llvm-project/mlir/lib/Conversion/LLVMCommon/Pattern.cpp

346 lines
14 KiB
C++

//===- Pattern.cpp - Conversion pattern to the LLVM dialect ---------------===//
//
// 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/Conversion/LLVMCommon/Pattern.h"
#include "mlir/Dialect/LLVMIR/FunctionCallUtils.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/LLVMIR/LLVMTypes.h"
#include "mlir/IR/AffineMap.h"
using namespace mlir;
//===----------------------------------------------------------------------===//
// ConvertToLLVMPattern
//===----------------------------------------------------------------------===//
ConvertToLLVMPattern::ConvertToLLVMPattern(StringRef rootOpName,
MLIRContext *context,
LLVMTypeConverter &typeConverter,
PatternBenefit benefit)
: ConversionPattern(typeConverter, rootOpName, benefit, context) {}
LLVMTypeConverter *ConvertToLLVMPattern::getTypeConverter() const {
return static_cast<LLVMTypeConverter *>(
ConversionPattern::getTypeConverter());
}
LLVM::LLVMDialect &ConvertToLLVMPattern::getDialect() const {
return *getTypeConverter()->getDialect();
}
Type ConvertToLLVMPattern::getIndexType() const {
return getTypeConverter()->getIndexType();
}
Type ConvertToLLVMPattern::getIntPtrType(unsigned addressSpace) const {
return IntegerType::get(&getTypeConverter()->getContext(),
getTypeConverter()->getPointerBitwidth(addressSpace));
}
Type ConvertToLLVMPattern::getVoidType() const {
return LLVM::LLVMVoidType::get(&getTypeConverter()->getContext());
}
Type ConvertToLLVMPattern::getVoidPtrType() const {
return LLVM::LLVMPointerType::get(
IntegerType::get(&getTypeConverter()->getContext(), 8));
}
Value ConvertToLLVMPattern::createIndexAttrConstant(OpBuilder &builder,
Location loc,
Type resultType,
int64_t value) {
return builder.create<LLVM::ConstantOp>(
loc, resultType, builder.getIntegerAttr(builder.getIndexType(), value));
}
Value ConvertToLLVMPattern::createIndexConstant(
ConversionPatternRewriter &builder, Location loc, uint64_t value) const {
return createIndexAttrConstant(builder, loc, getIndexType(), value);
}
Value ConvertToLLVMPattern::getStridedElementPtr(
Location loc, MemRefType type, Value memRefDesc, ValueRange indices,
ConversionPatternRewriter &rewriter) const {
int64_t offset;
SmallVector<int64_t, 4> strides;
auto successStrides = getStridesAndOffset(type, strides, offset);
assert(succeeded(successStrides) && "unexpected non-strided memref");
(void)successStrides;
MemRefDescriptor memRefDescriptor(memRefDesc);
Value base = memRefDescriptor.alignedPtr(rewriter, loc);
Value index;
if (offset != 0) // Skip if offset is zero.
index = ShapedType::isDynamicStrideOrOffset(offset)
? memRefDescriptor.offset(rewriter, loc)
: createIndexConstant(rewriter, loc, offset);
for (int i = 0, e = indices.size(); i < e; ++i) {
Value increment = indices[i];
if (strides[i] != 1) { // Skip if stride is 1.
Value stride = ShapedType::isDynamicStrideOrOffset(strides[i])
? memRefDescriptor.stride(rewriter, loc, i)
: createIndexConstant(rewriter, loc, strides[i]);
increment = rewriter.create<LLVM::MulOp>(loc, increment, stride);
}
index =
index ? rewriter.create<LLVM::AddOp>(loc, index, increment) : increment;
}
Type elementPtrType = memRefDescriptor.getElementPtrType();
return index ? rewriter.create<LLVM::GEPOp>(loc, elementPtrType, base, index)
: base;
}
// Check if the MemRefType `type` is supported by the lowering. We currently
// only support memrefs with identity maps.
bool ConvertToLLVMPattern::isConvertibleAndHasIdentityMaps(
MemRefType type) const {
if (!typeConverter->convertType(type.getElementType()))
return false;
return type.getLayout().isIdentity();
}
Type ConvertToLLVMPattern::getElementPtrType(MemRefType type) const {
auto elementType = type.getElementType();
auto structElementType = typeConverter->convertType(elementType);
return LLVM::LLVMPointerType::get(structElementType,
type.getMemorySpaceAsInt());
}
void ConvertToLLVMPattern::getMemRefDescriptorSizes(
Location loc, MemRefType memRefType, ValueRange dynamicSizes,
ConversionPatternRewriter &rewriter, SmallVectorImpl<Value> &sizes,
SmallVectorImpl<Value> &strides, Value &sizeBytes) const {
assert(isConvertibleAndHasIdentityMaps(memRefType) &&
"layout maps must have been normalized away");
assert(count(memRefType.getShape(), ShapedType::kDynamicSize) ==
static_cast<ssize_t>(dynamicSizes.size()) &&
"dynamicSizes size doesn't match dynamic sizes count in memref shape");
sizes.reserve(memRefType.getRank());
unsigned dynamicIndex = 0;
for (int64_t size : memRefType.getShape()) {
sizes.push_back(size == ShapedType::kDynamicSize
? dynamicSizes[dynamicIndex++]
: createIndexConstant(rewriter, loc, size));
}
// Strides: iterate sizes in reverse order and multiply.
