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//===- StandardToLLVM.cpp - Standard 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
//
//===----------------------------------------------------------------------===//
//
// This file implements a pass to convert MLIR standard and builtin dialects
// into the LLVM IR dialect.
//
//===----------------------------------------------------------------------===//
#include "../PassDetail.h"
#include "mlir/Analysis/DataLayoutAnalysis.h"
#include "mlir/Conversion/ArithmeticToLLVM/ArithmeticToLLVM.h"
#include "mlir/Conversion/LLVMCommon/ConversionTarget.h"
#include "mlir/Conversion/LLVMCommon/Pattern.h"
#include "mlir/Conversion/LLVMCommon/VectorPattern.h"
#include "mlir/Conversion/StandardToLLVM/ConvertStandardToLLVM.h"
#include "mlir/Conversion/StandardToLLVM/ConvertStandardToLLVMPass.h"
#include "mlir/Dialect/LLVMIR/FunctionCallUtils.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/StandardOps/IR/Ops.h"
#include "mlir/Dialect/Utils/StaticValueUtils.h"
#include "mlir/IR/Attributes.h"
#include "mlir/IR/BlockAndValueMapping.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/BuiltinOps.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/IR/TypeUtilities.h"
#include "mlir/Support/LogicalResult.h"
#include "mlir/Support/MathExtras.h"
#include "mlir/Transforms/DialectConversion.h"
#include "mlir/Transforms/Passes.h"
#include "mlir/Transforms/Utils.h"
#include "llvm/ADT/TypeSwitch.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FormatVariadic.h"
#include <functional>
using namespace mlir;
#define PASS_NAME "convert-std-to-llvm"
/// Only retain those attributes that are not constructed by
/// `LLVMFuncOp::build`. If `filterArgAttrs` is set, also filter out argument
/// attributes.
static void filterFuncAttributes(ArrayRef<NamedAttribute> attrs,
bool filterArgAttrs,
SmallVectorImpl<NamedAttribute> &result) {
for (const auto &attr : attrs) {
if (attr.getName() == SymbolTable::getSymbolAttrName() ||
attr.getName() == function_like_impl::getTypeAttrName() ||
attr.getName() == "std.varargs" ||
(filterArgAttrs &&
attr.getName() == function_like_impl::getArgDictAttrName()))
continue;
result.push_back(attr);
}
}
/// Creates an auxiliary function with pointer-to-memref-descriptor-struct
/// arguments instead of unpacked arguments. This function can be called from C
/// by passing a pointer to a C struct corresponding to a memref descriptor.
/// Similarly, returned memrefs are passed via pointers to a C struct that is
/// passed as additional argument.
/// Internally, the auxiliary function unpacks the descriptor into individual
/// components and forwards them to `newFuncOp` and forwards the results to
/// the extra arguments.
static void wrapForExternalCallers(OpBuilder &rewriter, Location loc,
LLVMTypeConverter &typeConverter,
FuncOp funcOp, LLVM::LLVMFuncOp newFuncOp) {
auto type = funcOp.getType();
SmallVector<NamedAttribute, 4> attributes;
filterFuncAttributes(funcOp->getAttrs(), /*filterArgAttrs=*/false,
attributes);
Type wrapperFuncType;
bool resultIsNowArg;
std::tie(wrapperFuncType, resultIsNowArg) =
typeConverter.convertFunctionTypeCWrapper(type);
auto wrapperFuncOp = rewriter.create<LLVM::LLVMFuncOp>(
loc, llvm::formatv("_mlir_ciface_{0}", funcOp.getName()).str(),
wrapperFuncType, LLVM::Linkage::External, /*dsoLocal*/ false, attributes);
OpBuilder::InsertionGuard guard(rewriter);
rewriter.setInsertionPointToStart(wrapperFuncOp.addEntryBlock());
SmallVector<Value, 8> args;
size_t argOffset = resultIsNowArg ? 1 : 0;
for (auto &en : llvm::enumerate(type.getInputs())) {
Value arg = wrapperFuncOp.getArgument(en.index() + argOffset);
if (auto memrefType = en.value().dyn_cast<MemRefType>()) {
Value loaded = rewriter.create<LLVM::LoadOp>(loc, arg);
MemRefDescriptor::unpack(rewriter, loc, loaded, memrefType, args);
continue;
}
if (en.value().isa<UnrankedMemRefType>()) {
Value loaded = rewriter.create<LLVM::LoadOp>(loc, arg);
UnrankedMemRefDescriptor::unpack(rewriter, loc, loaded, args);
continue;
}
args.push_back(arg);
}
auto call = rewriter.create<LLVM::CallOp>(loc, newFuncOp, args);
if (resultIsNowArg) {
rewriter.create<LLVM::StoreOp>(loc, call.getResult(0),
wrapperFuncOp.getArgument(0));
rewriter.create<LLVM::ReturnOp>(loc, ValueRange{});
} else {
rewriter.create<LLVM::ReturnOp>(loc, call.getResults());
}
}
/// Creates an auxiliary function with pointer-to-memref-descriptor-struct
/// arguments instead of unpacked arguments. Creates a body for the (external)
/// `newFuncOp` that allocates a memref descriptor on stack, packs the
/// individual arguments into this descriptor and passes a pointer to it into
/// the auxiliary function. If the result of the function cannot be directly
/// returned, we write it to a special first argument that provides a pointer
/// to a corresponding struct. This auxiliary external function is now
/// compatible with functions defined in C using pointers to C structs
/// corresponding to a memref descriptor.
