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llvm-project/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

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//===- OpenMPIRBuilder.cpp - Builder for LLVM-IR for OpenMP directives ----===//
//
// 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
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file implements the OpenMPIRBuilder class, which is used as a
/// convenient way to create LLVM instructions for OpenMP directives.
///
//===----------------------------------------------------------------------===//
#include "llvm/Frontend/OpenMP/OMPIRBuilder.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Error.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/CodeExtractor.h"
#include <sstream>
#define DEBUG_TYPE "openmp-ir-builder"
using namespace llvm;
using namespace omp;
using namespace types;
static cl::opt<bool>
OptimisticAttributes("openmp-ir-builder-optimistic-attributes", cl::Hidden,
cl::desc("Use optimistic attributes describing "
"'as-if' properties of runtime calls."),
cl::init(false));
void OpenMPIRBuilder::addAttributes(omp::RuntimeFunction FnID, Function &Fn) {
LLVMContext &Ctx = Fn.getContext();
#define OMP_ATTRS_SET(VarName, AttrSet) AttributeSet VarName = AttrSet;
#include "llvm/Frontend/OpenMP/OMPKinds.def"
// Add attributes to the new declaration.
switch (FnID) {
#define OMP_RTL_ATTRS(Enum, FnAttrSet, RetAttrSet, ArgAttrSets) \
case Enum: \
Fn.setAttributes( \
AttributeList::get(Ctx, FnAttrSet, RetAttrSet, ArgAttrSets)); \
break;
#include "llvm/Frontend/OpenMP/OMPKinds.def"
default:
// Attributes are optional.
break;
}
}
Function *OpenMPIRBuilder::getOrCreateRuntimeFunction(RuntimeFunction FnID) {
Function *Fn = nullptr;
// Try to find the declation in the module first.
switch (FnID) {
#define OMP_RTL(Enum, Str, IsVarArg, ReturnType, ...) \
case Enum: \
Fn = M.getFunction(Str); \
break;
#include "llvm/Frontend/OpenMP/OMPKinds.def"
}
if (!Fn) {
// Create a new declaration if we need one.
switch (FnID) {
#define OMP_RTL(Enum, Str, IsVarArg, ReturnType, ...) \
case Enum: \
Fn = Function::Create(FunctionType::get(ReturnType, \
ArrayRef<Type *>{__VA_ARGS__}, \
IsVarArg), \
GlobalValue::ExternalLinkage, Str, M); \
break;
#include "llvm/Frontend/OpenMP/OMPKinds.def"
}
addAttributes(FnID, *Fn);
}
assert(Fn && "Failed to create OpenMP runtime function");
return Fn;
}
void OpenMPIRBuilder::initialize() { initializeTypes(M); }
void OpenMPIRBuilder::finalize() {
for (OutlineInfo &OI : OutlineInfos) {
assert(!OI.Blocks.empty() &&
"Outlined regions should have at least a single block!");
BasicBlock *RegEntryBB = OI.Blocks.front();
Function *OuterFn = RegEntryBB->getParent();
CodeExtractorAnalysisCache CEAC(*OuterFn);
CodeExtractor Extractor(OI.Blocks, /* DominatorTree */ nullptr,
/* AggregateArgs */ false,
/* BlockFrequencyInfo */ nullptr,
/* BranchProbabilityInfo */ nullptr,
/* AssumptionCache */ nullptr,
/* AllowVarArgs */ true,
/* AllowAlloca */ true,
/* Suffix */ ".omp_par");
LLVM_DEBUG(dbgs() << "Before outlining: " << *OuterFn << "\n");
assert(Extractor.isEligible() &&
"Expected OpenMP outlining to be possible!");
Function *OutlinedFn = Extractor.extractCodeRegion(CEAC);
LLVM_DEBUG(dbgs() << "After outlining: " << *OuterFn << "\n");
LLVM_DEBUG(dbgs() << " Outlined function: " << *OutlinedFn << "\n");
assert(OutlinedFn->getReturnType()->isVoidTy() &&
"OpenMP outlined functions should not return a value!");
// For compability with the clang CG we move the outlined function after the
// one with the parallel region.
OutlinedFn->removeFromParent();
M.getFunctionList().insertAfter(OuterFn->getIterator(), OutlinedFn);
// Remove the artificial entry introduced by the extractor right away, we
// made our own entry block after all.
{
BasicBlock &ArtificialEntry = OutlinedFn->getEntryBlock();
assert(ArtificialEntry.getUniqueSuccessor() == RegEntryBB);
assert(RegEntryBB->getUniquePredecessor() == &ArtificialEntry);
RegEntryBB->moveBefore(&ArtificialEntry);
ArtificialEntry.eraseFromParent();
}
assert(&OutlinedFn->getEntryBlock() == RegEntryBB);
assert(OutlinedFn && OutlinedFn->getNumUses() == 1);
// Run a user callback, e.g. to add attributes.
if (OI.PostOutlineCB)
OI.PostOutlineCB(*OutlinedFn);
}
// Allow finalize to be called multiple times.
