Files
clang-p2996/mlir/lib/Dialect/Linalg/ComprehensiveBufferize/ModuleBufferization.cpp
Matthias Springer bd1d87e3d1 [mlir][bufferization][NFC] Remove layout post processing step
The layout postprocessing step was removed and is now part of the FuncOp bufferization. If the user specified a certain layout map for a tensor function arg, use that layout map directly when bufferizing the function signature. Previously, the bufferization used a generic layout map for every tensor function arg and then updated function signatures and CallOps in a separate step.

Differential Revision: https://reviews.llvm.org/D122228
2022-04-22 18:49:47 +09:00

1038 lines
42 KiB
C++

//===- ModuleBufferization.cpp - Bufferization across Func. Boundaries ----===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Module Bufferization is an extension of One-Shot Bufferize that
// bufferizes function boundaries. It provides `BufferizableOpInterface`
// implementations for FuncOp, CallOp and ReturnOp.
//
// Module Bufferization is run via `runModuleBufferize(ModuleOp, ...)`. This
// function analyzes the given module and determines the order of analysis and
// bufferization: Functions that are called are processed before their
// respective callers.
//
// After analyzing a FuncOp, additional information about its bbArgs is
// gathered through PostAnalysisStepFns and stored in `FuncAnalysisState`.
//
// * `aliasingFuncOpBBArgsAnalysis` determines the equivalent/aliasing bbArgs
// for
// each tensor return value (if any).
// * `funcOpBbArgReadWriteAnalysis` determines whether or not a tensor bbArg is
// read/written.
//
// Only tensors that are equivalent to some FuncOp bbArg may be returned.
// Bufferization currently fails if other tensors (in particular tensors that
// bufferize out-of-place and result in a new buffer allocation) are returned.
// In the future, such allocations could be hoisted to the caller.
//
// Example: `foo` fails bufferization because %0 is not equivalent to any bbArg.
// ```
// func @foo() -> tensor<?xf32> {
// %0 = linalg.init_tensor [...] : tensor<?xf32>
// return %0 : tensor<?xf32>
// }
// ```
//
// Module Bufferization implements the following calling convention.
//
// * In the absence of conflicts within a FuncOp, the FuncOp's bbArgs may always
// be written to in-place.
// * If a tensor operand of a CallOp is read after the CallOp, the operand of
// the CallOp must bufferize out-of-place.
//
// Example: The tensor.insert op bufferizes in-place because it is allowed to
// modify the buffer of `%t1` directly. The CallOp in `caller` must bufferize
// out-of-place because `%t0` is modified by the callee but read by the
// tensor.extract op. The analysis of CallOps decides whether an OpOperand must
// bufferize out-of-place based on results of `funcOpBbArgReadWriteAnalysis`.
// ```
// func @callee(%t1 : tensor<?xf32>) -> tensor<?xf32> {
// %f = ... : f32
// %0 = tensor.insert %f into %t1[...] : tensor<?xf32>
// return %0 : tensor<?xf32>
// }
//
// func @caller() -> () {
// %t0 = ... : tensor<?xf32>
// %1 = call @callee(%t0) : (tensor<?xf32>) -> (tensor<?xf32>)
// %2 = tensor.extract %1[...] : tensor<?xf32>
// }
// ```
//
// Note: If a function is external, `funcOpBbArgReadWriteAnalysis` cannot
// analyze the function body. In such a case, the CallOp analysis conservatively
// assumes that each tensor OpOperand is both read and written.
//
// TODO: Add FuncOp attributes so that bbArgs of external FuncOps can be marked
// as "not reading" and/or "not writing".
#include "mlir/Dialect/Linalg/ComprehensiveBufferize/ModuleBufferization.h"
#include "mlir/Dialect/Bufferization/IR/BufferizableOpInterface.h"
#include "mlir/Dialect/Bufferization/IR/Bufferization.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/Operation.h"
using namespace mlir;
using namespace linalg;
using namespace tensor;
using namespace comprehensive_bufferize;
using namespace mlir::bufferization;
/// A mapping of FuncOps to their callers.
using FuncCallerMap = DenseMap<func::FuncOp, DenseSet<Operation *>>;
namespace {
/// The state of analysis of a FuncOp.
enum class FuncOpAnalysisState { NotAnalyzed, InProgress, Analyzed };
/// Extra analysis state that is required for bufferization of function
/// boundaries.
struct FuncAnalysisState : public DialectAnalysisState {
// Note: Function arguments and/or function return values may disappear during
// bufferization. Functions and their CallOps are analyzed and bufferized
// separately. To ensure that a CallOp analysis/bufferization can access an
// already bufferized function's analysis results, we store bbArg/return value
// indices instead of BlockArguments/OpOperand pointers.
