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//===- ModuleTranslation.cpp - MLIR to LLVM 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 the translation between an MLIR LLVM dialect module and
// the corresponding LLVMIR module. It only handles core LLVM IR operations.
//
//===----------------------------------------------------------------------===//
#include "mlir/Target/LLVMIR/ModuleTranslation.h"
#include "DebugTranslation.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/OpenMP/OpenMPDialect.h"
#include "mlir/IR/Attributes.h"
#include "mlir/IR/BuiltinOps.h"
#include "mlir/IR/BuiltinTypes.h"
#include "mlir/IR/RegionGraphTraits.h"
#include "mlir/Support/LLVM.h"
#include "mlir/Target/LLVMIR/TypeTranslation.h"
#include "llvm/ADT/TypeSwitch.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Frontend/OpenMP/OMPIRBuilder.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
using namespace mlir;
using namespace mlir::LLVM;
using namespace mlir::LLVM::detail;
#include "mlir/Dialect/LLVMIR/LLVMConversionEnumsToLLVM.inc"
/// Builds a constant of a sequential LLVM type `type`, potentially containing
/// other sequential types recursively, from the individual constant values
/// provided in `constants`. `shape` contains the number of elements in nested
/// sequential types. Reports errors at `loc` and returns nullptr on error.
static llvm::Constant *
buildSequentialConstant(ArrayRef<llvm::Constant *> &constants,
ArrayRef<int64_t> shape, llvm::Type *type,
Location loc) {
if (shape.empty()) {
llvm::Constant *result = constants.front();
constants = constants.drop_front();
return result;
}
llvm::Type *elementType;
if (auto *arrayTy = dyn_cast<llvm::ArrayType>(type)) {
elementType = arrayTy->getElementType();
} else if (auto *vectorTy = dyn_cast<llvm::VectorType>(type)) {
elementType = vectorTy->getElementType();
} else {
emitError(loc) << "expected sequential LLVM types wrapping a scalar";
return nullptr;
}
SmallVector<llvm::Constant *, 8> nested;
nested.reserve(shape.front());
for (int64_t i = 0; i < shape.front(); ++i) {
nested.push_back(buildSequentialConstant(constants, shape.drop_front(),
elementType, loc));
if (!nested.back())
return nullptr;
}
if (shape.size() == 1 && type->isVectorTy())
return llvm::ConstantVector::get(nested);
return llvm::ConstantArray::get(
llvm::ArrayType::get(elementType, shape.front()), nested);
}
/// Returns the first non-sequential type nested in sequential types.
static llvm::Type *getInnermostElementType(llvm::Type *type) {
do {
if (auto *arrayTy = dyn_cast<llvm::ArrayType>(type)) {
type = arrayTy->getElementType();
} else if (auto *vectorTy = dyn_cast<llvm::VectorType>(type)) {
type = vectorTy->getElementType();
} else {
return type;
}
} while (1);
}
/// Create an LLVM IR constant of `llvmType` from the MLIR attribute `attr`.
/// This currently supports integer, floating point, splat and dense element
/// attributes and combinations thereof. In case of error, report it to `loc`
/// and return nullptr.
llvm::Constant *ModuleTranslation::getLLVMConstant(llvm::Type *llvmType,
Attribute attr,
Location loc) {
if (!attr)
return llvm::UndefValue::get(llvmType);
if (llvmType->isStructTy()) {
emitError(loc, "struct types are not supported in constants");
return nullptr;
}
// For integer types, we allow a mismatch in sizes as the index type in
// MLIR might have a different size than the index type in the LLVM module.
if (auto intAttr = attr.dyn_cast<IntegerAttr>())
return llvm::ConstantInt::get(
llvmType,
intAttr.getValue().sextOrTrunc(llvmType->getIntegerBitWidth()));
if (auto floatAttr = attr.dyn_cast<FloatAttr>())
return llvm::ConstantFP::get(llvmType, floatAttr.getValue());
if (auto funcAttr = attr.dyn_cast<FlatSymbolRefAttr>())
return llvm::ConstantExpr::getBitCast(
functionMapping.lookup(funcAttr.getValue()), llvmType);
if (auto splatAttr = attr.dyn_cast<SplatElementsAttr>()) {
llvm::Type *elementType;
uint64_t numElements;
if (auto *arrayTy = dyn_cast<llvm::ArrayType>(llvmType)) {
elementType = arrayTy->getElementType();
numElements = arrayTy->getNumElements();
} else {
auto *vectorTy = cast<llvm::FixedVectorType>(llvmType);
elementType = vectorTy->getElementType();
numElements = vectorTy->getNumElements();
}
// Splat value is a scalar. Extract it only if the element type is not
// another sequence type. The recursion terminates because each step removes
// one outer sequential type.