static void wrapExternalFunction(OpBuilder &builder, Location loc,
LLVMTypeConverter &typeConverter,
FuncOp funcOp, LLVM::LLVMFuncOp newFuncOp) {
OpBuilder::InsertionGuard guard(builder);
Type wrapperType;
bool resultIsNowArg;
std::tie(wrapperType, resultIsNowArg) =
typeConverter.convertFunctionTypeCWrapper(funcOp.getType());
// This conversion can only fail if it could not convert one of the argument
// types. But since it has been applied to a non-wrapper function before, it
// should have failed earlier and not reach this point at all.
assert(wrapperType && "unexpected type conversion failure");
SmallVector<NamedAttribute, 4> attributes;
filterFuncAttributes(funcOp->getAttrs(), /*filterArgAttrs=*/false,
attributes);
// Create the auxiliary function.
auto wrapperFunc = builder.create<LLVM::LLVMFuncOp>(
loc, llvm::formatv("_mlir_ciface_{0}", funcOp.getName()).str(),
wrapperType, LLVM::Linkage::External, /*dsoLocal*/ false, attributes);
builder.setInsertionPointToStart(newFuncOp.addEntryBlock());
// Get a ValueRange containing arguments.
FunctionType type = funcOp.getType();
SmallVector<Value, 8> args;
args.reserve(type.getNumInputs());
ValueRange wrapperArgsRange(newFuncOp.getArguments());
if (resultIsNowArg) {
// Allocate the struct on the stack and pass the pointer.
Type resultType =
wrapperType.cast<LLVM::LLVMFunctionType>().getParamType(0);
Value one = builder.create<LLVM::ConstantOp>(
loc, typeConverter.convertType(builder.getIndexType()),
builder.getIntegerAttr(builder.getIndexType(), 1));
Value result = builder.create<LLVM::AllocaOp>(loc, resultType, one);
args.push_back(result);
}
// Iterate over the inputs of the original function and pack values into
// memref descriptors if the original type is a memref.
for (auto &en : llvm::enumerate(type.getInputs())) {
Value arg;
int numToDrop = 1;
auto memRefType = en.value().dyn_cast<MemRefType>();
auto unrankedMemRefType = en.value().dyn_cast<UnrankedMemRefType>();
if (memRefType || unrankedMemRefType) {
numToDrop = memRefType
? MemRefDescriptor::getNumUnpackedValues(memRefType)
: UnrankedMemRefDescriptor::getNumUnpackedValues();
Value packed =
memRefType
? MemRefDescriptor::pack(builder, loc, typeConverter, memRefType,
wrapperArgsRange.take_front(numToDrop))
: UnrankedMemRefDescriptor::pack(
builder, loc, typeConverter, unrankedMemRefType,
wrapperArgsRange.take_front(numToDrop));
auto ptrTy = LLVM::LLVMPointerType::get(packed.getType());
Value one = builder.create<LLVM::ConstantOp>(
loc, typeConverter.convertType(builder.getIndexType()),
builder.getIntegerAttr(builder.getIndexType(), 1));
Value allocated =
builder.create<LLVM::AllocaOp>(loc, ptrTy, one, /*alignment=*/0);
builder.create<LLVM::StoreOp>(loc, packed, allocated);
arg = allocated;
} else {
arg = wrapperArgsRange[0];
}
args.push_back(arg);
wrapperArgsRange = wrapperArgsRange.drop_front(numToDrop);
}
assert(wrapperArgsRange.empty() && "did not map some of the arguments");
auto call = builder.create<LLVM::CallOp>(loc, wrapperFunc, args);
if (resultIsNowArg) {
Value result = builder.create<LLVM::LoadOp>(loc, args.front());
builder.create<LLVM::ReturnOp>(loc, ValueRange{result});
} else {
builder.create<LLVM::ReturnOp>(loc, call.getResults());
}
}
namespace {
struct FuncOpConversionBase : public ConvertOpToLLVMPattern<FuncOp> {
protected:
using ConvertOpToLLVMPattern<FuncOp>::ConvertOpToLLVMPattern;
// Convert input FuncOp to LLVMFuncOp by using the LLVMTypeConverter provided
// to this legalization pattern.
