[mlir][bufferization][NFC] Add error handling to getBuffer

[springerm]

Summary

This is in preparation of adding memory space support.

Depends On D128422

[springerm]

rebase

[springerm]

rebase

mlir/include/mlir/Dialect/Bufferization/IR/BufferizableOpInterface.h

 /// undefined contents is allocated.
 Value allocateTensorForShapedValue(OpBuilder &b, Location loc,
                                    Value shapedValue, bool escape,
                                    bool copy = true);
 
 /// Lookup the buffer for the given value. If the value was not bufferized
 /// yet, wrap it in a ToMemrefOp. Otherwise, it is the result of a ToTensorOp,
 /// from which the memref operand is returned.
-Value getBuffer(RewriterBase &rewriter, Value value,
+FailureOr<Value> getBuffer(RewriterBase &rewriter, Value value,
                            const BufferizationOptions &options);
 
 /// Return the buffer type for a given Value (tensor) after bufferization.
 ///
 /// Note: Op implementations should preferrably call `getBuffer()->getType()`.
 /// This function should only be used if `getBuffer` cannot be used.
-BaseMemRefType getBufferType(Value value, const BufferizationOptions &options);
+FailureOr<BaseMemRefType> getBufferType(Value value,
+                                        const BufferizationOptions &options);
 
 /// Replace an op with replacement values. The op is deleted. Tensor OpResults
 /// must be replaced with memref values.
 void replaceOpWithBufferizedValues(RewriterBase &rewriter, Operation *op,
                                    ValueRange values);
 
 /// Replace an op with a new op. The new op must have the same number of
 /// results as the replaced op. The new op may not return any tensor values.

mlir/lib/Dialect/Arithmetic/Transforms/BufferizableOpInterfaceImpl.cpp

BufferRelation bufferRelation(Operation *op, OpResult opResult,
     return BufferRelation::Equivalent;
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto castOp = cast<arith::IndexCastOp>(op);
     auto resultTensorType = castOp.getType().cast<TensorType>();
 
-    Value source = getBuffer(rewriter, castOp.getIn(), options);
-    auto sourceType = source.getType().cast<BaseMemRefType>();
+    FailureOr<Value> source = getBuffer(rewriter, castOp.getIn(), options);
+    if (failed(source))
+      return failure();
+    auto sourceType = source->getType().cast<BaseMemRefType>();
 
     // Result type should have same layout and address space as the source type.
     BaseMemRefType resultType;
     if (auto rankedMemRefType = sourceType.dyn_cast<MemRefType>()) {
       resultType = MemRefType::get(
           rankedMemRefType.getShape(), resultTensorType.getElementType(),
           rankedMemRefType.getLayout(), rankedMemRefType.getMemorySpace());
     } else {
       auto unrankedMemrefType = sourceType.cast<UnrankedMemRefType>();
       resultType = UnrankedMemRefType::get(resultTensorType.getElementType(),
                                            unrankedMemrefType.getMemorySpace());
     }
 
     replaceOpWithNewBufferizedOp<arith::IndexCastOp>(rewriter, op, resultType,
-                                                     source);
+                                                     *source);
     return success();
   }
 };
 
 /// Bufferization of arith.select. Just replace the operands.
 struct SelectOpInterface
     : public BufferizableOpInterface::ExternalModel<SelectOpInterface,
                                                     arith::SelectOp> {
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto selectOp = cast<arith::SelectOp>(op);
     Location loc = selectOp.getLoc();
 
     // TODO: It would be more efficient to copy the result of the `select` op
     // instead of its OpOperands. In the worst case, 2 copies are inserted at
     // the moment (one for each tensor). When copying the op result, only one
     // copy would be needed.
-    Value trueBuffer = getBuffer(rewriter, selectOp.getTrueValue(), options);
-    Value falseBuffer = getBuffer(rewriter, selectOp.getFalseValue(), options);
+    FailureOr<Value> maybeTrueBuffer =
+        getBuffer(rewriter, selectOp.getTrueValue(), options);
+    FailureOr<Value> maybeFalseBuffer =
+        getBuffer(rewriter, selectOp.getFalseValue(), options);
+    if (failed(maybeTrueBuffer) || failed(maybeFalseBuffer))
+      return failure();
+    Value trueBuffer = *maybeTrueBuffer;
+    Value falseBuffer = *maybeFalseBuffer;
 
     // The "true" and the "false" operands must have the same type. If the
     // buffers have different types, they differ only in their layout map. Cast
     // both of them to the most dynamic MemRef type.
     if (trueBuffer.getType() != falseBuffer.getType()) {
       auto trueType = trueBuffer.getType().cast<MemRefType>();
       int64_t dynamicOffset = ShapedType::kDynamicStrideOrOffset;
       SmallVector<int64_t> dynamicStrides(trueType.getRank(),

mlir/lib/Dialect/Bufferization/IR/BufferizableOpInterface.cpp

 #ifndef NDEBUG
   auto rankedTensorType = tensor.getType().dyn_cast<RankedTensorType>();
   assert((!rankedTensorType || memrefType.cast<MemRefType>().getRank() ==
                                    rankedTensorType.getRank()) &&
          "to_memref would be invalid: mismatching ranks");
 #endif
 }
 
