[mlir] optional verbose debug messages for transform application

[ftynse]

Summary

Introduce the additional "transform-dialect-print-top-level-after-all" debug
category that allows the user to print the paylaod IR after each transformation
performed by the transform dialect. This is useful for understanding and
debugging the effects of individual transformations in complex transformations
scripts, including in downstreams, without having to modify the transformation
script itself.

[mravishankar]

Thanks!

mlir/lib/Dialect/Transform/IR/TransformInterfaces.cpp

 //===- TransformInterfaces.cpp - Transform Dialect Interfaces -------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "mlir/Dialect/Transform/IR/TransformInterfaces.h"
 #include "mlir/Dialect/PDL/IR/PDLTypes.h"
 #include "mlir/IR/Diagnostics.h"
 #include "mlir/IR/Operation.h"
 #include "llvm/Support/Debug.h"
 
 #define DEBUG_TYPE "transform-dialect"
+#define DEBUG_PRINT_AFTER_ALL "transform-dialect-print-top-level-after-all"
 #define DBGS() (llvm::dbgs() << "[" DEBUG_TYPE "] ")
 
 using namespace mlir;
 
 //===----------------------------------------------------------------------===//
 // TransformState
 //===----------------------------------------------------------------------===//
 
if (llvm::any_of(effects, consumesTarget))
       recordHandleInvalidation(target);
   }
   return success();
 }
 
 DiagnosedSilenceableFailure
 transform::TransformState::applyTransform(TransformOpInterface transform) {
   LLVM_DEBUG(DBGS() << "applying: " << transform << "\n");
+  auto printOnFailureRAII = llvm::make_scope_exit([this] {
+    DEBUG_WITH_TYPE(DEBUG_PRINT_AFTER_ALL, {
+      DBGS() << "Top-level payload:\n";
+      getTopLevel()->print(llvm::dbgs(),
+                           mlir::OpPrintingFlags().printGenericOpForm());
+    });
+  });
   if (options.getExpensiveChecksEnabled()) {
     if (failed(checkAndRecordHandleInvalidation(transform)))
       return DiagnosedSilenceableFailure::definiteFailure();
 
     for (OpOperand &operand : transform->getOpOperands()) {
       if (!isHandleConsumed(operand.get(), transform))
         continue;
 
transform::TransformState::applyTransform(TransformOpInterface transform) {
   for (OpResult result : transform->getResults()) {
     assert(result.getDefiningOp() == transform.getOperation() &&
            "payload IR association for a value other than the result of the "
            "current transform op");
     if (failed(setPayloadOps(result, results.get(result.getResultNumber()))))
       return DiagnosedSilenceableFailure::definiteFailure();
   }
 
+  printOnFailureRAII.release();
+  DEBUG_WITH_TYPE(DEBUG_PRINT_AFTER_ALL, {
+    DBGS() << "Top-level payload:\n";
+    getTopLevel()->print(llvm::dbgs());
+  });
   return DiagnosedSilenceableFailure::success();
 }
 
 //===----------------------------------------------------------------------===//
 // TransformState::Extension
 //===----------------------------------------------------------------------===//
 
 transform::TransformState::Extension::~Extension() = default;