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MemRefToLLVM.cpp
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MemRefToLLVM.cpp
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//===- MemRefToLLVM.cpp - MemRef to LLVM dialect conversion ---------------===//
//
// 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/MemRefToLLVM/MemRefToLLVM.h"
#include "../PassDetail.h"
#include "mlir/Analysis/DataLayoutAnalysis.h"
#include "mlir/Conversion/LLVMCommon/ConversionTarget.h"
#include "mlir/Conversion/LLVMCommon/Pattern.h"
#include "mlir/Conversion/LLVMCommon/TypeConverter.h"
#include "mlir/Conversion/MemRefToLLVM/AllocLikeConversion.h"
#include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/LLVMIR/FunctionCallUtils.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/IR/AffineMap.h"
#include "mlir/IR/BlockAndValueMapping.h"
#include "llvm/ADT/SmallBitVector.h"
using namespace mlir;
namespace {
bool isStaticStrideOrOffset(int64_t strideOrOffset) {
return !ShapedType::isDynamicStrideOrOffset(strideOrOffset);
}
struct AllocOpLowering : public AllocLikeOpLLVMLowering {
AllocOpLowering(LLVMTypeConverter &converter)
: AllocLikeOpLLVMLowering(memref::AllocOp::getOperationName(),
converter) {}
std::tuple<Value, Value> allocateBuffer(ConversionPatternRewriter &rewriter,
Location loc, Value sizeBytes,
Operation *op) const override {
// Heap allocations.
memref::AllocOp allocOp = cast<memref::AllocOp>(op);
MemRefType memRefType = allocOp.getType();
Value alignment;
if (auto alignmentAttr = allocOp.alignment()) {
alignment = createIndexConstant(rewriter, loc, *alignmentAttr);
} else if (!memRefType.getElementType().isSignlessIntOrIndexOrFloat()) {
// In the case where no alignment is specified, we may want to override
// `malloc's` behavior. `malloc` typically aligns at the size of the
// biggest scalar on a target HW. For non-scalars, use the natural
// alignment of the LLVM type given by the LLVM DataLayout.
alignment = getSizeInBytes(loc, memRefType.getElementType(), rewriter);
}
if (alignment) {
// Adjust the allocation size to consider alignment.
sizeBytes = rewriter.create<LLVM::AddOp>(loc, sizeBytes, alignment);
}
// Allocate the underlying buffer and store a pointer to it in the MemRef
// descriptor.
Type elementPtrType = this->getElementPtrType(memRefType);
auto allocFuncOp = LLVM::lookupOrCreateMallocFn(
allocOp->getParentOfType<ModuleOp>(), getIndexType());
auto results = createLLVMCall(rewriter, loc, allocFuncOp, {sizeBytes},
getVoidPtrType());
Value allocatedPtr =
rewriter.create<LLVM::BitcastOp>(loc, elementPtrType, results[0]);
Value alignedPtr = allocatedPtr;
if (alignment) {
// Compute the aligned type pointer.
Value allocatedInt =
rewriter.create<LLVM::PtrToIntOp>(loc, getIndexType(), allocatedPtr);
Value alignmentInt =
createAligned(rewriter, loc, allocatedInt, alignment);
alignedPtr =
rewriter.create<LLVM::IntToPtrOp>(loc, elementPtrType, alignmentInt);
}
return std::make_tuple(allocatedPtr, alignedPtr);
}
};
struct AlignedAllocOpLowering : public AllocLikeOpLLVMLowering {
AlignedAllocOpLowering(LLVMTypeConverter &converter)
: AllocLikeOpLLVMLowering(memref::AllocOp::getOperationName(),
converter) {}
/// Returns the memref's element size in bytes using the data layout active at
/// `op`.
// TODO: there are other places where this is used. Expose publicly?
unsigned getMemRefEltSizeInBytes(MemRefType memRefType, Operation *op) const {
const DataLayout *layout = &defaultLayout;
if (const DataLayoutAnalysis *analysis =
getTypeConverter()->getDataLayoutAnalysis()) {
layout = &analysis->getAbove(op);
}
Type elementType = memRefType.getElementType();
if (auto memRefElementType = elementType.dyn_cast<MemRefType>())
return getTypeConverter()->getMemRefDescriptorSize(memRefElementType,
*layout);
if (auto memRefElementType = elementType.dyn_cast<UnrankedMemRefType>())
return getTypeConverter()->getUnrankedMemRefDescriptorSize(
memRefElementType, *layout);
return layout->getTypeSize(elementType);
}
/// Returns true if the memref size in bytes is known to be a multiple of
/// factor assuming the data layout active at `op`.
bool isMemRefSizeMultipleOf(MemRefType type, uint64_t factor,
Operation *op) const {
uint64_t sizeDivisor = getMemRefEltSizeInBytes(type, op);
for (unsigned i = 0, e = type.getRank(); i < e; i++) {
if (ShapedType::isDynamic(type.getDimSize(i)))
continue;
sizeDivisor = sizeDivisor * type.getDimSize(i);
}
return sizeDivisor % factor == 0;
}
/// Returns the alignment to be used for the allocation call itself.
