Files
clang-p2996/mlir/lib/Dialect/Bufferization/IR/BufferizationOps.cpp
Matthias Springer ec55f0bd58 [mlir][bufferization][NFC] Improve assembly format of AllocTensorOp
No longer pass static dim sizes as an attribute. This was redundant and required extra checks in the verifier. This change also makes the op symmetrical to memref::AllocOp.

Differential Revision: https://reviews.llvm.org/D126178
2022-05-23 16:58:01 +02:00

483 lines
18 KiB
C++

//===----------------------------------------------------------------------===//
//
// 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/Arithmetic/IR/Arithmetic.h"
#include "mlir/Dialect/Bufferization/IR/BufferizableOpInterface.h"
#include "mlir/Dialect/Bufferization/IR/Bufferization.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/Dialect/MemRef/Utils/MemRefUtils.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/IR/Matchers.h"
using namespace mlir;
using namespace mlir::bufferization;
//===----------------------------------------------------------------------===//
// Helper functions
//===----------------------------------------------------------------------===//
FailureOr<Value>
mlir::bufferization::castOrReallocMemRefValue(OpBuilder &b, Value value,
MemRefType destType) {
auto srcType = value.getType().cast<MemRefType>();
// Element type, rank and memory space must match.
if (srcType.getElementType() != destType.getElementType())
return failure();
if (srcType.getMemorySpaceAsInt() != destType.getMemorySpaceAsInt())
return failure();
if (srcType.getRank() != destType.getRank())
return failure();
// In case the affine maps are different, we may need to use a copy if we go
// from dynamic to static offset or stride (the canonicalization cannot know
// at this point that it is really cast compatible).
auto isGuaranteedCastCompatible = [](MemRefType source, MemRefType target) {
int64_t sourceOffset, targetOffset;
SmallVector<int64_t, 4> sourceStrides, targetStrides;
if (failed(getStridesAndOffset(source, sourceStrides, sourceOffset)) ||
failed(getStridesAndOffset(target, targetStrides, targetOffset)))
return false;
auto dynamicToStatic = [](int64_t a, int64_t b) {
return a == MemRefType::getDynamicStrideOrOffset() &&
b != MemRefType::getDynamicStrideOrOffset();
};
if (dynamicToStatic(sourceOffset, targetOffset))
return false;
for (auto it : zip(sourceStrides, targetStrides))
if (dynamicToStatic(std::get<0>(it), std::get<1>(it)))
return false;
return true;
};
// Note: If `areCastCompatible`, a cast is valid, but may fail at runtime. To
// ensure that we only generate casts that always succeed at runtime, we check
// a fix extra conditions in `isGuaranteedCastCompatible`.
if (memref::CastOp::areCastCompatible(srcType, destType) &&
isGuaranteedCastCompatible(srcType, destType)) {
Value casted = b.create<memref::CastOp>(value.getLoc(), destType, value);
return casted;
}
auto loc = value.getLoc();
SmallVector<Value, 4> dynamicOperands;
for (int i = 0; i < destType.getRank(); ++i) {
if (destType.getShape()[i] != ShapedType::kDynamicSize)
continue;
auto index = b.createOrFold<arith::ConstantIndexOp>(loc, i);
Value size = b.create<memref::DimOp>(loc, value, index);
dynamicOperands.push_back(size);
}
// TODO: Use alloc/memcpy callback from BufferizationOptions if called via
// BufferizableOpInterface impl of ToMemrefOp.
Value copy = b.create<memref::AllocOp>(loc, destType, dynamicOperands);
b.create<memref::CopyOp>(loc, value, copy);
return copy;
}
/// Try to fold to_memref(to_tensor(x)). If x's type and the result type of the
/// to_memref op are different, a memref.cast is needed.
LogicalResult mlir::bufferization::foldToMemrefToTensorPair(
RewriterBase &rewriter, ToMemrefOp toMemref, bool allowSameType) {
auto memrefToTensor = toMemref.tensor().getDefiningOp<ToTensorOp>();
if (!memrefToTensor)
return failure();
Type srcType = memrefToTensor.memref().getType();
Type destType = toMemref.getType();
// Directly rewrite if the type did not change.
if (srcType == destType) {
// Function can be configured to only handle cases where a cast is needed.
if (!allowSameType)
return failure();
rewriter.replaceOp(toMemref, memrefToTensor.memref());
return success();
}
auto rankedSrcType = srcType.dyn_cast<MemRefType>();
auto rankedDestType = destType.dyn_cast<MemRefType>();
auto unrankedSrcType = srcType.dyn_cast<UnrankedMemRefType>();
// Ranked memref -> Ranked memref cast.
if (rankedSrcType && rankedDestType) {
FailureOr<Value> replacement = castOrReallocMemRefValue(
rewriter, memrefToTensor.memref(), rankedDestType);
if (failed(replacement))
return failure();
rewriter.replaceOp(toMemref, *replacement);
return success();
}
// Unranked memref -> Ranked memref cast: May require a copy.