-Value bufferization::getBuffer(RewriterBase &rewriter, Value value,
+FailureOr<Value> bufferization::getBuffer(RewriterBase &rewriter, Value value,
                                           const BufferizationOptions &options) {
   auto tensorType = value.getType().dyn_cast<TensorType>();
   assert(tensorType && "unexpected non-tensor type");
 
   // Replace "%t = to_tensor %m" with %m.
   if (auto toTensorOp = value.getDefiningOp<bufferization::ToTensorOp>())
     return toTensorOp.getMemref();
 
   // Insert to_memref op.
   OpBuilder::InsertionGuard g(rewriter);
   setInsertionPointAfter(rewriter, value);
   Type memrefType = getMemRefType(tensorType, options);
   ensureToMemrefOpIsValid(value, memrefType);
-  return rewriter.create<bufferization::ToMemrefOp>(value.getLoc(), memrefType,
-                                                    value);
+  return rewriter
+      .create<bufferization::ToMemrefOp>(value.getLoc(), memrefType, value)
+      .getResult();
 }
 
 /// Return the buffer type for a given Value (tensor) after bufferization.
-BaseMemRefType
+FailureOr<BaseMemRefType>
 bufferization::getBufferType(Value value, const BufferizationOptions &options) {
   auto tensorType = value.getType().dyn_cast<TensorType>();
   assert(tensorType && "unexpected non-tensor type");
 
   if (auto toTensorOp = value.getDefiningOp<bufferization::ToTensorOp>())
     return toTensorOp.getMemref().getType().cast<BaseMemRefType>();
 
   return getMemRefType(tensorType, options);

mlir/lib/Dialect/Bufferization/IR/BufferizationOps.cpp

LogicalResult AllocTensorOp::bufferize(RewriterBase &rewriter,
   // Nothing to do for dead AllocTensorOps.
   if (getOperation()->getUses().empty()) {
     rewriter.eraseOp(getOperation());
     return success();
   }
 
   // Get "copy" buffer.
   Value copyBuffer;
-  if (getCopy())
-    copyBuffer = getBuffer(rewriter, getCopy(), options);
+  if (getCopy()) {
+    FailureOr<Value> maybeCopyBuffer = getBuffer(rewriter, getCopy(), options);
+    if (failed(maybeCopyBuffer))
+      return failure();
+    copyBuffer = *maybeCopyBuffer;
+  }
 
   // Compute memory space of this allocation.
   unsigned memorySpace;
   if (op->hasAttr(BufferizationDialect::kMemorySpaceAttrName)) {
     memorySpace = op->getAttrOfType<ArrayAttr>(
                         BufferizationDialect::kMemorySpaceAttrName)[0]
                       .cast<IntegerAttr>()
                       .getValue()

mlir/lib/Dialect/Bufferization/Transforms/FuncBufferizableOpInterfaceImpl.cpp

for (OpOperand &opOperand : callOp->getOpOperands()) {
       // Non-tensor operands are just copied.
       if (!tensorOperand.getType().isa<TensorType>()) {
         newOperands[idx] = tensorOperand;
         continue;
       }
 
       // Retrieve buffers for tensor operands.
       Value buffer = newOperands[idx];
-      if (!buffer)
-        buffer = getBuffer(rewriter, opOperand.get(), options);
+      if (!buffer) {
+        FailureOr<Value> maybeBuffer =
+            getBuffer(rewriter, opOperand.get(), options);
+        if (failed(maybeBuffer))
+          return failure();
+        buffer = *maybeBuffer;
+      }
 
       // Caller / callee type mismatch is handled with a CastOp.
       auto memRefType = funcType.getInput(idx);
       // Since we don't yet have a clear layout story, to_memref may
       // conservatively turn tensors into more dynamic memref than necessary.
       // If the memref type of the callee fails, introduce an extra memref.cast
       // that will either canonicalize away or fail compilation until we can do
       // something better.

mlir/lib/Dialect/Linalg/Transforms/BufferizableOpInterfaceImpl.cpp

static LogicalResult bufferizeLinalgOp(RewriterBase &rewriter, LinalgOp op,
   // New input operands for the cloned op.
   SmallVector<Value> newInputBuffers;
   newInputBuffers.reserve(op.getNumInputs());
   for (OpOperand *opOperand : op.getInputOperands()) {
     if (op.isScalar(opOperand)) {
       newInputBuffers.push_back(opOperand->get());
       continue;
     }
-    newInputBuffers.push_back(getBuffer(rewriter, opOperand->get(), options));
+    FailureOr<Value> buffer = getBuffer(rewriter, opOperand->get(), options);
+    if (failed(buffer))
+      return failure();
+    newInputBuffers.push_back(*buffer);
   }
 
   // New output operands for the cloned op.
   SmallVector<Value> newOutputBuffers;
   for (OpResult opResult : op->getOpResults()) {
     OpOperand *opOperand = op.getOutputOperand(opResult.getResultNumber());
-    Value resultBuffer = getBuffer(rewriter, opOperand->get(), options);
-    newOutputBuffers.push_back(resultBuffer);
+    FailureOr<Value> resultBuffer =
+        getBuffer(rewriter, opOperand->get(), options);
+    if (failed(resultBuffer))
+      return failure();
+    newOutputBuffers.push_back(*resultBuffer);
   }
 