/// aligned_alloc requires the allocation size to be a power of two, and the
/// allocation size to be a multiple of alignment,
int64_t getAllocationAlignment(memref::AllocOp allocOp) const {
if (Optional<uint64_t> alignment = allocOp.alignment())
return *alignment;
// Whenever we don't have alignment set, we will use an alignment
// consistent with the element type; since the allocation size has to be a
// power of two, we will bump to the next power of two if it already isn't.
auto eltSizeBytes = getMemRefEltSizeInBytes(allocOp.getType(), allocOp);
return std::max(kMinAlignedAllocAlignment,
llvm::PowerOf2Ceil(eltSizeBytes));
}
std::tuple<Value, Value> allocateBuffer(ConversionPatternRewriter &rewriter,
Location loc, Value sizeBytes,
Operation *op) const override {
// Heap allocations.
memref::AllocOp allocOp = cast<memref::AllocOp>(op);
MemRefType memRefType = allocOp.getType();
int64_t alignment = getAllocationAlignment(allocOp);
Value allocAlignment = createIndexConstant(rewriter, loc, alignment);
// aligned_alloc requires size to be a multiple of alignment; we will pad
// the size to the next multiple if necessary.
if (!isMemRefSizeMultipleOf(memRefType, alignment, op))
sizeBytes = createAligned(rewriter, loc, sizeBytes, allocAlignment);
Type elementPtrType = this->getElementPtrType(memRefType);
auto allocFuncOp = LLVM::lookupOrCreateAlignedAllocFn(
allocOp->getParentOfType<ModuleOp>(), getIndexType());
auto results =
createLLVMCall(rewriter, loc, allocFuncOp, {allocAlignment, sizeBytes},
getVoidPtrType());
Value allocatedPtr =
rewriter.create<LLVM::BitcastOp>(loc, elementPtrType, results[0]);
return std::make_tuple(allocatedPtr, allocatedPtr);
}
/// The minimum alignment to use with aligned_alloc (has to be a power of 2).
static constexpr uint64_t kMinAlignedAllocAlignment = 16UL;
/// Default layout to use in absence of the corresponding analysis.
DataLayout defaultLayout;
};
// Out of line definition, required till C++17.
constexpr uint64_t AlignedAllocOpLowering::kMinAlignedAllocAlignment;
struct AllocaOpLowering : public AllocLikeOpLLVMLowering {
AllocaOpLowering(LLVMTypeConverter &converter)
: AllocLikeOpLLVMLowering(memref::AllocaOp::getOperationName(),
converter) {}
/// Allocates the underlying buffer using the right call. `allocatedBytePtr`
/// is set to null for stack allocations. `accessAlignment` is set if
/// alignment is needed post allocation (for eg. in conjunction with malloc).
std::tuple<Value, Value> allocateBuffer(ConversionPatternRewriter &rewriter,
Location loc, Value sizeBytes,
Operation *op) const override {
// With alloca, one gets a pointer to the element type right away.
// For stack allocations.
auto allocaOp = cast<memref::AllocaOp>(op);
auto elementPtrType = this->getElementPtrType(allocaOp.getType());
auto allocatedElementPtr = rewriter.create<LLVM::AllocaOp>(
loc, elementPtrType, sizeBytes,
allocaOp.alignment() ? *allocaOp.alignment() : 0);
return std::make_tuple(allocatedElementPtr, allocatedElementPtr);
}
};
struct AllocaScopeOpLowering
: public ConvertOpToLLVMPattern<memref::AllocaScopeOp> {
using ConvertOpToLLVMPattern<memref::AllocaScopeOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(memref::AllocaScopeOp allocaScopeOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
OpBuilder::InsertionGuard guard(rewriter);
Location loc = allocaScopeOp.getLoc();
// Split the current block before the AllocaScopeOp to create the inlining
// point.
auto *currentBlock = rewriter.getInsertionBlock();
auto *remainingOpsBlock =
rewriter.splitBlock(currentBlock, rewriter.getInsertionPoint());
Block *continueBlock;
if (allocaScopeOp.getNumResults() == 0) {
continueBlock = remainingOpsBlock;
} else {
continueBlock = rewriter.createBlock(
remainingOpsBlock, allocaScopeOp.getResultTypes(),
SmallVector<Location>(allocaScopeOp->getNumResults(),
allocaScopeOp.getLoc()));
rewriter.create<LLVM::BrOp>(loc, ValueRange(), remainingOpsBlock);
}
// Inline body region.
Block *beforeBody = &allocaScopeOp.bodyRegion().front();
Block *afterBody = &allocaScopeOp.bodyRegion().back();
rewriter.inlineRegionBefore(allocaScopeOp.bodyRegion(), continueBlock);
// Save stack and then branch into the body of the region.
rewriter.setInsertionPointToEnd(currentBlock);
auto stackSaveOp =
rewriter.create<LLVM::StackSaveOp>(loc, getVoidPtrType());
rewriter.create<LLVM::BrOp>(loc, ValueRange(), beforeBody);
// Replace the alloca_scope return with a branch that jumps out of the body.
