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bolt/deps/llvm-18.1.8/mlir/lib/Dialect/Bufferization/Transforms/FuncBufferizableOpInterfaceImpl.cpp
Sam Vervaeck 174b6f4d4e
Embed LLVM 18.1.8
2025-02-14 19:21:04 +01:00

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//===- BufferizableOpInterfaceImpl.cpp - Impl. of BufferizableOpInterface -===//
//
// 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/Bufferization/Transforms/FuncBufferizableOpInterfaceImpl.h"
#include "mlir/Dialect/Bufferization/IR/BufferizableOpInterface.h"
#include "mlir/Dialect/Bufferization/IR/Bufferization.h"
#include "mlir/Dialect/Bufferization/IR/UnstructuredControlFlow.h"
#include "mlir/Dialect/Bufferization/Transforms/Bufferize.h"
#include "mlir/Dialect/Bufferization/Transforms/OneShotAnalysis.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/IR/Dialect.h"
#include "mlir/IR/Operation.h"
#include <optional>
namespace mlir {
namespace bufferization {
namespace func_ext {
void FuncAnalysisState::startFunctionAnalysis(FuncOp funcOp) {
analyzedFuncOps[funcOp] = FuncOpAnalysisState::InProgress;
auto createdEquiv = equivalentFuncArgs.try_emplace(funcOp, IndexMapping());
auto createdAliasingResults =
aliasingReturnVals.try_emplace(funcOp, IndexToIndexListMapping());
auto createdRead = readBbArgs.try_emplace(funcOp, BbArgIndexSet());
auto createdWritten = writtenBbArgs.try_emplace(funcOp, BbArgIndexSet());
(void)createdEquiv;
(void)createdAliasingResults;
(void)createdRead;
(void)createdWritten;
#ifndef NDEBUG
assert(createdEquiv.second && "equivalence info exists already");
assert(createdAliasingResults.second && "aliasing info exists already");
assert(createdRead.second && "bbarg access info exists already");
assert(createdWritten.second && "bbarg access info exists already");
#endif // NDEBUG
}
/// Return the unique ReturnOp that terminates `funcOp`.
/// Return nullptr if there is no such unique ReturnOp.
static func::ReturnOp getAssumedUniqueReturnOp(FuncOp funcOp) {
func::ReturnOp returnOp;
for (Block &b : funcOp.getBody()) {
if (auto candidateOp = dyn_cast<func::ReturnOp>(b.getTerminator())) {
if (returnOp)
return nullptr;
returnOp = candidateOp;
}
}
return returnOp;
}
/// Return the index-th bufferized function argument type. This assumes that the
/// specified argument is a tensor. If the tensor is ranked, a layout map may be
/// specified by the user (as per `options.functionArgTypeConverterFn`).
static BaseMemRefType
getBufferizedFunctionArgType(FuncOp funcOp, int64_t index,
const BufferizationOptions &options) {
auto tensorType =
dyn_cast<TensorType>(funcOp.getFunctionType().getInput(index));
assert(tensorType && "expected TensorType");
BaseMemRefType memrefType = options.functionArgTypeConverterFn(
tensorType, *options.defaultMemorySpace, funcOp, options);
auto layoutAttr = funcOp.getArgAttrOfType<AffineMapAttr>(
index, BufferizationDialect::kBufferLayoutAttrName);
if (!layoutAttr)
return memrefType;
auto rankedMemrefType = dyn_cast<MemRefType>(memrefType);
assert(rankedMemrefType && "buffer layout not supported on unranked tensors");
return MemRefType::get(
rankedMemrefType.getShape(), rankedMemrefType.getElementType(),
layoutAttr.getValue(), rankedMemrefType.getMemorySpace());
}
/// Return the FuncOp called by `callOp`.
static FuncOp getCalledFunction(CallOpInterface callOp) {
SymbolRefAttr sym = llvm::dyn_cast_if_present<SymbolRefAttr>(callOp.getCallableForCallee());
if (!sym)
return nullptr;
return dyn_cast_or_null<FuncOp>(
SymbolTable::lookupNearestSymbolFrom(callOp, sym));
}
/// Get FuncAnalysisState.
static const FuncAnalysisState &
getFuncAnalysisState(const AnalysisState &state) {
assert(isa<OneShotAnalysisState>(state) && "expected OneShotAnalysisState");
auto *result = static_cast<const OneShotAnalysisState &>(state)
.getExtension<FuncAnalysisState>();
assert(result && "FuncAnalysisState does not exist");
return *result;
}
/// Return the state (phase) of analysis of the FuncOp.