/// A set of block argument indices.
using BbArgIndexSet = DenseSet<int64_t>;
/// A mapping of indices to indices.
using IndexMapping = DenseMap<int64_t, int64_t>;
/// A mapping of indices to a list of indices.
using IndexToIndexListMapping = DenseMap<int64_t, SmallVector<int64_t>>;
/// A mapping of ReturnOp OpOperand indices to equivalent FuncOp BBArg
/// indices.
DenseMap<func::FuncOp, IndexMapping> equivalentFuncArgs;
/// A mapping of ReturnOp OpOperand indices to aliasing FuncOp BBArg indices.
DenseMap<func::FuncOp, IndexToIndexListMapping> aliasingFuncArgs;
/// A mapping of FuncOp BBArg indices to aliasing ReturnOp OpOperand indices.
DenseMap<func::FuncOp, IndexToIndexListMapping> aliasingReturnVals;
/// A set of all read BlockArguments of FuncOps.
DenseMap<func::FuncOp, BbArgIndexSet> readBbArgs;
/// A set of all written-to BlockArguments of FuncOps.
DenseMap<func::FuncOp, BbArgIndexSet> writtenBbArgs;
/// Keep track of which FuncOps are fully analyzed or currently being
/// analyzed.
DenseMap<func::FuncOp, FuncOpAnalysisState> analyzedFuncOps;
/// This function is called right before analyzing the given FuncOp. It
/// initializes the data structures for the FuncOp in this state object.
void startFunctionAnalysis(func::FuncOp funcOp) {
analyzedFuncOps[funcOp] = FuncOpAnalysisState::InProgress;
auto createdEquiv = equivalentFuncArgs.try_emplace(funcOp, IndexMapping());
auto createdAliasingOperands =
aliasingFuncArgs.try_emplace(funcOp, IndexToIndexListMapping());
auto createdAliasingResults =
aliasingReturnVals.try_emplace(funcOp, IndexToIndexListMapping());
auto createdRead = readBbArgs.try_emplace(funcOp, BbArgIndexSet());
auto createdWritten = writtenBbArgs.try_emplace(funcOp, BbArgIndexSet());
(void)createdEquiv;
(void)createdAliasingOperands;
(void)createdAliasingResults;
(void)createdRead;
(void)createdWritten;
#ifndef NDEBUG
assert(createdEquiv.second && "equivalence info exists already");
assert(createdAliasingOperands.second && "aliasing 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
}
};
} // namespace
/// Get FuncAnalysisState.
static const FuncAnalysisState &
getFuncAnalysisState(const AnalysisState &state) {
Optional<const FuncAnalysisState *> maybeState =
state.getDialectState<FuncAnalysisState>(
func::FuncDialect::getDialectNamespace());
assert(maybeState.hasValue() && "FuncAnalysisState does not exist");
return **maybeState;
}
/// Get or create FuncAnalysisState.
static FuncAnalysisState &getFuncAnalysisState(AnalysisState &state) {
return state.getOrCreateDialectState<FuncAnalysisState>(
func::FuncDialect::getDialectNamespace());
}
/// Return the state (phase) of analysis of the FuncOp.
static FuncOpAnalysisState getFuncOpAnalysisState(const AnalysisState &state,
func::FuncOp funcOp) {
const FuncAnalysisState &moduleState = getFuncAnalysisState(state);
auto it = moduleState.analyzedFuncOps.find(funcOp);
if (it == moduleState.analyzedFuncOps.end())
return FuncOpAnalysisState::NotAnalyzed;
return it->second;
}
/// Return the unique ReturnOp that terminates `funcOp`.
/// Return nullptr if there is no such unique ReturnOp.
static func::ReturnOp getAssumedUniqueReturnOp(func::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;
}
namespace {
/// Annotate IR with the results of the analysis. For testing purposes only.
static void annotateEquivalentReturnBbArg(OpOperand &returnVal,
BlockArgument bbArg) {
const char *kEquivalentArgsAttr = "__equivalent_func_args__";
Operation *op = returnVal.getOwner();
SmallVector<int64_t> equivBbArgs;
if (op->hasAttr(kEquivalentArgsAttr)) {
auto attr = op->getAttr(kEquivalentArgsAttr).cast<ArrayAttr>();
equivBbArgs = llvm::to_vector<4>(llvm::map_range(attr, [](Attribute a) {
return a.cast<IntegerAttr>().getValue().getSExtValue();
}));
} else {
equivBbArgs.append(op->getNumOperands(), -1);
}
equivBbArgs[returnVal.getOperandNumber()] = bbArg.getArgNumber();
OpBuilder b(op->getContext());
op->setAttr(kEquivalentArgsAttr, b.getI64ArrayAttr(equivBbArgs));
}
/// Store function BlockArguments that are equivalent to/aliasing a returned
/// value in FuncAnalysisState.