// Stack restore before leaving the body region.
rewriter.setInsertionPointToEnd(afterBody);
auto returnOp =
cast<memref::AllocaScopeReturnOp>(afterBody->getTerminator());
auto branchOp = rewriter.replaceOpWithNewOp<LLVM::BrOp>(
returnOp, returnOp.results(), continueBlock);
// Insert stack restore before jumping out the body of the region.
rewriter.setInsertionPoint(branchOp);
rewriter.create<LLVM::StackRestoreOp>(loc, stackSaveOp);
// Replace the op with values return from the body region.
rewriter.replaceOp(allocaScopeOp, continueBlock->getArguments());
return success();
}
};
struct AssumeAlignmentOpLowering
: public ConvertOpToLLVMPattern<memref::AssumeAlignmentOp> {
using ConvertOpToLLVMPattern<
memref::AssumeAlignmentOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(memref::AssumeAlignmentOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Value memref = adaptor.memref();
unsigned alignment = op.alignment();
auto loc = op.getLoc();
MemRefDescriptor memRefDescriptor(memref);
Value ptr = memRefDescriptor.alignedPtr(rewriter, memref.getLoc());
// Emit llvm.assume(memref.alignedPtr & (alignment - 1) == 0). Notice that
// the asserted memref.alignedPtr isn't used anywhere else, as the real
// users like load/store/views always re-extract memref.alignedPtr as they
// get lowered.
//
// This relies on LLVM's CSE optimization (potentially after SROA), since
// after CSE all memref.alignedPtr instances get de-duplicated into the same
// pointer SSA value.
auto intPtrType =
getIntPtrType(memRefDescriptor.getElementPtrType().getAddressSpace());
Value zero = createIndexAttrConstant(rewriter, loc, intPtrType, 0);
Value mask =
createIndexAttrConstant(rewriter, loc, intPtrType, alignment - 1);
Value ptrValue = rewriter.create<LLVM::PtrToIntOp>(loc, intPtrType, ptr);
rewriter.create<LLVM::AssumeOp>(
loc, rewriter.create<LLVM::ICmpOp>(
loc, LLVM::ICmpPredicate::eq,
rewriter.create<LLVM::AndOp>(loc, ptrValue, mask), zero));
rewriter.eraseOp(op);
return success();
}
};
// A `dealloc` is converted into a call to `free` on the underlying data buffer.
// The memref descriptor being an SSA value, there is no need to clean it up
// in any way.
struct DeallocOpLowering : public ConvertOpToLLVMPattern<memref::DeallocOp> {
using ConvertOpToLLVMPattern<memref::DeallocOp>::ConvertOpToLLVMPattern;
explicit DeallocOpLowering(LLVMTypeConverter &converter)
: ConvertOpToLLVMPattern<memref::DeallocOp>(converter) {}
LogicalResult
matchAndRewrite(memref::DeallocOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
// Insert the `free` declaration if it is not already present.
auto freeFunc = LLVM::lookupOrCreateFreeFn(op->getParentOfType<ModuleOp>());
MemRefDescriptor memref(adaptor.memref());
Value casted = rewriter.create<LLVM::BitcastOp>(
op.getLoc(), getVoidPtrType(),
memref.allocatedPtr(rewriter, op.getLoc()));
rewriter.replaceOpWithNewOp<LLVM::CallOp>(
op, TypeRange(), SymbolRefAttr::get(freeFunc), casted);
return success();
}
};
// A `dim` is converted to a constant for static sizes and to an access to the
// size stored in the memref descriptor for dynamic sizes.
struct DimOpLowering : public ConvertOpToLLVMPattern<memref::DimOp> {
using ConvertOpToLLVMPattern<memref::DimOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(memref::DimOp dimOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type operandType = dimOp.source().getType();
if (operandType.isa<UnrankedMemRefType>()) {
rewriter.replaceOp(
dimOp, {extractSizeOfUnrankedMemRef(
operandType, dimOp, adaptor.getOperands(), rewriter)});
return success();
}
if (operandType.isa<MemRefType>()) {
rewriter.replaceOp(
dimOp, {extractSizeOfRankedMemRef(operandType, dimOp,
adaptor.getOperands(), rewriter)});
return success();
}
llvm_unreachable("expected MemRefType or UnrankedMemRefType");
}
private:
Value extractSizeOfUnrankedMemRef(Type operandType, memref::DimOp dimOp,
OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const {
Location loc = dimOp.getLoc();
auto unrankedMemRefType = operandType.cast<UnrankedMemRefType>();
auto scalarMemRefType =
MemRefType::get({}, unrankedMemRefType.getElementType());
unsigned addressSpace = unrankedMemRefType.getMemorySpaceAsInt();
// Extract pointer to the underlying ranked descriptor and bitcast it to a
// memref<element_type> descriptor pointer to minimize the number of GEP
// operations.
UnrankedMemRefDescriptor unrankedDesc(adaptor.source());
Value underlyingRankedDesc = unrankedDesc.memRefDescPtr(rewriter, loc);
Value scalarMemRefDescPtr = rewriter.create<LLVM::BitcastOp>(
loc,
LLVM::LLVMPointerType::get(typeConverter->convertType(scalarMemRefType),
addressSpace),
underlyingRankedDesc);
// Get pointer to offset field of memref<element_type> descriptor.
Type indexPtrTy = LLVM::LLVMPointerType::get(
getTypeConverter()->getIndexType(), addressSpace);
Value two = rewriter.create<LLVM::ConstantOp>(
loc, typeConverter->convertType(rewriter.getI32Type()),
rewriter.getI32IntegerAttr(2));
Value offsetPtr = rewriter.create<LLVM::GEPOp>(
loc, indexPtrTy, scalarMemRefDescPtr,
ValueRange({createIndexConstant(rewriter, loc, 0), two}));
// The size value that we have to extract can be obtained using GEPop with
// `dimOp.index() + 1` index argument.