LLVM::LLVMFuncOp
convertFuncOpToLLVMFuncOp(FuncOp funcOp,
ConversionPatternRewriter &rewriter) const {
// Convert the original function arguments. They are converted using the
// LLVMTypeConverter provided to this legalization pattern.
auto varargsAttr = funcOp->getAttrOfType<BoolAttr>("std.varargs");
TypeConverter::SignatureConversion result(funcOp.getNumArguments());
auto llvmType = getTypeConverter()->convertFunctionSignature(
funcOp.getType(), varargsAttr && varargsAttr.getValue(), result);
if (!llvmType)
return nullptr;
// Propagate argument attributes to all converted arguments obtained after
// converting a given original argument.
SmallVector<NamedAttribute, 4> attributes;
filterFuncAttributes(funcOp->getAttrs(), /*filterArgAttrs=*/true,
attributes);
if (ArrayAttr argAttrDicts = funcOp.getAllArgAttrs()) {
SmallVector<Attribute, 4> newArgAttrs(
llvmType.cast<LLVM::LLVMFunctionType>().getNumParams());
for (unsigned i = 0, e = funcOp.getNumArguments(); i < e; ++i) {
auto mapping = result.getInputMapping(i);
assert(mapping.hasValue() &&
"unexpected deletion of function argument");
for (size_t j = 0; j < mapping->size; ++j)
newArgAttrs[mapping->inputNo + j] = argAttrDicts[i];
}
attributes.push_back(
rewriter.getNamedAttr(function_like_impl::getArgDictAttrName(),
rewriter.getArrayAttr(newArgAttrs)));
}
for (auto pair : llvm::enumerate(attributes)) {
if (pair.value().getName() == "llvm.linkage") {
attributes.erase(attributes.begin() + pair.index());
break;
}
}
// Create an LLVM function, use external linkage by default until MLIR
// functions have linkage.
LLVM::Linkage linkage = LLVM::Linkage::External;
if (funcOp->hasAttr("llvm.linkage")) {
auto attr =
funcOp->getAttr("llvm.linkage").dyn_cast<mlir::LLVM::LinkageAttr>();
if (!attr) {
funcOp->emitError()
<< "Contains llvm.linkage attribute not of type LLVM::LinkageAttr";
return nullptr;
}
linkage = attr.getLinkage();
}
auto newFuncOp = rewriter.create<LLVM::LLVMFuncOp>(
funcOp.getLoc(), funcOp.getName(), llvmType, linkage,
/*dsoLocal*/ false, attributes);
rewriter.inlineRegionBefore(funcOp.getBody(), newFuncOp.getBody(),
newFuncOp.end());
if (failed(rewriter.convertRegionTypes(&newFuncOp.getBody(), *typeConverter,
&result)))
return nullptr;
return newFuncOp;
}
};
/// FuncOp legalization pattern that converts MemRef arguments to pointers to
/// MemRef descriptors (LLVM struct data types) containing all the MemRef type
/// information.
static constexpr StringRef kEmitIfaceAttrName = "llvm.emit_c_interface";
struct FuncOpConversion : public FuncOpConversionBase {
FuncOpConversion(LLVMTypeConverter &converter)
: FuncOpConversionBase(converter) {}
LogicalResult
matchAndRewrite(FuncOp funcOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto newFuncOp = convertFuncOpToLLVMFuncOp(funcOp, rewriter);
if (!newFuncOp)
return failure();
if (getTypeConverter()->getOptions().emitCWrappers ||
funcOp->getAttrOfType<UnitAttr>(kEmitIfaceAttrName)) {
if (newFuncOp.isExternal())
wrapExternalFunction(rewriter, funcOp.getLoc(), *getTypeConverter(),
funcOp, newFuncOp);
else
wrapForExternalCallers(rewriter, funcOp.getLoc(), *getTypeConverter(),
funcOp, newFuncOp);
}
rewriter.eraseOp(funcOp);
return success();
}
};
/// FuncOp legalization pattern that converts MemRef arguments to bare pointers
/// to the MemRef element type. This will impact the calling convention and ABI.
struct BarePtrFuncOpConversion : public FuncOpConversionBase {
using FuncOpConversionBase::FuncOpConversionBase;
LogicalResult
matchAndRewrite(FuncOp funcOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
// TODO: bare ptr conversion could be handled by argument materialization
// and most of the code below would go away. But to do this, we would need a
// way to distinguish between FuncOp and other regions in the
// addArgumentMaterialization hook.
// Store the type of memref-typed arguments before the conversion so that we
// can promote them to MemRef descriptor at the beginning of the function.
SmallVector<Type, 8> oldArgTypes =
llvm::to_vector<8>(funcOp.getType().getInputs());
auto newFuncOp = convertFuncOpToLLVMFuncOp(funcOp, rewriter);
if (!newFuncOp)
return failure();
if (newFuncOp.getBody().empty()) {
rewriter.eraseOp(funcOp);
return success();
}
// Promote bare pointers from memref arguments to memref descriptors at the
// beginning of the function so that all the memrefs in the function have a
// uniform representation.
