[mlir] [MLIR][Linalg] Introduce broadcast/transpose semantic to 'linalg.batc… (PR #122275)

[Andrzej Warzyński]

================
@@ -680,6 +680,130 @@ def MatmulOp : LinalgStructuredBase_Op<"matmul", [
     }];
 }
 
+//===----------------------------------------------------------------------===//
+// Op definition for BatchMatmulOp
+//===----------------------------------------------------------------------===//
+
+def BatchMatmulOp : LinalgStructuredBase_Op<"batch_matmul", !listconcat([AttrSizedOperandSegments],
+  /*extraInterfaces=*/[LinalgContractionOpInterface])> {
+    
+  let summary = [{Performs a batched matrix multiplication of two 3D inputs.}];
+  let description = [{Numeric casting is performed on the operands to the inner multiply, promoting
+    them to the same data type as the accumulator/output.
+
+    Broadcast and Transpose semantics can be appiled by specifying the explicit attribute
+    'indexing_maps' as shown below.This is a list attribute, so the list must include all
+    the maps if specified.
+
+    Example Transpose:
+    ```
+    linalg.batch_matmul indexing_maps = [
+                   affine_map<(d0, d1, d2, d3) -> (d0, d3, d1)>, // transpose
+                   affine_map<(d0, d1, d2, d3) -> (d0, d3, d2)>,
+                   affine_map<(d0, d1, d2, d3) -> (d0, d1, d2)>
+                   ]
+                   ins(%arg0, %arg1 : memref<2x5x3xf32>,memref<2x5x7xf32>)
+                   outs(%arg2: memref<2x3x7xf32>)
+    ```
+
+    Example Broadcast:
+    ```
+    linalg.batch_matmul indexing_maps = [
+                       affine_map<(d0, d1, d2, d3) -> (d3)>,     // broadcast
+                       affine_map<(d0, d1, d2, d3) -> (d0, d3, d2)>,
+                       affine_map<(d0, d1, d2, d3) -> (d0, d1, d2)>
----------------
banach-space wrote:

Please use consistent formatting for all examples.
```suggestion
                       affine_map<(d0, d1, d2, d3) -> (d3)>,              // broadcast
                       affine_map<(d0, d1, d2, d3) -> (d0, d3, d2)>,
                       affine_map<(d0, d1, d2, d3) -> (d0, d1, d2)>
```

https://github.com/llvm/llvm-project/pull/122275