Value idxPlusOne = rewriter.create<LLVM::AddOp>(
loc, createIndexConstant(rewriter, loc, 1), adaptor.index());
Value sizePtr = rewriter.create<LLVM::GEPOp>(loc, indexPtrTy, offsetPtr,
ValueRange({idxPlusOne}));
return rewriter.create<LLVM::LoadOp>(loc, sizePtr);
}
Optional<int64_t> getConstantDimIndex(memref::DimOp dimOp) const {
if (Optional<int64_t> idx = dimOp.getConstantIndex())
return idx;
if (auto constantOp = dimOp.index().getDefiningOp<LLVM::ConstantOp>())
return constantOp.getValue()
.cast<IntegerAttr>()
.getValue()
.getSExtValue();
return llvm::None;
}
Value extractSizeOfRankedMemRef(Type operandType, memref::DimOp dimOp,
OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const {
Location loc = dimOp.getLoc();
// Take advantage if index is constant.
MemRefType memRefType = operandType.cast<MemRefType>();
if (Optional<int64_t> index = getConstantDimIndex(dimOp)) {
int64_t i = index.getValue();
if (memRefType.isDynamicDim(i)) {
// extract dynamic size from the memref descriptor.
MemRefDescriptor descriptor(adaptor.source());
return descriptor.size(rewriter, loc, i);
}
// Use constant for static size.
int64_t dimSize = memRefType.getDimSize(i);
return createIndexConstant(rewriter, loc, dimSize);
}
Value index = adaptor.index();
int64_t rank = memRefType.getRank();
MemRefDescriptor memrefDescriptor(adaptor.source());
return memrefDescriptor.size(rewriter, loc, index, rank);
}
};
/// Common base for load and store operations on MemRefs. Restricts the match
/// to supported MemRef types. Provides functionality to emit code accessing a
/// specific element of the underlying data buffer.
template <typename Derived>
struct LoadStoreOpLowering : public ConvertOpToLLVMPattern<Derived> {
using ConvertOpToLLVMPattern<Derived>::ConvertOpToLLVMPattern;
using ConvertOpToLLVMPattern<Derived>::isConvertibleAndHasIdentityMaps;
using Base = LoadStoreOpLowering<Derived>;
LogicalResult match(Derived op) const override {
MemRefType type = op.getMemRefType();
return isConvertibleAndHasIdentityMaps(type) ? success() : failure();
}
};
/// Wrap a llvm.cmpxchg operation in a while loop so that the operation can be
/// retried until it succeeds in atomically storing a new value into memory.
///
/// +---------------------------------+
/// | <code before the AtomicRMWOp> |
/// | <compute initial %loaded> |
/// | cf.br loop(%loaded) |
/// +---------------------------------+
/// |
/// -------| |
/// | v v
/// | +--------------------------------+
/// | | loop(%loaded): |
/// | | <body contents> |
/// | | %pair = cmpxchg |
/// | | %ok = %pair[0] |
/// | | %new = %pair[1] |
/// | | cf.cond_br %ok, end, loop(%new) |
/// | +--------------------------------+
/// | | |
/// |----------- |
/// v
/// +--------------------------------+
/// | end: |
/// | <code after the AtomicRMWOp> |
/// +--------------------------------+
///
struct GenericAtomicRMWOpLowering
: public LoadStoreOpLowering<memref::GenericAtomicRMWOp> {
using Base::Base;
LogicalResult
matchAndRewrite(memref::GenericAtomicRMWOp atomicOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto loc = atomicOp.getLoc();
Type valueType = typeConverter->convertType(atomicOp.getResult().getType());
// Split the block into initial, loop, and ending parts.
auto *initBlock = rewriter.getInsertionBlock();
auto *loopBlock = rewriter.createBlock(
initBlock->getParent(), std::next(Region::iterator(initBlock)),
valueType, loc);
auto *endBlock = rewriter.createBlock(
loopBlock->getParent(), std::next(Region::iterator(loopBlock)));
// Operations range to be moved to `endBlock`.
auto opsToMoveStart = atomicOp->getIterator();
auto opsToMoveEnd = initBlock->back().getIterator();
// Compute the loaded value and branch to the loop block.
rewriter.setInsertionPointToEnd(initBlock);
auto memRefType = atomicOp.memref().getType().cast<MemRefType>();
auto dataPtr = getStridedElementPtr(loc, memRefType, adaptor.memref(),
adaptor.indices(), rewriter);
Value init = rewriter.create<LLVM::LoadOp>(loc, dataPtr);
rewriter.create<LLVM::BrOp>(loc, init, loopBlock);
// Prepare the body of the loop block.
rewriter.setInsertionPointToStart(loopBlock);
// Clone the GenericAtomicRMWOp region and extract the result.
auto loopArgument = loopBlock->getArgument(0);
BlockAndValueMapping mapping;
mapping.map(atomicOp.getCurrentValue(), loopArgument);
Block &entryBlock = atomicOp.body().front();
for (auto &nestedOp : entryBlock.without_terminator()) {
Operation *clone = rewriter.clone(nestedOp, mapping);
mapping.map(nestedOp.getResults(), clone->getResults());
}
Value result = mapping.lookup(entryBlock.getTerminator()->getOperand(0));
// Prepare the epilog of the loop block.