static FuncOpAnalysisState getFuncOpAnalysisState(const AnalysisState &state,
FuncOp funcOp) {
if (!isa<OneShotAnalysisState>(state))
return FuncOpAnalysisState::NotAnalyzed;
auto *funcState = static_cast<const OneShotAnalysisState &>(state)
.getExtension<FuncAnalysisState>();
if (!funcState)
return FuncOpAnalysisState::NotAnalyzed;
const auto &analyzedFuncOps = funcState->analyzedFuncOps;
auto it = analyzedFuncOps.find(funcOp);
if (it == analyzedFuncOps.end())
return FuncOpAnalysisState::NotAnalyzed;
return it->second;
}
/// Return the index of the bbArg in the given FuncOp that is equivalent to the
/// specified return value (if any).
static std::optional<int64_t>
getEquivalentFuncArgIdx(FuncOp funcOp, const FuncAnalysisState &state,
int64_t returnValIdx) {
auto funcOpIt = state.equivalentFuncArgs.find(funcOp);
if (funcOpIt == state.equivalentFuncArgs.end())
// No equivalence info stores for funcOp.
return std::nullopt;
auto retValIt = funcOpIt->getSecond().find(returnValIdx);
if (retValIt == funcOpIt->getSecond().end())
// Return value has no equivalent bbArg.
return std::nullopt;
return retValIt->getSecond();
}
struct CallOpInterface
: public BufferizableOpInterface::ExternalModel<CallOpInterface,
func::CallOp> {
bool bufferizesToMemoryRead(Operation *op, OpOperand &opOperand,
const AnalysisState &state) const {
func::CallOp callOp = cast<func::CallOp>(op);
FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a FuncOp");
if (getFuncOpAnalysisState(state, funcOp) != FuncOpAnalysisState::Analyzed)
// FuncOp not analyzed yet. Assume that OpOperand is read.
return true;
const FuncAnalysisState &funcState = getFuncAnalysisState(state);
return funcState.readBbArgs.lookup(funcOp).contains(
opOperand.getOperandNumber());
}
bool bufferizesToMemoryWrite(Operation *op, OpOperand &opOperand,
const AnalysisState &state) const {
func::CallOp callOp = cast<func::CallOp>(op);
FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a FuncOp");
if (getFuncOpAnalysisState(state, funcOp) != FuncOpAnalysisState::Analyzed)
// FuncOp not analyzed yet. Assume that OpOperand is written.
return true;
const FuncAnalysisState &funcState = getFuncAnalysisState(state);
return funcState.writtenBbArgs.lookup(funcOp).contains(
opOperand.getOperandNumber());
}
AliasingValueList getAliasingValues(Operation *op, OpOperand &opOperand,
const AnalysisState &state) const {
func::CallOp callOp = cast<func::CallOp>(op);
FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a FuncOp");
if (getFuncOpAnalysisState(state, funcOp) != FuncOpAnalysisState::Analyzed)
// FuncOp not analyzed yet. Any OpResult may be aliasing.
return detail::unknownGetAliasingValues(opOperand);
// Get aliasing results from state.
const FuncAnalysisState &funcState = getFuncAnalysisState(state);
auto aliasingReturnVals =
funcState.aliasingReturnVals.lookup(funcOp).lookup(
opOperand.getOperandNumber());
// Check if the aliasing OpResult is equivalent to the OpOperand.
std::optional<int64_t> equivalent = {};
if (aliasingReturnVals.size() == 1) {
equivalent = getEquivalentFuncArgIdx(funcOp, funcState,
aliasingReturnVals.front());
assert((!equivalent.has_value() ||
*equivalent == opOperand.getOperandNumber()) &&
"inconsistent analysis state");
}
AliasingValueList result;
for (int64_t resultIdx : aliasingReturnVals)
result.addAlias({callOp->getOpResult(resultIdx),
equivalent.has_value() ? BufferRelation::Equivalent
: BufferRelation::Unknown,
/*isDefinite=*/equivalent.has_value()});
return result;
}
FailureOr<BaseMemRefType>
getBufferType(Operation *op, Value value, const BufferizationOptions &options,
SmallVector<Value> &invocationStack) const {
auto callOp = cast<func::CallOp>(op);
FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a FuncOp");
// The callee was already bufferized, so we can directly take the type from
// its signature.
FunctionType funcType = funcOp.getFunctionType();
return cast<BaseMemRefType>(
funcType.getResult(cast<OpResult>(value).getResultNumber()));
}
/// All function arguments are writable. It is the responsibility of the
/// CallOp to insert buffer copies where necessary.
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
const BufferizationOptions &options) const {
func::CallOp callOp = cast<func::CallOp>(op);
// 1. Compute the result types of the new CallOp.