   // Merge input/output operands.
   SmallVector<Value> newOperands = newInputBuffers;
   newOperands.append(newOutputBuffers.begin(), newOutputBuffers.end());
 
   // Set insertion point now that potential alloc/dealloc are introduced.
   rewriter.setInsertionPoint(op);

mlir/lib/Dialect/SCF/Transforms/BufferizableOpInterfaceImpl.cpp

static Value castBuffer(OpBuilder &b, Value buffer, Type type) {
   // iter_arg's layout map must be changed (see uses of `castBuffer`).
   assert(memref::CastOp::areCastCompatible(buffer.getType(), type) &&
          "scf.while op bufferization: cast incompatible");
   return b.create<memref::CastOp>(buffer.getLoc(), type, buffer).getResult();
 }
 
 /// Helper function for loop bufferization. Return the bufferized values of the
 /// given OpOperands. If an operand is not a tensor, return the original value.
-static SmallVector<Value> getBuffers(RewriterBase &rewriter,
-                                     MutableArrayRef<OpOperand> operands,
-                                     const BufferizationOptions &options) {
+static FailureOr<SmallVector<Value>>
+getBuffers(RewriterBase &rewriter, MutableArrayRef<OpOperand> operands,
   SmallVector<Value> result;
   for (OpOperand &opOperand : operands) {
     if (opOperand.get().getType().isa<TensorType>()) {
-      Value resultBuffer = getBuffer(rewriter, opOperand.get(), options);
-      result.push_back(resultBuffer);
+      FailureOr<Value> resultBuffer =
+          getBuffer(rewriter, opOperand.get(), options);
+      if (failed(resultBuffer))
+        return failure();
+      result.push_back(*resultBuffer);
     } else {
       result.push_back(opOperand.get());
     }
   }
   return result;
 }
 
 /// Helper function for loop bufferization. Compute the buffer that should be
 /// yielded from a loop block (loop body or loop condition).
-static Value getYieldedBuffer(RewriterBase &rewriter, Value tensor,
+static FailureOr<Value> getYieldedBuffer(RewriterBase &rewriter, Value tensor,
                                          BaseMemRefType type,
                                          const BufferizationOptions &options) {
   assert(tensor.getType().isa<TensorType>() && "expected tensor");
   ensureToMemrefOpIsValid(tensor, type);
-  Value yieldedVal = getBuffer(rewriter, tensor, options);
-  return castBuffer(rewriter, yieldedVal, type);
+  FailureOr<Value> yieldedVal = getBuffer(rewriter, tensor, options);
+  if (failed(yieldedVal))
+    return failure();
+  return castBuffer(rewriter, *yieldedVal, type);
 }
 
 /// Helper function for loop bufferization. Given a range of values, apply
 /// `func` to those marked in `tensorIndices`. Otherwise, store the unmodified
 /// value in the result vector.
-static SmallVector<Value>
+static FailureOr<SmallVector<Value>>
 convertTensorValues(ValueRange values, const DenseSet<int64_t> &tensorIndices,
-                    llvm::function_ref<Value(Value, int64_t)> func) {
+                    llvm::function_ref<FailureOr<Value>(Value, int64_t)> func) {
   SmallVector<Value> result;
   for (const auto &it : llvm::enumerate(values)) {
     size_t idx = it.index();
     Value val = it.value();
-    result.push_back(tensorIndices.contains(idx) ? func(val, idx) : val);
+    if (tensorIndices.contains(idx)) {
+      FailureOr<Value> maybeVal = func(val, idx);
+      if (failed(maybeVal))
+        return failure();
+      result.push_back(*maybeVal);
+    } else {
+      result.push_back(val);
+    }
   }
   return result;
 }
 
 /// Helper function for loop bufferization. Given a list of pre-bufferization
 /// yielded values, compute the list of bufferized yielded values.
-SmallVector<Value> getYieldedValues(RewriterBase &rewriter, ValueRange values,
-                                    TypeRange bufferizedTypes,
-                                    const DenseSet<int64_t> &tensorIndices,
-                                    const BufferizationOptions &options) {
+FailureOr<SmallVector<Value>>
+getYieldedValues(RewriterBase &rewriter, ValueRange values,
   return convertTensorValues(
       values, tensorIndices, [&](Value val, int64_t index) {
         return getYieldedBuffer(rewriter, val,
                                 bufferizedTypes[index].cast<BaseMemRefType>(),
                                 options);
       });
 }
 