bool elementTypeSequential =
isa<llvm::ArrayType, llvm::VectorType>(elementType);
llvm::Constant *child = getLLVMConstant(
elementType,
elementTypeSequential ? splatAttr : splatAttr.getSplatValue(), loc);
if (!child)
return nullptr;
if (llvmType->isVectorTy())
return llvm::ConstantVector::getSplat(
llvm::ElementCount::get(numElements, /*Scalable=*/false), child);
if (llvmType->isArrayTy()) {
auto *arrayType = llvm::ArrayType::get(elementType, numElements);
SmallVector<llvm::Constant *, 8> constants(numElements, child);
return llvm::ConstantArray::get(arrayType, constants);
}
}
if (auto elementsAttr = attr.dyn_cast<ElementsAttr>()) {
assert(elementsAttr.getType().hasStaticShape());
assert(elementsAttr.getNumElements() != 0 &&
"unexpected empty elements attribute");
assert(!elementsAttr.getType().getShape().empty() &&
"unexpected empty elements attribute shape");
SmallVector<llvm::Constant *, 8> constants;
constants.reserve(elementsAttr.getNumElements());
llvm::Type *innermostType = getInnermostElementType(llvmType);
for (auto n : elementsAttr.getValues<Attribute>()) {
constants.push_back(getLLVMConstant(innermostType, n, loc));
if (!constants.back())
return nullptr;
}
ArrayRef<llvm::Constant *> constantsRef = constants;
llvm::Constant *result = buildSequentialConstant(
constantsRef, elementsAttr.getType().getShape(), llvmType, loc);
assert(constantsRef.empty() && "did not consume all elemental constants");
return result;
}
if (auto stringAttr = attr.dyn_cast<StringAttr>()) {
return llvm::ConstantDataArray::get(
llvmModule->getContext(), ArrayRef<char>{stringAttr.getValue().data(),
stringAttr.getValue().size()});
}
emitError(loc, "unsupported constant value");
return nullptr;
}
/// Convert MLIR integer comparison predicate to LLVM IR comparison predicate.
static llvm::CmpInst::Predicate getLLVMCmpPredicate(ICmpPredicate p) {
switch (p) {
case LLVM::ICmpPredicate::eq:
return llvm::CmpInst::Predicate::ICMP_EQ;
case LLVM::ICmpPredicate::ne:
return llvm::CmpInst::Predicate::ICMP_NE;
case LLVM::ICmpPredicate::slt:
return llvm::CmpInst::Predicate::ICMP_SLT;
case LLVM::ICmpPredicate::sle:
return llvm::CmpInst::Predicate::ICMP_SLE;
case LLVM::ICmpPredicate::sgt:
return llvm::CmpInst::Predicate::ICMP_SGT;
case LLVM::ICmpPredicate::sge:
return llvm::CmpInst::Predicate::ICMP_SGE;
case LLVM::ICmpPredicate::ult:
return llvm::CmpInst::Predicate::ICMP_ULT;
case LLVM::ICmpPredicate::ule:
return llvm::CmpInst::Predicate::ICMP_ULE;
case LLVM::ICmpPredicate::ugt:
return llvm::CmpInst::Predicate::ICMP_UGT;
case LLVM::ICmpPredicate::uge:
return llvm::CmpInst::Predicate::ICMP_UGE;
}
llvm_unreachable("incorrect comparison predicate");
}
static llvm::CmpInst::Predicate getLLVMCmpPredicate(FCmpPredicate p) {
switch (p) {
case LLVM::FCmpPredicate::_false:
return llvm::CmpInst::Predicate::FCMP_FALSE;
case LLVM::FCmpPredicate::oeq:
return llvm::CmpInst::Predicate::FCMP_OEQ;
case LLVM::FCmpPredicate::ogt:
return llvm::CmpInst::Predicate::FCMP_OGT;
case LLVM::FCmpPredicate::oge:
return llvm::CmpInst::Predicate::FCMP_OGE;
case LLVM::FCmpPredicate::olt:
return llvm::CmpInst::Predicate::FCMP_OLT;
case LLVM::FCmpPredicate::ole:
return llvm::CmpInst::Predicate::FCMP_OLE;
case LLVM::FCmpPredicate::one:
return llvm::CmpInst::Predicate::FCMP_ONE;
case LLVM::FCmpPredicate::ord:
return llvm::CmpInst::Predicate::FCMP_ORD;
case LLVM::FCmpPredicate::ueq:
return llvm::CmpInst::Predicate::FCMP_UEQ;
case LLVM::FCmpPredicate::ugt:
return llvm::CmpInst::Predicate::FCMP_UGT;
case LLVM::FCmpPredicate::uge:
return llvm::CmpInst::Predicate::FCMP_UGE;
case LLVM::FCmpPredicate::ult:
return llvm::CmpInst::Predicate::FCMP_ULT;
case LLVM::FCmpPredicate::ule:
return llvm::CmpInst::Predicate::FCMP_ULE;
case LLVM::FCmpPredicate::une:
return llvm::CmpInst::Predicate::FCMP_UNE;
case LLVM::FCmpPredicate::uno:
return llvm::CmpInst::Predicate::FCMP_UNO;
case LLVM::FCmpPredicate::_true:
return llvm::CmpInst::Predicate::FCMP_TRUE;
}
llvm_unreachable("incorrect comparison predicate");
}
static llvm::AtomicRMWInst::BinOp getLLVMAtomicBinOp(AtomicBinOp op) {
switch (op) {
case LLVM::AtomicBinOp::xchg:
return llvm::AtomicRMWInst::BinOp::Xchg;
case LLVM::AtomicBinOp::add:
return llvm::AtomicRMWInst::BinOp::Add;
case LLVM::AtomicBinOp::sub:
return llvm::AtomicRMWInst::BinOp::Sub;
case LLVM::AtomicBinOp::_and:
return llvm::AtomicRMWInst::BinOp::And;
case LLVM::AtomicBinOp::nand:
return llvm::AtomicRMWInst::BinOp::Nand;
case LLVM::AtomicBinOp::_or:
return llvm::AtomicRMWInst::BinOp::Or;
