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llvm-mirror/lib/Frontend/OpenMP/OMPIRBuilder.cpp
Valentin Clement c463fa6cad [mlir][openacc] Initial translation for DataOp to LLVM IR 
Add basic translation of acc.data to LLVM IR with runtime calls.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D104301
2021-07-27 22:04:04 -04:00

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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/Triple.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Value.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;
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();
// Get the function's current attributes.
auto Attrs = Fn.getAttributes();
auto FnAttrs = Attrs.getFnAttributes();
auto RetAttrs = Attrs.getRetAttributes();
SmallVector<AttributeSet, 4> ArgAttrs;
for (size_t ArgNo = 0; ArgNo < Fn.arg_size(); ++ArgNo)
ArgAttrs.emplace_back(Attrs.getParamAttributes(ArgNo));
#define OMP_ATTRS_SET(VarName, AttrSet) AttributeSet VarName = AttrSet;
#include "llvm/Frontend/OpenMP/OMPKinds.def"
// Add attributes to the function declaration.
switch (FnID) {
#define OMP_RTL_ATTRS(Enum, FnAttrSet, RetAttrSet, ArgAttrSets) \
case Enum: \
FnAttrs = FnAttrs.addAttributes(Ctx, FnAttrSet); \
RetAttrs = RetAttrs.addAttributes(Ctx, RetAttrSet); \
for (size_t ArgNo = 0; ArgNo < ArgAttrSets.size(); ++ArgNo) \
ArgAttrs[ArgNo] = \
ArgAttrs[ArgNo].addAttributes(Ctx, ArgAttrSets[ArgNo]); \
Fn.setAttributes(AttributeList::get(Ctx, FnAttrs, RetAttrs, ArgAttrs)); \
break;
#include "llvm/Frontend/OpenMP/OMPKinds.def"
default:
// Attributes are optional.
break;
}
}
FunctionCallee
OpenMPIRBuilder::getOrCreateRuntimeFunction(Module &M, RuntimeFunction FnID) {
FunctionType *FnTy = nullptr;
Function *Fn = nullptr;
// Try to find the declation in the module first.
switch (FnID) {
#define OMP_RTL(Enum, Str, IsVarArg, ReturnType, ...) \
case Enum: \
FnTy = FunctionType::get(ReturnType, ArrayRef<Type *>{__VA_ARGS__}, \
IsVarArg); \
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, ...) \
case Enum: \
Fn = Function::Create(FnTy, GlobalValue::ExternalLinkage, Str, M); \
break;
#include "llvm/Frontend/OpenMP/OMPKinds.def"
}
// Add information if the runtime function takes a callback function
if (FnID == OMPRTL___kmpc_fork_call || FnID == OMPRTL___kmpc_fork_teams) {
if (!Fn->hasMetadata(LLVMContext::MD_callback)) {
LLVMContext &Ctx = Fn->getContext();
MDBuilder MDB(Ctx);
// Annotate the callback behavior of the runtime function:
// - The callback callee is argument number 2 (microtask).
// - The first two arguments of the callback callee are unknown (-1).
// - All variadic arguments to the runtime function are passed to the
// callback callee.
Fn->addMetadata(
LLVMContext::MD_callback,
*MDNode::get(Ctx, {MDB.createCallbackEncoding(
2, {-1, -1}, /* VarArgsArePassed */ true)}));
}
}
LLVM_DEBUG(dbgs() << "Created OpenMP runtime function " << Fn->getName()
<< " with type " << *Fn->getFunctionType() << "\n");
addAttributes(FnID, *Fn);
} else {
LLVM_DEBUG(dbgs() << "Found OpenMP runtime function " << Fn->getName()
<< " with type " << *Fn->getFunctionType() << "\n");
}
assert(Fn && "Failed to create OpenMP runtime function");
// Cast the function to the expected type if necessary
Constant *C = ConstantExpr::getBitCast(Fn, FnTy->getPointerTo());
return {FnTy, C};
}
Function *OpenMPIRBuilder::getOrCreateRuntimeFunctionPtr(RuntimeFunction FnID) {
FunctionCallee RTLFn = getOrCreateRuntimeFunction(M, FnID);
auto *Fn = dyn_cast<llvm::Function>(RTLFn.getCallee());
assert(Fn && "Failed to create OpenMP runtime function pointer");
return Fn;
}
void OpenMPIRBuilder::initialize() { initializeTypes(M); }
void OpenMPIRBuilder::finalize(Function *Fn, bool AllowExtractorSinking) {
SmallPtrSet<BasicBlock *, 32> ParallelRegionBlockSet;
SmallVector<BasicBlock *, 32> Blocks;
SmallVector<OutlineInfo, 16> DeferredOutlines;
for (OutlineInfo &OI : OutlineInfos) {
// Skip functions that have not finalized yet; may happen with nested
// function generation.