 /// Helper function for loop bufferization. Given a list of bbArgs of the new
 /// (bufferized) loop op, wrap the bufferized tensor args (now memrefs) into
 /// ToTensorOps, so that the block body can be moved over to the new op.
 SmallVector<Value>
 getBbArgReplacements(RewriterBase &rewriter, Block::BlockArgListType bbArgs,
                      const DenseSet<int64_t> &tensorIndices) {
-  return convertTensorValues(
-      bbArgs, tensorIndices, [&](Value val, int64_t index) {
-        return rewriter.create<bufferization::ToTensorOp>(val.getLoc(), val);
-      });
+  SmallVector<Value> result;
+  for (const auto &it : llvm::enumerate(bbArgs)) {
+    size_t idx = it.index();
+    Value val = it.value();
+    if (tensorIndices.contains(idx)) {
+      result.push_back(
+          rewriter.create<bufferization::ToTensorOp>(val.getLoc(), val)
+              .getResult());
+    } else {
+      result.push_back(val);
+    }
+  }
+  return result;
 }
 
 /// Bufferization of scf.for. Replace with a new scf.for that operates on
 /// memrefs.
 struct ForOpInterface
     : public BufferizableOpInterface::ExternalModel<ForOpInterface,
                                                     scf::ForOp> {
   bool bufferizesToMemoryRead(Operation *op, OpOperand &opOperand,
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
     auto forOp = cast<scf::ForOp>(op);
     Block *oldLoopBody = &forOp.getLoopBody().front();
 
     // Indices of all iter_args that have tensor type. These are the ones that
     // are bufferized.
     DenseSet<int64_t> indices = getTensorIndices(forOp.getInitArgs());
 
     // The new memref init_args of the loop.
-    SmallVector<Value> initArgs =
+    FailureOr<SmallVector<Value>> maybeInitArgs =
         getBuffers(rewriter, forOp.getIterOpOperands(), options);
+    if (failed(maybeInitArgs))
+      return failure();
+    SmallVector<Value> initArgs = *maybeInitArgs;
 
     // Construct a new scf.for op with memref instead of tensor values.
     auto newForOp = rewriter.create<scf::ForOp>(
         forOp.getLoc(), forOp.getLowerBound(), forOp.getUpperBound(),
         forOp.getStep(), initArgs);
     newForOp->setAttrs(forOp->getAttrs());
     ValueRange initArgsRange(initArgs);
     TypeRange initArgsTypes(initArgsRange);
if (iterArgs.size() == 1)
       rewriter.eraseOp(loopBody->getTerminator());
 
     // Move loop body to new loop.
     rewriter.mergeBlocks(oldLoopBody, loopBody, iterArgs);
 
     // Update scf.yield of new loop.
     auto yieldOp = cast<scf::YieldOp>(loopBody->getTerminator());
     rewriter.setInsertionPoint(yieldOp);
-    SmallVector<Value> yieldValues = getYieldedValues(
+    FailureOr<SmallVector<Value>> yieldValues = getYieldedValues(
         rewriter, yieldOp.getResults(), initArgsTypes, indices, options);
-    yieldOp.getResultsMutable().assign(yieldValues);
+    if (failed(yieldValues))
+      return failure();
+    yieldOp.getResultsMutable().assign(*yieldValues);
 
     // Replace loop results.
     replaceOpWithBufferizedValues(rewriter, op, newForOp->getResults());
 
     return success();
   }
 
   /// Assert that yielded values of an scf.for op are equivalent to their
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
 
     // Indices of all bbArgs that have tensor type. These are the ones that
     // are bufferized. The "before" and "after" regions may have different args.
     DenseSet<int64_t> indicesBefore = getTensorIndices(whileOp.getInits());
     DenseSet<int64_t> indicesAfter =
         getTensorIndices(whileOp.getAfterArguments());
 
     // The new memref init_args of the loop.
-    SmallVector<Value> initArgs =
+    FailureOr<SmallVector<Value>> maybeInitArgs =
         getBuffers(rewriter, whileOp->getOpOperands(), options);
+    if (failed(maybeInitArgs))
+      return failure();
+    SmallVector<Value> initArgs = *maybeInitArgs;
 
     // The result types of a WhileOp are the same as the "after" bbArg types.
     SmallVector<Type> argsTypesAfter = llvm::to_vector(
         llvm::map_range(whileOp.getAfterArguments(), [&](BlockArgument bbArg) {
-          return getBufferType(bbArg, options).cast<Type>();
+          // TODO: error handling
+          return getBufferType(bbArg, options)->cast<Type>();
         }));
 
     // Construct a new scf.while op with memref instead of tensor values.
     ValueRange argsRangeBefore(initArgs);
     TypeRange argsTypesBefore(argsRangeBefore);
     auto newWhileOp = rewriter.create<scf::WhileOp>(whileOp.getLoc(),
                                                     argsTypesAfter, initArgs);
 
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
     rewriter.mergeBlocks(beforeBody, newBeforeBody, newBeforeArgs);
 
     // Update scf.condition of new loop.
     auto newConditionOp = newWhileOp.getConditionOp();
     rewriter.setInsertionPoint(newConditionOp);
     // Only equivalent buffers or new buffer allocations may be yielded to the
     // "after" region.
     // TODO: This could be relaxed for better bufferization results.
-    SmallVector<Value> newConditionArgs =
+    FailureOr<SmallVector<Value>> newConditionArgs =
         getYieldedValues(rewriter, newConditionOp.getArgs(), argsTypesAfter,
                          indicesAfter, options);
-    newConditionOp.getArgsMutable().assign(newConditionArgs);
+    if (failed(newConditionArgs))
+      return failure();
+    newConditionOp.getArgsMutable().assign(*newConditionArgs);
 
