[mlir][linalg][transform] Extend diagnostics of FuseIntoContainingOp.

[ingomueller-net]

Summary

This patch extends the diagnostic output of FuseIntoContainingOp when
it fails to find the next producer by also provided the location of the
affected transform op.

[ftynse]

Would be nice to have a test for this.

[ingomueller-net]

Addressing @ftynse's comments:

• Add test.

[ingomueller-net]

• Rebase to latest main.
• Fix expected-error offset, which changed due to last-minute formatting.

mlir/lib/Dialect/Linalg/TransformOps/LinalgTransformOps.cpp

for (const auto &it : enumerate(remainingProducers)) {
       }
     }
     return failure();
   };
 
   while (!remainingProducers.empty()) {
     auto nextProducer = getNextProducer();
     if (failed(nextProducer)) {
-      return mlir::emitSilenceableFailure(containingOp->getLoc())
+      auto diag = mlir::emitSilenceableFailure(getLoc())
              << "could not find next producer to fuse into container";
+      diag.attachNote(containingOp->getLoc()) << "containing op";
+      return diag;
     }
 
     Operation *producerOp = *nextProducer;
 
     // Default diagnostic, to be complemented with more failure information.
     Diagnostic diag(producerOp->getLoc(), DiagnosticSeverity::Remark);
     diag << "could not fuse " << *producerOp << " into " << *containingOp;
 

mlir/test/Dialect/Linalg/transform-op-fuse-into-containing.mlir

module {
   transform.sequence failures(propagate) {
   ^bb1(%arg1: !transform.any_op):
     %0 = transform.structured.match attributes{producer} in %arg1 : (!transform.any_op) -> !transform.op<"linalg.generic">
     %1 = transform.structured.match ops{["scf.forall"]} in %arg1 : (!transform.any_op) -> !transform.op<"scf.forall">
     transform.structured.fuse_into_containing_op %0 into %1
       : (!transform.op<"linalg.generic">, !transform.op<"scf.forall">) -> (!transform.any_op, !transform.any_op)
   }
 }
+
+
+////////////////////////////////////////////////////////////////////////////////
+// Tests below are expected to fail.
+////////////////////////////////////////////////////////////////////////////////
+
+// -----
+
+// NO-CHECK-LABEL-ON-EXPECTED-ERROR
+func.func @copy_1d_1024xf16(%arg0: tensor<123x456xf32>, %arg1: tensor<456x789xf32>, %arg2 : tensor<123x789xf32>) -> tensor<123x789xf32> {
+  %0 = arith.constant 0.000000e+00 : f32
+  %1 = linalg.fill ins(%0 : f32) outs(%arg2 : tensor<123x789xf32>) -> tensor<123x789xf32>
+  // expected-note @below {{containing op}}
+  %2 = linalg.matmul ins(%arg0, %arg1 : tensor<123x456xf32>, tensor<456x789xf32>) outs(%1 : tensor<123x789xf32>) -> tensor<123x789xf32>
+  return %2 : tensor<123x789xf32>
+}
+
+transform.sequence failures(propagate) {
+^bb1(%arg1: !transform.any_op):
+  %0 = transform.structured.match ops{["linalg.fill"]} in %arg1
+    : (!transform.any_op) -> !transform.any_op
+  %1 = transform.structured.match ops{["linalg.matmul"]} in %arg1
+    : (!transform.any_op) -> !transform.any_op
+  %forall_op, %tiled_op = transform.structured.tile_to_forall_op %1
+    num_threads [] tile_sizes [50, 16]
+    : (!transform.any_op) -> (!transform.any_op, !transform.any_op)
+  // Note that we pass in %tiled_op, which isn't a container op.
+  // expected-error @+2 {{could not find next producer to fuse into container}}
+  %fused_op, %new_containing_op =
+    transform.structured.fuse_into_containing_op %0 into %tiled_op
+      : (!transform.any_op, !transform.any_op)
+        -> (!transform.any_op, !transform.any_op)
+}