Block *entryBlock = &newFuncOp.getBody().front();
auto blockArgs = entryBlock->getArguments();
assert(blockArgs.size() == oldArgTypes.size() &&
"The number of arguments and types doesn't match");
OpBuilder::InsertionGuard guard(rewriter);
rewriter.setInsertionPointToStart(entryBlock);
for (auto it : llvm::zip(blockArgs, oldArgTypes)) {
BlockArgument arg = std::get<0>(it);
Type argTy = std::get<1>(it);
// Unranked memrefs are not supported in the bare pointer calling
// convention. We should have bailed out before in the presence of
// unranked memrefs.
assert(!argTy.isa<UnrankedMemRefType>() &&
"Unranked memref is not supported");
auto memrefTy = argTy.dyn_cast<MemRefType>();
if (!memrefTy)
continue;
// Replace barePtr with a placeholder (undef), promote barePtr to a ranked
// or unranked memref descriptor and replace placeholder with the last
// instruction of the memref descriptor.
// TODO: The placeholder is needed to avoid replacing barePtr uses in the
// MemRef descriptor instructions. We may want to have a utility in the
// rewriter to properly handle this use case.
Location loc = funcOp.getLoc();
auto placeholder = rewriter.create<LLVM::UndefOp>(
loc, getTypeConverter()->convertType(memrefTy));
rewriter.replaceUsesOfBlockArgument(arg, placeholder);
Value desc = MemRefDescriptor::fromStaticShape(
rewriter, loc, *getTypeConverter(), memrefTy, arg);
rewriter.replaceOp(placeholder, {desc});
}
rewriter.eraseOp(funcOp);
return success();
}
};
// Straightforward lowerings.
using SelectOpLowering = VectorConvertToLLVMPattern<SelectOp, LLVM::SelectOp>;
/// Lower `std.assert`. The default lowering calls the `abort` function if the
/// assertion is violated and has no effect otherwise. The failure message is
/// ignored by the default lowering but should be propagated by any custom
/// lowering.
struct AssertOpLowering : public ConvertOpToLLVMPattern<AssertOp> {
using ConvertOpToLLVMPattern<AssertOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(AssertOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto loc = op.getLoc();
// Insert the `abort` declaration if necessary.
auto module = op->getParentOfType<ModuleOp>();
auto abortFunc = module.lookupSymbol<LLVM::LLVMFuncOp>("abort");
if (!abortFunc) {
OpBuilder::InsertionGuard guard(rewriter);
rewriter.setInsertionPointToStart(module.getBody());
auto abortFuncTy = LLVM::LLVMFunctionType::get(getVoidType(), {});
abortFunc = rewriter.create<LLVM::LLVMFuncOp>(rewriter.getUnknownLoc(),
"abort", abortFuncTy);
}
// Split block at `assert` operation.
Block *opBlock = rewriter.getInsertionBlock();
auto opPosition = rewriter.getInsertionPoint();
Block *continuationBlock = rewriter.splitBlock(opBlock, opPosition);
// Generate IR to call `abort`.
Block *failureBlock = rewriter.createBlock(opBlock->getParent());
rewriter.create<LLVM::CallOp>(loc, abortFunc, llvm::None);
rewriter.create<LLVM::UnreachableOp>(loc);
// Generate assertion test.
rewriter.setInsertionPointToEnd(opBlock);
rewriter.replaceOpWithNewOp<LLVM::CondBrOp>(
op, adaptor.getArg(), continuationBlock, failureBlock);
return success();
}
};
struct ConstantOpLowering : public ConvertOpToLLVMPattern<ConstantOp> {
using ConvertOpToLLVMPattern<ConstantOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(ConstantOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
// If constant refers to a function, convert it to "addressof".
if (auto symbolRef = op.getValue().dyn_cast<FlatSymbolRefAttr>()) {
auto type = typeConverter->convertType(op.getResult().getType());
if (!type || !LLVM::isCompatibleType(type))
return rewriter.notifyMatchFailure(op, "failed to convert result type");
auto newOp = rewriter.create<LLVM::AddressOfOp>(op.getLoc(), type,
symbolRef.getValue());
for (const NamedAttribute &attr : op->getAttrs()) {
if (attr.getName().strref() == "value")
continue;
newOp->setAttr(attr.getName(), attr.getValue());
}
rewriter.replaceOp(op, newOp->getResults());
return success();
}
// Calling into other scopes (non-flat reference) is not supported in LLVM.
if (op.getValue().isa<SymbolRefAttr>())
return rewriter.notifyMatchFailure(
op, "referring to a symbol outside of the current module");
return LLVM::detail::oneToOneRewrite(
op, LLVM::ConstantOp::getOperationName(), adaptor.getOperands(),
*getTypeConverter(), rewriter);
}
};
// A CallOp automatically promotes MemRefType to a sequence of alloca/store and
// passes the pointer to the MemRef across function boundaries.
template <typename CallOpType>
struct CallOpInterfaceLowering : public ConvertOpToLLVMPattern<CallOpType> {
using ConvertOpToLLVMPattern<CallOpType>::ConvertOpToLLVMPattern;
using Super = CallOpInterfaceLowering<CallOpType>;
using Base = ConvertOpToLLVMPattern<CallOpType>;
LogicalResult
matchAndRewrite(CallOpType callOp, typename CallOpType::Adaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
// Pack the result types into a struct.