static LogicalResult
aliasingFuncOpBBArgsAnalysis(Operation *op, AnalysisState &state,
BufferizationAliasInfo &aliasInfo,
SmallVector<Operation *> &newOps) {
FuncAnalysisState &funcState = getFuncAnalysisState(state);
// Support only single return-terminated block in the function.
auto funcOp = cast<func::FuncOp>(op);
func::ReturnOp returnOp = getAssumedUniqueReturnOp(funcOp);
assert(returnOp && "expected func with single return op");
for (OpOperand &returnVal : returnOp->getOpOperands())
if (returnVal.get().getType().isa<RankedTensorType>())
for (BlockArgument bbArg : funcOp.getArguments())
if (bbArg.getType().isa<RankedTensorType>()) {
int64_t returnIdx = returnVal.getOperandNumber();
int64_t bbArgIdx = bbArg.getArgNumber();
if (aliasInfo.areEquivalentBufferizedValues(returnVal.get(), bbArg)) {
funcState.equivalentFuncArgs[funcOp][returnIdx] = bbArgIdx;
if (state.getOptions().testAnalysisOnly)
annotateEquivalentReturnBbArg(returnVal, bbArg);
}
if (aliasInfo.areAliasingBufferizedValues(returnVal.get(), bbArg)) {
funcState.aliasingFuncArgs[funcOp][returnIdx].push_back(bbArgIdx);
funcState.aliasingReturnVals[funcOp][bbArgIdx].push_back(returnIdx);
}
}
return success();
}
/// Return true if the buffer of the given tensor value is written to. Must not
/// be called for values inside not yet analyzed functions. (Post-analysis
/// steps do not have to be run yet, i.e., "in progress" is also OK.)
static bool isValueWritten(Value value, const AnalysisState &state,
const BufferizationAliasInfo &aliasInfo) {
#ifndef NDEBUG
assert(value.getType().isa<TensorType>() && "expected TensorType");
func::FuncOp funcOp;
if (auto bbArg = value.dyn_cast<BlockArgument>()) {
Operation *owner = bbArg.getOwner()->getParentOp();
funcOp = isa<func::FuncOp>(owner) ? cast<func::FuncOp>(owner)
: owner->getParentOfType<func::FuncOp>();
} else {
funcOp = value.getDefiningOp()->getParentOfType<func::FuncOp>();
}
assert(getFuncOpAnalysisState(state, funcOp) !=
FuncOpAnalysisState::NotAnalyzed &&
"FuncOp must be fully analyzed or analysis in progress");
#endif // NDEBUG
bool isWritten = false;
aliasInfo.applyOnAliases(value, [&](Value val) {
for (OpOperand &use : val.getUses())
if (state.isInPlace(use) && state.bufferizesToMemoryWrite(use))
isWritten = true;
});
return isWritten;
}
static void annotateFuncArgAccess(func::FuncOp funcOp, BlockArgument bbArg,
bool isRead, bool isWritten) {
OpBuilder b(funcOp.getContext());
Attribute accessType;
if (isRead && isWritten) {
accessType = b.getStringAttr("read-write");
} else if (isRead) {
accessType = b.getStringAttr("read");
} else if (isWritten) {
accessType = b.getStringAttr("write");
} else {
accessType = b.getStringAttr("none");
}
funcOp.setArgAttr(bbArg.getArgNumber(), "bufferization.access", accessType);
}
/// Determine which FuncOp bbArgs are read and which are written. If this
/// PostAnalysisStepFn is run on a function with unknown ops, it will
/// conservatively assume that such ops bufferize to a read + write.
static LogicalResult
funcOpBbArgReadWriteAnalysis(Operation *op, AnalysisState &state,
BufferizationAliasInfo &aliasInfo,
SmallVector<Operation *> &newOps) {
FuncAnalysisState &funcState = getFuncAnalysisState(state);
auto funcOp = cast<func::FuncOp>(op);
// If the function has no body, conservatively assume that all args are
// read + written.
if (funcOp.getBody().empty()) {
for (BlockArgument bbArg : funcOp.getArguments()) {
funcState.readBbArgs[funcOp].insert(bbArg.getArgNumber());
funcState.writtenBbArgs[funcOp].insert(bbArg.getArgNumber());
}
return success();
}
for (BlockArgument bbArg : funcOp.getArguments()) {
if (!bbArg.getType().isa<TensorType>())
continue;
bool isRead = state.isValueRead(bbArg);
bool isWritten = isValueWritten(bbArg, state, aliasInfo);
if (state.getOptions().testAnalysisOnly)
annotateFuncArgAccess(funcOp, bbArg, isRead, isWritten);
if (isRead)
funcState.readBbArgs[funcOp].insert(bbArg.getArgNumber());
if (isWritten)
funcState.writtenBbArgs[funcOp].insert(bbArg.getArgNumber());
}
return success();
}
} // namespace
/// Remove the attribute that triggers inplace bufferization on a func::FuncOp
/// argument `bbArg`.
