[Mlir-commits] [mlir] [MLIR][Vector]Generalize DropUnitDimFromElementwiseOps (PR #92934)

[Han-Chung Wang]

================
@@ -1652,42 +1668,30 @@ struct DropUnitDimFromElementwiseOps final
     // guaranteed to have identical shapes (with some exceptions such as
     // `arith.select`) and it suffices to only check one of them.
     auto sourceVectorType = dyn_cast<VectorType>(op->getOperand(0).getType());
-    if (!sourceVectorType)
-      return failure();
-    if (sourceVectorType.getRank() < 2)
-      return failure();
-
-    bool hasTrailingDimUnitFixed =
-        ((sourceVectorType.getShape().back() == 1) &&
-         (!sourceVectorType.getScalableDims().back()));
-    bool hasLeadingDimUnitFixed =
-        ((sourceVectorType.getShape().front() == 1) &&
-         (!sourceVectorType.getScalableDims().front()));
-    if (!hasLeadingDimUnitFixed && !hasTrailingDimUnitFixed)
+    if (!sourceVectorType || sourceVectorType.getRank() < 2)
       return failure();
 
-    // Drop leading/trailing unit dim by applying vector.shape_cast to all
-    // operands
-    int64_t dim = hasLeadingDimUnitFixed ? 0 : sourceVectorType.getRank() - 1;
-
     SmallVector<Value> newOperands;
     auto loc = op->getLoc();
     for (auto operand : op->getOperands()) {
       auto opVectorType = cast<VectorType>(operand.getType());
-      VectorType newVType = VectorType::Builder(opVectorType).dropDim(dim);
-      auto opSC = rewriter.create<vector::ShapeCastOp>(loc, newVType, operand);
+      auto newVType = dropNonScalableUnitDimType(opVectorType);
+      if (failed(newVType)) {
+        return failure();
+      }
----------------
hanhanW wrote:

I don't expect a failure in `dropNonScalableUnitDimType`. If there are no unit dims, it should just return the same type. It is not a failure to me. Then we check that if `newVType == opVectorType` or not. If they are the same, we return a matching failure here. Because it means that there nothing to do in the pattern.

```suggestion
      auto = dropNonScalableUnitDimType(opVectorType);
      if (newVType == opVectorType) {
        return return rewriter.notifyMatchFailure(op, ".... message");
      }
```

https://github.com/llvm/llvm-project/pull/92934