// TODO: Not implemented at the moment.
if (unrankedSrcType && rankedDestType)
return failure();
// Unranked memref -> unranked memref cast
// Ranked memref -> unranked memref cast: No copy needed.
assert(memref::CastOp::areCastCompatible(srcType, destType) &&
"expected that types are cast compatible");
rewriter.replaceOpWithNewOp<memref::CastOp>(toMemref, destType,
memrefToTensor.memref());
return success();
}
//===----------------------------------------------------------------------===//
// AllocTensorOp
//===----------------------------------------------------------------------===//
LogicalResult AllocTensorOp::bufferize(RewriterBase &rewriter,
BufferizationState &state) {
// Nothing to do for dead AllocTensorOps.
if (getOperation()->getUses().empty())
return success();
FailureOr<Value> alloc = state.createAlloc(rewriter, getLoc(), getResult());
if (failed(alloc))
return failure();
replaceOpWithBufferizedValues(rewriter, getOperation(), *alloc);
return success();
}
LogicalResult AllocTensorOp::verify() {
if (getType().getNumDynamicDims() !=
static_cast<int64_t>(dynamicSizes().size()))
return emitError("expected ")
<< getType().getNumDynamicDims() << " dynamic sizes";
return success();
}
namespace {
/// Change the type of the result of a `bufferization.alloc_tensor` by making
/// the result type statically sized along dimension that in the original
/// operation where defined as dynamic, but the size was defined using a
/// `constant` op. For example:
///
/// %c5 = arith.constant 5: index
/// %0 = bufferization.alloc_tensor(%arg0, %c5) : tensor<?x?xf32>
///
/// to
///
/// %0 = bufferization.alloc_tensor(%arg0) : tensor<?x5xf32>
struct ReplaceStaticShapeDims : OpRewritePattern<AllocTensorOp> {
using OpRewritePattern<AllocTensorOp>::OpRewritePattern;
LogicalResult matchAndRewrite(AllocTensorOp op,
PatternRewriter &rewriter) const override {
SmallVector<int64_t> newShape = llvm::to_vector(op.getType().getShape());
SmallVector<Value> newDynamicSizes;
unsigned int dynValCounter = 0;
for (int64_t i = 0; i < op.getType().getRank(); ++i) {
if (!op.isDynamicDim(i))
continue;
Value value = op.dynamicSizes()[dynValCounter++];
APInt intVal;
if (matchPattern(value, m_ConstantInt(&intVal))) {
newShape[i] = intVal.getSExtValue();
} else {
newDynamicSizes.push_back(value);
}
}
RankedTensorType newType = RankedTensorType::get(
newShape, op.getType().getElementType(), op.getType().getEncoding());
if (newType == op.getType())
return failure();
auto newOp =
rewriter.create<AllocTensorOp>(op.getLoc(), newType, newDynamicSizes);
rewriter.replaceOpWithNewOp<tensor::CastOp>(op, op.getType(), newOp);
return success();
}
};
struct FoldDimOfAllocTensorOp : public OpRewritePattern<tensor::DimOp> {
using OpRewritePattern<tensor::DimOp>::OpRewritePattern;
LogicalResult matchAndRewrite(tensor::DimOp dimOp,
PatternRewriter &rewriter) const override {
Optional<int64_t> maybeConstantIndex = dimOp.getConstantIndex();
auto allocTensorOp = dimOp.source().getDefiningOp<AllocTensorOp>();
if (!allocTensorOp || !maybeConstantIndex)
return failure();
if (!allocTensorOp.getType().isDynamicDim(*maybeConstantIndex))
return failure();
rewriter.replaceOp(dimOp,
allocTensorOp.getDynamicSize(*maybeConstantIndex));
return success();
}
};
} // namespace
void AllocTensorOp::getCanonicalizationPatterns(RewritePatternSet &results,
MLIRContext *ctx) {
results.add<FoldDimOfAllocTensorOp, ReplaceStaticShapeDims>(ctx);
}
LogicalResult AllocTensorOp::reifyResultShapes(
OpBuilder &builder, ReifiedRankedShapedTypeDims &reifiedReturnShapes) {
auto shapes = llvm::to_vector<4>(llvm::map_range(
llvm::seq<int64_t>(0, getType().getRank()), [&](int64_t dim) -> Value {
if (isDynamicDim(dim))
return getDynamicSize(dim);
return builder.create<arith::ConstantIndexOp>(getLoc(),
getStaticSize(dim));
}));
reifiedReturnShapes.emplace_back(std::move(shapes));
return success();
}
//===----------------------------------------------------------------------===//
// CloneOp
//===----------------------------------------------------------------------===//
void CloneOp::getEffects(
SmallVectorImpl<SideEffects::EffectInstance<MemoryEffects::Effect>>
&effects) {
effects.emplace_back(MemoryEffects::Read::get(), input(),
SideEffects::DefaultResource::get());
effects.emplace_back(MemoryEffects::Write::get(), output(),
SideEffects::DefaultResource::get());
effects.emplace_back(MemoryEffects::Allocate::get(), output(),
SideEffects::DefaultResource::get());
}
OpFoldResult CloneOp::fold(ArrayRef<Attribute> operands) {
return succeeded(memref::foldMemRefCast(*this)) ? getResult() : Value();
}
namespace {
/// Merge the clone and its source (by converting the clone to a cast) when
/// possible.