// Append the cmpxchg op to the end of the loop block.
auto successOrdering = LLVM::AtomicOrdering::acq_rel;
auto failureOrdering = LLVM::AtomicOrdering::monotonic;
auto boolType = IntegerType::get(rewriter.getContext(), 1);
auto pairType = LLVM::LLVMStructType::getLiteral(rewriter.getContext(),
{valueType, boolType});
auto cmpxchg = rewriter.create<LLVM::AtomicCmpXchgOp>(
loc, pairType, dataPtr, loopArgument, result, successOrdering,
failureOrdering);
// Extract the %new_loaded and %ok values from the pair.
Value newLoaded = rewriter.create<LLVM::ExtractValueOp>(
loc, valueType, cmpxchg, rewriter.getI64ArrayAttr({0}));
Value ok = rewriter.create<LLVM::ExtractValueOp>(
loc, boolType, cmpxchg, rewriter.getI64ArrayAttr({1}));
// Conditionally branch to the end or back to the loop depending on %ok.
rewriter.create<LLVM::CondBrOp>(loc, ok, endBlock, ArrayRef<Value>(),
loopBlock, newLoaded);
rewriter.setInsertionPointToEnd(endBlock);
moveOpsRange(atomicOp.getResult(), newLoaded, std::next(opsToMoveStart),
std::next(opsToMoveEnd), rewriter);
// The 'result' of the atomic_rmw op is the newly loaded value.
rewriter.replaceOp(atomicOp, {newLoaded});
return success();
}
private:
// Clones a segment of ops [start, end) and erases the original.
void moveOpsRange(ValueRange oldResult, ValueRange newResult,
Block::iterator start, Block::iterator end,
ConversionPatternRewriter &rewriter) const {
BlockAndValueMapping mapping;
mapping.map(oldResult, newResult);
SmallVector<Operation *, 2> opsToErase;
for (auto it = start; it != end; ++it) {
rewriter.clone(*it, mapping);
opsToErase.push_back(&*it);
}
for (auto *it : opsToErase)
rewriter.eraseOp(it);
}
};
/// Returns the LLVM type of the global variable given the memref type `type`.
static Type convertGlobalMemrefTypeToLLVM(MemRefType type,
LLVMTypeConverter &typeConverter) {
// LLVM type for a global memref will be a multi-dimension array. For
// declarations or uninitialized global memrefs, we can potentially flatten
// this to a 1D array. However, for memref.global's with an initial value,
// we do not intend to flatten the ElementsAttribute when going from std ->
// LLVM dialect, so the LLVM type needs to me a multi-dimension array.
Type elementType = typeConverter.convertType(type.getElementType());
Type arrayTy = elementType;
// Shape has the outermost dim at index 0, so need to walk it backwards
for (int64_t dim : llvm::reverse(type.getShape()))
arrayTy = LLVM::LLVMArrayType::get(arrayTy, dim);
return arrayTy;
}
/// GlobalMemrefOp is lowered to a LLVM Global Variable.
struct GlobalMemrefOpLowering
: public ConvertOpToLLVMPattern<memref::GlobalOp> {
using ConvertOpToLLVMPattern<memref::GlobalOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(memref::GlobalOp global, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
MemRefType type = global.type();
if (!isConvertibleAndHasIdentityMaps(type))
return failure();
Type arrayTy = convertGlobalMemrefTypeToLLVM(type, *getTypeConverter());
LLVM::Linkage linkage =
global.isPublic() ? LLVM::Linkage::External : LLVM::Linkage::Private;
Attribute initialValue = nullptr;
if (!global.isExternal() && !global.isUninitialized()) {
auto elementsAttr = global.initial_value()->cast<ElementsAttr>();
initialValue = elementsAttr;
// For scalar memrefs, the global variable created is of the element type,
// so unpack the elements attribute to extract the value.
if (type.getRank() == 0)
initialValue = elementsAttr.getSplatValue<Attribute>();
}
uint64_t alignment = global.alignment().getValueOr(0);
auto newGlobal = rewriter.replaceOpWithNewOp<LLVM::GlobalOp>(
global, arrayTy, global.constant(), linkage, global.sym_name(),
initialValue, alignment, type.getMemorySpaceAsInt());
if (!global.isExternal() && global.isUninitialized()) {
Block *blk = new Block();
newGlobal.getInitializerRegion().push_back(blk);
rewriter.setInsertionPointToStart(blk);
Value undef[] = {
rewriter.create<LLVM::UndefOp>(global.getLoc(), arrayTy)};
rewriter.create<LLVM::ReturnOp>(global.getLoc(), undef);
}
return success();
}
};
/// GetGlobalMemrefOp is lowered into a Memref descriptor with the pointer to
/// the first element stashed into the descriptor. This reuses
/// `AllocLikeOpLowering` to reuse the Memref descriptor construction.
struct GetGlobalMemrefOpLowering : public AllocLikeOpLLVMLowering {
GetGlobalMemrefOpLowering(LLVMTypeConverter &converter)
: AllocLikeOpLLVMLowering(memref::GetGlobalOp::getOperationName(),
converter) {}
/// Buffer "allocation" for memref.get_global op is getting the address of
/// the global variable referenced.
std::tuple<Value, Value> allocateBuffer(ConversionPatternRewriter &rewriter,
Location loc, Value sizeBytes,
Operation *op) const override {
auto getGlobalOp = cast<memref::GetGlobalOp>(op);
MemRefType type = getGlobalOp.result().getType().cast<MemRefType>();
unsigned memSpace = type.getMemorySpaceAsInt();
Type arrayTy = convertGlobalMemrefTypeToLLVM(type, *getTypeConverter());
auto addressOf = rewriter.create<LLVM::AddressOfOp>(
loc, LLVM::LLVMPointerType::get(arrayTy, memSpace), getGlobalOp.name());
// Get the address of the first element in the array by creating a GEP with
// the address of the GV as the base, and (rank + 1) number of 0 indices.