     // Set up new iter_args and move the loop body block to the new op.
     // The old block uses tensors, so wrap the (memref) bbArgs of the new block
     // in ToTensorOps.
     rewriter.setInsertionPointToStart(newAfterBody);
     SmallVector<Value> newAfterArgs = getBbArgReplacements(
         rewriter, newWhileOp.getAfterArguments(), indicesAfter);
     rewriter.mergeBlocks(afterBody, newAfterBody, newAfterArgs);
 
     // Update scf.yield of the new loop.
     auto newYieldOp = newWhileOp.getYieldOp();
     rewriter.setInsertionPoint(newYieldOp);
     // Only equivalent buffers or new buffer allocations may be yielded to the
     // "before" region.
     // TODO: This could be relaxed for better bufferization results.
-    SmallVector<Value> newYieldValues =
+    FailureOr<SmallVector<Value>> newYieldValues =
         getYieldedValues(rewriter, newYieldOp.getResults(), argsTypesBefore,
                          indicesBefore, options);
-    newYieldOp.getResultsMutable().assign(newYieldValues);
+    if (failed(newYieldValues))
+      return failure();
+    newYieldOp.getResultsMutable().assign(*newYieldValues);
 
     // Replace loop results.
     replaceOpWithBufferizedValues(rewriter, op, newWhileOp->getResults());
 
     return success();
   }
 
   /// Assert that yielded values of an scf.while op are equivalent to their
LogicalResult bufferize(Operation *op, RewriterBase &b,
     // Gather new results of the ForeachThreadOp.
     SmallVector<Value> newResults;
     for (OpResult opResult : foreachThreadOp->getOpResults()) {
       OpOperand *insertDest =
           getInsertionDest(foreachThreadOp)[opResult.getResultNumber()];
       // Insert copies right before the PerformConcurrentlyOp terminator. They
       // should not be inside terminator (which would be the default insertion
       // point).
-      Value buffer = getBuffer(b, insertDest->get(), options);
-      newResults.push_back(buffer);
+      FailureOr<Value> buffer = getBuffer(b, insertDest->get(), options);
+      if (failed(buffer))
+        return failure();
+      newResults.push_back(*buffer);
     }
 
     // Create new ForeachThreadOp without any results and drop the automatically
     // introduced terminator.
     TypeRange newResultTypes;
     auto newForeachThreadOp =
         b.create<ForeachThreadOp>(foreachThreadOp.getLoc(), newResultTypes,
                                   foreachThreadOp.getNumThreads());

mlir/lib/Dialect/Tensor/Transforms/BufferizableOpInterfaceImpl.cpp

BufferRelation bufferRelation(Operation *op, OpResult opResult,
     return BufferRelation::Equivalent;
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto castOp = cast<tensor::CastOp>(op);
 
     // The result buffer still has the old (pre-cast) type.
-    Value resultBuffer = getBuffer(rewriter, castOp.getSource(), options);
-    auto sourceMemRefType = resultBuffer.getType().cast<BaseMemRefType>();
+    FailureOr<Value> resultBuffer =
+        getBuffer(rewriter, castOp.getSource(), options);
+    if (failed(resultBuffer))
+      return failure();
+    auto sourceMemRefType = resultBuffer->getType().cast<BaseMemRefType>();
     TensorType resultTensorType =
         castOp.getResult().getType().cast<TensorType>();
     Optional<AffineMap> layout = None;
 
     if (auto rankedMemRefType = sourceMemRefType.dyn_cast<MemRefType>())
       if (resultTensorType.isa<RankedTensorType>())
         layout = rankedMemRefType.getLayout().getAffineMap();
 
     // Compute the new memref type.
     Type resultMemRefType =
         getMemRefType(resultTensorType, options, layout,
                       sourceMemRefType.getMemorySpaceAsInt());
 
     // Replace the op with a memref.cast.
-    assert(memref::CastOp::areCastCompatible(resultBuffer.getType(),
+    assert(memref::CastOp::areCastCompatible(resultBuffer->getType(),
                                              resultMemRefType) &&
            "CallOp::bufferize: cast incompatible");
     replaceOpWithNewBufferizedOp<memref::CastOp>(rewriter, op, resultMemRefType,
-                                                 resultBuffer);
+                                                 *resultBuffer);
 
     return success();
   }
 };
 