case LLVM::AtomicBinOp::_xor:
return llvm::AtomicRMWInst::BinOp::Xor;
case LLVM::AtomicBinOp::max:
return llvm::AtomicRMWInst::BinOp::Max;
case LLVM::AtomicBinOp::min:
return llvm::AtomicRMWInst::BinOp::Min;
case LLVM::AtomicBinOp::umax:
return llvm::AtomicRMWInst::BinOp::UMax;
case LLVM::AtomicBinOp::umin:
return llvm::AtomicRMWInst::BinOp::UMin;
case LLVM::AtomicBinOp::fadd:
return llvm::AtomicRMWInst::BinOp::FAdd;
case LLVM::AtomicBinOp::fsub:
return llvm::AtomicRMWInst::BinOp::FSub;
}
llvm_unreachable("incorrect atomic binary operator");
}
static llvm::AtomicOrdering getLLVMAtomicOrdering(AtomicOrdering ordering) {
switch (ordering) {
case LLVM::AtomicOrdering::not_atomic:
return llvm::AtomicOrdering::NotAtomic;
case LLVM::AtomicOrdering::unordered:
return llvm::AtomicOrdering::Unordered;
case LLVM::AtomicOrdering::monotonic:
return llvm::AtomicOrdering::Monotonic;
case LLVM::AtomicOrdering::acquire:
return llvm::AtomicOrdering::Acquire;
case LLVM::AtomicOrdering::release:
return llvm::AtomicOrdering::Release;
case LLVM::AtomicOrdering::acq_rel:
return llvm::AtomicOrdering::AcquireRelease;
case LLVM::AtomicOrdering::seq_cst:
return llvm::AtomicOrdering::SequentiallyConsistent;
}
llvm_unreachable("incorrect atomic ordering");
}
ModuleTranslation::ModuleTranslation(Operation *module,
std::unique_ptr<llvm::Module> llvmModule)
: mlirModule(module), llvmModule(std::move(llvmModule)),
debugTranslation(
std::make_unique<DebugTranslation>(module, *this->llvmModule)),
ompDialect(module->getContext()->getLoadedDialect("omp")),
typeTranslator(this->llvmModule->getContext()) {
assert(satisfiesLLVMModule(mlirModule) &&
"mlirModule should honor LLVM's module semantics.");
}
ModuleTranslation::~ModuleTranslation() {
if (ompBuilder)
ompBuilder->finalize();
}
/// Get the SSA value passed to the current block from the terminator operation
/// of its predecessor.
static Value getPHISourceValue(Block *current, Block *pred,
unsigned numArguments, unsigned index) {
Operation &terminator = *pred->getTerminator();
if (isa<LLVM::BrOp>(terminator))
return terminator.getOperand(index);
// For conditional branches, we need to check if the current block is reached
// through the "true" or the "false" branch and take the relevant operands.
auto condBranchOp = dyn_cast<LLVM::CondBrOp>(terminator);
assert(condBranchOp &&
"only branch operations can be terminators of a block that "
"has successors");
assert((condBranchOp.getSuccessor(0) != condBranchOp.getSuccessor(1)) &&
"successors with arguments in LLVM conditional branches must be "
"different blocks");
return condBranchOp.getSuccessor(0) == current
? condBranchOp.trueDestOperands()[index]
: condBranchOp.falseDestOperands()[index];
}
/// Connect the PHI nodes to the results of preceding blocks.
template <typename T>
static void
connectPHINodes(T &func, const DenseMap<Value, llvm::Value *> &valueMapping,
const DenseMap<Block *, llvm::BasicBlock *> &blockMapping) {
// Skip the first block, it cannot be branched to and its arguments correspond
// to the arguments of the LLVM function.
for (auto it = std::next(func.begin()), eit = func.end(); it != eit; ++it) {
Block *bb = &*it;
llvm::BasicBlock *llvmBB = blockMapping.lookup(bb);
auto phis = llvmBB->phis();
auto numArguments = bb->getNumArguments();
assert(numArguments == std::distance(phis.begin(), phis.end()));
for (auto &numberedPhiNode : llvm::enumerate(phis)) {
auto &phiNode = numberedPhiNode.value();
unsigned index = numberedPhiNode.index();
for (auto *pred : bb->getPredecessors()) {
phiNode.addIncoming(valueMapping.lookup(getPHISourceValue(
bb, pred, numArguments, index)),
blockMapping.lookup(pred));
}
}
}
}
/// Sort function blocks topologically.
template <typename T>
static llvm::SetVector<Block *> topologicalSort(T &f) {
// For each block that has not been visited yet (i.e. that has no
// predecessors), add it to the list as well as its successors.
llvm::SetVector<Block *> blocks;
for (Block &b : f) {
if (blocks.count(&b) == 0) {
llvm::ReversePostOrderTraversal<Block *> traversal(&b);
blocks.insert(traversal.begin(), traversal.end());
}
}
assert(blocks.size() == f.getBlocks().size() && "some blocks are not sorted");
return blocks;
}
/// Convert the OpenMP parallel Operation to LLVM IR.
LogicalResult
ModuleTranslation::convertOmpParallel(Operation &opInst,
llvm::IRBuilder<> &builder) {
using InsertPointTy = llvm::OpenMPIRBuilder::InsertPointTy;
// TODO: support error propagation in OpenMPIRBuilder and use it instead of
// relying on captured variables.