Type packedResult = nullptr;
unsigned numResults = callOp.getNumResults();
auto resultTypes = llvm::to_vector<4>(callOp.getResultTypes());
if (numResults != 0) {
if (!(packedResult =
this->getTypeConverter()->packFunctionResults(resultTypes)))
return failure();
}
auto promoted = this->getTypeConverter()->promoteOperands(
callOp.getLoc(), /*opOperands=*/callOp->getOperands(),
adaptor.getOperands(), rewriter);
auto newOp = rewriter.create<LLVM::CallOp>(
callOp.getLoc(), packedResult ? TypeRange(packedResult) : TypeRange(),
promoted, callOp->getAttrs());
SmallVector<Value, 4> results;
if (numResults < 2) {
// If < 2 results, packing did not do anything and we can just return.
results.append(newOp.result_begin(), newOp.result_end());
} else {
// Otherwise, it had been converted to an operation producing a structure.
// Extract individual results from the structure and return them as list.
results.reserve(numResults);
for (unsigned i = 0; i < numResults; ++i) {
auto type =
this->typeConverter->convertType(callOp.getResult(i).getType());
results.push_back(rewriter.create<LLVM::ExtractValueOp>(
callOp.getLoc(), type, newOp->getResult(0),
rewriter.getI64ArrayAttr(i)));
}
}
if (this->getTypeConverter()->getOptions().useBarePtrCallConv) {
// For the bare-ptr calling convention, promote memref results to
// descriptors.
assert(results.size() == resultTypes.size() &&
"The number of arguments and types doesn't match");
this->getTypeConverter()->promoteBarePtrsToDescriptors(
rewriter, callOp.getLoc(), resultTypes, results);
} else if (failed(this->copyUnrankedDescriptors(rewriter, callOp.getLoc(),
resultTypes, results,
/*toDynamic=*/false))) {
return failure();
}
rewriter.replaceOp(callOp, results);
return success();
}
};
struct CallOpLowering : public CallOpInterfaceLowering<CallOp> {
using Super::Super;
};
struct CallIndirectOpLowering : public CallOpInterfaceLowering<CallIndirectOp> {
using Super::Super;
};
struct UnrealizedConversionCastOpLowering
: public ConvertOpToLLVMPattern<UnrealizedConversionCastOp> {
using ConvertOpToLLVMPattern<
UnrealizedConversionCastOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(UnrealizedConversionCastOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
SmallVector<Type> convertedTypes;
if (succeeded(typeConverter->convertTypes(op.outputs().getTypes(),
convertedTypes)) &&
convertedTypes == adaptor.inputs().getTypes()) {
rewriter.replaceOp(op, adaptor.inputs());
return success();
}
convertedTypes.clear();
if (succeeded(typeConverter->convertTypes(adaptor.inputs().getTypes(),
convertedTypes)) &&
convertedTypes == op.outputs().getType()) {
rewriter.replaceOp(op, adaptor.inputs());
return success();
}
return failure();
}
};
struct RankOpLowering : public ConvertOpToLLVMPattern<RankOp> {
using ConvertOpToLLVMPattern<RankOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(RankOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Location loc = op.getLoc();
Type operandType = op.getMemrefOrTensor().getType();
if (auto unrankedMemRefType = operandType.dyn_cast<UnrankedMemRefType>()) {
UnrankedMemRefDescriptor desc(adaptor.getMemrefOrTensor());
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();
}
};
// 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();
}
};
// Base class for LLVM IR lowering terminator operations with successors.
template <typename SourceOp, typename TargetOp>
struct OneToOneLLVMTerminatorLowering
: public ConvertOpToLLVMPattern<SourceOp> {
using ConvertOpToLLVMPattern<SourceOp>::ConvertOpToLLVMPattern;
using Super = OneToOneLLVMTerminatorLowering<SourceOp, TargetOp>;
LogicalResult
matchAndRewrite(SourceOp op, typename SourceOp::Adaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
rewriter.replaceOpWithNewOp<TargetOp>(op, adaptor.getOperands(),
op->getSuccessors(), op->getAttrs());
return success();
}
};
// Special lowering pattern for `ReturnOps`. Unlike all other operations,
// `ReturnOp` interacts with the function signature and must have as many
// operands as the function has return values. Because in LLVM IR, functions
// can only return 0 or 1 value, we pack multiple values into a structure type.