OutlineInfos.clear();
}
Value *OpenMPIRBuilder::getOrCreateIdent(Constant *SrcLocStr,
IdentFlag LocFlags) {
// Enable "C-mode".
LocFlags |= OMP_IDENT_FLAG_KMPC;
GlobalVariable *&DefaultIdent = IdentMap[{SrcLocStr, uint64_t(LocFlags)}];
if (!DefaultIdent) {
Constant *I32Null = ConstantInt::getNullValue(Int32);
Constant *IdentData[] = {I32Null,
ConstantInt::get(Int32, uint64_t(LocFlags)),
I32Null, I32Null, SrcLocStr};
Constant *Initializer = ConstantStruct::get(
cast<StructType>(IdentPtr->getPointerElementType()), IdentData);
// Look for existing encoding of the location + flags, not needed but
// minimizes the difference to the existing solution while we transition.
for (GlobalVariable &GV : M.getGlobalList())
if (GV.getType() == IdentPtr && GV.hasInitializer())
if (GV.getInitializer() == Initializer)
return DefaultIdent = &GV;
DefaultIdent = new GlobalVariable(M, IdentPtr->getPointerElementType(),
/* isConstant = */ false,
GlobalValue::PrivateLinkage, Initializer);
DefaultIdent->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
DefaultIdent->setAlignment(Align(8));
}
return DefaultIdent;
}
Constant *OpenMPIRBuilder::getOrCreateSrcLocStr(StringRef LocStr) {
Constant *&SrcLocStr = SrcLocStrMap[LocStr];
if (!SrcLocStr) {
Constant *Initializer =
ConstantDataArray::getString(M.getContext(), LocStr);
// Look for existing encoding of the location, not needed but minimizes the
// difference to the existing solution while we transition.
for (GlobalVariable &GV : M.getGlobalList())
if (GV.isConstant() && GV.hasInitializer() &&
GV.getInitializer() == Initializer)
return SrcLocStr = ConstantExpr::getPointerCast(&GV, Int8Ptr);
SrcLocStr = Builder.CreateGlobalStringPtr(LocStr);
}
return SrcLocStr;
}
Constant *OpenMPIRBuilder::getOrCreateDefaultSrcLocStr() {
return getOrCreateSrcLocStr(";unknown;unknown;0;0;;");
}
Constant *
OpenMPIRBuilder::getOrCreateSrcLocStr(const LocationDescription &Loc) {
DILocation *DIL = Loc.DL.get();
if (!DIL)
return getOrCreateDefaultSrcLocStr();
StringRef Filename =
!DIL->getFilename().empty() ? DIL->getFilename() : M.getName();
StringRef Function = DIL->getScope()->getSubprogram()->getName();
Function =
!Function.empty() ? Function : Loc.IP.getBlock()->getParent()->getName();
std::string LineStr = std::to_string(DIL->getLine());
std::string ColumnStr = std::to_string(DIL->getColumn());
std::stringstream SrcLocStr;
SrcLocStr << ";" << Filename.data() << ";" << Function.data() << ";"
<< LineStr << ";" << ColumnStr << ";;";
return getOrCreateSrcLocStr(SrcLocStr.str());
}
Value *OpenMPIRBuilder::getOrCreateThreadID(Value *Ident) {
return Builder.CreateCall(
getOrCreateRuntimeFunction(OMPRTL___kmpc_global_thread_num), Ident,
"omp_global_thread_num");
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::CreateBarrier(const LocationDescription &Loc, Directive DK,
bool ForceSimpleCall, bool CheckCancelFlag) {
if (!updateToLocation(Loc))
return Loc.IP;
return emitBarrierImpl(Loc, DK, ForceSimpleCall, CheckCancelFlag);
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::emitBarrierImpl(const LocationDescription &Loc, Directive Kind,
bool ForceSimpleCall, bool CheckCancelFlag) {
// Build call __kmpc_cancel_barrier(loc, thread_id) or
// __kmpc_barrier(loc, thread_id);
IdentFlag BarrierLocFlags;
switch (Kind) {
case OMPD_for:
BarrierLocFlags = OMP_IDENT_FLAG_BARRIER_IMPL_FOR;
break;
case OMPD_sections:
BarrierLocFlags = OMP_IDENT_FLAG_BARRIER_IMPL_SECTIONS;
break;
case OMPD_single:
BarrierLocFlags = OMP_IDENT_FLAG_BARRIER_IMPL_SINGLE;
break;
case OMPD_barrier:
BarrierLocFlags = OMP_IDENT_FLAG_BARRIER_EXPL;
break;
default:
BarrierLocFlags = OMP_IDENT_FLAG_BARRIER_IMPL;
break;
}
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Args[] = {getOrCreateIdent(SrcLocStr, BarrierLocFlags),
getOrCreateThreadID(getOrCreateIdent(SrcLocStr))};
// If we are in a cancellable parallel region, barriers are cancellation
// points.