LogicalResult bodyGenStatus = success();
auto bodyGenCB = [&](InsertPointTy allocaIP, InsertPointTy codeGenIP,
llvm::BasicBlock &continuationIP) {
llvm::LLVMContext &llvmContext = llvmModule->getContext();
llvm::BasicBlock *codeGenIPBB = codeGenIP.getBlock();
llvm::Instruction *codeGenIPBBTI = codeGenIPBB->getTerminator();
ompContinuationIPStack.push_back(&continuationIP);
// ParallelOp has only `1` region associated with it.
auto &region = cast<omp::ParallelOp>(opInst).getRegion();
for (auto &bb : region) {
auto *llvmBB = llvm::BasicBlock::Create(
llvmContext, "omp.par.region", codeGenIP.getBlock()->getParent());
blockMapping[&bb] = llvmBB;
}
convertOmpOpRegions(region, valueMapping, blockMapping, codeGenIPBBTI,
continuationIP, builder, bodyGenStatus);
ompContinuationIPStack.pop_back();
};
// TODO: Perform appropriate actions according to the data-sharing
// attribute (shared, private, firstprivate, ...) of variables.
// Currently defaults to shared.
auto privCB = [&](InsertPointTy allocaIP, InsertPointTy codeGenIP,
llvm::Value &, llvm::Value &vPtr,
llvm::Value *&replacementValue) -> InsertPointTy {
replacementValue = &vPtr;
return codeGenIP;
};
// TODO: Perform finalization actions for variables. This has to be
// called for variables which have destructors/finalizers.
auto finiCB = [&](InsertPointTy codeGenIP) {};
llvm::Value *ifCond = nullptr;
if (auto ifExprVar = cast<omp::ParallelOp>(opInst).if_expr_var())
ifCond = valueMapping.lookup(ifExprVar);
llvm::Value *numThreads = nullptr;
if (auto numThreadsVar = cast<omp::ParallelOp>(opInst).num_threads_var())
numThreads = valueMapping.lookup(numThreadsVar);
llvm::omp::ProcBindKind pbKind = llvm::omp::OMP_PROC_BIND_default;
if (auto bind = cast<omp::ParallelOp>(opInst).proc_bind_val())
pbKind = llvm::omp::getProcBindKind(bind.getValue());
// TODO: Is the Parallel construct cancellable?
bool isCancellable = false;
// TODO: Determine the actual alloca insertion point, e.g., the function
// entry or the alloca insertion point as provided by the body callback
// above.
llvm::OpenMPIRBuilder::InsertPointTy allocaIP(builder.saveIP());
if (failed(bodyGenStatus))
return failure();
builder.restoreIP(
ompBuilder->createParallel(builder, allocaIP, bodyGenCB, privCB, finiCB,
ifCond, numThreads, pbKind, isCancellable));
return success();
}
void ModuleTranslation::convertOmpOpRegions(
Region &region, DenseMap<Value, llvm::Value *> &valueMapping,
DenseMap<Block *, llvm::BasicBlock *> &blockMapping,
llvm::Instruction *codeGenIPBBTI, llvm::BasicBlock &continuationIP,
llvm::IRBuilder<> &builder, LogicalResult &bodyGenStatus) {
// Convert blocks one by one in topological order to ensure
// defs are converted before uses.
llvm::SetVector<Block *> blocks = topologicalSort(region);
for (auto indexedBB : llvm::enumerate(blocks)) {
Block *bb = indexedBB.value();
llvm::BasicBlock *curLLVMBB = blockMapping[bb];
if (bb->isEntryBlock()) {
assert(codeGenIPBBTI->getNumSuccessors() == 1 &&
"OpenMPIRBuilder provided entry block has multiple successors");
assert(codeGenIPBBTI->getSuccessor(0) == &continuationIP &&
"ContinuationIP is not the successor of OpenMPIRBuilder "
"provided entry block");
codeGenIPBBTI->setSuccessor(0, curLLVMBB);
}
if (failed(convertBlock(*bb, /*ignoreArguments=*/indexedBB.index() == 0))) {
bodyGenStatus = failure();
return;
}
}
// Finally, after all blocks have been traversed and values mapped,
// connect the PHI nodes to the results of preceding blocks.
connectPHINodes(region, valueMapping, blockMapping);
}
LogicalResult ModuleTranslation::convertOmpMaster(Operation &opInst,
llvm::IRBuilder<> &builder) {
using InsertPointTy = llvm::OpenMPIRBuilder::InsertPointTy;
// TODO: support error propagation in OpenMPIRBuilder and use it instead of
// relying on captured variables.
LogicalResult bodyGenStatus = success();
auto bodyGenCB = [&](InsertPointTy allocaIP, InsertPointTy codeGenIP,
llvm::BasicBlock &continuationIP) {
llvm::LLVMContext &llvmContext = llvmModule->getContext();
llvm::BasicBlock *codeGenIPBB = codeGenIP.getBlock();
llvm::Instruction *codeGenIPBBTI = codeGenIPBB->getTerminator();
ompContinuationIPStack.push_back(&continuationIP);
// MasterOp has only `1` region associated with it.
auto &region = cast<omp::MasterOp>(opInst).getRegion();
for (auto &bb : region) {
auto *llvmBB = llvm::BasicBlock::Create(
llvmContext, "omp.master.region", codeGenIP.getBlock()->getParent());
blockMapping[&bb] = llvmBB;
}
convertOmpOpRegions(region, valueMapping, blockMapping, codeGenIPBBTI,
continuationIP, builder, bodyGenStatus);
ompContinuationIPStack.pop_back();
};
// TODO: Perform finalization actions for variables. This has to be
// called for variables which have destructors/finalizers.
auto finiCB = [&](InsertPointTy codeGenIP) {};
builder.restoreIP(ompBuilder->createMaster(builder, bodyGenCB, finiCB));
return success();
}
/// Given an OpenMP MLIR operation, create the corresponding LLVM IR
/// (including OpenMP runtime calls).