// Emit `UndefOp` followed by `InsertValueOp`s to create such structure if
// necessary before returning it
struct ReturnOpLowering : public ConvertOpToLLVMPattern<ReturnOp> {
using ConvertOpToLLVMPattern<ReturnOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(ReturnOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Location loc = op.getLoc();
unsigned numArguments = op.getNumOperands();
SmallVector<Value, 4> updatedOperands;
if (getTypeConverter()->getOptions().useBarePtrCallConv) {
// For the bare-ptr calling convention, extract the aligned pointer to
// be returned from the memref descriptor.
for (auto it : llvm::zip(op->getOperands(), adaptor.getOperands())) {
Type oldTy = std::get<0>(it).getType();
Value newOperand = std::get<1>(it);
if (oldTy.isa<MemRefType>()) {
MemRefDescriptor memrefDesc(newOperand);
newOperand = memrefDesc.alignedPtr(rewriter, loc);
} else if (oldTy.isa<UnrankedMemRefType>()) {
// Unranked memref is not supported in the bare pointer calling
// convention.
return failure();
}
updatedOperands.push_back(newOperand);
}
} else {
updatedOperands = llvm::to_vector<4>(adaptor.getOperands());
(void)copyUnrankedDescriptors(rewriter, loc, op.getOperands().getTypes(),
updatedOperands,
/*toDynamic=*/true);
}
// If ReturnOp has 0 or 1 operand, create it and return immediately.
if (numArguments == 0) {
rewriter.replaceOpWithNewOp<LLVM::ReturnOp>(op, TypeRange(), ValueRange(),
op->getAttrs());
return success();
}
if (numArguments == 1) {
rewriter.replaceOpWithNewOp<LLVM::ReturnOp>(
op, TypeRange(), updatedOperands, op->getAttrs());
return success();
}
// Otherwise, we need to pack the arguments into an LLVM struct type before
// returning.
auto packedType = getTypeConverter()->packFunctionResults(
llvm::to_vector<4>(op.getOperandTypes()));
Value packed = rewriter.create<LLVM::UndefOp>(loc, packedType);
for (unsigned i = 0; i < numArguments; ++i) {
packed = rewriter.create<LLVM::InsertValueOp>(
loc, packedType, packed, updatedOperands[i],
rewriter.getI64ArrayAttr(i));
}
rewriter.replaceOpWithNewOp<LLVM::ReturnOp>(op, TypeRange(), packed,
op->getAttrs());
return success();
}
};
// FIXME: this should be tablegen'ed as well.
struct BranchOpLowering
: public OneToOneLLVMTerminatorLowering<BranchOp, LLVM::BrOp> {
using Super::Super;
};
struct CondBranchOpLowering
: public OneToOneLLVMTerminatorLowering<CondBranchOp, LLVM::CondBrOp> {
using Super::Super;
};
struct SwitchOpLowering
: public OneToOneLLVMTerminatorLowering<SwitchOp, LLVM::SwitchOp> {
using Super::Super;
};
// The Splat operation is lowered to an insertelement + a shufflevector
// operation. Splat to only 0-d and 1-d vector result types are lowered.
struct SplatOpLowering : public ConvertOpToLLVMPattern<SplatOp> {
using ConvertOpToLLVMPattern<SplatOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(SplatOp splatOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
VectorType resultType = splatOp.getType().dyn_cast<VectorType>();
if (!resultType || resultType.getRank() > 1)
return failure();
// First insert it into an undef vector so we can shuffle it.
auto vectorType = typeConverter->convertType(splatOp.getType());
Value undef = rewriter.create<LLVM::UndefOp>(splatOp.getLoc(), vectorType);
auto zero = rewriter.create<LLVM::ConstantOp>(
splatOp.getLoc(),
typeConverter->convertType(rewriter.getIntegerType(32)),
rewriter.getZeroAttr(rewriter.getIntegerType(32)));
// For 0-d vector, we simply do `insertelement`.
if (resultType.getRank() == 0) {
rewriter.replaceOpWithNewOp<LLVM::InsertElementOp>(
splatOp, vectorType, undef, adaptor.getInput(), zero);
return success();
}
// For 1-d vector, we additionally do a `vectorshuffle`.
auto v = rewriter.create<LLVM::InsertElementOp>(
splatOp.getLoc(), vectorType, undef, adaptor.getInput(), zero);
int64_t width = splatOp.getType().cast<VectorType>().getDimSize(0);
SmallVector<int32_t, 4> zeroValues(width, 0);
// Shuffle the value across the desired number of elements.