struct SimplifyClones : public OpRewritePattern<CloneOp> {
using OpRewritePattern<CloneOp>::OpRewritePattern;
LogicalResult matchAndRewrite(CloneOp cloneOp,
PatternRewriter &rewriter) const override {
if (cloneOp.use_empty()) {
rewriter.eraseOp(cloneOp);
return success();
}
Value source = cloneOp.input();
// This only finds dealloc operations for the immediate value. It should
// also consider aliases. That would also make the safety check below
// redundant.
llvm::Optional<Operation *> maybeCloneDeallocOp =
memref::findDealloc(cloneOp.output());
// Skip if either of them has > 1 deallocate operations.
if (!maybeCloneDeallocOp.hasValue())
return failure();
llvm::Optional<Operation *> maybeSourceDeallocOp =
memref::findDealloc(source);
if (!maybeSourceDeallocOp.hasValue())
return failure();
Operation *cloneDeallocOp = *maybeCloneDeallocOp;
Operation *sourceDeallocOp = *maybeSourceDeallocOp;
// If both are deallocated in the same block, their in-block lifetimes
// might not fully overlap, so we cannot decide which one to drop.
if (cloneDeallocOp && sourceDeallocOp &&
cloneDeallocOp->getBlock() == sourceDeallocOp->getBlock())
return failure();
Block *currentBlock = cloneOp->getBlock();
Operation *redundantDealloc = nullptr;
if (cloneDeallocOp && cloneDeallocOp->getBlock() == currentBlock) {
redundantDealloc = cloneDeallocOp;
} else if (sourceDeallocOp && sourceDeallocOp->getBlock() == currentBlock) {
redundantDealloc = sourceDeallocOp;
}
if (!redundantDealloc)
return failure();
// Safety check that there are no other deallocations inbetween
// cloneOp and redundantDealloc, as otherwise we might deallocate an alias
// of source before the uses of the clone. With alias information, we could
// restrict this to only fail of the dealloc's operand is an alias
// of the source.
for (Operation *pos = cloneOp->getNextNode(); pos != redundantDealloc;
pos = pos->getNextNode()) {
auto effectInterface = dyn_cast<MemoryEffectOpInterface>(pos);
if (!effectInterface)
continue;
if (effectInterface.hasEffect<MemoryEffects::Free>())
return failure();
}
rewriter.replaceOpWithNewOp<memref::CastOp>(cloneOp, cloneOp.getType(),
source);
rewriter.eraseOp(redundantDealloc);
return success();
}
};
} // namespace
void CloneOp::getCanonicalizationPatterns(RewritePatternSet &results,
MLIRContext *context) {
results.add<SimplifyClones>(context);
}
//===----------------------------------------------------------------------===//
// ToTensorOp
//===----------------------------------------------------------------------===//
OpFoldResult ToTensorOp::fold(ArrayRef<Attribute>) {
if (auto toMemref = memref().getDefiningOp<ToMemrefOp>())
// Approximate alias analysis by conservatively folding only when no there
// is no interleaved operation.
if (toMemref->getBlock() == this->getOperation()->getBlock() &&
toMemref->getNextNode() == this->getOperation())
return toMemref.tensor();
return {};
}
namespace {
struct DimOfToTensorFolder : public OpRewritePattern<tensor::DimOp> {
using OpRewritePattern<tensor::DimOp>::OpRewritePattern;
LogicalResult matchAndRewrite(tensor::DimOp dimOp,
PatternRewriter &rewriter) const override {
auto memrefToTensorOp = dimOp.source().getDefiningOp<ToTensorOp>();
if (!memrefToTensorOp)
return failure();
rewriter.replaceOpWithNewOp<memref::DimOp>(dimOp, memrefToTensorOp.memref(),
dimOp.index());
return success();
}
};
} // namespace
void ToTensorOp::getCanonicalizationPatterns(RewritePatternSet &results,
MLIRContext *context) {
results.add<DimOfToTensorFolder>(context);
}
//===----------------------------------------------------------------------===//
// ToMemrefOp
//===----------------------------------------------------------------------===//
OpFoldResult ToMemrefOp::fold(ArrayRef<Attribute>) {
if (auto memrefToTensor = tensor().getDefiningOp<ToTensorOp>())
if (memrefToTensor.memref().getType() == getType())
return memrefToTensor.memref();
return {};
}
namespace {
/// Replace tensor.cast + to_memref by to_memref + memref.cast.