int64_t stride = 1;
Value runningStride = createIndexConstant(rewriter, loc, 1);
strides.resize(memRefType.getRank());
for (auto i = memRefType.getRank(); i-- > 0;) {
strides[i] = runningStride;
int64_t size = memRefType.getShape()[i];
if (size == 0)
continue;
bool useSizeAsStride = stride == 1;
if (size == ShapedType::kDynamicSize)
stride = ShapedType::kDynamicSize;
if (stride != ShapedType::kDynamicSize)
stride *= size;
if (useSizeAsStride)
runningStride = sizes[i];
else if (stride == ShapedType::kDynamicSize)
runningStride =
rewriter.create<LLVM::MulOp>(loc, runningStride, sizes[i]);
else
runningStride = createIndexConstant(rewriter, loc, stride);
}
// Buffer size in bytes.
Type elementPtrType = getElementPtrType(memRefType);
Value nullPtr = rewriter.create<LLVM::NullOp>(loc, elementPtrType);
Value gepPtr = rewriter.create<LLVM::GEPOp>(loc, elementPtrType, nullPtr,
ArrayRef<Value>{runningStride});
sizeBytes = rewriter.create<LLVM::PtrToIntOp>(loc, getIndexType(), gepPtr);
}
Value ConvertToLLVMPattern::getSizeInBytes(
Location loc, Type type, ConversionPatternRewriter &rewriter) const {
// Compute the size of an individual element. This emits the MLIR equivalent
// of the following sizeof(...) implementation in LLVM IR:
// %0 = getelementptr %elementType* null, %indexType 1
// %1 = ptrtoint %elementType* %0 to %indexType
// which is a common pattern of getting the size of a type in bytes.
auto convertedPtrType =
LLVM::LLVMPointerType::get(typeConverter->convertType(type));
auto nullPtr = rewriter.create<LLVM::NullOp>(loc, convertedPtrType);
auto gep = rewriter.create<LLVM::GEPOp>(
loc, convertedPtrType, nullPtr,
ArrayRef<Value>{createIndexConstant(rewriter, loc, 1)});
return rewriter.create<LLVM::PtrToIntOp>(loc, getIndexType(), gep);
}
Value ConvertToLLVMPattern::getNumElements(
Location loc, ArrayRef<Value> shape,
ConversionPatternRewriter &rewriter) const {
// Compute the total number of memref elements.
Value numElements =
shape.empty() ? createIndexConstant(rewriter, loc, 1) : shape.front();
for (unsigned i = 1, e = shape.size(); i < e; ++i)
numElements = rewriter.create<LLVM::MulOp>(loc, numElements, shape[i]);
return numElements;
}
/// Creates and populates the memref descriptor struct given all its fields.
MemRefDescriptor ConvertToLLVMPattern::createMemRefDescriptor(
Location loc, MemRefType memRefType, Value allocatedPtr, Value alignedPtr,
ArrayRef<Value> sizes, ArrayRef<Value> strides,
ConversionPatternRewriter &rewriter) const {
auto structType = typeConverter->convertType(memRefType);
auto memRefDescriptor = MemRefDescriptor::undef(rewriter, loc, structType);
// Field 1: Allocated pointer, used for malloc/free.
memRefDescriptor.setAllocatedPtr(rewriter, loc, allocatedPtr);
// Field 2: Actual aligned pointer to payload.
memRefDescriptor.setAlignedPtr(rewriter, loc, alignedPtr);
// Field 3: Offset in aligned pointer.
memRefDescriptor.setOffset(rewriter, loc,
createIndexConstant(rewriter, loc, 0));
// Fields 4: Sizes.
for (const auto &en : llvm::enumerate(sizes))
memRefDescriptor.setSize(rewriter, loc, en.index(), en.value());
// Field 5: Strides.
for (const auto &en : llvm::enumerate(strides))
memRefDescriptor.setStride(rewriter, loc, en.index(), en.value());
return memRefDescriptor;
}
LogicalResult ConvertToLLVMPattern::copyUnrankedDescriptors(
OpBuilder &builder, Location loc, TypeRange origTypes,
SmallVectorImpl<Value> &operands, bool toDynamic) const {
assert(origTypes.size() == operands.size() &&
"expected as may original types as operands");
// Find operands of unranked memref type and store them.
