[mlir][MemRef][TransformOps] Fix error reporting for multibuffer

[qcolombet]

Summary

Multibuffer will fail to apply on allocs that are used outside of loops.
This was properly caught in the current implementation but the way we report
it was broken.
Notes cannot be emitted on their own, they need to be attached to another
main diagnostic.

Long story short, change the severity of the report from Note to Remark.

Note: I'm making another patch to not even bother running the multibuffer transformation on such allocs

[ftynse]

mlir/lib/Dialect/MemRef/TransformOps/MemRefTransformOps.cpp

27–28

We now have emitSilenceableError() << "message", no need to do the creation dance manually here.

[qcolombet]

mlir/lib/Dialect/MemRef/TransformOps/MemRefTransformOps.cpp

27–28

Ah cool!
Let me adopt that.

[qcolombet]

Adopt emitSilenceableFailure

[nicolasvasilache]

mlir/lib/Dialect/MemRef/TransformOps/MemRefTransformOps.cpp

27–28

Don't hesitate to clean a few other things as you go: usage has not been consistently improved as you can see ..

Thank you!

[qcolombet]

Update the added test check-lines.

[qcolombet]

mlir/lib/Dialect/MemRef/TransformOps/MemRefTransformOps.cpp

27–28

@ftynse @nicolasvasilache
Should we introduce a emitSilenceableRemark?

Scanning through the code, it looks like we still use the old style in a few places, and sometimes we emit Remark not Error and I don't know if we want to promote these to errors.
E.g.,
https://github.com/llvm/llvm-project/blob/af39acda8873cc75db116e326588447f018a99d9/mlir/lib/Dialect/Linalg/TransformOps/LinalgTransformOps.cpp#L668

[ftynse]

mlir/lib/Dialect/MemRef/TransformOps/MemRefTransformOps.cpp

27–28

Places that emit Remark are wrong and should emit Error instead.

[qcolombet]

mlir/lib/Dialect/MemRef/TransformOps/MemRefTransformOps.cpp

27–28

Changed that in https://github.com/llvm/llvm-project.git

2a58be423963..5a028cc8ffa5  main -> main

mlir/lib/Dialect/MemRef/TransformOps/MemRefTransformOps.cpp

 
 //===----------------------------------------------------------------------===//
 // MemRefMultiBufferOp
 //===----------------------------------------------------------------------===//
 
 DiagnosedSilenceableFailure transform::MemRefMultiBufferOp::applyToOne(
     memref::AllocOp target, transform::ApplyToEachResultList &results,
     transform::TransformState &state) {
   auto newBuffer = memref::multiBuffer(target, getFactor());
-  if (failed(newBuffer)) {
-    Diagnostic diag(target->getLoc(), DiagnosticSeverity::Note);
-    diag << "op failed to multibuffer";
-    return DiagnosedSilenceableFailure::silenceableFailure(std::move(diag));
-  }
+  if (failed(newBuffer))
+    return emitSilenceableFailure(target->getLoc())
+           << "op failed to multibuffer";
 
   results.push_back(*newBuffer);
   return DiagnosedSilenceableFailure::success();
 }
 
 //===----------------------------------------------------------------------===//
 // Transform op registration
 //===----------------------------------------------------------------------===//

mlir/test/Dialect/MemRef/transform-ops.mlir

-// RUN: mlir-opt %s -test-transform-dialect-interpreter -verify-diagnostics -allow-unregistered-dialect | FileCheck %s
+// RUN: mlir-opt %s -test-transform-dialect-interpreter -verify-diagnostics -allow-unregistered-dialect -split-input-file | FileCheck %s
 
 // CHECK-DAG: #[[$MAP0:.*]] = affine_map<(d0) -> ((d0 floordiv 4) mod 2)>
 // CHECK-DAG: #[[$MAP1:.*]] = affine_map<(d0)[s0] -> (d0 + s0)>
 
 // CHECK-LABEL: func @multi_buffer
 func.func @multi_buffer(%in: memref<16xf32>) {
   // CHECK: %[[A:.*]] = memref.alloc() : memref<2x4xf32>
   // expected-remark @below {{transformed}}

 
 transform.sequence failures(propagate) {
 ^bb1(%arg1: !pdl.operation):
   %0 = transform.structured.match ops{["memref.alloc"]} in %arg1 : (!pdl.operation) -> !pdl.operation
   %1 = transform.memref.multibuffer %0 {factor = 2 : i64}
   // Verify that the returned handle is usable.
   transform.test_print_remark_at_operand %1, "transformed" : !pdl.operation
 }
+
+// -----
+
+// Trying to use multibuffer on alloc that are used outside of loops is
+// going to fail.
+// Check that we emit a proper error for that.
+func.func @multi_buffer_uses_outside_of_loop(%in: memref<16xf32>) {
+  // expected-error @below {{op failed to multibuffer}}
+  %tmp = memref.alloc() : memref<4xf32>
+
+  "some_outside_loop_use"(%tmp) : (memref<4xf32>) -> ()
+
+  %c0 = arith.constant 0 : index
+  %c4 = arith.constant 4 : index
+  %c16 = arith.constant 16 : index
+
+  scf.for %i0 = %c0 to %c16 step %c4 {
+    %1 = memref.subview %in[%i0] [4] [1] : memref<16xf32> to memref<4xf32, affine_map<(d0)[s0] -> (d0 + s0)>>
+    memref.copy %1, %tmp :  memref<4xf32, affine_map<(d0)[s0] -> (d0 + s0)>> to memref<4xf32>
+
+    "some_use"(%tmp) : (memref<4xf32>) ->()
+  }
+  return
+}
+
+transform.sequence failures(propagate) {
+^bb1(%arg1: !pdl.operation):
+  %0 = transform.structured.match ops{["memref.alloc"]} in %arg1 : (!pdl.operation) -> !pdl.operation
+  %1 = transform.memref.multibuffer %0 {factor = 2 : i64}
+}