LogicalResult
ModuleTranslation::convertOmpOperation(Operation &opInst,
llvm::IRBuilder<> &builder) {
if (!ompBuilder) {
ompBuilder = std::make_unique<llvm::OpenMPIRBuilder>(*llvmModule);
ompBuilder->initialize();
}
return llvm::TypeSwitch<Operation *, LogicalResult>(&opInst)
.Case([&](omp::BarrierOp) {
ompBuilder->createBarrier(builder.saveIP(), llvm::omp::OMPD_barrier);
return success();
})
.Case([&](omp::TaskwaitOp) {
ompBuilder->createTaskwait(builder.saveIP());
return success();
})
.Case([&](omp::TaskyieldOp) {
ompBuilder->createTaskyield(builder.saveIP());
return success();
})
.Case([&](omp::FlushOp) {
// No support in Openmp runtime function (__kmpc_flush) to accept
// the argument list.
// OpenMP standard states the following:
// "An implementation may implement a flush with a list by ignoring
// the list, and treating it the same as a flush without a list."
//
// The argument list is discarded so that, flush with a list is treated
// same as a flush without a list.
ompBuilder->createFlush(builder.saveIP());
return success();
})
.Case([&](omp::TerminatorOp) {
builder.CreateBr(ompContinuationIPStack.back());
return success();
})
.Case(
[&](omp::ParallelOp) { return convertOmpParallel(opInst, builder); })
.Case([&](omp::MasterOp) { return convertOmpMaster(opInst, builder); })
.Default([&](Operation *inst) {
return inst->emitError("unsupported OpenMP operation: ")
<< inst->getName();
});
}
/// Given a single MLIR operation, create the corresponding LLVM IR operation
/// using the `builder`. LLVM IR Builder does not have a generic interface so
/// this has to be a long chain of `if`s calling different functions with a
/// different number of arguments.
LogicalResult ModuleTranslation::convertOperation(Operation &opInst,
llvm::IRBuilder<> &builder) {
auto extractPosition = [](ArrayAttr attr) {
SmallVector<unsigned, 4> position;
position.reserve(attr.size());
for (Attribute v : attr)
position.push_back(v.cast<IntegerAttr>().getValue().getZExtValue());
return position;
};
#include "mlir/Dialect/LLVMIR/LLVMConversions.inc"
// Emit function calls. If the "callee" attribute is present, this is a
// direct function call and we also need to look up the remapped function
// itself. Otherwise, this is an indirect call and the callee is the first
// operand, look it up as a normal value. Return the llvm::Value representing
// the function result, which may be of llvm::VoidTy type.
auto convertCall = [this, &builder](Operation &op) -> llvm::Value * {
auto operands = lookupValues(op.getOperands());
ArrayRef<llvm::Value *> operandsRef(operands);
if (auto attr = op.getAttrOfType<FlatSymbolRefAttr>("callee")) {
return builder.CreateCall(functionMapping.lookup(attr.getValue()),
operandsRef);
} else {
auto *calleePtrType =
cast<llvm::PointerType>(operandsRef.front()->getType());
auto *calleeType =
cast<llvm::FunctionType>(calleePtrType->getElementType());
return builder.CreateCall(calleeType, operandsRef.front(),
operandsRef.drop_front());
}
};
// Emit calls. If the called function has a result, remap the corresponding
// value. Note that LLVM IR dialect CallOp has either 0 or 1 result.
if (isa<LLVM::CallOp>(opInst)) {
llvm::Value *result = convertCall(opInst);
if (opInst.getNumResults() != 0) {
valueMapping[opInst.getResult(0)] = result;
return success();
}
// Check that LLVM call returns void for 0-result functions.
return success(result->getType()->isVoidTy());
}
if (auto inlineAsmOp = dyn_cast<LLVM::InlineAsmOp>(opInst)) {
// TODO: refactor function type creation which usually occurs in std-LLVM
// conversion.