if (Fn && OI.getFunction() != Fn) {
DeferredOutlines.push_back(OI);
continue;
}
ParallelRegionBlockSet.clear();
Blocks.clear();
OI.collectBlocks(ParallelRegionBlockSet, Blocks);
Function *OuterFn = OI.getFunction();
CodeExtractorAnalysisCache CEAC(*OuterFn);
CodeExtractor Extractor(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");
LLVM_DEBUG(dbgs() << "Entry " << OI.EntryBB->getName()
<< " Exit: " << OI.ExitBB->getName() << "\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() == OI.EntryBB);
assert(OI.EntryBB->getUniquePredecessor() == &ArtificialEntry);
if (AllowExtractorSinking) {
// Move instructions from the to-be-deleted ArtificialEntry to the entry
// basic block of the parallel region. CodeExtractor may have sunk
// allocas/bitcasts for values that are solely used in the outlined
// region and do not escape.
assert(!ArtificialEntry.empty() &&
"Expected instructions to sink in the outlined region");
for (BasicBlock::iterator It = ArtificialEntry.begin(),
End = ArtificialEntry.end();
It != End;) {
Instruction &I = *It;
It++;
if (I.isTerminator())
continue;
I.moveBefore(*OI.EntryBB, OI.EntryBB->getFirstInsertionPt());
}
}
OI.EntryBB->moveBefore(&ArtificialEntry);
ArtificialEntry.eraseFromParent();
}
assert(&OutlinedFn->getEntryBlock() == OI.EntryBB);
assert(OutlinedFn && OutlinedFn->getNumUses() == 1);
// Run a user callback, e.g. to add attributes.
if (OI.PostOutlineCB)
OI.PostOutlineCB(*OutlinedFn);
}
// Remove work items that have been completed.
OutlineInfos = std::move(DeferredOutlines);
}
OpenMPIRBuilder::~OpenMPIRBuilder() {
assert(OutlineInfos.empty() && "There must be no outstanding outlinings");
}
Value *OpenMPIRBuilder::getOrCreateIdent(Constant *SrcLocStr,
IdentFlag LocFlags,
unsigned Reserve2Flags) {
// Enable "C-mode".