ArrayAttr zeroAttrs = rewriter.getI32ArrayAttr(zeroValues);
rewriter.replaceOpWithNewOp<LLVM::ShuffleVectorOp>(splatOp, v, undef,
zeroAttrs);
return success();
}
};
// The Splat operation is lowered to an insertelement + a shufflevector
// operation. Splat to only 2+-d vector result types are lowered by the
// SplatNdOpLowering, the 1-d case is handled by SplatOpLowering.
struct SplatNdOpLowering : public ConvertOpToLLVMPattern<SplatOp> {
using ConvertOpToLLVMPattern<SplatOp>::ConvertOpToLLVMPattern;
LogicalResult
matchAndRewrite(SplatOp splatOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
VectorType resultType = splatOp.getType().dyn_cast<VectorType>();
if (!resultType || resultType.getRank() <= 1)
return failure();
// First insert it into an undef vector so we can shuffle it.
auto loc = splatOp.getLoc();
auto vectorTypeInfo =
LLVM::detail::extractNDVectorTypeInfo(resultType, *getTypeConverter());
auto llvmNDVectorTy = vectorTypeInfo.llvmNDVectorTy;
auto llvm1DVectorTy = vectorTypeInfo.llvm1DVectorTy;
if (!llvmNDVectorTy || !llvm1DVectorTy)
return failure();
// Construct returned value.
Value desc = rewriter.create<LLVM::UndefOp>(loc, llvmNDVectorTy);
// Construct a 1-D vector with the splatted value that we insert in all the
// places within the returned descriptor.
Value vdesc = rewriter.create<LLVM::UndefOp>(loc, llvm1DVectorTy);
auto zero = rewriter.create<LLVM::ConstantOp>(
loc, typeConverter->convertType(rewriter.getIntegerType(32)),
rewriter.getZeroAttr(rewriter.getIntegerType(32)));
Value v = rewriter.create<LLVM::InsertElementOp>(loc, llvm1DVectorTy, vdesc,
adaptor.getInput(), zero);
// Shuffle the value across the desired number of elements.
int64_t width = resultType.getDimSize(resultType.getRank() - 1);
SmallVector<int32_t, 4> zeroValues(width, 0);
ArrayAttr zeroAttrs = rewriter.getI32ArrayAttr(zeroValues);
v = rewriter.create<LLVM::ShuffleVectorOp>(loc, v, v, zeroAttrs);
// Iterate of linear index, convert to coords space and insert splatted 1-D
// vector in each position.
nDVectorIterate(vectorTypeInfo, rewriter, [&](ArrayAttr position) {
desc = rewriter.create<LLVM::InsertValueOp>(loc, llvmNDVectorTy, desc, v,
position);
});
rewriter.replaceOp(splatOp, desc);
return success();
}
};
} // namespace
/// Try to match the kind of a std.atomic_rmw to determine whether to use a
/// lowering to llvm.atomicrmw or fallback to llvm.cmpxchg.
static Optional<LLVM::AtomicBinOp> matchSimpleAtomicOp(AtomicRMWOp atomicOp) {
switch (atomicOp.getKind()) {
case AtomicRMWKind::addf:
return LLVM::AtomicBinOp::fadd;
case AtomicRMWKind::addi:
return LLVM::AtomicBinOp::add;
case AtomicRMWKind::assign:
return LLVM::AtomicBinOp::xchg;
case AtomicRMWKind::maxs:
return LLVM::AtomicBinOp::max;
case AtomicRMWKind::maxu:
return LLVM::AtomicBinOp::umax;
case AtomicRMWKind::mins:
return LLVM::AtomicBinOp::min;
case AtomicRMWKind::minu:
return LLVM::AtomicBinOp::umin;
default:
return llvm::None;
}
llvm_unreachable("Invalid AtomicRMWKind");
}
namespace {
struct AtomicRMWOpLowering : public LoadStoreOpLowering<AtomicRMWOp> {
using Base::Base;
LogicalResult
matchAndRewrite(AtomicRMWOp atomicOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
if (failed(match(atomicOp)))
return failure();
auto maybeKind = matchSimpleAtomicOp(atomicOp);
if (!maybeKind)
return failure();
auto resultType = adaptor.getValue().getType();
auto memRefType = atomicOp.getMemRefType();
auto dataPtr =
getStridedElementPtr(atomicOp.getLoc(), memRefType, adaptor.getMemref(),
adaptor.getIndices(), rewriter);
rewriter.replaceOpWithNewOp<LLVM::AtomicRMWOp>(
atomicOp, resultType, *maybeKind, dataPtr, adaptor.getValue(),
LLVM::AtomicOrdering::acq_rel);
return success();
}
};
/// 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> |
/// | br loop(%loaded) |
/// +---------------------------------+
/// |
/// -------| |
/// | v v
/// | +--------------------------------+
/// | | loop(%loaded): |
/// | | <body contents> |
/// | | %pair = cmpxchg |
/// | | %ok = %pair[0] |
/// | | %new = %pair[1] |
/// | | cond_br %ok, end, loop(%new) |
/// | +--------------------------------+