// TODO: Check why we would force simple calls or to ignore the cancel flag.
bool UseCancelBarrier =
!ForceSimpleCall && isLastFinalizationInfoCancellable(OMPD_parallel);
Value *Result = Builder.CreateCall(
getOrCreateRuntimeFunction(UseCancelBarrier ? OMPRTL___kmpc_cancel_barrier
: OMPRTL___kmpc_barrier),
Args);
if (UseCancelBarrier && CheckCancelFlag)
emitCancelationCheckImpl(Result, OMPD_parallel);
return Builder.saveIP();
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::CreateCancel(const LocationDescription &Loc,
Value *IfCondition,
omp::Directive CanceledDirective) {
if (!updateToLocation(Loc))
return Loc.IP;
// LLVM utilities like blocks with terminators.
auto *UI = Builder.CreateUnreachable();
Instruction *ThenTI = UI, *ElseTI = nullptr;
if (IfCondition)
SplitBlockAndInsertIfThenElse(IfCondition, UI, &ThenTI, &ElseTI);
Builder.SetInsertPoint(ThenTI);
Value *CancelKind = nullptr;
switch (CanceledDirective) {
#define OMP_CANCEL_KIND(Enum, Str, DirectiveEnum, Value) \
case DirectiveEnum: \
CancelKind = Builder.getInt32(Value); \
break;
#include "llvm/Frontend/OpenMP/OMPKinds.def"
default:
llvm_unreachable("Unknown cancel kind!");
}
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *Args[] = {Ident, getOrCreateThreadID(Ident), CancelKind};
Value *Result = Builder.CreateCall(
getOrCreateRuntimeFunction(OMPRTL___kmpc_cancel), Args);
// The actual cancel logic is shared with others, e.g., cancel_barriers.
emitCancelationCheckImpl(Result, CanceledDirective);
// Update the insertion point and remove the terminator we introduced.
Builder.SetInsertPoint(UI->getParent());
UI->eraseFromParent();
return Builder.saveIP();
}
void OpenMPIRBuilder::emitCancelationCheckImpl(
Value *CancelFlag, omp::Directive CanceledDirective) {
assert(isLastFinalizationInfoCancellable(CanceledDirective) &&
"Unexpected cancellation!");
// For a cancel barrier we create two new blocks.
BasicBlock *BB = Builder.GetInsertBlock();
BasicBlock *NonCancellationBlock;
if (Builder.GetInsertPoint() == BB->end()) {
// TODO: This branch will not be needed once we moved to the
// OpenMPIRBuilder codegen completely.
NonCancellationBlock = BasicBlock::Create(
BB->getContext(), BB->getName() + ".cont", BB->getParent());
} else {
NonCancellationBlock = SplitBlock(BB, &*Builder.GetInsertPoint());
BB->getTerminator()->eraseFromParent();
Builder.SetInsertPoint(BB);
}
BasicBlock *CancellationBlock = BasicBlock::Create(
BB->getContext(), BB->getName() + ".cncl", BB->getParent());
// Jump to them based on the return value.
Value *Cmp = Builder.CreateIsNull(CancelFlag);
Builder.CreateCondBr(Cmp, NonCancellationBlock, CancellationBlock,
/* TODO weight */ nullptr, nullptr);
// From the cancellation block we finalize all variables and go to the
// post finalization block that is known to the FiniCB callback.
Builder.SetInsertPoint(CancellationBlock);
auto &FI = FinalizationStack.back();
FI.FiniCB(Builder.saveIP());
// The continuation block is where code generation continues.
Builder.SetInsertPoint(NonCancellationBlock, NonCancellationBlock->begin());
}
IRBuilder<>::InsertPoint OpenMPIRBuilder::CreateParallel(
const LocationDescription &Loc, BodyGenCallbackTy BodyGenCB,
PrivatizeCallbackTy PrivCB, FinalizeCallbackTy FiniCB, Value *IfCondition,
Value *NumThreads, omp::ProcBindKind ProcBind, bool IsCancellable) {
if (!updateToLocation(Loc))
return Loc.IP;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadID = getOrCreateThreadID(Ident);
if (NumThreads) {
// Build call __kmpc_push_num_threads(&Ident, global_tid, num_threads)
Value *Args[] = {
Ident, ThreadID,
Builder.CreateIntCast(NumThreads, Int32, /*isSigned*/ false)};
Builder.CreateCall(
getOrCreateRuntimeFunction(OMPRTL___kmpc_push_num_threads), Args);
}
if (ProcBind != OMP_PROC_BIND_default) {
// Build call __kmpc_push_proc_bind(&Ident, global_tid, proc_bind)
Value *Args[] = {
Ident, ThreadID,
ConstantInt::get(Int32, unsigned(ProcBind), /*isSigned=*/true)};
Builder.CreateCall(getOrCreateRuntimeFunction(OMPRTL___kmpc_push_proc_bind),
Args);
}
BasicBlock *InsertBB = Builder.GetInsertBlock();
Function *OuterFn = InsertBB->getParent();
// Vector to remember instructions we used only during the modeling but which
// we want to delete at the end.
