[mlir] Remove 'valuesToRemoveIfDead' from PatternRewriter API

[dcaballe]

Summary

Remove 'valuesToRemoveIfDead' from PatternRewriter API. The removal
functionality wasn't implemented and we decided [1] not to implement it in
favor of having more powerful DCE approaches.

[1] https://github.com/tensorflow/mlir/pull/212

[dcaballe]

Thanks River! I'll commit this in a while if no more comments.

mlir/examples/toy/Ch3/mlir/ToyCombine.cpp

matchAndRewrite(TransposeOp op,
     TransposeOp transposeInputOp =
         llvm::dyn_cast_or_null<TransposeOp>(transposeInput.getDefiningOp());
 
     // If the input is defined by another Transpose, bingo!
     if (!transposeInputOp)
       return matchFailure();
 
     // Use the rewriter to perform the replacement.
-    rewriter.replaceOp(op, {transposeInputOp.getOperand()}, {transposeInputOp});
+    rewriter.replaceOp(op, {transposeInputOp.getOperand()});
     return matchSuccess();
   }
 };
 
 /// Register our patterns as "canonicalization" patterns on the TransposeOp so
 /// that they can be picked up by the Canonicalization framework.
 void TransposeOp::getCanonicalizationPatterns(OwningRewritePatternList &results,
                                               MLIRContext *context) {

mlir/examples/toy/Ch4/mlir/ToyCombine.cpp

matchAndRewrite(TransposeOp op,
     TransposeOp transposeInputOp =
         llvm::dyn_cast_or_null<TransposeOp>(transposeInput.getDefiningOp());
 
     // If the input is defined by another Transpose, bingo!
     if (!transposeInputOp)
       return matchFailure();
 
     // Use the rewriter to perform the replacement.
-    rewriter.replaceOp(op, {transposeInputOp.getOperand()}, {transposeInputOp});
+    rewriter.replaceOp(op, {transposeInputOp.getOperand()});
     return matchSuccess();
   }
 };
 
 /// Register our patterns as "canonicalization" patterns on the TransposeOp so
 /// that they can be picked up by the Canonicalization framework.
 void TransposeOp::getCanonicalizationPatterns(OwningRewritePatternList &results,
                                               MLIRContext *context) {

mlir/examples/toy/Ch5/mlir/ToyCombine.cpp

matchAndRewrite(TransposeOp op,
     TransposeOp transposeInputOp =
         llvm::dyn_cast_or_null<TransposeOp>(transposeInput.getDefiningOp());
 
     // If the input is defined by another Transpose, bingo!
     if (!transposeInputOp)
       return matchFailure();
 
     // Use the rewriter to perform the replacement.
-    rewriter.replaceOp(op, {transposeInputOp.getOperand()}, {transposeInputOp});
+    rewriter.replaceOp(op, {transposeInputOp.getOperand()});
     return matchSuccess();
   }
 };
 
 /// Register our patterns as "canonicalization" patterns on the TransposeOp so
 /// that they can be picked up by the Canonicalization framework.
 void TransposeOp::getCanonicalizationPatterns(OwningRewritePatternList &results,
                                               MLIRContext *context) {

mlir/examples/toy/Ch6/mlir/ToyCombine.cpp

matchAndRewrite(TransposeOp op,
     TransposeOp transposeInputOp =
         llvm::dyn_cast_or_null<TransposeOp>(transposeInput.getDefiningOp());
 
     // If the input is defined by another Transpose, bingo!
     if (!transposeInputOp)
       return matchFailure();
 
     // Use the rewriter to perform the replacement.
-    rewriter.replaceOp(op, {transposeInputOp.getOperand()}, {transposeInputOp});
+    rewriter.replaceOp(op, {transposeInputOp.getOperand()});
     return matchSuccess();
   }
 };
 