Type elementType = typeConverter->convertType(type.getElementType());
Type elementPtrType = LLVM::LLVMPointerType::get(elementType, memSpace);
SmallVector<Value> operands;
operands.insert(operands.end(), type.getRank() + 1,
createIndexConstant(rewriter, loc, 0));
auto gep =
rewriter.create<LLVM::GEPOp>(loc, elementPtrType, addressOf, operands);
// We do not expect the memref obtained using `memref.get_global` to be
// ever deallocated. Set the allocated pointer to be known bad value to
// help debug if that ever happens.
auto intPtrType = getIntPtrType(memSpace);
Value deadBeefConst =
createIndexAttrConstant(rewriter, op->getLoc(), intPtrType, 0xdeadbeef);
auto deadBeefPtr =
rewriter.create<LLVM::IntToPtrOp>(loc, elementPtrType, deadBeefConst);
// Both allocated and aligned pointers are same. We could potentially stash
// a nullptr for the allocated pointer since we do not expect any dealloc.
return std::make_tuple(deadBeefPtr, gep);
}
};
// Load operation is lowered to obtaining a pointer to the indexed element
// and loading it.
struct LoadOpLowering : public LoadStoreOpLowering<memref::LoadOp> {
using Base::Base;
LogicalResult
matchAndRewrite(memref::LoadOp loadOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto type = loadOp.getMemRefType();
Value dataPtr = getStridedElementPtr(
loadOp.getLoc(), type, adaptor.memref(), adaptor.indices(), rewriter);
rewriter.replaceOpWithNewOp<LLVM::LoadOp>(loadOp, dataPtr);
return success();
}
};
// Store operation is lowered to obtaining a pointer to the indexed element,
// and storing the given value to it.
struct StoreOpLowering : public LoadStoreOpLowering<memref::StoreOp> {
using Base::Base;
LogicalResult
matchAndRewrite(memref::StoreOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto type = op.getMemRefType();
Value dataPtr = getStridedElementPtr(op.getLoc(), type, adaptor.memref(),
adaptor.indices(), rewriter);
rewriter.replaceOpWithNewOp<LLVM::StoreOp>(op, adaptor.value(), dataPtr);
return success();
}
};
// The prefetch operation is lowered in a way similar to the load operation
// except that the llvm.prefetch operation is used for replacement.
struct PrefetchOpLowering : public LoadStoreOpLowering<memref::PrefetchOp> {
using Base::Base;
LogicalResult
matchAndRewrite(memref::PrefetchOp prefetchOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto type = prefetchOp.getMemRefType();
auto loc = prefetchOp.getLoc();
Value dataPtr = getStridedElementPtr(loc, type, adaptor.memref(),
adaptor.indices(), rewriter);
// Replace with llvm.prefetch.
auto llvmI32Type = typeConverter->convertType(rewriter.getIntegerType(32));
auto isWrite = rewriter.create<LLVM::ConstantOp>(
loc, llvmI32Type, rewriter.getI32IntegerAttr(prefetchOp.isWrite()));
auto localityHint = rewriter.create<LLVM::ConstantOp>(
loc, llvmI32Type,
rewriter.getI32IntegerAttr(prefetchOp.localityHint()));
auto isData = rewriter.create<LLVM::ConstantOp>(
loc, llvmI32Type, rewriter.getI32IntegerAttr(prefetchOp.isDataCache()));
rewriter.replaceOpWithNewOp<LLVM::Prefetch>(prefetchOp, dataPtr, isWrite,
localityHint, isData);
return success();
}
};
struct RankOpLowering : public ConvertOpToLLVMPattern<memref::RankOp> {
using ConvertOpToLLVMPattern<memref::RankOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(memref::RankOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Location loc = op.getLoc();
Type operandType = op.memref().getType();
if (auto unrankedMemRefType = operandType.dyn_cast<UnrankedMemRefType>()) {
UnrankedMemRefDescriptor desc(adaptor.memref());
rewriter.replaceOp(op, {desc.rank(rewriter, loc)});
return success();
}
if (auto rankedMemRefType = operandType.dyn_cast<MemRefType>()) {
rewriter.replaceOp(
op, {createIndexConstant(rewriter, loc, rankedMemRefType.getRank())});
return success();
}
return failure();
}
};
struct MemRefCastOpLowering : public ConvertOpToLLVMPattern<memref::CastOp> {
using ConvertOpToLLVMPattern<memref::CastOp>::ConvertOpToLLVMPattern;
LogicalResult match(memref::CastOp memRefCastOp) const override {
Type srcType = memRefCastOp.getOperand().getType();
Type dstType = memRefCastOp.getType();
// memref::CastOp reduce to bitcast in the ranked MemRef case and can be
// used for type erasure. For now they must preserve underlying element type
// and require source and result type to have the same rank. Therefore,
// perform a sanity check that the underlying structs are the same. Once op
// semantics are relaxed we can revisit.