SmallVector<Instruction *, 4> ToBeDeleted;
Builder.SetInsertPoint(OuterFn->getEntryBlock().getFirstNonPHI());
AllocaInst *TIDAddr = Builder.CreateAlloca(Int32, nullptr, "tid.addr");
AllocaInst *ZeroAddr = Builder.CreateAlloca(Int32, nullptr, "zero.addr");
// If there is an if condition we actually use the TIDAddr and ZeroAddr in the
// program, otherwise we only need them for modeling purposes to get the
// associated arguments in the outlined function. In the former case,
// initialize the allocas properly, in the latter case, delete them later.
if (IfCondition) {
Builder.CreateStore(Constant::getNullValue(Int32), TIDAddr);
Builder.CreateStore(Constant::getNullValue(Int32), ZeroAddr);
} else {
ToBeDeleted.push_back(TIDAddr);
ToBeDeleted.push_back(ZeroAddr);
}
// Create an artificial insertion point that will also ensure the blocks we
// are about to split are not degenerated.
auto *UI = new UnreachableInst(Builder.getContext(), InsertBB);
Instruction *ThenTI = UI, *ElseTI = nullptr;
if (IfCondition)
SplitBlockAndInsertIfThenElse(IfCondition, UI, &ThenTI, &ElseTI);
BasicBlock *ThenBB = ThenTI->getParent();
BasicBlock *PRegEntryBB = ThenBB->splitBasicBlock(ThenTI, "omp.par.entry");
BasicBlock *PRegBodyBB =
PRegEntryBB->splitBasicBlock(ThenTI, "omp.par.region");
BasicBlock *PRegPreFiniBB =
PRegBodyBB->splitBasicBlock(ThenTI, "omp.par.pre_finalize");
BasicBlock *PRegExitBB =
PRegPreFiniBB->splitBasicBlock(ThenTI, "omp.par.exit");
auto FiniCBWrapper = [&](InsertPointTy IP) {
// Hide "open-ended" blocks from the given FiniCB by setting the right jump
// target to the region exit block.
if (IP.getBlock()->end() == IP.getPoint()) {
IRBuilder<>::InsertPointGuard IPG(Builder);
Builder.restoreIP(IP);
Instruction *I = Builder.CreateBr(PRegExitBB);
IP = InsertPointTy(I->getParent(), I->getIterator());
}
assert(IP.getBlock()->getTerminator()->getNumSuccessors() == 1 &&
IP.getBlock()->getTerminator()->getSuccessor(0) == PRegExitBB &&
"Unexpected insertion point for finalization call!");
return FiniCB(IP);
};
FinalizationStack.push_back({FiniCBWrapper, OMPD_parallel, IsCancellable});
// Generate the privatization allocas in the block that will become the entry
// of the outlined function.
InsertPointTy AllocaIP(PRegEntryBB,
PRegEntryBB->getTerminator()->getIterator());
Builder.restoreIP(AllocaIP);
AllocaInst *PrivTIDAddr =
Builder.CreateAlloca(Int32, nullptr, "tid.addr.local");
Instruction *PrivTID = Builder.CreateLoad(PrivTIDAddr, "tid");
// Add some fake uses for OpenMP provided arguments.
ToBeDeleted.push_back(Builder.CreateLoad(TIDAddr, "tid.addr.use"));
ToBeDeleted.push_back(Builder.CreateLoad(ZeroAddr, "zero.addr.use"));
// ThenBB
// |
// V
// PRegionEntryBB <- Privatization allocas are placed here.
// |
// V
// PRegionBodyBB <- BodeGen is invoked here.
// |
// V
// PRegPreFiniBB <- The block we will start finalization from.
// |
// V
// PRegionExitBB <- A common exit to simplify block collection.
//
LLVM_DEBUG(dbgs() << "Before body codegen: " << *OuterFn << "\n");
// Let the caller create the body.
assert(BodyGenCB && "Expected body generation callback!");
InsertPointTy CodeGenIP(PRegBodyBB, PRegBodyBB->begin());
BodyGenCB(AllocaIP, CodeGenIP, *PRegPreFiniBB);
LLVM_DEBUG(dbgs() << "After body codegen: " << *OuterFn << "\n");
FunctionCallee RTLFn = getOrCreateRuntimeFunction(OMPRTL___kmpc_fork_call);
if (auto *F = dyn_cast<llvm::Function>(RTLFn.getCallee())) {
if (!F->hasMetadata(llvm::LLVMContext::MD_callback)) {
llvm::LLVMContext &Ctx = F->getContext();
MDBuilder MDB(Ctx);
// Annotate the callback behavior of the __kmpc_fork_call:
// - The callback callee is argument number 2 (microtask).
// - The first two arguments of the callback callee are unknown (-1).