LocFlags |= OMP_IDENT_FLAG_KMPC;
Value *&Ident =
IdentMap[{SrcLocStr, uint64_t(LocFlags) << 31 | Reserve2Flags}];
if (!Ident) {
Constant *I32Null = ConstantInt::getNullValue(Int32);
Constant *IdentData[] = {
I32Null, ConstantInt::get(Int32, uint32_t(LocFlags)),
ConstantInt::get(Int32, Reserve2Flags), 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 Ident = &GV;
auto *GV = new GlobalVariable(M, IdentPtr->getPointerElementType(),
/* isConstant = */ true,
GlobalValue::PrivateLinkage, Initializer);
GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
GV->setAlignment(Align(8));
Ident = GV;
}
return Builder.CreatePointerCast(Ident, IdentPtr);
}
Type *OpenMPIRBuilder::getLanemaskType() {
LLVMContext &Ctx = M.getContext();
Triple triple(M.getTargetTriple());
// This test is adequate until deviceRTL has finer grained lane widths
return triple.isAMDGCN() ? Type::getInt64Ty(Ctx) : Type::getInt32Ty(Ctx);
}
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, /* Name */ "",
/* AddressSpace */ 0, &M);
}
return SrcLocStr;
}
Constant *OpenMPIRBuilder::getOrCreateSrcLocStr(StringRef FunctionName,
StringRef FileName,
unsigned Line,
unsigned Column) {
SmallString<128> Buffer;
Buffer.push_back(';');
Buffer.append(FileName);
Buffer.push_back(';');
Buffer.append(FunctionName);
Buffer.push_back(';');
Buffer.append(std::to_string(Line));
Buffer.push_back(';');
Buffer.append(std::to_string(Column));
Buffer.push_back(';');
Buffer.push_back(';');
return getOrCreateSrcLocStr(Buffer.str());
}
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 = M.getName();
if (DIFile *DIF = DIL->getFile())
if (Optional<StringRef> Source = DIF->getSource())
FileName = *Source;
StringRef Function = DIL->getScope()->getSubprogram()->getName();
Function =
!Function.empty() ? Function : Loc.IP.getBlock()->getParent()->getName();
return getOrCreateSrcLocStr(Function, FileName, DIL->getLine(),
DIL->getColumn());
}
Value *OpenMPIRBuilder::getOrCreateThreadID(Value *Ident) {
return Builder.CreateCall(
getOrCreateRuntimeFunctionPtr(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(getOrCreateRuntimeFunctionPtr(
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(
getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_cancel), Args);
auto ExitCB = [this, CanceledDirective, Loc](InsertPointTy IP) {
if (CanceledDirective == OMPD_parallel) {
IRBuilder<>::InsertPointGuard IPG(Builder);
Builder.restoreIP(IP);
createBarrier(LocationDescription(Builder.saveIP(), Loc.DL),
omp::Directive::OMPD_unknown, /* ForceSimpleCall */ false,
/* CheckCancelFlag */ false);
}
};
// The actual cancel logic is shared with others, e.g., cancel_barriers.
emitCancelationCheckImpl(Result, CanceledDirective, ExitCB);
// 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,
FinalizeCallbackTy ExitCB) {
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);
if (ExitCB)
ExitCB(Builder.saveIP());
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, InsertPointTy OuterAllocaIP,
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(
getOrCreateRuntimeFunctionPtr(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(
getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_push_proc_bind), Args);
}
BasicBlock *InsertBB = Builder.GetInsertBlock();
Function *OuterFn = InsertBB->getParent();
// Save the outer alloca block because the insertion iterator may get
// invalidated and we still need this later.
BasicBlock *OuterAllocaBlock = OuterAllocaIP.getBlock();
// Vector to remember instructions we used only during the modeling but which
// we want to delete at the end.
SmallVector<Instruction *, 4> ToBeDeleted;
// Change the location to the outer alloca insertion point to create and
// initialize the allocas we pass into the parallel region.
Builder.restoreIP(OuterAllocaIP);
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.
Builder.SetInsertPoint(PRegEntryBB->getTerminator());
InsertPointTy InnerAllocaIP = Builder.saveIP();
AllocaInst *PrivTIDAddr =
Builder.CreateAlloca(Int32, nullptr, "tid.addr.local");
Instruction *PrivTID = Builder.CreateLoad(Int32, PrivTIDAddr, "tid");
// Add some fake uses for OpenMP provided arguments.
