[Mlir-commits] [mlir] [mlir][tensor][memref] Enhance collapse(expand(src)) canonicalization pattern. (PR #145995)

[Han-Chung Wang]

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@@ -305,8 +306,42 @@ struct ComposeCollapseOfExpandOp : public OpRewritePattern<CollapseOpTy> {
       rewriter.replaceOpWithNewOp<CollapseOpTy>(
           collapseOp, resultType, expandOp.getSrc(), composedReassociation);
     } else if (srcRank < resultRank) {
+      // Compute the dynamic output shape for the new expand_shape op.
+      Location loc = collapseOp.getLoc();
+      SmallVector<OpFoldResult> origOutputShape =
+          expandOp.getMixedOutputShape();
+      SmallVector<OpFoldResult> newOutputShape;
+      for (auto indices : collapseOp.getReassociationIndices()) {
+        int64_t numStaticElems = 1;
+        SmallVector<Value> dynamicSizes;
+        for (auto idx : indices) {
+          OpFoldResult size = origOutputShape[idx];
+          if (auto maybeCst = getConstantIntValue(size)) {
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hanhanW wrote:

> Use auto if and only if it makes the code more readable or easier to maintain.

https://llvm.org/docs/CodingStandards.html#use-auto-type-deduction-to-make-code-more-readable

This is a neutral case to me, because I think we don't really are the actual type name and it makes it easier to maintain. E.g., I've been wanting to remove `, 2` from the SmallVector, and you don't need to update it if we use auto here. reassociation indices is a list of int array is quite common in MLIR, so I don't think spelling the type is necessary. I can see some people find it helpful, so I'm going to make the change.


https://github.com/llvm/llvm-project/pull/145995