// - All variadic arguments to the __kmpc_fork_call are passed to the
// callback callee.
F->addMetadata(
llvm::LLVMContext::MD_callback,
*llvm::MDNode::get(
Ctx, {MDB.createCallbackEncoding(2, {-1, -1},
/* VarArgsArePassed */ true)}));
}
}
OutlineInfo OI;
OI.PostOutlineCB = [=](Function &OutlinedFn) {
// Add some known attributes.
OutlinedFn.addParamAttr(0, Attribute::NoAlias);
OutlinedFn.addParamAttr(1, Attribute::NoAlias);
OutlinedFn.addFnAttr(Attribute::NoUnwind);
OutlinedFn.addFnAttr(Attribute::NoRecurse);
assert(OutlinedFn.arg_size() >= 2 &&
"Expected at least tid and bounded tid as arguments");
unsigned NumCapturedVars =
OutlinedFn.arg_size() - /* tid & bounded tid */ 2;
CallInst *CI = cast<CallInst>(OutlinedFn.user_back());
CI->getParent()->setName("omp_parallel");
Builder.SetInsertPoint(CI);
// Build call __kmpc_fork_call(Ident, n, microtask, var1, .., varn);
Value *ForkCallArgs[] = {
Ident, Builder.getInt32(NumCapturedVars),
Builder.CreateBitCast(&OutlinedFn, ParallelTaskPtr)};
SmallVector<Value *, 16> RealArgs;
RealArgs.append(std::begin(ForkCallArgs), std::end(ForkCallArgs));
RealArgs.append(CI->arg_begin() + /* tid & bound tid */ 2, CI->arg_end());
Builder.CreateCall(RTLFn, RealArgs);
LLVM_DEBUG(dbgs() << "With fork_call placed: "
<< *Builder.GetInsertBlock()->getParent() << "\n");
InsertPointTy ExitIP(PRegExitBB, PRegExitBB->end());
// Initialize the local TID stack location with the argument value.
Builder.SetInsertPoint(PrivTID);
Function::arg_iterator OutlinedAI = OutlinedFn.arg_begin();
Builder.CreateStore(Builder.CreateLoad(OutlinedAI), PrivTIDAddr);
// If no "if" clause was present we do not need the call created during
// outlining, otherwise we reuse it in the serialized parallel region.
if (!ElseTI) {
CI->eraseFromParent();
} else {
// If an "if" clause was present we are now generating the serialized
// version into the "else" branch.
Builder.SetInsertPoint(ElseTI);
// Build calls __kmpc_serialized_parallel(&Ident, GTid);
Value *SerializedParallelCallArgs[] = {Ident, ThreadID};
Builder.CreateCall(
getOrCreateRuntimeFunction(OMPRTL___kmpc_serialized_parallel),
SerializedParallelCallArgs);
// OutlinedFn(&GTid, &zero, CapturedStruct);
CI->removeFromParent();
Builder.Insert(CI);
// __kmpc_end_serialized_parallel(&Ident, GTid);
Value *EndArgs[] = {Ident, ThreadID};
Builder.CreateCall(
getOrCreateRuntimeFunction(OMPRTL___kmpc_end_serialized_parallel),
EndArgs);
LLVM_DEBUG(dbgs() << "With serialized parallel region: "
<< *Builder.GetInsertBlock()->getParent() << "\n");
}
for (Instruction *I : ToBeDeleted)
I->eraseFromParent();
};
// Adjust the finalization stack, verify the adjustment, and call the
// finalize function a last time to finalize values between the pre-fini
// block and the exit block if we left the parallel "the normal way".
auto FiniInfo = FinalizationStack.pop_back_val();
(void)FiniInfo;
assert(FiniInfo.DK == OMPD_parallel &&
"Unexpected finalization stack state!");
Instruction *PRegPreFiniTI = PRegPreFiniBB->getTerminator();
assert(PRegPreFiniTI->getNumSuccessors() == 1 &&
PRegPreFiniTI->getSuccessor(0) == PRegExitBB &&
"Unexpected CFG structure!");
InsertPointTy PreFiniIP(PRegPreFiniBB, PRegPreFiniTI->getIterator());
FiniCB(PreFiniIP);
SmallPtrSet<BasicBlock *, 32> ParallelRegionBlockSet;
SmallVector<BasicBlock *, 32> Worklist;
ParallelRegionBlockSet.insert(PRegEntryBB);
ParallelRegionBlockSet.insert(PRegExitBB);
// Collect all blocks in-between PRegEntryBB and PRegExitBB.
Worklist.push_back(PRegEntryBB);
while (!Worklist.empty()) {
BasicBlock *BB = Worklist.pop_back_val();
OI.Blocks.push_back(BB);
for (BasicBlock *SuccBB : successors(BB))
if (ParallelRegionBlockSet.insert(SuccBB).second)
Worklist.push_back(SuccBB);
}
// Ensure a single exit node for the outlined region by creating one.