if (srcType.isa<MemRefType>() && dstType.isa<MemRefType>())
return success(typeConverter->convertType(srcType) ==
typeConverter->convertType(dstType));
// At least one of the operands is unranked type
assert(srcType.isa<UnrankedMemRefType>() ||
dstType.isa<UnrankedMemRefType>());
// Unranked to unranked cast is disallowed
return !(srcType.isa<UnrankedMemRefType>() &&
dstType.isa<UnrankedMemRefType>())
? success()
: failure();
}
void rewrite(memref::CastOp memRefCastOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto srcType = memRefCastOp.getOperand().getType();
auto dstType = memRefCastOp.getType();
auto targetStructType = typeConverter->convertType(memRefCastOp.getType());
auto loc = memRefCastOp.getLoc();
// For ranked/ranked case, just keep the original descriptor.
if (srcType.isa<MemRefType>() && dstType.isa<MemRefType>())
return rewriter.replaceOp(memRefCastOp, {adaptor.source()});
if (srcType.isa<MemRefType>() && dstType.isa<UnrankedMemRefType>()) {
// Casting ranked to unranked memref type
// Set the rank in the destination from the memref type
// Allocate space on the stack and copy the src memref descriptor
// Set the ptr in the destination to the stack space
auto srcMemRefType = srcType.cast<MemRefType>();
int64_t rank = srcMemRefType.getRank();
// ptr = AllocaOp sizeof(MemRefDescriptor)
auto ptr = getTypeConverter()->promoteOneMemRefDescriptor(
loc, adaptor.source(), rewriter);
// voidptr = BitCastOp srcType* to void*
auto voidPtr =
rewriter.create<LLVM::BitcastOp>(loc, getVoidPtrType(), ptr)
.getResult();
// rank = ConstantOp srcRank
auto rankVal = rewriter.create<LLVM::ConstantOp>(
loc, getIndexType(), rewriter.getIndexAttr(rank));
// undef = UndefOp
UnrankedMemRefDescriptor memRefDesc =
UnrankedMemRefDescriptor::undef(rewriter, loc, targetStructType);
// d1 = InsertValueOp undef, rank, 0
memRefDesc.setRank(rewriter, loc, rankVal);
// d2 = InsertValueOp d1, voidptr, 1
memRefDesc.setMemRefDescPtr(rewriter, loc, voidPtr);
rewriter.replaceOp(memRefCastOp, (Value)memRefDesc);
} else if (srcType.isa<UnrankedMemRefType>() && dstType.isa<MemRefType>()) {
// Casting from unranked type to ranked.
// The operation is assumed to be doing a correct cast. If the destination
// type mismatches the unranked the type, it is undefined behavior.
UnrankedMemRefDescriptor memRefDesc(adaptor.source());
// ptr = ExtractValueOp src, 1
auto ptr = memRefDesc.memRefDescPtr(rewriter, loc);
// castPtr = BitCastOp i8* to structTy*
auto castPtr =
rewriter
.create<LLVM::BitcastOp>(
loc, LLVM::LLVMPointerType::get(targetStructType), ptr)
.getResult();
// struct = LoadOp castPtr
auto loadOp = rewriter.create<LLVM::LoadOp>(loc, castPtr);
rewriter.replaceOp(memRefCastOp, loadOp.getResult());
} else {
llvm_unreachable("Unsupported unranked memref to unranked memref cast");
}
}
};
/// Pattern to lower a `memref.copy` to llvm.
///
/// For memrefs with identity layouts, the copy is lowered to the llvm
/// `memcpy` intrinsic. For non-identity layouts, the copy is lowered to a call
/// to the generic `MemrefCopyFn`.
struct MemRefCopyOpLowering : public ConvertOpToLLVMPattern<memref::CopyOp> {
using ConvertOpToLLVMPattern<memref::CopyOp>::ConvertOpToLLVMPattern;
LogicalResult
lowerToMemCopyIntrinsic(memref::CopyOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const {
auto loc = op.getLoc();
auto srcType = op.source().getType().dyn_cast<MemRefType>();
MemRefDescriptor srcDesc(adaptor.source());
// Compute number of elements.
Value numElements = rewriter.create<LLVM::ConstantOp>(
loc, getIndexType(), rewriter.getIndexAttr(1));
for (int pos = 0; pos < srcType.getRank(); ++pos) {
auto size = srcDesc.size(rewriter, loc, pos);
numElements = rewriter.create<LLVM::MulOp>(loc, numElements, size);
}
// Get element size.
auto sizeInBytes = getSizeInBytes(loc, srcType.getElementType(), rewriter);
// Compute total.
Value totalSize =
rewriter.create<LLVM::MulOp>(loc, numElements, sizeInBytes);
Value srcBasePtr = srcDesc.alignedPtr(rewriter, loc);
Value srcOffset = srcDesc.offset(rewriter, loc);
Value srcPtr = rewriter.create<LLVM::GEPOp>(loc, srcBasePtr.getType(),
srcBasePtr, srcOffset);
MemRefDescriptor targetDesc(adaptor.target());
Value targetBasePtr = targetDesc.alignedPtr(rewriter, loc);
Value targetOffset = targetDesc.offset(rewriter, loc);
Value targetPtr = rewriter.create<LLVM::GEPOp>(loc, targetBasePtr.getType(),
targetBasePtr, targetOffset);
Value isVolatile = rewriter.create<LLVM::ConstantOp>(
loc, typeConverter->convertType(rewriter.getI1Type()),
rewriter.getBoolAttr(false));
rewriter.create<LLVM::MemcpyOp>(loc, targetPtr, srcPtr, totalSize,
isVolatile);
rewriter.eraseOp(op);
return success();
}
LogicalResult
lowerToMemCopyFunctionCall(memref::CopyOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const {
auto loc = op.getLoc();
auto srcType = op.source().getType().cast<BaseMemRefType>();
auto targetType = op.target().getType().cast<BaseMemRefType>();
// First make sure we have an unranked memref descriptor representation.