 /// Register our patterns as "canonicalization" patterns on the TransposeOp so
 /// that they can be picked up by the Canonicalization framework.
 void TransposeOp::getCanonicalizationPatterns(OwningRewritePatternList &results,
                                               MLIRContext *context) {

mlir/examples/toy/Ch7/mlir/ToyCombine.cpp

matchAndRewrite(TransposeOp op,
     TransposeOp transposeInputOp =
         llvm::dyn_cast_or_null<TransposeOp>(transposeInput.getDefiningOp());
 
     // If the input is defined by another Transpose, bingo!
     if (!transposeInputOp)
       return matchFailure();
 
     // Use the rewriter to perform the replacement.
-    rewriter.replaceOp(op, {transposeInputOp.getOperand()}, {transposeInputOp});
+    rewriter.replaceOp(op, {transposeInputOp.getOperand()});
     return matchSuccess();
   }
 };
 
 /// Register our patterns as "canonicalization" patterns on the TransposeOp so
 /// that they can be picked up by the Canonicalization framework.
 void TransposeOp::getCanonicalizationPatterns(OwningRewritePatternList &results,
                                               MLIRContext *context) {

mlir/include/mlir/IR/PatternMatch.h

virtual void cloneRegionBefore(Region &region, Region &parent,
                                  Region::iterator before,
                                  BlockAndValueMapping &mapping);
   void cloneRegionBefore(Region &region, Region &parent,
                          Region::iterator before);
   void cloneRegionBefore(Region &region, Block *before);
 
   /// This method performs the final replacement for a pattern, where the
   /// results of the operation are updated to use the specified list of SSA
-  /// values.  In addition to replacing and removing the specified operation,
-  /// clients can specify a list of other nodes that this replacement may make
-  /// (perhaps transitively) dead.  If any of those values are dead, this will
-  /// remove them as well.
-  virtual void replaceOp(Operation *op, ValueRange newValues,
-                         ValueRange valuesToRemoveIfDead);
-  void replaceOp(Operation *op, ValueRange newValues) {
-    replaceOp(op, newValues, llvm::None);
-  }
+  /// values.
+  virtual void replaceOp(Operation *op, ValueRange newValues);
 
   /// Replaces the result op with a new op that is created without verification.
   /// The result values of the two ops must be the same types.
   template <typename OpTy, typename... Args>
   void replaceOpWithNewOp(Operation *op, Args &&... args) {
     auto newOp = create<OpTy>(op->getLoc(), std::forward<Args>(args)...);
-    replaceOpWithResultsOfAnotherOp(op, newOp.getOperation(), {});
-  }
-
-  /// Replaces the result op with a new op that is created without verification.
-  /// The result values of the two ops must be the same types.  This allows
-  /// specifying a list of ops that may be removed if dead.
-  template <typename OpTy, typename... Args>
-  void replaceOpWithNewOp(ValueRange valuesToRemoveIfDead, Operation *op,
-                          Args &&... args) {
-    auto newOp = create<OpTy>(op->getLoc(), std::forward<Args>(args)...);
-    replaceOpWithResultsOfAnotherOp(op, newOp.getOperation(),
-                                    valuesToRemoveIfDead);
+    replaceOpWithResultsOfAnotherOp(op, newOp.getOperation());
   }
 
   /// This method erases an operation that is known to have no uses.
   virtual void eraseOp(Operation *op);
 
   /// Merge the operations of block 'source' into the end of block 'dest'.
   /// 'source's predecessors must either be empty or only contain 'dest`.
   /// 'argValues' is used to replace the block arguments of 'source' after
protected:
   virtual void notifyRootReplaced(Operation *op) {}
 
   /// This is called on an operation that a pattern match is removing, right
   /// before the operation is deleted.  At this point, the operation has zero
   /// uses.
   virtual void notifyOperationRemoved(Operation *op) {}
 
 private:
-  /// op and newOp are known to have the same number of results, replace the
-  /// uses of op with uses of newOp
-  void replaceOpWithResultsOfAnotherOp(Operation *op, Operation *newOp,
-                                       ValueRange valuesToRemoveIfDead);
+  /// 'op' and 'newOp' are known to have the same number of results, replace the
+  /// uses of op with uses of newOp.
+  void replaceOpWithResultsOfAnotherOp(Operation *op, Operation *newOp);
 };
 