// We might have multiple incoming edges to the exit now due to finalizations,
// e.g., cancel calls that cause the control flow to leave the region.
BasicBlock *PRegOutlinedExitBB = PRegExitBB;
PRegExitBB = SplitBlock(PRegExitBB, &*PRegExitBB->getFirstInsertionPt());
PRegOutlinedExitBB->setName("omp.par.outlined.exit");
OI.Blocks.push_back(PRegOutlinedExitBB);
CodeExtractorAnalysisCache CEAC(*OuterFn);
CodeExtractor Extractor(OI.Blocks, /* DominatorTree */ nullptr,
/* AggregateArgs */ false,
/* BlockFrequencyInfo */ nullptr,
/* BranchProbabilityInfo */ nullptr,
/* AssumptionCache */ nullptr,
/* AllowVarArgs */ true,
/* AllowAlloca */ true,
/* Suffix */ ".omp_par");
// Find inputs to, outputs from the code region.
BasicBlock *CommonExit = nullptr;
SetVector<Value *> Inputs, Outputs, SinkingCands, HoistingCands;
Extractor.findAllocas(CEAC, SinkingCands, HoistingCands, CommonExit);
Extractor.findInputsOutputs(Inputs, Outputs, SinkingCands);
LLVM_DEBUG(dbgs() << "Before privatization: " << *OuterFn << "\n");
FunctionCallee TIDRTLFn =
getOrCreateRuntimeFunction(OMPRTL___kmpc_global_thread_num);
auto PrivHelper = [&](Value &V) {
if (&V == TIDAddr || &V == ZeroAddr)
return;
SmallVector<Use *, 8> Uses;
for (Use &U : V.uses())
if (auto *UserI = dyn_cast<Instruction>(U.getUser()))
if (ParallelRegionBlockSet.count(UserI->getParent()))
Uses.push_back(&U);
Value *ReplacementValue = nullptr;
CallInst *CI = dyn_cast<CallInst>(&V);
if (CI && CI->getCalledFunction() == TIDRTLFn.getCallee()) {
ReplacementValue = PrivTID;
} else {
Builder.restoreIP(
PrivCB(AllocaIP, Builder.saveIP(), V, ReplacementValue));
assert(ReplacementValue &&
"Expected copy/create callback to set replacement value!");
if (ReplacementValue == &V)
return;
}
for (Use *UPtr : Uses)
UPtr->set(ReplacementValue);
};
for (Value *Input : Inputs) {
LLVM_DEBUG(dbgs() << "Captured input: " << *Input << "\n");
PrivHelper(*Input);
}
assert(Outputs.empty() &&
"OpenMP outlining should not produce live-out values!");
LLVM_DEBUG(dbgs() << "After privatization: " << *OuterFn << "\n");
LLVM_DEBUG({
for (auto *BB : OI.Blocks)
dbgs() << " PBR: " << BB->getName() << "\n";
});
// Register the outlined info.
addOutlineInfo(std::move(OI));
InsertPointTy AfterIP(UI->getParent(), UI->getParent()->end());
UI->eraseFromParent();
return AfterIP;
}
void OpenMPIRBuilder::emitFlush(const LocationDescription &Loc) {
// Build call void __kmpc_flush(ident_t *loc)
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Args[] = {getOrCreateIdent(SrcLocStr)};
Builder.CreateCall(getOrCreateRuntimeFunction(OMPRTL___kmpc_flush), Args);
}
void OpenMPIRBuilder::CreateFlush(const LocationDescription &Loc) {
if (!updateToLocation(Loc))
return;
emitFlush(Loc);
}
void OpenMPIRBuilder::emitTaskwaitImpl(const LocationDescription &Loc) {
// Build call kmp_int32 __kmpc_omp_taskwait(ident_t *loc, kmp_int32
// global_tid);
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *Args[] = {Ident, getOrCreateThreadID(Ident)};
// Ignore return result until untied tasks are supported.
