[mlir][linalg] Don't drop existing attributes when creating ops

mlir/lib/Dialect/Linalg/IR/LinalgOps.cpp

LogicalResult matchAndRewrite(GenericOp genericOp,
 
     // Clone the old op with new operands.
     SmallVector<Value> outputOperands = genericOp.getOutputOperands();
     auto newOp = rewriter.create<GenericOp>(
         genericOp.getLoc(), genericOp->getResultTypes(), newInputOperands,
         outputOperands, rewriter.getAffineMapArrayAttr(newIndexingMaps),
         genericOp.iterator_types(), genericOp.docAttr(),
         genericOp.library_callAttr());
+
+    // Copy over unknown attributes. They might be load bearing for some flow.
+    ArrayRef<StringRef> odsAttrs = genericOp.getAttributeNames();
+    for (NamedAttribute kv : genericOp->getAttrs()) {
+      if (!llvm::is_contained(odsAttrs, kv.first.c_str())) {
+        newOp->setAttr(kv.first, kv.second);
+      }
+    }
+
     rewriter.inlineRegionBefore(genericOp.region(), newOp.region(),
                                 newOp.region().begin());
 
     // Repair the payload entry block by RAUW'ing redundant arguments and
     // erasing them.
     Block &payload = newOp.region().front();
     SmallVector<OpOperand *> inputOperands = genericOp.getInputOperands();
     for (OpOperand *opOperand : llvm::reverse(inputOperands)) {

mlir/test/Dialect/Linalg/canonicalize-duplicate-inputs.mlir

 // RUN: mlir-opt %s -split-input-file -canonicalize | FileCheck %s
 
 // Test case: Most basic case. Adding a vector to itself.
 
 #map = affine_map<(d0) -> (d0)>
 
 // CHECK: #[[$MAP:.*]] = affine_map<(d0) -> (d0)>
 // CHECK-LABEL: @basic
 func @basic(%arg0: tensor<?xf32>) -> tensor<?xf32> {
   // CHECK: linalg.generic{{.*}}[#[[$MAP]], #[[$MAP]]]
+  // CHECK:   attrs =  {someattr}
   // CHECK:   ^bb0(%[[BBARG:.*]]: f32, %{{.*}}: f32):
   // CHECK:     addf %[[BBARG]], %[[BBARG]]
   %0 = linalg.generic {indexing_maps = [#map, #map, #map], iterator_types = ["parallel"]}
      ins(%arg0, %arg0 : tensor<?xf32>, tensor<?xf32>)
-    outs(%arg0 : tensor<?xf32>) {
+    outs(%arg0 : tensor<?xf32>) attrs = {someattr} {
   ^bb0(%arg1: f32, %arg2: f32, %arg3: f32):
     %1 = addf %arg1, %arg2 : f32
     linalg.yield %1 : f32
   } -> tensor<?xf32>
   return %0 : tensor<?xf32>
 }
 
 // -----