 //===----------------------------------------------------------------------===//
 // Pattern-driven rewriters
 //===----------------------------------------------------------------------===//
 
 class OwningRewritePatternList {
   using PatternListT = std::vector<std::unique_ptr<RewritePattern>>;

mlir/include/mlir/Transforms/DialectConversion.h

public:
   /// no such a converted value.
   Value getRemappedValue(Value key);
 
   //===--------------------------------------------------------------------===//
   // PatternRewriter Hooks
   //===--------------------------------------------------------------------===//
 
   /// PatternRewriter hook for replacing the results of an operation.
-  void replaceOp(Operation *op, ValueRange newValues,
-                 ValueRange valuesToRemoveIfDead) override;
+  void replaceOp(Operation *op, ValueRange newValues) override;
   using PatternRewriter::replaceOp;
 
   /// PatternRewriter hook for erasing a dead operation. The uses of this
   /// operation *must* be made dead by the end of the conversion process,
   /// otherwise an assert will be issued.
   void eraseOp(Operation *op) override;
 
   /// PatternRewriter hook for splitting a block into two parts.

mlir/lib/Dialect/QuantOps/Transforms/ConvertConst.cpp

QuantizedConstRewrite::matchAndRewrite(QuantizeCastOp qbarrier,
 
   // When creating the new const op, use a fused location that combines the
   // original const and the qbarrier that led to the quantization.
   auto fusedLoc = FusedLoc::get(
       {qbarrier.arg().getDefiningOp()->getLoc(), qbarrier.getLoc()},
       rewriter.getContext());
   auto newConstOp =
       rewriter.create<ConstantOp>(fusedLoc, newConstValueType, newConstValue);
-  rewriter.replaceOpWithNewOp<StorageCastOp>({qbarrier.arg()}, qbarrier,
-                                             qbarrier.getType(), newConstOp);
+  rewriter.replaceOpWithNewOp<StorageCastOp>(qbarrier, qbarrier.getType(),
+                                             newConstOp);
   return matchSuccess();
 }
 
 void ConvertConstPass::runOnFunction() {
   OwningRewritePatternList patterns;
   auto func = getFunction();
   auto *context = &getContext();
   patterns.insert<QuantizedConstRewrite>(context);

mlir/lib/Dialect/StandardOps/Ops.cpp

PatternMatchResult matchAndRewrite(AllocOp alloc,
 
     auto memrefType = alloc.getType();
 
     // Ok, we have one or more constant operands.  Collect the non-constant ones
     // and keep track of the resultant memref type to build.
     SmallVector<int64_t, 4> newShapeConstants;
     newShapeConstants.reserve(memrefType.getRank());
     SmallVector<Value, 4> newOperands;
-    SmallVector<Value, 4> droppedOperands;
 
     unsigned dynamicDimPos = 0;
     for (unsigned dim = 0, e = memrefType.getRank(); dim < e; ++dim) {
       int64_t dimSize = memrefType.getDimSize(dim);
       // If this is already static dimension, keep it.
       if (dimSize != -1) {
         newShapeConstants.push_back(dimSize);
         continue;
       }
       auto *defOp = alloc.getOperand(dynamicDimPos).getDefiningOp();
       if (auto constantIndexOp = dyn_cast_or_null<ConstantIndexOp>(defOp)) {
         // Dynamic shape dimension will be folded.
         newShapeConstants.push_back(constantIndexOp.getValue());
-        // Record to check for zero uses later below.
-        droppedOperands.push_back(constantIndexOp);
       } else {
         // Dynamic shape dimension not folded; copy operand from old memref.
         newShapeConstants.push_back(-1);
         newOperands.push_back(alloc.getOperand(dynamicDimPos));
       }
       dynamicDimPos++;
     }
 