Builder.CreateCall(getOrCreateRuntimeFunction(OMPRTL___kmpc_omp_taskwait),
Args);
}
void OpenMPIRBuilder::CreateTaskwait(const LocationDescription &Loc) {
if (!updateToLocation(Loc))
return;
emitTaskwaitImpl(Loc);
}
void OpenMPIRBuilder::emitTaskyieldImpl(const LocationDescription &Loc) {
// Build call __kmpc_omp_taskyield(loc, thread_id, 0);
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Constant *I32Null = ConstantInt::getNullValue(Int32);
Value *Args[] = {Ident, getOrCreateThreadID(Ident), I32Null};
Builder.CreateCall(getOrCreateRuntimeFunction(OMPRTL___kmpc_omp_taskyield),
Args);
}
void OpenMPIRBuilder::CreateTaskyield(const LocationDescription &Loc) {
if (!updateToLocation(Loc))
return;
emitTaskyieldImpl(Loc);
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::CreateMaster(const LocationDescription &Loc,
BodyGenCallbackTy BodyGenCB,
FinalizeCallbackTy FiniCB) {
if (!updateToLocation(Loc))
return Loc.IP;
Directive OMPD = Directive::OMPD_master;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadId = getOrCreateThreadID(Ident);
Value *Args[] = {Ident, ThreadId};
Function *EntryRTLFn = getOrCreateRuntimeFunction(OMPRTL___kmpc_master);
Instruction *EntryCall = Builder.CreateCall(EntryRTLFn, Args);
Function *ExitRTLFn = getOrCreateRuntimeFunction(OMPRTL___kmpc_end_master);
Instruction *ExitCall = Builder.CreateCall(ExitRTLFn, Args);
return EmitOMPInlinedRegion(OMPD, EntryCall, ExitCall, BodyGenCB, FiniCB,
/*Conditional*/ true, /*hasFinalize*/ true);
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::CreateCritical(
const LocationDescription &Loc, BodyGenCallbackTy BodyGenCB,
FinalizeCallbackTy FiniCB, StringRef CriticalName, Value *HintInst) {
if (!updateToLocation(Loc))
return Loc.IP;
Directive OMPD = Directive::OMPD_critical;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadId = getOrCreateThreadID(Ident);
Value *LockVar = getOMPCriticalRegionLock(CriticalName);
Value *Args[] = {Ident, ThreadId, LockVar};
SmallVector<llvm::Value *, 4> EnterArgs(std::begin(Args), std::end(Args));
Function *RTFn = nullptr;
if (HintInst) {
// Add Hint to entry Args and create call
EnterArgs.push_back(HintInst);
RTFn = getOrCreateRuntimeFunction(OMPRTL___kmpc_critical_with_hint);
} else {
RTFn = getOrCreateRuntimeFunction(OMPRTL___kmpc_critical);
}
Instruction *EntryCall = Builder.CreateCall(RTFn, EnterArgs);
Function *ExitRTLFn = getOrCreateRuntimeFunction(OMPRTL___kmpc_end_critical);
Instruction *ExitCall = Builder.CreateCall(ExitRTLFn, Args);
return EmitOMPInlinedRegion(OMPD, EntryCall, ExitCall, BodyGenCB, FiniCB,
/*Conditional*/ false, /*hasFinalize*/ true);
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::EmitOMPInlinedRegion(
Directive OMPD, Instruction *EntryCall, Instruction *ExitCall,
BodyGenCallbackTy BodyGenCB, FinalizeCallbackTy FiniCB, bool Conditional,
bool HasFinalize) {
if (HasFinalize)
FinalizationStack.push_back({FiniCB, OMPD, /*IsCancellable*/ false});
// Create inlined region's entry and body blocks, in preparation
// for conditional creation
BasicBlock *EntryBB = Builder.GetInsertBlock();
Instruction *SplitPos = EntryBB->getTerminator();
if (!isa_and_nonnull<BranchInst>(SplitPos))
SplitPos = new UnreachableInst(Builder.getContext(), EntryBB);
BasicBlock *ExitBB = EntryBB->splitBasicBlock(SplitPos, "omp_region.end");
BasicBlock *FiniBB =
EntryBB->splitBasicBlock(EntryBB->getTerminator(), "omp_region.finalize");
Builder.SetInsertPoint(EntryBB->getTerminator());
emitCommonDirectiveEntry(OMPD, EntryCall, ExitBB, Conditional);
// generate body
BodyGenCB(/* AllocaIP */ InsertPointTy(),
/* CodeGenIP */ Builder.saveIP(), *FiniBB);
// If we didn't emit a branch to FiniBB during body generation, it means
// FiniBB is unreachable (e.g. while(1);). stop generating all the
// unreachable blocks, and remove anything we are not going to use.
auto SkipEmittingRegion = FiniBB->hasNPredecessors(0);
if (SkipEmittingRegion) {
FiniBB->eraseFromParent();
ExitCall->eraseFromParent();
// Discard finalization if we have it.
if (HasFinalize) {
assert(!FinalizationStack.empty() &&
"Unexpected finalization stack state!");
FinalizationStack.pop_back();
}
} else {
// emit exit call and do any needed finalization.
auto FinIP = InsertPointTy(FiniBB, FiniBB->getFirstInsertionPt());
assert(FiniBB->getTerminator()->getNumSuccessors() == 1 &&
FiniBB->getTerminator()->getSuccessor(0) == ExitBB &&
"Unexpected control flow graph state!!");
emitCommonDirectiveExit(OMPD, FinIP, ExitCall, HasFinalize);
assert(FiniBB->getUniquePredecessor()->getUniqueSuccessor() == FiniBB &&
"Unexpected Control Flow State!");
MergeBlockIntoPredecessor(FiniBB);
}
// If we are skipping the region of a non conditional, remove the exit
// block, and clear the builder's insertion point.