 /// Bufferization of tensor.collapse_shape. Replace with memref.collapse_shape.
 struct CollapseShapeOpInterface
     : public BufferizableOpInterface::ExternalModel<CollapseShapeOpInterface,
BufferRelation bufferRelation(Operation *op, OpResult opResult,
                                 const AnalysisState &state) const {
     return BufferRelation::Equivalent;
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto collapseShapeOp = cast<tensor::CollapseShapeOp>(op);
     RankedTensorType tensorResultType = collapseShapeOp.getResultType();
-    Value buffer = getBuffer(rewriter, collapseShapeOp.getSrc(), options);
+    FailureOr<Value> maybeBuffer =
+        getBuffer(rewriter, collapseShapeOp.getSrc(), options);
+    if (failed(maybeBuffer))
+      return failure();
+    Value buffer = *maybeBuffer;
     auto bufferType = buffer.getType().cast<MemRefType>();
 
     if (tensorResultType.getRank() == 0) {
       // 0-d collapses must go through a different op builder.
       MemRefType resultType;
 
       if (bufferType.getLayout().isIdentity()) {
         // Standard layout: result type has no offset.
struct DimOpInterface
   SmallVector<OpResult> getAliasingOpResult(Operation *op, OpOperand &opOperand,
                                             const AnalysisState &state) const {
     return {};
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto dimOp = cast<tensor::DimOp>(op);
-    auto v = getBuffer(rewriter, dimOp.getSource(), options);
-    replaceOpWithNewBufferizedOp<memref::DimOp>(rewriter, op, v,
-                                                dimOp.getIndex());
+    FailureOr<Value> v = getBuffer(rewriter, dimOp.getSource(), options);
+    if (failed(v))
+      return failure();
+    replaceOpWithNewBufferizedOp<memref::DimOp>(rewriter, op, *v,
+                                                dimOp.index());
     return success();
   }
 };
 
 /// Bufferization of tensor.expand_shape. Replace with memref.expand_shape.
 struct ExpandShapeOpInterface
     : public BufferizableOpInterface::ExternalModel<ExpandShapeOpInterface,
                                                     tensor::ExpandShapeOp> {
BufferRelation bufferRelation(Operation *op, OpResult opResult,
                                 const AnalysisState &state) const {
     return BufferRelation::Equivalent;
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto expandShapeOp = cast<tensor::ExpandShapeOp>(op);
     auto tensorResultType = expandShapeOp.getResultType();
-    auto buffer = getBuffer(rewriter, expandShapeOp.getSrc(), options);
+    FailureOr<Value> buffer =
+        getBuffer(rewriter, expandShapeOp.getSrc(), options);
+    if (failed(buffer))
+      return failure();
 
     // Memref result type is inferred by the builder based on reassociation
     // indices and result shape.
     replaceOpWithNewBufferizedOp<memref::ExpandShapeOp>(
-        rewriter, op, tensorResultType.getShape(), buffer,
+        rewriter, op, tensorResultType.getShape(), *buffer,
         expandShapeOp.getReassociationIndices());
     return success();
   }
 };
 
 /// Bufferization of tensor.extract_slice. Replace with memref.subview.
 struct ExtractSliceOpInterface
     : public BufferizableOpInterface::ExternalModel<ExtractSliceOpInterface,
struct ExtractSliceOpInterface
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto extractSliceOp = cast<tensor::ExtractSliceOp>(op);
     Location loc = extractSliceOp.getLoc();
 
     // Even if this op was decided to bufferize out-of-place, do not insert the
     // buffer copy yet. This is done later in this function.
-    auto srcMemref = getBuffer(rewriter, extractSliceOp.getSource(), options);
-    auto srcMemrefType = srcMemref.getType().cast<MemRefType>();
+    FailureOr<Value> srcMemref =
+        getBuffer(rewriter, extractSliceOp.getSource(), options);
+    if (failed(srcMemref))
+      return failure();
+    auto srcMemrefType = srcMemref->getType().cast<MemRefType>();
     auto dstTensorType =
         extractSliceOp.getResult().getType().cast<RankedTensorType>();
 
     // Expand offsets, sizes and strides to the full rank to handle the
     // rank-reducing case.
     SmallVector<OpFoldResult> mixedOffsets = extractSliceOp.getMixedOffsets();
     SmallVector<OpFoldResult> mixedSizes = extractSliceOp.getMixedSizes();
     SmallVector<OpFoldResult> mixedStrides = extractSliceOp.getMixedStrides();
     OffsetSizeAndStrideOpInterface::expandToRank(
-        srcMemref, mixedOffsets, mixedSizes, mixedStrides,
+        *srcMemref, mixedOffsets, mixedSizes, mixedStrides,
         [&](Value target, int64_t dim) -> OpFoldResult {
           auto shapedType = target.getType().cast<ShapedType>();
           if (shapedType.isDynamicDim(dim))
             return rewriter.create<memref::DimOp>(loc, target, dim).result();
           return rewriter.getIndexAttr(shapedType.getDimSize(dim));
         });
     // Bufferize to subview.
     auto subviewMemRefType = memref::SubViewOp::inferRankReducedResultType(
                                  dstTensorType.getRank(), srcMemrefType,
                                  mixedOffsets, mixedSizes, mixedStrides)
                                  .cast<MemRefType>();
     Value subView = rewriter.create<memref::SubViewOp>(
-        loc, subviewMemRefType, srcMemref, mixedOffsets, mixedSizes,
+        loc, subviewMemRefType, *srcMemref, mixedOffsets, mixedSizes,
         mixedStrides);
 
     replaceOpWithBufferizedValues(rewriter, op, subView);
     return success();
   }
 };
 