ToBeDeleted.push_back(Builder.CreateLoad(Int32, TIDAddr, "tid.addr.use"));
Instruction *ZeroAddrUse = Builder.CreateLoad(Int32, ZeroAddr,
"zero.addr.use");
ToBeDeleted.push_back(ZeroAddrUse);
// 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(InnerAllocaIP, CodeGenIP, *PRegPreFiniBB);
LLVM_DEBUG(dbgs() << "After body codegen: " << *OuterFn << "\n");
FunctionCallee RTLFn = getOrCreateRuntimeFunctionPtr(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(Int32, 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(
getOrCreateRuntimeFunctionPtr(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(
getOrCreateRuntimeFunctionPtr(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();
InsertPointTy PreFiniIP(PRegPreFiniBB, PRegPreFiniTI->getIterator());
FiniCB(PreFiniIP);
OI.EntryBB = PRegEntryBB;
OI.ExitBB = PRegExitBB;
SmallPtrSet<BasicBlock *, 32> ParallelRegionBlockSet;
SmallVector<BasicBlock *, 32> Blocks;
OI.collectBlocks(ParallelRegionBlockSet, Blocks);
// 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");
Blocks.push_back(PRegOutlinedExitBB);
CodeExtractorAnalysisCache CEAC(*OuterFn);
CodeExtractor Extractor(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 =
getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_global_thread_num);
auto PrivHelper = [&](Value &V) {
if (&V == TIDAddr || &V == ZeroAddr)
return;
SetVector<Use *> Uses;
for (Use &U : V.uses())
if (auto *UserI = dyn_cast<Instruction>(U.getUser()))
if (ParallelRegionBlockSet.count(UserI->getParent()))
Uses.insert(&U);
// __kmpc_fork_call expects extra arguments as pointers. If the input
// already has a pointer type, everything is fine. Otherwise, store the
// value onto stack and load it back inside the to-be-outlined region. This
// will ensure only the pointer will be passed to the function.
// FIXME: if there are more than 15 trailing arguments, they must be
// additionally packed in a struct.
Value *Inner = &V;
if (!V.getType()->isPointerTy()) {
IRBuilder<>::InsertPointGuard Guard(Builder);
LLVM_DEBUG(llvm::dbgs() << "Forwarding input as pointer: " << V << "\n");
Builder.restoreIP(OuterAllocaIP);
Value *Ptr =
Builder.CreateAlloca(V.getType(), nullptr, V.getName() + ".reloaded");
// Store to stack at end of the block that currently branches to the entry
// block of the to-be-outlined region.
Builder.SetInsertPoint(InsertBB,
InsertBB->getTerminator()->getIterator());
Builder.CreateStore(&V, Ptr);
// Load back next to allocations in the to-be-outlined region.
Builder.restoreIP(InnerAllocaIP);
Inner = Builder.CreateLoad(V.getType(), Ptr);
}
Value *ReplacementValue = nullptr;
CallInst *CI = dyn_cast<CallInst>(&V);
if (CI && CI->getCalledFunction() == TIDRTLFn.getCallee()) {
ReplacementValue = PrivTID;
} else {
Builder.restoreIP(
PrivCB(InnerAllocaIP, Builder.saveIP(), V, *Inner, ReplacementValue));
assert(ReplacementValue &&
"Expected copy/create callback to set replacement value!");
if (ReplacementValue == &V)
return;
}
for (Use *UPtr : Uses)
UPtr->set(ReplacementValue);
};
// Reset the inner alloca insertion as it will be used for loading the values
// wrapped into pointers before passing them into the to-be-outlined region.
// Configure it to insert immediately after the fake use of zero address so
// that they are available in the generated body and so that the
// OpenMP-related values (thread ID and zero address pointers) remain leading
// in the argument list.
InnerAllocaIP = IRBuilder<>::InsertPoint(
ZeroAddrUse->getParent(), ZeroAddrUse->getNextNode()->getIterator());
// Reset the outer alloca insertion point to the entry of the relevant block
// in case it was invalidated.