SmallVector<Type> resultTypes;
for (Value result : callOp.getResults()) {
Type returnType = result.getType();
if (!isa<TensorType>(returnType)) {
// Non-tensor values are returned.
resultTypes.push_back(returnType);
continue;
}
// Returning a memref.
FailureOr<BaseMemRefType> resultType =
bufferization::getBufferType(result, options);
if (failed(resultType))
return failure();
resultTypes.push_back(*resultType);
}
// 2. Rewrite tensor operands as memrefs based on type of the already
// bufferized callee.
SmallVector<Value> newOperands;
FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a FuncOp");
FunctionType funcType = funcOp.getFunctionType();
for (OpOperand &opOperand : callOp->getOpOperands()) {
// Non-tensor operands are just copied.
if (!isa<TensorType>(opOperand.get().getType())) {
newOperands.push_back(opOperand.get());
continue;
}
// Retrieve buffers for tensor operands.
FailureOr<Value> maybeBuffer =
getBuffer(rewriter, opOperand.get(), options);
if (failed(maybeBuffer))
return failure();
Value buffer = *maybeBuffer;
// Caller / callee type mismatch is handled with a CastOp.
auto memRefType = funcType.getInput(opOperand.getOperandNumber());
// 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.
if (buffer.getType() != memRefType) {
assert(
memref::CastOp::areCastCompatible(buffer.getType(), memRefType) &&
"CallOp::bufferize: cast incompatible");
Value castBuffer = rewriter.create<memref::CastOp>(callOp.getLoc(),
memRefType, buffer);
buffer = castBuffer;
}
newOperands.push_back(buffer);
}
// 3. Create the new CallOp.
Operation *newCallOp = rewriter.create<func::CallOp>(
callOp.getLoc(), funcOp.getSymName(), resultTypes, newOperands);
newCallOp->setAttrs(callOp->getAttrs());
// 4. Replace the old op with the new op.
replaceOpWithBufferizedValues(rewriter, callOp, newCallOp->getResults());
return success();
}
};
struct ReturnOpInterface
: public BufferizableOpInterface::ExternalModel<ReturnOpInterface,
func::ReturnOp> {
bool bufferizesToMemoryRead(Operation *op, OpOperand &opOperand,
const AnalysisState &state) const {
return true;
}
bool bufferizesToMemoryWrite(Operation *op, OpOperand &opOperand,
const AnalysisState &state) const {
return false;
}
AliasingValueList getAliasingValues(Operation *op, OpOperand &opOperand,
const AnalysisState &state) const {
return {};
}
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
const BufferizationOptions &options) const {
#ifndef NDEBUG
auto returnOp = cast<func::ReturnOp>(op);
assert(isa<FuncOp>(returnOp->getParentOp()) &&
"only support FuncOp parent for ReturnOp");
#endif // NDEBUG
// ReturnOps are bufferized as part of FuncOps.
return success();
}
};
struct FuncOpInterface
: public OpWithUnstructuredControlFlowBufferizableOpInterfaceExternalModel<
FuncOpInterface, FuncOp> {
static bool supportsUnstructuredControlFlow() { return true; }
bool hasTensorSemantics(Operation *op) const {
auto isaTensor = [](Type type) { return isa<TensorType>(type); };
// A function has tensor semantics if it has tensor arguments/results.
auto funcOp = cast<FuncOp>(op);
bool hasTensorArg = any_of(funcOp.getArgumentTypes(), isaTensor);
bool hasTensorResult = any_of(funcOp.getResultTypes(), isaTensor);
if (hasTensorArg || hasTensorResult)
return true;
// It also has tensor semantics if it has tensor block arguments.
// TODO: Decouple bufferization of unstructured control flow from
// BufferizableOpInterface implementations. We should only care about
// region entry block arguments here (which are already covered by the
// argument types of the function).
for (Block &block : funcOp.getBody())
if (any_of(block.getArgumentTypes(), isaTensor))
return true;
return false;
}
AliasingOpOperandList
getAliasingOpOperands(Operation *op, Value value,
const AnalysisState &state) const {
return getAliasingBranchOpOperands(op, cast<BlockArgument>(value), state);
}
FailureOr<BaseMemRefType>
getBufferType(Operation *op, Value value, const BufferizationOptions &options,
SmallVector<Value> &invocationStack) const {
auto funcOp = cast<FuncOp>(op);
auto bbArg = cast<BlockArgument>(value);
// Function arguments are special.
if (bbArg.getOwner() == &funcOp.getBody().front())
return getBufferizedFunctionArgType(funcOp, bbArg.getArgNumber(),
options);
return OpWithUnstructuredControlFlowBufferizableOpInterfaceExternalModel::
getBufferType(op, value, options, invocationStack);
}
LogicalResult verifyAnalysis(Operation *op,
const AnalysisState &state) const {
auto funcOp = cast<func::FuncOp>(op);
// TODO: func.func with multiple returns are not supported.
if (!getAssumedUniqueReturnOp(funcOp) && !funcOp.isExternal())
return op->emitOpError("op without unique func.return is not supported");
return success();
}
/// Rewrite function bbArgs and return values into buffer form. This function
/// bufferizes the function signature and the ReturnOp. When the entire
/// function body has been bufferized, function return types can be switched
/// to more concise memref types as part of `foldMemRefCasts`.