SmallVector<LLVM::LLVMType, 8> operandTypes;
operandTypes.reserve(inlineAsmOp.operands().size());
for (auto t : inlineAsmOp.operands().getTypes())
operandTypes.push_back(t.cast<LLVM::LLVMType>());
LLVM::LLVMType resultType;
if (inlineAsmOp.getNumResults() == 0) {
resultType = LLVM::LLVMType::getVoidTy(mlirModule->getContext());
} else {
assert(inlineAsmOp.getNumResults() == 1);
resultType = inlineAsmOp.getResultTypes()[0].cast<LLVM::LLVMType>();
}
auto ft = LLVM::LLVMType::getFunctionTy(resultType, operandTypes,
/*isVarArg=*/false);
llvm::InlineAsm *inlineAsmInst =
inlineAsmOp.asm_dialect().hasValue()
? llvm::InlineAsm::get(
static_cast<llvm::FunctionType *>(convertType(ft)),
inlineAsmOp.asm_string(), inlineAsmOp.constraints(),
inlineAsmOp.has_side_effects(), inlineAsmOp.is_align_stack(),
convertAsmDialectToLLVM(*inlineAsmOp.asm_dialect()))
: llvm::InlineAsm::get(
static_cast<llvm::FunctionType *>(convertType(ft)),
inlineAsmOp.asm_string(), inlineAsmOp.constraints(),
inlineAsmOp.has_side_effects(), inlineAsmOp.is_align_stack());
llvm::Value *result =
builder.CreateCall(inlineAsmInst, lookupValues(inlineAsmOp.operands()));
if (opInst.getNumResults() != 0)
valueMapping[opInst.getResult(0)] = result;
return success();
}
if (auto invOp = dyn_cast<LLVM::InvokeOp>(opInst)) {
auto operands = lookupValues(opInst.getOperands());
ArrayRef<llvm::Value *> operandsRef(operands);
if (auto attr = opInst.getAttrOfType<FlatSymbolRefAttr>("callee")) {
builder.CreateInvoke(functionMapping.lookup(attr.getValue()),
blockMapping[invOp.getSuccessor(0)],
blockMapping[invOp.getSuccessor(1)], operandsRef);
} else {
auto *calleePtrType =
cast<llvm::PointerType>(operandsRef.front()->getType());
auto *calleeType =
cast<llvm::FunctionType>(calleePtrType->getElementType());
builder.CreateInvoke(
calleeType, operandsRef.front(), blockMapping[invOp.getSuccessor(0)],
blockMapping[invOp.getSuccessor(1)], operandsRef.drop_front());
}
return success();
}
if (auto lpOp = dyn_cast<LLVM::LandingpadOp>(opInst)) {
llvm::Type *ty = convertType(lpOp.getType().cast<LLVMType>());
llvm::LandingPadInst *lpi =
builder.CreateLandingPad(ty, lpOp.getNumOperands());
// Add clauses
for (auto operand : lookupValues(lpOp.getOperands())) {
// All operands should be constant - checked by verifier
if (auto constOperand = dyn_cast<llvm::Constant>(operand))
lpi->addClause(constOperand);
}
valueMapping[lpOp.getResult()] = lpi;
return success();
}
// Emit branches. We need to look up the remapped blocks and ignore the block
// arguments that were transformed into PHI nodes.
if (auto brOp = dyn_cast<LLVM::BrOp>(opInst)) {
builder.CreateBr(blockMapping[brOp.getSuccessor()]);
return success();
}
if (auto condbrOp = dyn_cast<LLVM::CondBrOp>(opInst)) {
auto weights = condbrOp.branch_weights();
llvm::MDNode *branchWeights = nullptr;
if (weights) {
// Map weight attributes to LLVM metadata.
auto trueWeight =
weights.getValue().getValue(0).cast<IntegerAttr>().getInt();
auto falseWeight =
weights.getValue().getValue(1).cast<IntegerAttr>().getInt();
branchWeights =
llvm::MDBuilder(llvmModule->getContext())
.createBranchWeights(static_cast<uint32_t>(trueWeight),
static_cast<uint32_t>(falseWeight));
}
builder.CreateCondBr(valueMapping.lookup(condbrOp.getOperand(0)),
blockMapping[condbrOp.getSuccessor(0)],
blockMapping[condbrOp.getSuccessor(1)], branchWeights);
return success();
}
// Emit addressof. We need to look up the global value referenced by the
// operation and store it in the MLIR-to-LLVM value mapping. This does not
// emit any LLVM instruction.
if (auto addressOfOp = dyn_cast<LLVM::AddressOfOp>(opInst)) {
LLVM::GlobalOp global = addressOfOp.getGlobal();
LLVM::LLVMFuncOp function = addressOfOp.getFunction();
// The verifier should not have allowed this.
assert((global || function) &&
"referencing an undefined global or function");
valueMapping[addressOfOp.getResult()] =
global ? globalsMapping.lookup(global)
: functionMapping.lookup(function.getName());
return success();
}
if (ompDialect && opInst.getDialect() == ompDialect)
return convertOmpOperation(opInst, builder);
return opInst.emitError("unsupported or non-LLVM operation: ")
<< opInst.getName();
}
/// Convert block to LLVM IR. Unless `ignoreArguments` is set, emit PHI nodes
/// to define values corresponding to the MLIR block arguments. These nodes
/// are not connected to the source basic blocks, which may not exist yet.
LogicalResult ModuleTranslation::convertBlock(Block &bb, bool ignoreArguments) {
llvm::IRBuilder<> builder(blockMapping[&bb]);
auto *subprogram = builder.GetInsertBlock()->getParent()->getSubprogram();
// Before traversing operations, make block arguments available through
// value remapping and PHI nodes, but do not add incoming edges for the PHI
// nodes just yet: those values may be defined by this or following blocks.
// This step is omitted if "ignoreArguments" is set. The arguments of the
// first block have been already made available through the remapping of
// LLVM function arguments.
if (!ignoreArguments) {
auto predecessors = bb.getPredecessors();
unsigned numPredecessors =
std::distance(predecessors.begin(), predecessors.end());
for (auto arg : bb.getArguments()) {
auto wrappedType = arg.getType().dyn_cast<LLVM::LLVMType>();
if (!wrappedType)
return emitError(bb.front().getLoc(),
"block argument does not have an LLVM type");
llvm::Type *type = convertType(wrappedType);
llvm::PHINode *phi = builder.CreatePHI(type, numPredecessors);
valueMapping[arg] = phi;
}
}
// Traverse operations.
for (auto &op : bb) {
// Set the current debug location within the builder.
builder.SetCurrentDebugLocation(
debugTranslation->translateLoc(op.getLoc(), subprogram));
if (failed(convertOperation(op, builder)))
return failure();
}
return success();
}
/// Create named global variables that correspond to llvm.mlir.global
/// definitions.