OuterAllocaIP = IRBuilder<>::InsertPoint(
OuterAllocaBlock, OuterAllocaBlock->getFirstInsertionPt());
for (Value *Input : Inputs) {
LLVM_DEBUG(dbgs() << "Captured input: " << *Input << "\n");
PrivHelper(*Input);
}
LLVM_DEBUG({
for (Value *Output : Outputs)
LLVM_DEBUG(dbgs() << "Captured output: " << *Output << "\n");
});
assert(Outputs.empty() &&
"OpenMP outlining should not produce live-out values!");
LLVM_DEBUG(dbgs() << "After privatization: " << *OuterFn << "\n");
LLVM_DEBUG({
for (auto *BB : 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(getOrCreateRuntimeFunctionPtr(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(getOrCreateRuntimeFunctionPtr(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(getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_taskyield),
Args);
}
void OpenMPIRBuilder::createTaskyield(const LocationDescription &Loc) {
if (!updateToLocation(Loc))
return;
emitTaskyieldImpl(Loc);
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::createSections(
const LocationDescription &Loc, InsertPointTy AllocaIP,
ArrayRef<StorableBodyGenCallbackTy> SectionCBs, PrivatizeCallbackTy PrivCB,
FinalizeCallbackTy FiniCB, bool IsCancellable, bool IsNowait) {
if (!updateToLocation(Loc))
return Loc.IP;
auto FiniCBWrapper = [&](InsertPointTy IP) {
if (IP.getBlock()->end() != IP.getPoint())
return FiniCB(IP);
// This must be done otherwise any nested constructs using FinalizeOMPRegion
// will fail because that function requires the Finalization Basic Block to
// have a terminator, which is already removed by EmitOMPRegionBody.
// IP is currently at cancelation block.
// We need to backtrack to the condition block to fetch
// the exit block and create a branch from cancelation
// to exit block.
IRBuilder<>::InsertPointGuard IPG(Builder);
Builder.restoreIP(IP);
auto *CaseBB = IP.getBlock()->getSinglePredecessor();
auto *CondBB = CaseBB->getSinglePredecessor()->getSinglePredecessor();
auto *ExitBB = CondBB->getTerminator()->getSuccessor(1);
Instruction *I = Builder.CreateBr(ExitBB);
IP = InsertPointTy(I->getParent(), I->getIterator());
return FiniCB(IP);
};
FinalizationStack.push_back({FiniCBWrapper, OMPD_sections, IsCancellable});
// Each section is emitted as a switch case
// Each finalization callback is handled from clang.EmitOMPSectionDirective()
// -> OMP.createSection() which generates the IR for each section
// Iterate through all sections and emit a switch construct:
// switch (IV) {
// case 0:
// <SectionStmt[0]>;
// break;
// ...
// case <NumSection> - 1:
// <SectionStmt[<NumSection> - 1]>;
// break;
// }
// ...
// section_loop.after:
// <FiniCB>;
auto LoopBodyGenCB = [&](InsertPointTy CodeGenIP, Value *IndVar) {
auto *CurFn = CodeGenIP.getBlock()->getParent();
auto *ForIncBB = CodeGenIP.getBlock()->getSingleSuccessor();
auto *ForExitBB = CodeGenIP.getBlock()
->getSinglePredecessor()
->getTerminator()
->getSuccessor(1);
SwitchInst *SwitchStmt = Builder.CreateSwitch(IndVar, ForIncBB);
Builder.restoreIP(CodeGenIP);
unsigned CaseNumber = 0;
for (auto SectionCB : SectionCBs) {
auto *CaseBB = BasicBlock::Create(M.getContext(),
"omp_section_loop.body.case", CurFn);
SwitchStmt->addCase(Builder.getInt32(CaseNumber), CaseBB);
Builder.SetInsertPoint(CaseBB);
SectionCB(InsertPointTy(), Builder.saveIP(), *ForExitBB);
CaseNumber++;
}
// remove the existing terminator from body BB since there can be no
// terminators after switch/case
CodeGenIP.getBlock()->getTerminator()->eraseFromParent();
};
// Loop body ends here
// LowerBound, UpperBound, and STride for createCanonicalLoop
Type *I32Ty = Type::getInt32Ty(M.getContext());
Value *LB = ConstantInt::get(I32Ty, 0);
Value *UB = ConstantInt::get(I32Ty, SectionCBs.size());
Value *ST = ConstantInt::get(I32Ty, 1);
llvm::CanonicalLoopInfo *LoopInfo = createCanonicalLoop(