     // Create new memref type (which will have fewer dynamic dimensions).
     auto newMemRefType = MemRefType::get(
         newShapeConstants, memrefType.getElementType(),
         memrefType.getAffineMaps(), memrefType.getMemorySpace());
     assert(static_cast<int64_t>(newOperands.size()) ==
            newMemRefType.getNumDynamicDims());
 
     // Create and insert the alloc op for the new memref.
     auto newAlloc = rewriter.create<AllocOp>(alloc.getLoc(), newMemRefType,
                                              newOperands, IntegerAttr());
     // Insert a cast so we have the same type as the old alloc.
     auto resultCast = rewriter.create<MemRefCastOp>(alloc.getLoc(), newAlloc,
                                                     alloc.getType());
 
-    rewriter.replaceOp(alloc, {resultCast}, droppedOperands);
+    rewriter.replaceOp(alloc, {resultCast});
     return matchSuccess();
   }
 };
 
 /// Fold alloc operations with no uses. Alloc has side effects on the heap,
 /// but can still be deleted if it has zero uses.
 struct SimplifyDeadAlloc : public OpRewritePattern<AllocOp> {
   using OpRewritePattern<AllocOp>::OpRewritePattern;
PatternMatchResult matchAndRewrite(ViewOp viewOp,
 
     // Get offset from old memref view type 'memRefType'.
     int64_t oldOffset;
     SmallVector<int64_t, 4> oldStrides;
     if (failed(getStridesAndOffset(memrefType, oldStrides, oldOffset)))
       return matchFailure();
 
     SmallVector<Value, 4> newOperands;
-    SmallVector<Value, 4> droppedOperands;
 
     // Fold dynamic offset operand if it is produced by a constant.
     auto dynamicOffset = viewOp.getDynamicOffset();
     int64_t newOffset = oldOffset;
     unsigned dynamicOffsetOperandCount = 0;
     if (dynamicOffset != nullptr) {
       auto *defOp = dynamicOffset.getDefiningOp();
       if (auto constantIndexOp = dyn_cast_or_null<ConstantIndexOp>(defOp)) {
         // Dynamic offset will be folded into the map.
         newOffset = constantIndexOp.getValue();
-        droppedOperands.push_back(dynamicOffset);
       } else {
         // Unable to fold dynamic offset. Add it to 'newOperands' list.
         newOperands.push_back(dynamicOffset);
         dynamicOffsetOperandCount = 1;
       }
     }
 
     // Fold any dynamic dim operands which are produced by a constant.
     SmallVector<int64_t, 4> newShapeConstants;
     newShapeConstants.reserve(memrefType.getRank());
 
     unsigned dynamicDimPos = viewOp.getDynamicSizesOperandStart();
     unsigned rank = memrefType.getRank();
     for (unsigned dim = 0, e = rank; dim < e; ++dim) {
       int64_t dimSize = memrefType.getDimSize(dim);
       // If this is already static dimension, keep it.
       if (!ShapedType::isDynamic(dimSize)) {
         newShapeConstants.push_back(dimSize);
         continue;
       }
       auto *defOp = viewOp.getOperand(dynamicDimPos).getDefiningOp();
       if (auto constantIndexOp = dyn_cast_or_null<ConstantIndexOp>(defOp)) {
         // Dynamic shape dimension will be folded.
         newShapeConstants.push_back(constantIndexOp.getValue());
-        // Record to check for zero uses later below.
-        droppedOperands.push_back(constantIndexOp);
       } else {
         // Dynamic shape dimension not folded; copy operand from old memref.
         newShapeConstants.push_back(dimSize);
         newOperands.push_back(viewOp.getOperand(dynamicDimPos));
       }
       dynamicDimPos++;
     }
 
PatternMatchResult matchAndRewrite(ViewOp viewOp,
     (void)dynamicOffsetOperandCount; // unused in opt mode
     assert(static_cast<int64_t>(newOperands.size()) ==
            dynamicOffsetOperandCount + newMemRefType.getNumDynamicDims());
 