SmallVector<UnrankedMemRefDescriptor, 4> unrankedMemrefs;
for (unsigned i = 0, e = operands.size(); i < e; ++i)
if (origTypes[i].isa<UnrankedMemRefType>())
unrankedMemrefs.emplace_back(operands[i]);
if (unrankedMemrefs.empty())
return success();
// Compute allocation sizes.
SmallVector<Value, 4> sizes;
UnrankedMemRefDescriptor::computeSizes(builder, loc, *getTypeConverter(),
unrankedMemrefs, sizes);
// Get frequently used types.
MLIRContext *context = builder.getContext();
Type voidPtrType = LLVM::LLVMPointerType::get(IntegerType::get(context, 8));
auto i1Type = IntegerType::get(context, 1);
Type indexType = getTypeConverter()->getIndexType();
// Find the malloc and free, or declare them if necessary.
auto module = builder.getInsertionPoint()->getParentOfType<ModuleOp>();
LLVM::LLVMFuncOp freeFunc, mallocFunc;
if (toDynamic)
mallocFunc = LLVM::lookupOrCreateMallocFn(module, indexType);
if (!toDynamic)
freeFunc = LLVM::lookupOrCreateFreeFn(module);
// Initialize shared constants.
Value zero =
builder.create<LLVM::ConstantOp>(loc, i1Type, builder.getBoolAttr(false));
unsigned unrankedMemrefPos = 0;
for (unsigned i = 0, e = operands.size(); i < e; ++i) {
Type type = origTypes[i];
if (!type.isa<UnrankedMemRefType>())
continue;
Value allocationSize = sizes[unrankedMemrefPos++];
UnrankedMemRefDescriptor desc(operands[i]);
// Allocate memory, copy, and free the source if necessary.
Value memory =
toDynamic
? builder.create<LLVM::CallOp>(loc, mallocFunc, allocationSize)
.getResult(0)
: builder.create<LLVM::AllocaOp>(loc, voidPtrType, allocationSize,
/*alignment=*/0);
Value source = desc.memRefDescPtr(builder, loc);
builder.create<LLVM::MemcpyOp>(loc, memory, source, allocationSize, zero);
if (!toDynamic)
builder.create<LLVM::CallOp>(loc, freeFunc, source);
// Create a new descriptor. The same descriptor can be returned multiple
// times, attempting to modify its pointer can lead to memory leaks
// (allocated twice and overwritten) or double frees (the caller does not
// know if the descriptor points to the same memory).
Type descriptorType = getTypeConverter()->convertType(type);
if (!descriptorType)
return failure();
auto updatedDesc =
UnrankedMemRefDescriptor::undef(builder, loc, descriptorType);
Value rank = desc.rank(builder, loc);
updatedDesc.setRank(builder, loc, rank);
updatedDesc.setMemRefDescPtr(builder, loc, memory);
operands[i] = updatedDesc;
}
return success();
}
//===----------------------------------------------------------------------===//
// Detail methods
//===----------------------------------------------------------------------===//
/// Replaces the given operation "op" with a new operation of type "targetOp"
/// and given operands.
LogicalResult LLVM::detail::oneToOneRewrite(
Operation *op, StringRef targetOp, ValueRange operands,
LLVMTypeConverter &typeConverter, ConversionPatternRewriter &rewriter) {
unsigned numResults = op->getNumResults();
Type packedType;
if (numResults != 0) {
packedType = typeConverter.packFunctionResults(op->getResultTypes());
if (!packedType)
return failure();
}
// Create the operation through state since we don't know its C++ type.
OperationState state(op->getLoc(), targetOp);
state.addTypes(packedType);
state.addOperands(operands);
state.addAttributes(op->getAttrs());
Operation *newOp = rewriter.createOperation(state);
// If the operation produced 0 or 1 result, return them immediately.
if (numResults == 0)
return rewriter.eraseOp(op), success();
if (numResults == 1)
return rewriter.replaceOp(op, newOp->getResult(0)), success();
// Otherwise, it had been converted to an operation producing a structure.
// Extract individual results from the structure and return them as list.
SmallVector<Value, 4> results;
results.reserve(numResults);
for (unsigned i = 0; i < numResults; ++i) {
auto type = typeConverter.convertType(op->getResult(i).getType());
results.push_back(rewriter.create<LLVM::ExtractValueOp>(
op->getLoc(), type, newOp->getResult(0), rewriter.getI64ArrayAttr(i)));
}
rewriter.replaceOp(op, results);
return success();
}