///
/// All function bbArgs are writable unless they are explicitly marked as
/// read-only. Callers must insert copies when needed.
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
const BufferizationOptions &options) const {
auto funcOp = cast<FuncOp>(op);
FunctionType funcType = funcOp.getFunctionType();
// Construct the bufferized function type.
SmallVector<Type> argTypes;
for (const auto &it : llvm::enumerate(funcType.getInputs())) {
Type argType = it.value();
if (dyn_cast<TensorType>(argType)) {
argTypes.push_back(
getBufferizedFunctionArgType(funcOp, it.index(), options));
continue;
}
argTypes.push_back(argType);
}
// Bodiless functions are assumed opaque and we cannot know the
// bufferization contract they want to enforce. As a consequence, only
// support functions that don't return any tensors atm.
if (funcOp.isExternal()) {
SmallVector<Type> retTypes;
for (Type resultType : funcType.getResults()) {
if (isa<TensorType>(resultType))
return funcOp->emitError() << "cannot bufferize bodiless function "
<< "that returns a tensor";
retTypes.push_back(resultType);
}
funcOp.setType(FunctionType::get(op->getContext(), argTypes, retTypes));
return success();
}
// TODO: Support functions with multiple returns.
func::ReturnOp returnOp = getAssumedUniqueReturnOp(funcOp);
assert(returnOp && "expected func with single return op");
Location loc = returnOp.getLoc();
// 1. Bufferize every block.
for (Block &block : funcOp.getBody())
if (failed(bufferization::bufferizeBlockSignature(&block, rewriter,
options)))
return failure();
// 2. For each result, keep track of which inplace argument it reuses.
SmallVector<Value> returnValues;
for (OpOperand &returnOperand : returnOp->getOpOperands()) {
Value returnVal = returnOperand.get();
auto tensorType = dyn_cast<TensorType>(returnVal.getType());
rewriter.setInsertionPoint(returnOp);
// If not a tensor type just forward it.
if (!tensorType) {
returnValues.push_back(returnVal);
continue;
}
// Note: If `inferFunctionResultLayout = true`, cast are later folded
// away.
BaseMemRefType resultType = options.functionArgTypeConverterFn(
tensorType, *options.defaultMemorySpace, funcOp, options);
Value toMemrefOp = rewriter.create<bufferization::ToMemrefOp>(
loc, resultType, returnVal);
returnValues.push_back(toMemrefOp);
}
// 3. Rewrite the terminator without the in-place bufferizable values.
returnOp.getOperandsMutable().assign(returnValues);
// 4. Rewrite the FuncOp type to buffer form.
funcOp.setType(FunctionType::get(op->getContext(), argTypes,
ValueRange(returnValues).getTypes()));
return success();
}
/// Return `true` if the given function argument is writable.
bool isWritable(Operation *op, Value value,
const AnalysisState &state) const {
auto funcOp = cast<FuncOp>(op);
BlockArgument bbArg = dyn_cast<BlockArgument>(value);
assert(bbArg && "expected BlockArgument");
// Non-entry block arguments are always writable. (They may alias with
// values that are not writable, which will turn them into read-only.)
if (bbArg.getOwner() != &funcOp.getBody().front())
return true;
// "bufferization.writable" overrides other writability decisions. This is
// currently used for testing only.
if (BoolAttr writable = funcOp.getArgAttrOfType<BoolAttr>(
bbArg.getArgNumber(), BufferizationDialect::kWritableAttrName))
return writable.getValue();
// All function arguments are writable by default.
return true;
}
};
} // namespace func_ext
} // namespace bufferization
} // namespace mlir
void mlir::bufferization::func_ext::
registerBufferizableOpInterfaceExternalModels(DialectRegistry &registry) {
registry.addExtension(+[](MLIRContext *ctx, func::FuncDialect *dialect) {
func::CallOp::attachInterface<func_ext::CallOpInterface>(*ctx);
func::FuncOp::attachInterface<func_ext::FuncOpInterface>(*ctx);
func::ReturnOp::attachInterface<func_ext::ReturnOpInterface>(*ctx);
});
}
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