[Mlir-commits] [mlir] [mlir][vector] Update `castAwayContractionLeadingOneDim` to omit transposes solely on leading unit dims. (PR #85694)

[Andrzej Warzyński]

================
@@ -399,13 +399,29 @@ mlir::vector::castAwayContractionLeadingOneDim(vector::ContractionOp contractOp,
           transposeResults.push_back(targetExpr);
         }
       }
+
+      // Checks if only the outer, unit dimensions (of size 1) are permuted.
+      // Such transposes do not materially effect the underlying vector and can
+      // be omitted. EG: perm [1, 0, 2] applied to vector<1x1x8xi32>
+      bool tranposeNonOuterUnitDims = false;
+      for (auto [index, dim] :
+           llvm::enumerate(ArrayRef<int64_t>(perm).drop_back(1))) {
+        if (dim != static_cast<int64_t>(index) &&
+            operands[it.index()].getType().cast<ShapedType>().getDimSize(
+                index) != 1) {
+          tranposeNonOuterUnitDims = true;
+        }
+      }
+
       // Do the tranpose now if needed so that we can drop the
       // correct dim using extract later.
       if (tranposeNeeded) {
----------------
banach-space wrote:

Shouldn't this be something like:
```cpp
if (tranposeNeeded && tranposeNonOuterUnitDims) {
```
?

https://github.com/llvm/llvm-project/pull/85694