/// | | |
/// |----------- |
/// v
/// +--------------------------------+
/// | end: |
/// | <code after the AtomicRMWOp> |
/// +--------------------------------+
///
struct GenericAtomicRMWOpLowering
: public LoadStoreOpLowering<GenericAtomicRMWOp> {
using Base::Base;
LogicalResult
matchAndRewrite(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);
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.getMemref().getType().cast<MemRefType>();
auto dataPtr = getStridedElementPtr(loc, memRefType, adaptor.getMemref(),
adaptor.getIndices(), 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);
}
};
} // namespace
void mlir::populateStdToLLVMFuncOpConversionPattern(
LLVMTypeConverter &converter, RewritePatternSet &patterns) {
if (converter.getOptions().useBarePtrCallConv)
patterns.add<BarePtrFuncOpConversion>(converter);
else
patterns.add<FuncOpConversion>(converter);
}
void mlir::populateStdToLLVMConversionPatterns(LLVMTypeConverter &converter,
RewritePatternSet &patterns) {
populateStdToLLVMFuncOpConversionPattern(converter, patterns);
// clang-format off
patterns.add<
AssertOpLowering,
AtomicRMWOpLowering,
BranchOpLowering,
CallIndirectOpLowering,
CallOpLowering,
CondBranchOpLowering,
ConstantOpLowering,
GenericAtomicRMWOpLowering,
RankOpLowering,
ReturnOpLowering,
SelectOpLowering,
SplatOpLowering,
SplatNdOpLowering,
SwitchOpLowering>(converter);
// clang-format on
}
namespace {
/// A pass converting MLIR operations into the LLVM IR dialect.
struct LLVMLoweringPass : public ConvertStandardToLLVMBase<LLVMLoweringPass> {
LLVMLoweringPass() = default;
LLVMLoweringPass(bool useBarePtrCallConv, bool emitCWrappers,
unsigned indexBitwidth, bool useAlignedAlloc,
const llvm::DataLayout &dataLayout) {
this->useBarePtrCallConv = useBarePtrCallConv;
this->emitCWrappers = emitCWrappers;
this->indexBitwidth = indexBitwidth;
this->dataLayout = dataLayout.getStringRepresentation();
}
/// Run the dialect converter on the module.
void runOnOperation() override {
if (useBarePtrCallConv && emitCWrappers) {
getOperation().emitError()
<< "incompatible conversion options: bare-pointer calling convention "
"and C wrapper emission";
signalPassFailure();
return;
}
if (failed(LLVM::LLVMDialect::verifyDataLayoutString(
this->dataLayout, [this](const Twine &message) {
getOperation().emitError() << message.str();
}))) {
signalPassFailure();
return;
}
ModuleOp m = getOperation();
const auto &dataLayoutAnalysis = getAnalysis<DataLayoutAnalysis>();
LowerToLLVMOptions options(&getContext(),
dataLayoutAnalysis.getAtOrAbove(m));
options.useBarePtrCallConv = useBarePtrCallConv;
options.emitCWrappers = emitCWrappers;
if (indexBitwidth != kDeriveIndexBitwidthFromDataLayout)
options.overrideIndexBitwidth(indexBitwidth);
options.dataLayout = llvm::DataLayout(this->dataLayout);
LLVMTypeConverter typeConverter(&getContext(), options,
&dataLayoutAnalysis);
RewritePatternSet patterns(&getContext());
populateStdToLLVMConversionPatterns(typeConverter, patterns);
arith::populateArithmeticToLLVMConversionPatterns(typeConverter, patterns);
LLVMConversionTarget target(getContext());
if (failed(applyPartialConversion(m, target, std::move(patterns))))
signalPassFailure();
m->setAttr(LLVM::LLVMDialect::getDataLayoutAttrName(),
StringAttr::get(m.getContext(), this->dataLayout));
}
};
} // end namespace
std::unique_ptr<OperationPass<ModuleOp>> mlir::createLowerToLLVMPass() {
return std::make_unique<LLVMLoweringPass>();
}
std::unique_ptr<OperationPass<ModuleOp>>
mlir::createLowerToLLVMPass(const LowerToLLVMOptions &options) {
auto allocLowering = options.allocLowering;
// There is no way to provide additional patterns for pass, so
// AllocLowering::None will always fail.
assert(allocLowering != LowerToLLVMOptions::AllocLowering::None &&
"LLVMLoweringPass doesn't support AllocLowering::None");
bool useAlignedAlloc =
(allocLowering == LowerToLLVMOptions::AllocLowering::AlignedAlloc);
return std::make_unique<LLVMLoweringPass>(
options.useBarePtrCallConv, options.emitCWrappers,
options.getIndexBitwidth(), useAlignedAlloc, options.dataLayout);
}