static void removeBufferizationFuncArguments(BlockArgument bbArg) {
auto funcOp = cast<func::FuncOp>(bbArg.getOwner()->getParentOp());
funcOp.removeArgAttr(bbArg.getArgNumber(),
BufferizableOpInterface::kBufferLayoutAttrName);
funcOp.removeArgAttr(bbArg.getArgNumber(),
BufferizableOpInterface::kInplaceableAttrName);
}
/// Return the func::FuncOp called by `callOp`.
static func::FuncOp getCalledFunction(CallOpInterface callOp) {
SymbolRefAttr sym = callOp.getCallableForCallee().dyn_cast<SymbolRefAttr>();
if (!sym)
return nullptr;
return dyn_cast_or_null<func::FuncOp>(
SymbolTable::lookupNearestSymbolFrom(callOp, sym));
}
/// 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. If no layout map is specified, a fully dynamic map is
/// used.
static BaseMemRefType
getBufferizedFunctionArgType(func::FuncOp funcOp, int64_t index,
const BufferizationOptions &options) {
auto tensorType =
funcOp.getFunctionType().getInput(index).dyn_cast<TensorType>();
assert(tensorType && "expected TensorType");
BaseMemRefType memrefType = getMemRefType(tensorType, options);
auto layoutAttr = funcOp.getArgAttrOfType<AffineMapAttr>(
index, BufferizableOpInterface::kBufferLayoutAttrName);
if (!layoutAttr)
return memrefType;
auto rankedMemrefType = memrefType.dyn_cast<MemRefType>();
assert(rankedMemrefType && "buffer layout not supported on unranked tensors");
return MemRefType::get(
rankedMemrefType.getShape(), rankedMemrefType.getElementType(),
layoutAttr.getValue(), rankedMemrefType.getMemorySpaceAsInt());
}
/// Gather equivalence info of CallOps.
/// Note: This only adds new equivalence info if the called function was already
/// analyzed.
// TODO: This does not handle cyclic function call graphs etc.
static void equivalenceAnalysis(func::FuncOp funcOp,
BufferizationAliasInfo &aliasInfo,
FuncAnalysisState &funcState) {
funcOp->walk([&](func::CallOp callOp) {
func::FuncOp calledFunction = getCalledFunction(callOp);
assert(calledFunction && "could not retrieved called func::FuncOp");
// No equivalence info available for the called function.
if (!funcState.equivalentFuncArgs.count(calledFunction))
return WalkResult::skip();
for (auto it : funcState.equivalentFuncArgs[calledFunction]) {
int64_t returnIdx = it.first;
int64_t bbargIdx = it.second;
Value returnVal = callOp.getResult(returnIdx);
Value argVal = callOp->getOperand(bbargIdx);
aliasInfo.unionEquivalenceClasses(returnVal, argVal);
}
return WalkResult::advance();
});
}
/// Store all functions of the `moduleOp` in `orderedFuncOps`, sorted by
/// callee-caller order (i.e. callees without callers first).
/// Store the map of FuncOp to all its callers in `callerMap`.
/// Return `failure()` if a cycle of calls is detected or if we are unable to
/// retrieve the called FuncOp from any CallOpInterface.
static LogicalResult
getFuncOpsOrderedByCalls(ModuleOp moduleOp,
SmallVectorImpl<func::FuncOp> &orderedFuncOps,
FuncCallerMap &callerMap) {
// For each FuncOp, the set of functions called by it (i.e. the union of
// symbols of all nested CallOpInterfaceOp).
DenseMap<func::FuncOp, DenseSet<func::FuncOp>> calledBy;
// For each FuncOp, the number of CallOpInterface it contains.
DenseMap<func::FuncOp, unsigned> numberCallOpsContainedInFuncOp;
WalkResult res = moduleOp.walk([&](func::FuncOp funcOp) -> WalkResult {
if (!funcOp.getBody().empty()) {
func::ReturnOp returnOp = getAssumedUniqueReturnOp(funcOp);
if (!returnOp)
return funcOp->emitError()
<< "cannot bufferize a FuncOp with tensors and "
"without a unique ReturnOp";
}
numberCallOpsContainedInFuncOp[funcOp] = 0;
return funcOp.walk([&](CallOpInterface callOp) -> WalkResult {
// Only support CallOp for now.
if (!isa<func::CallOp>(callOp.getOperation()))
return callOp->emitError() << "expected a CallOp";
func::FuncOp calledFunction = getCalledFunction(callOp);
assert(calledFunction && "could not retrieved called func::FuncOp");
auto it = callerMap.try_emplace(calledFunction, DenseSet<Operation *>{});
it.first->getSecond().insert(callOp);
if (calledBy[calledFunction].count(funcOp) == 0) {
calledBy[calledFunction].insert(funcOp);
numberCallOpsContainedInFuncOp[funcOp]++;
}
return WalkResult::advance();
});
});
if (res.wasInterrupted())
return failure();
// Iteratively remove function operation that do not call any of the
// functions remaining in the callCounter map and add them to the worklist.