Loc, LoopBodyGenCB, LB, UB, ST, true, false, AllocaIP, "section_loop");
LoopInfo = createStaticWorkshareLoop(Loc, LoopInfo, AllocaIP, true);
BasicBlock *LoopAfterBB = LoopInfo->getAfter();
Instruction *SplitPos = LoopAfterBB->getTerminator();
if (!isa_and_nonnull<BranchInst>(SplitPos))
SplitPos = new UnreachableInst(Builder.getContext(), LoopAfterBB);
// ExitBB after LoopAfterBB because LoopAfterBB is used for FinalizationCB,
// which requires a BB with branch
BasicBlock *ExitBB =
LoopAfterBB->splitBasicBlock(SplitPos, "omp_sections.end");
SplitPos->eraseFromParent();
// Apply the finalization callback in LoopAfterBB
auto FiniInfo = FinalizationStack.pop_back_val();
assert(FiniInfo.DK == OMPD_sections &&
"Unexpected finalization stack state!");
Builder.SetInsertPoint(LoopAfterBB->getTerminator());
FiniInfo.FiniCB(Builder.saveIP());
Builder.SetInsertPoint(ExitBB);
return Builder.saveIP();
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::createSection(const LocationDescription &Loc,
BodyGenCallbackTy BodyGenCB,
FinalizeCallbackTy FiniCB) {
if (!updateToLocation(Loc))
return Loc.IP;
auto FiniCBWrapper = [&](InsertPointTy IP) {
if (IP.getBlock()->end() != IP.getPoint())
return FiniCB(IP);
// This must be done otherwise any nested constructs using FinalizeOMPRegion
// will fail because that function requires the Finalization Basic Block to
// have a terminator, which is already removed by EmitOMPRegionBody.
// IP is currently at cancelation block.
// We need to backtrack to the condition block to fetch
// the exit block and create a branch from cancelation
// to exit block.
IRBuilder<>::InsertPointGuard IPG(Builder);
Builder.restoreIP(IP);
auto *CaseBB = Loc.IP.getBlock();
auto *CondBB = CaseBB->getSinglePredecessor()->getSinglePredecessor();
auto *ExitBB = CondBB->getTerminator()->getSuccessor(1);
Instruction *I = Builder.CreateBr(ExitBB);
IP = InsertPointTy(I->getParent(), I->getIterator());
return FiniCB(IP);
};
Directive OMPD = Directive::OMPD_sections;
// Since we are using Finalization Callback here, HasFinalize
// and IsCancellable have to be true
return EmitOMPInlinedRegion(OMPD, nullptr, nullptr, BodyGenCB, FiniCBWrapper,
/*Conditional*/ false, /*hasFinalize*/ true,
/*IsCancellable*/ true);
}
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 = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_master);
Instruction *EntryCall = Builder.CreateCall(EntryRTLFn, Args);
Function *ExitRTLFn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_end_master);
Instruction *ExitCall = Builder.CreateCall(ExitRTLFn, Args);
return EmitOMPInlinedRegion(OMPD, EntryCall, ExitCall, BodyGenCB, FiniCB,
/*Conditional*/ true, /*hasFinalize*/ true);
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::createMasked(const LocationDescription &Loc,
BodyGenCallbackTy BodyGenCB,
FinalizeCallbackTy FiniCB, Value *Filter) {
if (!updateToLocation(Loc))
return Loc.IP;
Directive OMPD = Directive::OMPD_masked;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadId = getOrCreateThreadID(Ident);
Value *Args[] = {Ident, ThreadId, Filter};
Value *ArgsEnd[] = {Ident, ThreadId};
Function *EntryRTLFn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_masked);
Instruction *EntryCall = Builder.CreateCall(EntryRTLFn, Args);
Function *ExitRTLFn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_end_masked);
Instruction *ExitCall = Builder.CreateCall(ExitRTLFn, ArgsEnd);
return EmitOMPInlinedRegion(OMPD, EntryCall, ExitCall, BodyGenCB, FiniCB,
/*Conditional*/ true, /*hasFinalize*/ true);
}
CanonicalLoopInfo *OpenMPIRBuilder::createLoopSkeleton(
DebugLoc DL, Value *TripCount, Function *F, BasicBlock *PreInsertBefore,
BasicBlock *PostInsertBefore, const Twine &Name) {
Module *M = F->getParent();
LLVMContext &Ctx = M->getContext();
Type *IndVarTy = TripCount->getType();
// Create the basic block structure.
