[mlir][Vector] Add vector to outerproduct lowering for the [reduction, parallel] case.

[nicolasvasilache]

Add test.

mlir/lib/Dialect/Vector/VectorTransforms.cpp

if (vectorTransformsOptions.vectorContractLowering !=
     return failure();
 
   if (failed(filter(op)))
     return failure();
 
   VectorType lhsType = op.getLhsType();
   Value lhs = op.lhs(), rhs = op.rhs(), res = op.acc();
 
-  // Set up the parallel/reduction structure in right form.
-  AffineExpr m, n, k;
-  bindDims(rewriter.getContext(), m, n, k);
-
   //
   // Two outer parallel, one inner reduction (matmat flavor).
   //
   UnrolledOuterProductEmitter e(rewriter, op);
   if (e.iters({Par(), Par(), Red()})) {
+    // Set up the parallel/reduction structure in right form.
+    AffineExpr m, n, k;
+    bindDims(rewriter.getContext(), m, n, k);
     // Classical row-major matmul:  Just permute the lhs.
     if (e.layout({{m, k}, {k, n}, {m, n}}))
       return e.outer_prod(e.t(lhs), rhs, res, lhsType.getDimSize(1));
     // TODO: may be better to fail and use some vector<k> -> scalar reduction.
     if (e.layout({{m, k}, {n, k}, {m, n}})) {
       Value tlhs = e.t(lhs);
       return e.outer_prod(tlhs, e.t(rhs), res, lhsType.getDimSize(1));
     }
if (e.layout({{k, m}, {n, k}, {n, m}}))
       return e.outer_prod(e.t(rhs), lhs, res, lhsType.getDimSize(0));
     return failure();
   }
 
   //
   // One outer parallel, one inner reduction (matvec flavor)
   //
   if (e.iters({Par(), Red()})) {
+    AffineExpr m, k;
+    bindDims(rewriter.getContext(), m, k);
+
+    // Case mat-vec: transpose.
+    if (e.layout({{m, k}, {k}, {m}}))
+      return e.outer_prod(e.t(lhs), rhs, res, lhsType.getDimSize(1));
+    // Case mat-trans-vec: ready to go.
+    if (e.layout({{k, m}, {k}, {m}}))
+      return e.outer_prod(lhs, rhs, res, lhsType.getDimSize(0));
+    // Case vec-mat: swap and transpose.
+    if (e.layout({{k}, {m, k}, {m}}))
+      return e.outer_prod(e.t(rhs), lhs, res, lhsType.getDimSize(0));
+    // Case vec-mat-trans: swap and ready to go.
+    if (e.layout({{k}, {k, m}, {m}}))
+      return e.outer_prod(rhs, lhs, res, lhsType.getDimSize(0));
+    return failure();
+  }
+
+  //
+  // One outer reduction, one inner parallel (tmatvec flavor)
+  //
+  if (e.iters({Red(), Par()})) {
+    AffineExpr k, m;
+    bindDims(rewriter.getContext(), k, m);
+
     // Case mat-vec: transpose.
-    if (e.layout({{m, n}, {n}, {m}}))
+    if (e.layout({{m, k}, {k}, {m}}))
       return e.outer_prod(e.t(lhs), rhs, res, lhsType.getDimSize(1));
     // Case mat-trans-vec: ready to go.
-    if (e.layout({{n, m}, {n}, {m}}))
+    if (e.layout({{k, m}, {k}, {m}}))
       return e.outer_prod(lhs, rhs, res, lhsType.getDimSize(0));
     // Case vec-mat: swap and transpose.
-    if (e.layout({{n}, {m, n}, {m}}))
+    if (e.layout({{k}, {m, k}, {m}}))
       return e.outer_prod(e.t(rhs), lhs, res, lhsType.getDimSize(0));
     // Case vec-mat-trans: swap and ready to go.
-    if (e.layout({{n}, {n, m}, {m}}))
+    if (e.layout({{k}, {k, m}, {m}}))
       return e.outer_prod(rhs, lhs, res, lhsType.getDimSize(0));
     return failure();
   }
 
   return failure();
 }
 
 LogicalResult