 /// Bufferization of tensor.extract. Replace with memref.load.
struct ExtractOpInterface
   SmallVector<OpResult> getAliasingOpResult(Operation *op, OpOperand &opOperand,
                                             const AnalysisState &state) const {
     return {};
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto extractOp = cast<tensor::ExtractOp>(op);
-    Value srcMemref = getBuffer(rewriter, extractOp.getTensor(), options);
-    replaceOpWithNewBufferizedOp<memref::LoadOp>(rewriter, op, srcMemref,
-                                                 extractOp.getIndices());
+    FailureOr<Value> srcMemref =
+        getBuffer(rewriter, extractOp.getTensor(), options);
+    if (failed(srcMemref))
+      return failure();
+    replaceOpWithNewBufferizedOp<memref::LoadOp>(rewriter, op, *srcMemref,
+                                                 extractOp.indices());
     return success();
   }
 };
 
 // Implements backtracking to traverse indices of the output buffer while
 // iterating over op.elements().
 static void createStores(RewriterBase &rewriter, Location loc, int dim,
                          Value buffer, ArrayRef<int64_t> shape,
struct InsertOpInterface
   getAliasingOpOperand(Operation *op, OpResult opResult,
                        const AnalysisState &state) const {
     return {&op->getOpOperand(1) /*dest*/};
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto insertOp = cast<tensor::InsertOp>(op);
-    Value destMemref = getBuffer(rewriter, insertOp.getDest(), options);
+    FailureOr<Value> destMemref =
+        getBuffer(rewriter, insertOp.getDest(), options);
+    if (failed(destMemref))
+      return failure();
     rewriter.create<memref::StoreOp>(insertOp.getLoc(), insertOp.getScalar(),
-                                     destMemref, insertOp.getIndices());
-    replaceOpWithBufferizedValues(rewriter, op, destMemref);
+                                     *destMemref, insertOp.getIndices());
+    replaceOpWithBufferizedValues(rewriter, op, *destMemref);
     return success();
   }
 
   BufferRelation bufferRelation(Operation *op, OpResult opResult,
                                 const AnalysisState &state) const {
     return BufferRelation::Equivalent;
   }
 };
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     // insert_slice ops arise from tiling and bufferizing them out-of-place is
     // generally a deal breaker. When used with loops, this ends up cloning the
     // whole tensor on every single iteration and is a symptom of a
     // catastrophically bad scheduling decision.
     // TODO: be very loud about it or even consider failing the pass.
     auto insertSliceOp = cast<tensor::InsertSliceOp>(op);
     Location loc = insertSliceOp.getLoc();
-    Value dstMemref = getBuffer(rewriter, insertSliceOp.getDest(), options);
+    FailureOr<Value> dstMemref =
+        getBuffer(rewriter, insertSliceOp.getDest(), options);
+    if (failed(dstMemref))
+      return failure();
 
     // Expand offsets, sizes and strides to the full rank to handle the
     // rank-reducing case.
     SmallVector<OpFoldResult> mixedOffsets = insertSliceOp.getMixedOffsets();
     SmallVector<OpFoldResult> mixedSizes = insertSliceOp.getMixedSizes();
     SmallVector<OpFoldResult> mixedStrides = insertSliceOp.getMixedStrides();
     OffsetSizeAndStrideOpInterface::expandToRank(
-        dstMemref, mixedOffsets, mixedSizes, mixedStrides,
+        *dstMemref, mixedOffsets, mixedSizes, mixedStrides,
         [&](Value target, int64_t dim) -> OpFoldResult {
           auto shapedType = target.getType().cast<ShapedType>();
           if (shapedType.isDynamicDim(dim))
             return rewriter.create<memref::DimOp>(loc, target, dim).result();
           return rewriter.getIndexAttr(shapedType.getDimSize(dim));
         });
     // Take a subview of the dst.
-    auto dstMemrefType = dstMemref.getType().cast<MemRefType>();
+    auto dstMemrefType = dstMemref->getType().cast<MemRefType>();
     auto subviewMemRefType =
         memref::SubViewOp::inferRankReducedResultType(
             insertSliceOp.getSourceType().getRank(), dstMemrefType,
             mixedOffsets, mixedSizes, mixedStrides)
             .cast<MemRefType>();
     Value subView = rewriter.create<memref::SubViewOp>(
-        loc, subviewMemRefType, dstMemref, mixedOffsets, mixedSizes,
+        loc, subviewMemRefType, *dstMemref, mixedOffsets, mixedSizes,
         mixedStrides);
 
     // Copy tensor. If this tensor.insert_slice has a matching
     // tensor.extract_slice, the copy operation will eventually fold away.
-    auto srcMemref = getBuffer(rewriter, insertSliceOp.getSource(), options);
-    if (failed(options.createMemCpy(rewriter, loc, srcMemref, subView)))
+    FailureOr<Value> srcMemref =
+        getBuffer(rewriter, insertSliceOp.getSource(), options);
+    if (failed(srcMemref))
+      return failure();
+    if (failed(options.createMemCpy(rewriter, loc, *srcMemref, subView)))
       return failure();
 