assert(SplitPos->getParent() == ExitBB &&
"Unexpected Insertion point location!");
if (!Conditional && SkipEmittingRegion) {
ExitBB->eraseFromParent();
Builder.ClearInsertionPoint();
} else {
auto merged = MergeBlockIntoPredecessor(ExitBB);
BasicBlock *ExitPredBB = SplitPos->getParent();
auto InsertBB = merged ? ExitPredBB : ExitBB;
if (!isa_and_nonnull<BranchInst>(SplitPos))
SplitPos->eraseFromParent();
Builder.SetInsertPoint(InsertBB);
}
return Builder.saveIP();
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::emitCommonDirectiveEntry(
Directive OMPD, Value *EntryCall, BasicBlock *ExitBB, bool Conditional) {
// if nothing to do, Return current insertion point.
if (!Conditional)
return Builder.saveIP();
BasicBlock *EntryBB = Builder.GetInsertBlock();
Value *CallBool = Builder.CreateIsNotNull(EntryCall);
auto *ThenBB = BasicBlock::Create(M.getContext(), "omp_region.body");
auto *UI = new UnreachableInst(Builder.getContext(), ThenBB);
// Emit thenBB and set the Builder's insertion point there for
// body generation next. Place the block after the current block.
Function *CurFn = EntryBB->getParent();
CurFn->getBasicBlockList().insertAfter(EntryBB->getIterator(), ThenBB);
// Move Entry branch to end of ThenBB, and replace with conditional
// branch (If-stmt)
Instruction *EntryBBTI = EntryBB->getTerminator();
Builder.CreateCondBr(CallBool, ThenBB, ExitBB);
EntryBBTI->removeFromParent();
Builder.SetInsertPoint(UI);
Builder.Insert(EntryBBTI);
UI->eraseFromParent();
Builder.SetInsertPoint(ThenBB->getTerminator());
// return an insertion point to ExitBB.
return IRBuilder<>::InsertPoint(ExitBB, ExitBB->getFirstInsertionPt());
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::emitCommonDirectiveExit(
omp::Directive OMPD, InsertPointTy FinIP, Instruction *ExitCall,
bool HasFinalize) {
Builder.restoreIP(FinIP);
// If there is finalization to do, emit it before the exit call
if (HasFinalize) {
assert(!FinalizationStack.empty() &&
"Unexpected finalization stack state!");
FinalizationInfo Fi = FinalizationStack.pop_back_val();
assert(Fi.DK == OMPD && "Unexpected Directive for Finalization call!");
Fi.FiniCB(FinIP);
BasicBlock *FiniBB = FinIP.getBlock();
Instruction *FiniBBTI = FiniBB->getTerminator();
// set Builder IP for call creation
Builder.SetInsertPoint(FiniBBTI);
}
// place the Exitcall as last instruction before Finalization block terminator
ExitCall->removeFromParent();
Builder.Insert(ExitCall);
return IRBuilder<>::InsertPoint(ExitCall->getParent(),
ExitCall->getIterator());
}
std::string OpenMPIRBuilder::getNameWithSeparators(ArrayRef<StringRef> Parts,
StringRef FirstSeparator,
StringRef Separator) {
SmallString<128> Buffer;
llvm::raw_svector_ostream OS(Buffer);
StringRef Sep = FirstSeparator;
for (StringRef Part : Parts) {
OS << Sep << Part;
Sep = Separator;
}
return OS.str().str();
}
Constant *OpenMPIRBuilder::getOrCreateOMPInternalVariable(
llvm::Type *Ty, const llvm::Twine &Name, unsigned AddressSpace) {
// TODO: Replace the twine arg with stringref to get rid of the conversion
// logic. However This is taken from current implementation in clang as is.
// Since this method is used in many places exclusively for OMP internal use
// we will keep it as is for temporarily until we move all users to the
// builder and then, if possible, fix it everywhere in one go.
SmallString<256> Buffer;
llvm::raw_svector_ostream Out(Buffer);
Out << Name;
StringRef RuntimeName = Out.str();
auto &Elem = *InternalVars.try_emplace(RuntimeName, nullptr).first;
if (Elem.second) {
assert(Elem.second->getType()->getPointerElementType() == Ty &&
"OMP internal variable has different type than requested");
} else {
// TODO: investigate the appropriate linkage type used for the global
// variable for possibly changing that to internal or private, or maybe
// create different versions of the function for different OMP internal
// variables.
Elem.second = new llvm::GlobalVariable(
M, Ty, /*IsConstant*/ false, llvm::GlobalValue::CommonLinkage,
llvm::Constant::getNullValue(Ty), Elem.first(),
/*InsertBefore=*/nullptr, llvm::GlobalValue::NotThreadLocal,
AddressSpace);
}
return Elem.second;
}
Value *OpenMPIRBuilder::getOMPCriticalRegionLock(StringRef CriticalName) {
std::string Prefix = Twine("gomp_critical_user_", CriticalName).str();
std::string Name = getNameWithSeparators({Prefix, "var"}, ".", ".");
return getOrCreateOMPInternalVariable(KmpCriticalNameTy, Name);
}
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