while (!numberCallOpsContainedInFuncOp.empty()) {
auto it = llvm::find_if(numberCallOpsContainedInFuncOp,
[](auto entry) { return entry.getSecond() == 0; });
if (it == numberCallOpsContainedInFuncOp.end())
return moduleOp.emitOpError(
"expected callgraph to be free of circular dependencies.");
orderedFuncOps.push_back(it->getFirst());
for (auto callee : calledBy[it->getFirst()])
numberCallOpsContainedInFuncOp[callee]--;
numberCallOpsContainedInFuncOp.erase(it);
}
return success();
}
namespace mlir {
namespace linalg {
namespace comprehensive_bufferize {
namespace std_ext {
/// Return the index of the bbArg in the given func::FuncOp that is equivalent
/// to the specified return value (if any).
static Optional<int64_t> getEquivalentFuncArgIdx(func::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 None;
auto retValIt = funcOpIt->getSecond().find(returnValIdx);
if (retValIt == funcOpIt->getSecond().end())
// Return value has no equivalent bbArg.
return None;
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);
func::FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a func::FuncOp");
const FuncAnalysisState &funcState = getFuncAnalysisState(state);
if (getFuncOpAnalysisState(state, funcOp) != FuncOpAnalysisState::Analyzed)
// FuncOp not analyzed yet. Assume that OpOperand is read.
return true;
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);
func::FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a func::FuncOp");
const FuncAnalysisState &funcState = getFuncAnalysisState(state);
if (getFuncOpAnalysisState(state, funcOp) != FuncOpAnalysisState::Analyzed)
// FuncOp not analyzed yet. Assume that OpOperand is written.
return true;
return funcState.writtenBbArgs.lookup(funcOp).contains(
opOperand.getOperandNumber());
}
SmallVector<OpResult> getAliasingOpResult(Operation *op, OpOperand &opOperand,
const AnalysisState &state) const {
func::CallOp callOp = cast<func::CallOp>(op);
func::FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a func::FuncOp");
const FuncAnalysisState &funcState = getFuncAnalysisState(state);
if (getFuncOpAnalysisState(state, funcOp) !=
FuncOpAnalysisState::Analyzed) {
// FuncOp not analyzed yet. Any OpResult may be aliasing.
SmallVector<OpResult> result;
for (OpResult opResult : op->getOpResults())
if (opResult.getType().isa<TensorType>())
result.push_back(opResult);
return result;
}
// Get aliasing results from state.
auto aliasingReturnVals =
funcState.aliasingReturnVals.lookup(funcOp).lookup(
opOperand.getOperandNumber());
SmallVector<OpResult> result;
for (int64_t resultIdx : aliasingReturnVals)
result.push_back(callOp->getOpResult(resultIdx));
return result;
}
SmallVector<OpOperand *>
getAliasingOpOperand(Operation *op, OpResult opResult,
const AnalysisState &state) const {
func::CallOp callOp = cast<func::CallOp>(op);
func::FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a func::FuncOp");
const FuncAnalysisState &funcState = getFuncAnalysisState(state);
if (getFuncOpAnalysisState(state, funcOp) !=
FuncOpAnalysisState::Analyzed) {
// FuncOp not analyzed yet. Any OpOperand may be aliasing.
SmallVector<OpOperand *> result;
for (OpOperand &opOperand : op->getOpOperands())
if (opOperand.get().getType().isa<TensorType>())
result.push_back(&opOperand);
return result;
}
// Get aliasing bbArgs from state.
auto aliasingFuncArgs = funcState.aliasingFuncArgs.lookup(funcOp).lookup(
opResult.getResultNumber());
SmallVector<OpOperand *> result;
for (int64_t bbArgIdx : aliasingFuncArgs)
result.push_back(&callOp->getOpOperand(bbArgIdx));
return result;
}
BufferRelation bufferRelation(Operation *op, OpResult opResult,
const AnalysisState &state) const {
return BufferRelation::Equivalent;
}
/// All function arguments are writable. It is the responsibility of the
/// CallOp to insert buffer copies where necessary.
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
BufferizationState &state) const {
func::CallOp callOp = cast<func::CallOp>(op);
unsigned numResults = callOp.getNumResults();
unsigned numOperands = callOp->getNumOperands();
func::FuncOp funcOp = getCalledFunction(callOp);
assert(funcOp && "expected CallOp to a func::FuncOp");
const FuncAnalysisState &funcState =
getFuncAnalysisState(state.getAnalysisState());
const OneShotBufferizationOptions &options =
static_cast<const OneShotBufferizationOptions &>(state.getOptions());
// Result types of the bufferized CallOp.