auto makeUnranked = [&, this](Value ranked, BaseMemRefType type) {
auto rank = rewriter.create<LLVM::ConstantOp>(
loc, getIndexType(), rewriter.getIndexAttr(type.getRank()));
auto *typeConverter = getTypeConverter();
auto ptr =
typeConverter->promoteOneMemRefDescriptor(loc, ranked, rewriter);
auto voidPtr =
rewriter.create<LLVM::BitcastOp>(loc, getVoidPtrType(), ptr)
.getResult();
auto unrankedType =
UnrankedMemRefType::get(type.getElementType(), type.getMemorySpace());
return UnrankedMemRefDescriptor::pack(rewriter, loc, *typeConverter,
unrankedType,
ValueRange{rank, voidPtr});
};
Value unrankedSource = srcType.hasRank()
? makeUnranked(adaptor.source(), srcType)
: adaptor.source();
Value unrankedTarget = targetType.hasRank()
? makeUnranked(adaptor.target(), targetType)
: adaptor.target();
// Now promote the unranked descriptors to the stack.
auto one = rewriter.create<LLVM::ConstantOp>(loc, getIndexType(),
rewriter.getIndexAttr(1));
auto promote = [&](Value desc) {
auto ptrType = LLVM::LLVMPointerType::get(desc.getType());
auto allocated =
rewriter.create<LLVM::AllocaOp>(loc, ptrType, ValueRange{one});
rewriter.create<LLVM::StoreOp>(loc, desc, allocated);
return allocated;
};
auto sourcePtr = promote(unrankedSource);
auto targetPtr = promote(unrankedTarget);
unsigned typeSize =
mlir::DataLayout::closest(op).getTypeSize(srcType.getElementType());
auto elemSize = rewriter.create<LLVM::ConstantOp>(
loc, getIndexType(), rewriter.getIndexAttr(typeSize));
auto copyFn = LLVM::lookupOrCreateMemRefCopyFn(
op->getParentOfType<ModuleOp>(), getIndexType(), sourcePtr.getType());
rewriter.create<LLVM::CallOp>(loc, copyFn,
ValueRange{elemSize, sourcePtr, targetPtr});
rewriter.eraseOp(op);
return success();
}
LogicalResult
matchAndRewrite(memref::CopyOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto srcType = op.source().getType().cast<BaseMemRefType>();
auto targetType = op.target().getType().cast<BaseMemRefType>();
auto isContiguousMemrefType = [](BaseMemRefType type) {
auto memrefType = type.dyn_cast<mlir::MemRefType>();
// We can use memcpy for memrefs if they have an identity layout or are
// contiguous with an arbitrary offset. Ignore empty memrefs, which is a
// special case handled by memrefCopy.
return memrefType &&
(memrefType.getLayout().isIdentity() ||
(memrefType.hasStaticShape() && memrefType.getNumElements() > 0 &&
isStaticShapeAndContiguousRowMajor(memrefType)));
};
if (isContiguousMemrefType(srcType) && isContiguousMemrefType(targetType))
return lowerToMemCopyIntrinsic(op, adaptor, rewriter);
return lowerToMemCopyFunctionCall(op, adaptor, rewriter);
}
};
/// Extracts allocated, aligned pointers and offset from a ranked or unranked
/// memref type. In unranked case, the fields are extracted from the underlying
/// ranked descriptor.
static void extractPointersAndOffset(Location loc,
ConversionPatternRewriter &rewriter,
LLVMTypeConverter &typeConverter,
Value originalOperand,
Value convertedOperand,
Value *allocatedPtr, Value *alignedPtr,
Value *offset = nullptr) {
Type operandType = originalOperand.getType();
if (operandType.isa<MemRefType>()) {
MemRefDescriptor desc(convertedOperand);
*allocatedPtr = desc.allocatedPtr(rewriter, loc);
*alignedPtr = desc.alignedPtr(rewriter, loc);
if (offset != nullptr)
*offset = desc.offset(rewriter, loc);
return;
}
unsigned memorySpace =
operandType.cast<UnrankedMemRefType>().getMemorySpaceAsInt();
Type elementType = operandType.cast<UnrankedMemRefType>().getElementType();
Type llvmElementType = typeConverter.convertType(elementType);
Type elementPtrPtrType = LLVM::LLVMPointerType::get(
LLVM::LLVMPointerType::get(llvmElementType, memorySpace));
// Extract pointer to the underlying ranked memref descriptor and cast it to
// ElemType**.
UnrankedMemRefDescriptor unrankedDesc(convertedOperand);
Value underlyingDescPtr = unrankedDesc.memRefDescPtr(rewriter, loc);
*allocatedPtr = UnrankedMemRefDescriptor::allocatedPtr(
rewriter, loc, underlyingDescPtr, elementPtrPtrType);
*alignedPtr = UnrankedMemRefDescriptor::alignedPtr(