     // Create new ViewOp.
     auto newViewOp = rewriter.create<ViewOp>(viewOp.getLoc(), newMemRefType,
                                              viewOp.getOperand(0), newOperands);
     // Insert a cast so we have the same type as the old memref type.
-    rewriter.replaceOpWithNewOp<MemRefCastOp>(droppedOperands, viewOp,
-                                              newViewOp, viewOp.getType());
+    rewriter.replaceOpWithNewOp<MemRefCastOp>(viewOp, newViewOp,
+                                              viewOp.getType());
     return matchSuccess();
   }
 };
 
 struct ViewOpMemrefCastFolder : public OpRewritePattern<ViewOp> {
   using OpRewritePattern<ViewOp>::OpRewritePattern;
 
   PatternMatchResult matchAndRewrite(ViewOp viewOp,
                                      PatternRewriter &rewriter) const override {
     Value memrefOperand = viewOp.getOperand(0);
     MemRefCastOp memrefCastOp =
         dyn_cast_or_null<MemRefCastOp>(memrefOperand.getDefiningOp());
     if (!memrefCastOp)
       return matchFailure();
     Value allocOperand = memrefCastOp.getOperand();
     AllocOp allocOp = dyn_cast_or_null<AllocOp>(allocOperand.getDefiningOp());
     if (!allocOp)
       return matchFailure();
-    rewriter.replaceOpWithNewOp<ViewOp>(memrefOperand, viewOp, viewOp.getType(),
-                                        allocOperand, viewOp.operands());
+    rewriter.replaceOpWithNewOp<ViewOp>(viewOp, viewOp.getType(), allocOperand,
+                                        viewOp.operands());
     return matchSuccess();
   }
 };
 
 } // end anonymous namespace
 
 void ViewOp::getCanonicalizationPatterns(OwningRewritePatternList &results,
                                          MLIRContext *context) {
PatternMatchResult matchAndRewrite(SubViewOp subViewOp,
     }
     MemRefType newMemRefType = MemRefType::get(
         staticShape, subViewType.getElementType(), subViewType.getAffineMaps(),
         subViewType.getMemorySpace());
     auto newSubViewOp = rewriter.create<SubViewOp>(
         subViewOp.getLoc(), subViewOp.source(), subViewOp.offsets(),
         ArrayRef<Value>(), subViewOp.strides(), newMemRefType);
     // Insert a memref_cast for compatibility of the uses of the op.
-    rewriter.replaceOpWithNewOp<MemRefCastOp>(
-        subViewOp.sizes(), subViewOp, newSubViewOp, subViewOp.getType());
+    rewriter.replaceOpWithNewOp<MemRefCastOp>(subViewOp, newSubViewOp,
+                                              subViewOp.getType());
     return matchSuccess();
   }
 };
 
 // Pattern to rewrite a subview op with constant stride arguments.
 class SubViewOpStrideFolder final : public OpRewritePattern<SubViewOp> {
 public:
   using OpRewritePattern<SubViewOp>::OpRewritePattern;
AffineMap layoutMap = makeStridedLinearLayoutMap(
         staticStrides, resultOffset, rewriter.getContext());
     MemRefType newMemRefType =
         MemRefType::get(subViewType.getShape(), subViewType.getElementType(),
                         layoutMap, subViewType.getMemorySpace());
     auto newSubViewOp = rewriter.create<SubViewOp>(
         subViewOp.getLoc(), subViewOp.source(), subViewOp.offsets(),
         subViewOp.sizes(), ArrayRef<Value>(), newMemRefType);
     // Insert a memref_cast for compatibility of the uses of the op.
-    rewriter.replaceOpWithNewOp<MemRefCastOp>(
-        subViewOp.strides(), subViewOp, newSubViewOp, subViewOp.getType());
+    rewriter.replaceOpWithNewOp<MemRefCastOp>(subViewOp, newSubViewOp,
+                                              subViewOp.getType());
     return matchSuccess();
   }
 };
 