SmallVector<Type> resultTypes;
// Replacement values for the existing CallOp. These are usually the results
// of the bufferized CallOp, unless a tensor result folds onto an operand.
SmallVector<Value> replacementValues(numResults, Value());
// For non-tensor results: A mapping from return val indices of the old
// CallOp to return val indices of the bufferized CallOp.
SmallVector<Optional<unsigned>> retValMapping(numResults, None);
// Operands of the bufferized CallOp.
SmallVector<Value> newOperands(numOperands, Value());
// Based on previously gathered equivalence information, we know if a
// tensor result folds onto an operand. These are the only tensor value
// results that are supported at the moment.
//
// For tensors return values that do not fold onto an operand, additional
// work is needed (TODO) to either:
// * hoist a result into an inplaceable operand or
// * devise a better representation to truly return a buffer.
//
// Note: If a function has no body, no equivalence information is
// available. Consequently, a tensor return value cannot be proven to fold
// onto a func::FuncOp bbArg, so calls to such functions are not
// bufferizable at the moment.
// 1. Compute the result types of the new CallOp. Tensor results that are
// equivalent to a func::FuncOp bbArg are no longer returned.
for (const auto &it : llvm::enumerate(callOp.getResultTypes())) {
unsigned returnValIdx = it.index();
Type returnType = it.value();
if (!returnType.isa<TensorType>()) {
// Non-tensor values are returned.
retValMapping[returnValIdx] = resultTypes.size();
resultTypes.push_back(returnType);
continue;
}
if (Optional<int64_t> bbArgIdx =
getEquivalentFuncArgIdx(funcOp, funcState, returnValIdx)) {
// Return operands that are equivalent to some bbArg, are not
// returned.
FailureOr<Value> bufferOrFailure =
state.getBuffer(rewriter, callOp->getOpOperand(*bbArgIdx));
if (failed(bufferOrFailure))
return failure();
replacementValues[returnValIdx] = *bufferOrFailure;
newOperands[*bbArgIdx] = *bufferOrFailure;
continue;
}
if (!options.allowReturnAllocs)
return callOp->emitError(
"call to FuncOp that returns non-equivalent tensors not supported");
// Returning a memref. This memref is not equivalent to any bbArg. It is
// likely a newly allocated buffer. We may want to hoist such allocations
// to the call site in the future.
retValMapping[returnValIdx] = resultTypes.size();
resultTypes.push_back(
funcOp.getFunctionType().getResult(resultTypes.size()));
}
// 2. Get the bufferized FunctionType of the called function. Recursive or
// circular call graphs are not currently supported, so we can be sure that
// the called function was already bufferized.
FunctionType bufferizedFuncType = funcOp.getFunctionType();
// 3. Rewrite tensor operands as memrefs based on `bufferizedFuncType`.
for (OpOperand &opOperand : callOp->getOpOperands()) {
unsigned idx = opOperand.getOperandNumber();
Value tensorOperand = opOperand.get();
// Non-tensor operands are just copied.
if (!tensorOperand.getType().isa<TensorType>()) {
newOperands[idx] = tensorOperand;
continue;
}
// Retrieve buffers for tensor operands. Tensor operand buffers, who's
// corresponding func::FuncOp bbArgs are equivalent to a returned tensor,
// were already stored in `newOperands` during Step 1.
Value buffer = newOperands[idx];
if (!buffer) {
FailureOr<Value> bufferOrFailure = state.getBuffer(rewriter, opOperand);
if (failed(bufferOrFailure))
return failure();
buffer = *bufferOrFailure;
}
// Caller / callee type mismatch is handled with a CastOp.
auto memRefType = bufferizedFuncType.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.
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[idx] = buffer;
}
// 4. Create the new CallOp.
Operation *newCallOp = rewriter.create<func::CallOp>(
callOp.getLoc(), funcOp.getSymName(), resultTypes, newOperands);
newCallOp->setAttrs(callOp->getAttrs());
// Get replacement values for non-tensor / non-equivalent results.
for (unsigned i = 0; i < replacementValues.size(); ++i) {
if (replacementValues[i])
continue;
replacementValues[i] = newCallOp->getResult(*retValMapping[i]);
}
// 5. Replace the old op with the new op.
replaceOpWithBufferizedValues(rewriter, callOp, replacementValues);
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;
}
SmallVector<OpResult> getAliasingOpResult(Operation *op, OpOperand &opOperand,
const AnalysisState &state) const {
return {};
}
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
BufferizationState &state) const {
#ifndef NDEBUG
auto returnOp = cast<func::ReturnOp>(op);
assert(isa<func::FuncOp>(returnOp->getParentOp()) &&
"only support FuncOp parent for ReturnOp");
#endif // NDEBUG
// ReturnOps are bufferized as part of FuncOps.
return failure();
}
};
struct FuncOpInterface
: public BufferizableOpInterface::ExternalModel<FuncOpInterface,
func::FuncOp> {
/// Rewrite function bbArgs and return values into buffer form (using the
/// canonical memref layout for now). 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`.