LogicalResult ModuleTranslation::convertGlobals() {
for (auto op : getModuleBody(mlirModule).getOps<LLVM::GlobalOp>()) {
llvm::Type *type = convertType(op.getType());
llvm::Constant *cst = llvm::UndefValue::get(type);
if (op.getValueOrNull()) {
// String attributes are treated separately because they cannot appear as
// in-function constants and are thus not supported by getLLVMConstant.
if (auto strAttr = op.getValueOrNull().dyn_cast_or_null<StringAttr>()) {
cst = llvm::ConstantDataArray::getString(
llvmModule->getContext(), strAttr.getValue(), /*AddNull=*/false);
type = cst->getType();
} else if (!(cst = getLLVMConstant(type, op.getValueOrNull(),
op.getLoc()))) {
return failure();
}
} else if (Block *initializer = op.getInitializerBlock()) {
llvm::IRBuilder<> builder(llvmModule->getContext());
for (auto &op : initializer->without_terminator()) {
if (failed(convertOperation(op, builder)) ||
!isa<llvm::Constant>(valueMapping.lookup(op.getResult(0))))
return emitError(op.getLoc(), "unemittable constant value");
}
ReturnOp ret = cast<ReturnOp>(initializer->getTerminator());
cst = cast<llvm::Constant>(valueMapping.lookup(ret.getOperand(0)));
}
auto linkage = convertLinkageToLLVM(op.linkage());
bool anyExternalLinkage =
((linkage == llvm::GlobalVariable::ExternalLinkage &&
isa<llvm::UndefValue>(cst)) ||
linkage == llvm::GlobalVariable::ExternalWeakLinkage);
auto addrSpace = op.addr_space();
auto *var = new llvm::GlobalVariable(
*llvmModule, type, op.constant(), linkage,
anyExternalLinkage ? nullptr : cst, op.sym_name(),
/*InsertBefore=*/nullptr, llvm::GlobalValue::NotThreadLocal, addrSpace);
globalsMapping.try_emplace(op, var);
}
return success();
}
/// Attempts to add an attribute identified by `key`, optionally with the given
/// `value` to LLVM function `llvmFunc`. Reports errors at `loc` if any. If the
/// attribute has a kind known to LLVM IR, create the attribute of this kind,
/// otherwise keep it as a string attribute. Performs additional checks for
/// attributes known to have or not have a value in order to avoid assertions
/// inside LLVM upon construction.
static LogicalResult checkedAddLLVMFnAttribute(Location loc,
llvm::Function *llvmFunc,
StringRef key,
StringRef value = StringRef()) {
auto kind = llvm::Attribute::getAttrKindFromName(key);
if (kind == llvm::Attribute::None) {
llvmFunc->addFnAttr(key, value);
return success();
}
if (llvm::Attribute::doesAttrKindHaveArgument(kind)) {
if (value.empty())
return emitError(loc) << "LLVM attribute '" << key << "' expects a value";
int result;
if (!value.getAsInteger(/*Radix=*/0, result))
llvmFunc->addFnAttr(
llvm::Attribute::get(llvmFunc->getContext(), kind, result));
else
llvmFunc->addFnAttr(key, value);
return success();
}
if (!value.empty())
return emitError(loc) << "LLVM attribute '" << key
<< "' does not expect a value, found '" << value
<< "'";
llvmFunc->addFnAttr(kind);
return success();
}
/// Attaches the attributes listed in the given array attribute to `llvmFunc`.
/// Reports error to `loc` if any and returns immediately. Expects `attributes`
/// to be an array attribute containing either string attributes, treated as
/// value-less LLVM attributes, or array attributes containing two string
/// attributes, with the first string being the name of the corresponding LLVM
/// attribute and the second string beings its value. Note that even integer
/// attributes are expected to have their values expressed as strings.
static LogicalResult
forwardPassthroughAttributes(Location loc, Optional<ArrayAttr> attributes,
llvm::Function *llvmFunc) {
if (!attributes)
return success();
for (Attribute attr : *attributes) {
if (auto stringAttr = attr.dyn_cast<StringAttr>()) {
if (failed(
checkedAddLLVMFnAttribute(loc, llvmFunc, stringAttr.getValue())))
return failure();
continue;
}
auto arrayAttr = attr.dyn_cast<ArrayAttr>();
if (!arrayAttr || arrayAttr.size() != 2)
return emitError(loc)
<< "expected 'passthrough' to contain string or array attributes";
auto keyAttr = arrayAttr[0].dyn_cast<StringAttr>();
auto valueAttr = arrayAttr[1].dyn_cast<StringAttr>();
if (!keyAttr || !valueAttr)
return emitError(loc)
<< "expected arrays within 'passthrough' to contain two strings";
if (failed(checkedAddLLVMFnAttribute(loc, llvmFunc, keyAttr.getValue(),
valueAttr.getValue())))
return failure();
}
return success();
}
LogicalResult ModuleTranslation::convertOneFunction(LLVMFuncOp func) {
// Clear the block and value mappings, they are only relevant within one
// function.
blockMapping.clear();
valueMapping.clear();
llvm::Function *llvmFunc = functionMapping.lookup(func.getName());
// Translate the debug information for this function.
debugTranslation->translate(func, *llvmFunc);
// Add function arguments to the value remapping table.