 // Pattern to rewrite a subview op with constant offset arguments.
 class SubViewOpOffsetFolder final : public OpRewritePattern<SubViewOp> {
 public:
   using OpRewritePattern<SubViewOp>::OpRewritePattern;
AffineMap layoutMap = makeStridedLinearLayoutMap(
         resultStrides, staticOffset, rewriter.getContext());
     MemRefType newMemRefType =
         MemRefType::get(subViewType.getShape(), subViewType.getElementType(),
                         layoutMap, subViewType.getMemorySpace());
     auto newSubViewOp = rewriter.create<SubViewOp>(
         subViewOp.getLoc(), subViewOp.source(), ArrayRef<Value>(),
         subViewOp.sizes(), subViewOp.strides(), newMemRefType);
     // Insert a memref_cast for compatibility of the uses of the op.
-    rewriter.replaceOpWithNewOp<MemRefCastOp>(
-        subViewOp.offsets(), subViewOp, newSubViewOp, subViewOp.getType());
+    rewriter.replaceOpWithNewOp<MemRefCastOp>(subViewOp, newSubViewOp,
+                                              subViewOp.getType());
     return matchSuccess();
   }
 };
 
 } // end anonymous namespace
 
 void SubViewOp::getCanonicalizationPatterns(OwningRewritePatternList &results,
                                             MLIRContext *context) {

mlir/lib/IR/PatternMatch.cpp

 //===- PatternMatch.cpp - Base classes for pattern match ------------------===//
 //
 // 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/IR/PatternMatch.h"
 #include "mlir/IR/BlockAndValueMapping.h"
 #include "mlir/IR/Operation.h"
 #include "mlir/IR/Value.h"
+
 using namespace mlir;
 
 PatternBenefit::PatternBenefit(unsigned benefit) : representation(benefit) {
   assert(representation == benefit && benefit != ImpossibleToMatchSentinel &&
          "This pattern match benefit is too large to represent");
 }
 
 unsigned short PatternBenefit::getBenefit() const {

 }
 
 PatternRewriter::~PatternRewriter() {
   // Out of line to provide a vtable anchor for the class.
 }
 
 /// This method performs the final replacement for a pattern, where the
 /// results of the operation are updated to use the specified list of SSA
-/// values.  In addition to replacing and removing the specified operation,
-/// clients can specify a list of other nodes that this replacement may make
-/// (perhaps transitively) dead.  If any of those ops are dead, this will
-/// remove them as well.
-void PatternRewriter::replaceOp(Operation *op, ValueRange newValues,
-                                ValueRange valuesToRemoveIfDead) {
+/// values.
+void PatternRewriter::replaceOp(Operation *op, ValueRange newValues) {
   // Notify the rewriter subclass that we're about to replace this root.
   notifyRootReplaced(op);
 
   assert(op->getNumResults() == newValues.size() &&
          "incorrect # of replacement values");
   op->replaceAllUsesWith(newValues);
 
   notifyOperationRemoved(op);
   op->erase();
-
-  // TODO: Process the valuesToRemoveIfDead list, removing things and calling
-  // the notifyOperationRemoved hook in the process.
 }
 
 /// This method erases an operation that is known to have no uses. The uses of
 /// the given operation *must* be known to be dead.
 void PatternRewriter::eraseOp(Operation *op) {
   assert(op->use_empty() && "expected 'op' to have no uses");
   notifyOperationRemoved(op);
   op->erase();

 }
 
 /// Split the operations starting at "before" (inclusive) out of the given
 /// block into a new block, and return it.
 Block *PatternRewriter::splitBlock(Block *block, Block::iterator before) {
   return block->splitBlock(before);
 }
 
-/// op and newOp are known to have the same number of results, replace the
+/// 'op' and 'newOp' are known to have the same number of results, replace the
 /// uses of op with uses of newOp
-void PatternRewriter::replaceOpWithResultsOfAnotherOp(
-    Operation *op, Operation *newOp, ValueRange valuesToRemoveIfDead) {
+void PatternRewriter::replaceOpWithResultsOfAnotherOp(Operation *op,
+                                                      Operation *newOp) {
   assert(op->getNumResults() == newOp->getNumResults() &&
          "replacement op doesn't match results of original op");
   if (op->getNumResults() == 1)
-    return replaceOp(op, newOp->getResult(0), valuesToRemoveIfDead);
-  return replaceOp(op, newOp->getResults(), valuesToRemoveIfDead);
+    return replaceOp(op, newOp->getResult(0));
+  return replaceOp(op, newOp->getResults());
 }
 