///
/// When a tensor function argument is known to be equivalent to a tensor
/// result, it is dropped from the return values.
///
/// All function bbArgs are writable unless they are explicitly marked as
/// read-only. Callers must insert copies when needed.
///
/// Note: Returning a memref is possible, but corresponding CallOp
/// bufferizations fail unless `allowReturnAllocs`.
LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
BufferizationState &state) const {
auto funcOp = cast<func::FuncOp>(op);
FunctionType funcType = funcOp.getFunctionType();
const FuncAnalysisState &moduleState =
getFuncAnalysisState(state.getAnalysisState());
const BufferizationOptions &options = state.getOptions();
// Construct the bufferized function type.
SmallVector<Type> argTypes;
for (const auto &it : llvm::enumerate(funcType.getInputs())) {
Type argType = it.value();
if (auto tensorType = argType.dyn_cast<TensorType>()) {
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.getBody().empty()) {
SmallVector<Type> retTypes;
for (Type resultType : funcType.getResults()) {
if (resultType.isa<TensorType>())
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");
// 1. Rewrite the bbArgs. Turn every tensor bbArg into a memref bbArg.
Block &frontBlock = funcOp.getBody().front();
for (BlockArgument &bbArg : frontBlock.getArguments()) {
auto tensorType = bbArg.getType().dyn_cast<TensorType>();
// Non-tensor types stay the same.
if (!tensorType)
continue;
// Collect all uses of the bbArg.
SmallVector<OpOperand *> bbArgUses;
for (OpOperand &use : bbArg.getUses())
bbArgUses.push_back(&use);
// Change the bbArg type to memref.
Type memrefType =
getBufferizedFunctionArgType(funcOp, bbArg.getArgNumber(), options);
bbArg.setType(memrefType);
// Replace all uses of the original tensor bbArg.
rewriter.setInsertionPointToStart(&frontBlock);
if (!bbArgUses.empty()) {
// Insert to_tensor because the remaining function body has not been
// bufferized yet.
Value toTensorOp =
rewriter.create<bufferization::ToTensorOp>(funcOp.getLoc(), bbArg);
for (OpOperand *use : bbArgUses)
use->set(toTensorOp);
}
}
// 2. For each result, keep track of which inplace argument it reuses.
SmallVector<Value> returnValues;
for (OpOperand &returnOperand : returnOp->getOpOperands()) {
Value returnVal = returnOperand.get();
// If not a tensor type just forward it.
if (!returnVal.getType().isa<RankedTensorType>()) {
returnValues.push_back(returnVal);
continue;
}
// If return operand is equivalent to some bbArg, no need to return it.
if (Optional<int64_t> equivBbArgIdx = getEquivalentFuncArgIdx(
funcOp, moduleState, returnOperand.getOperandNumber())) {
rewriter.setInsertionPoint(returnOp);
Location loc = returnOp.getLoc();
Value toMemrefOp = rewriter.create<bufferization::ToMemrefOp>(
loc, getMemRefType(returnVal.getType().cast<TensorType>(), options),
returnVal);
BlockArgument equivBbArg = funcOp.getArgument(*equivBbArgIdx);
// Note: This copy will fold away. It must be inserted here to ensure
// that `returnVal` still has at least one use and does not fold away.
if (failed(
createMemCpy(rewriter, loc, toMemrefOp, equivBbArg, options)))
return funcOp->emitError("could not generate copy for bbArg");
continue;
}
returnValues.push_back(*state.getBuffer(rewriter, returnOperand));
}
// 3. Rewrite the terminator without the in-place bufferizable values.
returnOp.operandsMutable().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<func::FuncOp>(op);
BlockArgument bbArg = value.dyn_cast<BlockArgument>();
assert(bbArg && "expected BlockArgument");
// "linalg.inplaceable" overrides other writability decisions. This is
// currently used for testing only.
if (BoolAttr inplaceAttr = funcOp.getArgAttrOfType<BoolAttr>(
bbArg.getArgNumber(),
BufferizableOpInterface::kInplaceableAttrName))
return inplaceAttr.getValue();
// All function arguments are writable by default.
return true;
}
bool isAllocationHoistingBarrier(Operation *op) const { return true; }
};
} // namespace std_ext
} // namespace comprehensive_bufferize
} // namespace linalg
} // namespace mlir
void mlir::linalg::comprehensive_bufferize::std_ext::
registerModuleBufferizationExternalModels(DialectRegistry &registry) {
registry.addExtension(+[](MLIRContext *ctx, func::FuncDialect *dialect) {
func::CallOp::attachInterface<std_ext::CallOpInterface>(*ctx);
func::ReturnOp::attachInterface<std_ext::ReturnOpInterface>(*ctx);
func::FuncOp::attachInterface<std_ext::FuncOpInterface>(*ctx);
});
}
/// Set the attribute that triggers inplace bufferization on a func::FuncOp
/// argument `bbArg`.
