[MLIR] Add a OpWithFlags class that acts as a "stream modifier" to customize Operation streaming

mlir/include/mlir/IR/Operation.h

@@ -1102,6 +1102,29 @@ inline raw_ostream &operator<<(raw_ostream &os, const Operation &op) {
   return os;
 }
 
+/// A wrapper class that allows for printing an operation with a set of flags,
+/// useful to act as a "stream modifier" to customize printing an operation
+/// with a stream using the operator<< overload, e.g.:
+///   llvm::dbgs() << OpWithFlags(op, OpPrintingFlags().skipRegions());
+class OpWithFlags {
+public:
+  OpWithFlags(Operation *op, OpPrintingFlags flags = {})
+      : op(op), theFlags(flags) {}
+  OpPrintingFlags &flags() { return theFlags; }
+  const OpPrintingFlags &flags() const { return theFlags; }
+
+private:
+  Operation *op;
+  OpPrintingFlags theFlags;
+  friend raw_ostream &operator<<(raw_ostream &os, const OpWithFlags &op);
+};
+
+inline raw_ostream &operator<<(raw_ostream &os,
+                               const OpWithFlags &opWithFlags) {
+  opWithFlags.op->print(os, opWithFlags.flags());
+  return os;
+}
+
 } // namespace mlir
 
 namespace llvm {

mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp

@@ -80,9 +80,8 @@ ChangeResult Liveness::meet(const AbstractSparseLattice &other) {
 LogicalResult
 LivenessAnalysis::visitOperation(Operation *op, ArrayRef<Liveness *> operands,
                                  ArrayRef<const Liveness *> results) {
-  LLVM_DEBUG(DBGS() << "[visitOperation] Enter: ";
-             op->print(llvm::dbgs(), OpPrintingFlags().skipRegions());
-             llvm::dbgs() << "\n");
+  LDBG() << "[visitOperation] Enter: "
+         << OpWithFlags(op, OpPrintingFlags().skipRegions());
   // This marks values of type (1.a) and (4) liveness as "live".
   if (!isMemoryEffectFree(op) || op->hasTrait<OpTrait::ReturnLike>()) {
     LDBG() << "[visitOperation] Operation has memory effects or is "

mlir/lib/Transforms/RemoveDeadValues.cpp

@@ -36,6 +36,7 @@
 #include "mlir/IR/Builders.h"
 #include "mlir/IR/BuiltinAttributes.h"
 #include "mlir/IR/Dialect.h"
+#include "mlir/IR/Operation.h"
 #include "mlir/IR/OperationSupport.h"
 #include "mlir/IR/SymbolTable.h"
 #include "mlir/IR/Value.h"
@@ -411,9 +412,8 @@ static void processRegionBranchOp(RegionBranchOpInterface regionBranchOp,
                                   RunLivenessAnalysis &la,
                                   DenseSet<Value> &nonLiveSet,
                                   RDVFinalCleanupList &cl) {
-  LLVM_DEBUG(DBGS() << "Processing region branch op: "; regionBranchOp->print(
-      llvm::dbgs(), OpPrintingFlags().skipRegions());
-             llvm::dbgs() << "\n");
+  LDBG() << "Processing region branch op: "
+         << OpWithFlags(regionBranchOp, OpPrintingFlags().skipRegions());
   // Mark live results of `regionBranchOp` in `liveResults`.
   auto markLiveResults = [&](BitVector &liveResults) {
     liveResults = markLives(regionBranchOp->getResults(), nonLiveSet, la);

mlir/lib/Transforms/Utils/DialectConversion.cpp

@@ -14,6 +14,7 @@
 #include "mlir/IR/Dominance.h"
 #include "mlir/IR/IRMapping.h"
 #include "mlir/IR/Iterators.h"
+#include "mlir/IR/Operation.h"
 #include "mlir/Interfaces/FunctionInterfaces.h"
 #include "mlir/Rewrite/PatternApplicator.h"
 #include "llvm/ADT/SmallPtrSet.h"
@@ -2092,8 +2093,9 @@ OperationLegalizer::legalize(Operation *op,
 
     // If the operation has no regions, just print it here.
     if (!isIgnored && op->getNumRegions() == 0) {
-      op->print(logger.startLine(), OpPrintingFlags().printGenericOpForm());
-      logger.getOStream() << "\n\n";
+      logger.startLine() << OpWithFlags(op,
+                                        OpPrintingFlags().printGenericOpForm())
+                         << "\n";
     }
   });