lowering for it,
+      //       rather than having to handle it here.
----------------
kuhar wrote:

If this pattern is only used by the dialect conversion driver, we should check if it is guaranteed to fold before applying rewrites: https://github.com/llvm/llvm-project/blob/36fb886f5a0c0af40095696ea7589309d3dd30d5/mlir/lib/Transforms/Utils/DialectConversion.cpp#L2001-L2081

https://github.com/llvm/llvm-project/pull/125560