static void setInPlaceFuncArgument(BlockArgument bbArg, bool inPlace) {
auto funcOp = cast<func::FuncOp>(bbArg.getOwner()->getParentOp());
funcOp.setArgAttr(bbArg.getArgNumber(),
BufferizableOpInterface::kInplaceableAttrName,
BoolAttr::get(bbArg.getContext(), inPlace));
}
/// Annotate the IR with the result of the analysis. For testing/debugging only.
static void annotateOpsWithBufferizationMarkers(func::FuncOp funcOp,
const AnalysisState &state) {
auto bufferizableOp = cast<BufferizableOpInterface>(funcOp.getOperation());
for (BlockArgument bbArg : funcOp.getArguments())
if (bbArg.getType().isa<TensorType>())
setInPlaceFuncArgument(bbArg, bufferizableOp.isWritable(bbArg, state));
}
/// Fold return values that are memref casts and update function return types.
///
/// During FuncOp bufferization, the exact type of the returned memrefs (if any)
/// is not known yet. Therefore, the bufferization uses memref types with the
/// most generic layout map as function return types. After bufferizing the
/// entire function body, a more concise memref type can potentially be used for
/// the return type of the function.
static void foldMemRefCasts(func::FuncOp funcOp) {
if (funcOp.getBody().empty())
return;
func::ReturnOp returnOp = getAssumedUniqueReturnOp(funcOp);
SmallVector<Type> resultTypes;
for (OpOperand &operand : returnOp->getOpOperands()) {
if (auto castOp = operand.get().getDefiningOp<memref::CastOp>()) {
operand.set(castOp.source());
resultTypes.push_back(castOp.source().getType());
} else {
resultTypes.push_back(operand.get().getType());
}
}
auto newFuncType = FunctionType::get(
funcOp.getContext(), funcOp.getFunctionType().getInputs(), resultTypes);
funcOp.setType(newFuncType);
}
LogicalResult mlir::linalg::comprehensive_bufferize::runModuleBufferize(
ModuleOp moduleOp, OneShotBufferizationOptions options) {
IRRewriter rewriter(moduleOp.getContext());
OneShotAnalysisState analysisState(moduleOp, options);
BufferizationState bufferizationState(analysisState);
FuncAnalysisState &funcState = getFuncAnalysisState(analysisState);
BufferizationAliasInfo &aliasInfo = analysisState.getAliasInfo();
// A list of functions in the order in which they are analyzed + bufferized.
SmallVector<func::FuncOp> orderedFuncOps;
// A mapping of FuncOps to their callers.
FuncCallerMap callerMap;
if (failed(getFuncOpsOrderedByCalls(moduleOp, orderedFuncOps, callerMap)))
return failure();
// Collect bbArg/return value information after the analysis.
options.addPostAnalysisStep(aliasingFuncOpBBArgsAnalysis);
options.addPostAnalysisStep(funcOpBbArgReadWriteAnalysis);
// Analyze ops.
for (func::FuncOp funcOp : orderedFuncOps) {
// No body => no analysis.
if (funcOp.getBody().empty())
continue;
// Now analyzing function.
funcState.startFunctionAnalysis(funcOp);
// Gather equivalence info for CallOps.
equivalenceAnalysis(funcOp, aliasInfo, funcState);
// Analyze funcOp.
if (failed(analyzeOp(funcOp, analysisState)))
return failure();
// Mark op as fully analyzed.
funcState.analyzedFuncOps[funcOp] = FuncOpAnalysisState::Analyzed;
// Add annotations to function arguments.
if (options.testAnalysisOnly)
annotateOpsWithBufferizationMarkers(funcOp, analysisState);
}
if (options.testAnalysisOnly)
return success();
// Bufferize functions.
for (func::FuncOp funcOp : orderedFuncOps) {
// Note: It would be good to apply cleanups here but we cannot as aliasInfo
// would be invalidated.
if (failed(bufferizeOp(funcOp, bufferizationState)))
return failure();
foldMemRefCasts(funcOp);
}
// Check result.
for (func::FuncOp funcOp : orderedFuncOps) {
if (!options.allowReturnAllocs &&
llvm::any_of(funcOp.getFunctionType().getResults(), [](Type t) {
return t.isa<MemRefType, UnrankedMemRefType>();
})) {
funcOp->emitError("memref return type is unsupported");
return failure();
}
}
// Finalize all buffers.
if (failed(finalizeBuffers(moduleOp, options)))
return failure();
// Post-pass cleanup of inplaceable and buffer_layout attributes.
moduleOp.walk([&](func::FuncOp op) {
for (BlockArgument bbArg : op.getArguments())
removeBufferizationFuncArguments(bbArg);
});
return success();
}