-    replaceOpWithBufferizedValues(rewriter, op, dstMemref);
+    replaceOpWithBufferizedValues(rewriter, op, *dstMemref);
     return success();
   }
 };
 
 /// Bufferization of tensor.rank. Replace with memref.rank.
 struct RankOpInterface
     : public BufferizableOpInterface::ExternalModel<RankOpInterface,
                                                     tensor::RankOp> {
struct RankOpInterface
   SmallVector<OpResult> getAliasingOpResult(Operation *op, OpOperand &opOperand,
                                             const AnalysisState &state) const {
     return {};
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto rankOp = cast<tensor::RankOp>(op);
-    auto v = getBuffer(rewriter, rankOp.getTensor(), options);
+    FailureOr<Value> v = getBuffer(rewriter, rankOp.getTensor(), options);
+    if (failed(v))
+      return failure();
     replaceOpWithNewBufferizedOp<memref::RankOp>(rewriter, op, rankOp.getType(),
-                                                 v);
+                                                 *v);
     return success();
   }
 };
 
 /// Bufferization of tensor.reshape. Replace with memref.reshape.
 struct ReshapeOpInterface
     : public BufferizableOpInterface::ExternalModel<ReshapeOpInterface,
                                                     tensor::ReshapeOp> {
struct ReshapeOpInterface
   BufferRelation bufferRelation(Operation *op, OpResult opResult,
                                 const AnalysisState &state) const {
     return BufferRelation::Equivalent;
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto reshapeOp = cast<tensor::ReshapeOp>(op);
-    Value srcBuffer = getBuffer(rewriter, reshapeOp.getSource(), options);
-    Value shapeBuffer = getBuffer(rewriter, reshapeOp.getShape(), options);
+    FailureOr<Value> srcBuffer =
+        getBuffer(rewriter, reshapeOp.getSource(), options);
+    FailureOr<Value> shapeBuffer =
+        getBuffer(rewriter, reshapeOp.getShape(), options);
+    if (failed(srcBuffer) || failed(shapeBuffer))
+      return failure();
     auto resultTensorType = reshapeOp.getResult().getType().cast<TensorType>();
     auto resultMemRefType = getMemRefType(resultTensorType, options);
     replaceOpWithNewBufferizedOp<memref::ReshapeOp>(
-        rewriter, op, resultMemRefType, srcBuffer, shapeBuffer);
+        rewriter, op, resultMemRefType, *srcBuffer, *shapeBuffer);
     return success();
   }
 };
 
 } // namespace
 } // namespace tensor
 } // namespace mlir
 

mlir/lib/Dialect/Vector/Transforms/BufferizableOpInterfaceImpl.cpp

SmallVector<OpResult> getAliasingOpResult(Operation *op, OpOperand &opOperand,
     return {};
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto readOp = cast<vector::TransferReadOp>(op);
     assert(readOp.getShapedType().isa<TensorType>() &&
            "only tensor types expected");
-    Value buffer = getBuffer(rewriter, readOp.getSource(), options);
+    FailureOr<Value> buffer = getBuffer(rewriter, readOp.getSource(), options);
+    if (failed(buffer))
+      return failure();
     replaceOpWithNewBufferizedOp<vector::TransferReadOp>(
-        rewriter, readOp, readOp.getVectorType(), buffer, readOp.getIndices(),
+        rewriter, readOp, readOp.getVectorType(), *buffer, readOp.getIndices(),
         readOp.getPermutationMap(), readOp.getPadding(), readOp.getMask(),
         readOp.getInBoundsAttr());
     return success();
   }
 };
 
 /// Bufferization of vector.transfer_write. Replace with a new
 /// vector.transfer_write that operates on a memref.
struct TransferWriteOpInterface
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     auto writeOp = cast<vector::TransferWriteOp>(op);
     assert(writeOp.getShapedType().isa<TensorType>() &&
            "only tensor types expected");
 
     // Create a new transfer_write on buffer that doesn't have a return value.
-    Value resultBuffer = getBuffer(rewriter, writeOp.getSource(), options);
+    FailureOr<Value> resultBuffer =
+        getBuffer(rewriter, writeOp.getSource(), options);
+    if (failed(resultBuffer))
+      return failure();
     rewriter.create<vector::TransferWriteOp>(
-        writeOp.getLoc(), writeOp.getVector(), resultBuffer,
+        writeOp.getLoc(), writeOp.getVector(), *resultBuffer,
         writeOp.getIndices(), writeOp.getPermutationMapAttr(),
         writeOp.getInBoundsAttr());
-    replaceOpWithBufferizedValues(rewriter, op, resultBuffer);
+    replaceOpWithBufferizedValues(rewriter, op, *resultBuffer);
 
     return success();
   }
 };
 
 } // namespace
 } // namespace vector
 } // namespace mlir
 
 void mlir::vector::registerBufferizableOpInterfaceExternalModels(
     DialectRegistry &registry) {
   registry.addExtension(+[](MLIRContext *ctx, vector::VectorDialect *dialect) {
     TransferReadOp::attachInterface<TransferReadOpInterface>(*ctx);
     TransferWriteOp::attachInterface<TransferWriteOpInterface>(*ctx);
   });
 }