struct ToMemrefOfCast : public OpRewritePattern<ToMemrefOp> {
using OpRewritePattern<ToMemrefOp>::OpRewritePattern;
LogicalResult matchAndRewrite(ToMemrefOp toMemref,
PatternRewriter &rewriter) const final {
auto tensorCastOperand =
toMemref.getOperand().getDefiningOp<tensor::CastOp>();
if (!tensorCastOperand)
return failure();
auto srcTensorType =
tensorCastOperand.getOperand().getType().dyn_cast<RankedTensorType>();
if (!srcTensorType)
return failure();
auto memrefType = MemRefType::get(srcTensorType.getShape(),
srcTensorType.getElementType());
Value memref = rewriter.create<ToMemrefOp>(toMemref.getLoc(), memrefType,
tensorCastOperand.getOperand());
rewriter.replaceOpWithNewOp<memref::CastOp>(toMemref, toMemref.getType(),
memref);
return success();
}
};
/// Canonicalize bufferization.to_tensor + bufferization.to_memref to
/// memref.cast when type mismatches prevent `ToMemrefOp::fold` to kick in.
struct TensorLoadToMemref : public OpRewritePattern<ToMemrefOp> {
using OpRewritePattern<ToMemrefOp>::OpRewritePattern;
LogicalResult matchAndRewrite(ToMemrefOp toMemref,
PatternRewriter &rewriter) const final {
// Only handle cases where a cast is needed. The other case is handled by
// the folder.
return foldToMemrefToTensorPair(rewriter, toMemref,
/*allowSameType=*/false);
}
};
/// Fold a load on a to_memref operation into an tensor.extract on the
/// corresponding tensor.
struct LoadOfToMemref : public OpRewritePattern<memref::LoadOp> {
using OpRewritePattern<memref::LoadOp>::OpRewritePattern;
LogicalResult matchAndRewrite(memref::LoadOp load,
PatternRewriter &rewriter) const override {
auto toMemref = load.memref().getDefiningOp<ToMemrefOp>();
if (!toMemref)
return failure();
rewriter.replaceOpWithNewOp<tensor::ExtractOp>(load, toMemref.tensor(),
load.indices());
return success();
}
};
/// Fold dim of a to_memref into the dim of the tensor.
struct DimOfCastOp : public OpRewritePattern<memref::DimOp> {
using OpRewritePattern<memref::DimOp>::OpRewritePattern;
LogicalResult matchAndRewrite(memref::DimOp dimOp,
PatternRewriter &rewriter) const override {
auto castOp = dimOp.source().getDefiningOp<ToMemrefOp>();
if (!castOp)
return failure();
Value newSource = castOp.getOperand();
rewriter.replaceOpWithNewOp<tensor::DimOp>(dimOp, newSource, dimOp.index());
return success();
}
};
} // namespace
void ToMemrefOp::getCanonicalizationPatterns(RewritePatternSet &results,
MLIRContext *context) {
results.add<DimOfCastOp, LoadOfToMemref, ToMemrefOfCast, TensorLoadToMemref>(
context);
}
LogicalResult ToMemrefOp::bufferize(RewriterBase &rewriter,
BufferizationState &state) {
// Fold to_memref(to_tensor(x)) to x. Insert a cast if necessary.
(void)foldToMemrefToTensorPair(rewriter, *this);
// Note: The return value of `bufferize` indicates whether there was an error
// or not. (And not whether the pattern matched or not.)
return success();
}
Optional<Operation *> CloneOp::buildDealloc(OpBuilder &builder, Value alloc) {
return builder.create<memref::DeallocOp>(alloc.getLoc(), alloc)
.getOperation();
}
Optional<Value> CloneOp::buildClone(OpBuilder &builder, Value alloc) {
return builder.create<CloneOp>(alloc.getLoc(), alloc).getResult();
}
//===----------------------------------------------------------------------===//
// TableGen'd op method definitions
//===----------------------------------------------------------------------===//
#define GET_OP_CLASSES
#include "mlir/Dialect/Bufferization/IR/BufferizationOps.cpp.inc"