// If there was noalias info then we decorate each argument accordingly.
unsigned int argIdx = 0;
for (auto kvp : llvm::zip(func.getArguments(), llvmFunc->args())) {
llvm::Argument &llvmArg = std::get<1>(kvp);
BlockArgument mlirArg = std::get<0>(kvp);
if (auto attr = func.getArgAttrOfType<BoolAttr>(
argIdx, LLVMDialect::getNoAliasAttrName())) {
// NB: Attribute already verified to be boolean, so check if we can indeed
// attach the attribute to this argument, based on its type.
auto argTy = mlirArg.getType().dyn_cast<LLVM::LLVMType>();
if (!argTy.isPointerTy())
return func.emitError(
"llvm.noalias attribute attached to LLVM non-pointer argument");
if (attr.getValue())
llvmArg.addAttr(llvm::Attribute::AttrKind::NoAlias);
}
if (auto attr = func.getArgAttrOfType<IntegerAttr>(
argIdx, LLVMDialect::getAlignAttrName())) {
// NB: Attribute already verified to be int, so check if we can indeed
// attach the attribute to this argument, based on its type.
auto argTy = mlirArg.getType().dyn_cast<LLVM::LLVMType>();
if (!argTy.isPointerTy())
return func.emitError(
"llvm.align attribute attached to LLVM non-pointer argument");
llvmArg.addAttrs(
llvm::AttrBuilder().addAlignmentAttr(llvm::Align(attr.getInt())));
}
valueMapping[mlirArg] = &llvmArg;
argIdx++;
}
// Check the personality and set it.
if (func.personality().hasValue()) {
llvm::Type *ty = llvm::Type::getInt8PtrTy(llvmFunc->getContext());
if (llvm::Constant *pfunc =
getLLVMConstant(ty, func.personalityAttr(), func.getLoc()))
llvmFunc->setPersonalityFn(pfunc);
}
// First, create all blocks so we can jump to them.
llvm::LLVMContext &llvmContext = llvmFunc->getContext();
for (auto &bb : func) {
auto *llvmBB = llvm::BasicBlock::Create(llvmContext);
llvmBB->insertInto(llvmFunc);
blockMapping[&bb] = llvmBB;
}
// Then, convert blocks one by one in topological order to ensure defs are
// converted before uses.
auto blocks = topologicalSort(func);
for (auto indexedBB : llvm::enumerate(blocks)) {
auto *bb = indexedBB.value();
if (failed(convertBlock(*bb, /*ignoreArguments=*/indexedBB.index() == 0)))
return failure();
}
// Finally, after all blocks have been traversed and values mapped, connect
// the PHI nodes to the results of preceding blocks.
connectPHINodes(func, valueMapping, blockMapping);
return success();
}
LogicalResult ModuleTranslation::checkSupportedModuleOps(Operation *m) {
for (Operation &o : getModuleBody(m).getOperations())
if (!isa<LLVM::LLVMFuncOp, LLVM::GlobalOp>(&o) && !o.isKnownTerminator())
return o.emitOpError("unsupported module-level operation");
return success();
}
LogicalResult ModuleTranslation::convertFunctionSignatures() {
// Declare all functions first because there may be function calls that form a
// call graph with cycles, or global initializers that reference functions.
for (auto function : getModuleBody(mlirModule).getOps<LLVMFuncOp>()) {
llvm::FunctionCallee llvmFuncCst = llvmModule->getOrInsertFunction(
function.getName(),
cast<llvm::FunctionType>(convertType(function.getType())));
llvm::Function *llvmFunc = cast<llvm::Function>(llvmFuncCst.getCallee());
llvmFunc->setLinkage(convertLinkageToLLVM(function.linkage()));
functionMapping[function.getName()] = llvmFunc;
// Forward the pass-through attributes to LLVM.
if (failed(forwardPassthroughAttributes(function.getLoc(),
function.passthrough(), llvmFunc)))
return failure();
}
return success();
}
LogicalResult ModuleTranslation::convertFunctions() {
// Convert functions.
for (auto function : getModuleBody(mlirModule).getOps<LLVMFuncOp>()) {
// Ignore external functions.
if (function.isExternal())
continue;
if (failed(convertOneFunction(function)))
return failure();
}
return success();
}
llvm::Type *ModuleTranslation::convertType(LLVMType type) {
return typeTranslator.translateType(type);
}
/// A helper to look up remapped operands in the value remapping table.`
SmallVector<llvm::Value *, 8>
ModuleTranslation::lookupValues(ValueRange values) {
SmallVector<llvm::Value *, 8> remapped;
remapped.reserve(values.size());
for (Value v : values) {
assert(valueMapping.count(v) && "referencing undefined value");
remapped.push_back(valueMapping.lookup(v));
}
return remapped;
}
std::unique_ptr<llvm::Module> ModuleTranslation::prepareLLVMModule(
Operation *m, llvm::LLVMContext &llvmContext, StringRef name) {
m->getContext()->getOrLoadDialect<LLVM::LLVMDialect>();
auto llvmModule = std::make_unique<llvm::Module>(name, llvmContext);
if (auto dataLayoutAttr =
m->getAttr(LLVM::LLVMDialect::getDataLayoutAttrName()))
llvmModule->setDataLayout(dataLayoutAttr.cast<StringAttr>().getValue());
if (auto targetTripleAttr =
m->getAttr(LLVM::LLVMDialect::getTargetTripleAttrName()))
llvmModule->setTargetTriple(targetTripleAttr.cast<StringAttr>().getValue());
// Inject declarations for `malloc` and `free` functions that can be used in
// memref allocation/deallocation coming from standard ops lowering.
llvm::IRBuilder<> builder(llvmContext);
llvmModule->getOrInsertFunction("malloc", builder.getInt8PtrTy(),
builder.getInt64Ty());
llvmModule->getOrInsertFunction("free", builder.getVoidTy(),
builder.getInt8PtrTy());
return llvmModule;
}