 /// Move the blocks that belong to "region" before the given position in
 /// another region.  The two regions must be different.  The caller is in
 /// charge to update create the operation transferring the control flow to the
 /// region and pass it the correct block arguments.
 void PatternRewriter::inlineRegionBefore(Region &region, Region &parent,
                                          Region::iterator before) {

mlir/lib/Transforms/DialectConversion.cpp

struct ConversionPatternRewriterImpl {
   LogicalResult convertBlockSignature(Block *block);
 
   /// Apply a signature conversion on the given region.
   Block *
   applySignatureConversion(Region *region,
                            TypeConverter::SignatureConversion &conversion);
 
   /// PatternRewriter hook for replacing the results of an operation.
-  void replaceOp(Operation *op, ValueRange newValues,
-                 ValueRange valuesToRemoveIfDead);
+  void replaceOp(Operation *op, ValueRange newValues);
 
   /// Notifies that a block was split.
   void notifySplitBlock(Block *block, Block *continuation);
 
   /// Notifies that the blocks of a region are about to be moved.
   void notifyRegionIsBeingInlinedBefore(Region &region, Region &parent,
                                         Region::iterator before);
 
Block *newEntry = argConverter.applySignatureConversion(
         &region->front(), conversion, mapping);
     blockActions.push_back(BlockAction::getTypeConversion(newEntry));
     return newEntry;
   }
   return nullptr;
 }
 
 void ConversionPatternRewriterImpl::replaceOp(Operation *op,
-                                              ValueRange newValues,
-                                              ValueRange valuesToRemoveIfDead) {
+                                              ValueRange newValues) {
   assert(newValues.size() == op->getNumResults());
 
   // Create mappings for each of the new result values.
   for (unsigned i = 0, e = newValues.size(); i < e; ++i)
     if (auto repl = newValues[i])
       mapping.map(op->getResult(i), repl);
 
   // Record the requested operation replacement.

 
 ConversionPatternRewriter::ConversionPatternRewriter(MLIRContext *ctx,
                                                      TypeConverter *converter)
     : PatternRewriter(ctx),
       impl(new detail::ConversionPatternRewriterImpl(*this, converter)) {}
 ConversionPatternRewriter::~ConversionPatternRewriter() {}
 
 /// PatternRewriter hook for replacing the results of an operation.
-void ConversionPatternRewriter::replaceOp(Operation *op, ValueRange newValues,
-                                          ValueRange valuesToRemoveIfDead) {
+void ConversionPatternRewriter::replaceOp(Operation *op,
+                                          ValueRange newValues) {
   LLVM_DEBUG(llvm::dbgs() << "** Replacing operation : " << op->getName()
                           << "\n");
-  impl->replaceOp(op, newValues, valuesToRemoveIfDead);
+  impl->replaceOp(op, newValues);
 }
 
 /// PatternRewriter hook for erasing a dead operation. The uses of this
 /// operation *must* be made dead by the end of the conversion process,
 /// otherwise an assert will be issued.
 void ConversionPatternRewriter::eraseOp(Operation *op) {
   LLVM_DEBUG(llvm::dbgs() << "** Erasing operation : " << op->getName()
                           << "\n");
   SmallVector<Value, 1> nullRepls(op->getNumResults(), nullptr);
-  impl->replaceOp(op, nullRepls, /*valuesToRemoveIfDead=*/llvm::None);
+  impl->replaceOp(op, nullRepls);
 }
 
 /// Apply a signature conversion to the entry block of the given region.
 Block *ConversionPatternRewriter::applySignatureConversion(
     Region *region, TypeConverter::SignatureConversion &conversion) {
   return impl->applySignatureConversion(region, conversion);
 }