BasicBlock *Preheader =
BasicBlock::Create(Ctx, "omp_" + Name + ".preheader", F, PreInsertBefore);
BasicBlock *Header =
BasicBlock::Create(Ctx, "omp_" + Name + ".header", F, PreInsertBefore);
BasicBlock *Cond =
BasicBlock::Create(Ctx, "omp_" + Name + ".cond", F, PreInsertBefore);
BasicBlock *Body =
BasicBlock::Create(Ctx, "omp_" + Name + ".body", F, PreInsertBefore);
BasicBlock *Latch =
BasicBlock::Create(Ctx, "omp_" + Name + ".inc", F, PostInsertBefore);
BasicBlock *Exit =
BasicBlock::Create(Ctx, "omp_" + Name + ".exit", F, PostInsertBefore);
BasicBlock *After =
BasicBlock::Create(Ctx, "omp_" + Name + ".after", F, PostInsertBefore);
// Use specified DebugLoc for new instructions.
Builder.SetCurrentDebugLocation(DL);
Builder.SetInsertPoint(Preheader);
Builder.CreateBr(Header);
Builder.SetInsertPoint(Header);
PHINode *IndVarPHI = Builder.CreatePHI(IndVarTy, 2, "omp_" + Name + ".iv");
IndVarPHI->addIncoming(ConstantInt::get(IndVarTy, 0), Preheader);
Builder.CreateBr(Cond);
Builder.SetInsertPoint(Cond);
Value *Cmp =
Builder.CreateICmpULT(IndVarPHI, TripCount, "omp_" + Name + ".cmp");
Builder.CreateCondBr(Cmp, Body, Exit);
Builder.SetInsertPoint(Body);
Builder.CreateBr(Latch);
Builder.SetInsertPoint(Latch);
Value *Next = Builder.CreateAdd(IndVarPHI, ConstantInt::get(IndVarTy, 1),
"omp_" + Name + ".next", /*HasNUW=*/true);
Builder.CreateBr(Header);
IndVarPHI->addIncoming(Next, Latch);
Builder.SetInsertPoint(Exit);
Builder.CreateBr(After);
// Remember and return the canonical control flow.
LoopInfos.emplace_front();
CanonicalLoopInfo *CL = &LoopInfos.front();
CL->Preheader = Preheader;
CL->Header = Header;
CL->Cond = Cond;
CL->Body = Body;
CL->Latch = Latch;
CL->Exit = Exit;
CL->After = After;
CL->IsValid = true;
#ifndef NDEBUG
CL->assertOK();
#endif
return CL;
}
CanonicalLoopInfo *
OpenMPIRBuilder::createCanonicalLoop(const LocationDescription &Loc,
LoopBodyGenCallbackTy BodyGenCB,
Value *TripCount, const Twine &Name) {
BasicBlock *BB = Loc.IP.getBlock();
BasicBlock *NextBB = BB->getNextNode();
CanonicalLoopInfo *CL = createLoopSkeleton(Loc.DL, TripCount, BB->getParent(),
NextBB, NextBB, Name);
BasicBlock *After = CL->getAfter();
// If location is not set, don't connect the loop.
if (updateToLocation(Loc)) {
// Split the loop at the insertion point: Branch to the preheader and move
// every following instruction to after the loop (the After BB). Also, the
// new successor is the loop's after block.
Builder.CreateBr(CL->Preheader);
After->getInstList().splice(After->begin(), BB->getInstList(),
Builder.GetInsertPoint(), BB->end());
After->replaceSuccessorsPhiUsesWith(BB, After);
}
// Emit the body content. We do it after connecting the loop to the CFG to
// avoid that the callback encounters degenerate BBs.
BodyGenCB(CL->getBodyIP(), CL->getIndVar());
#ifndef NDEBUG
CL->assertOK();
#endif
return CL;
}
CanonicalLoopInfo *OpenMPIRBuilder::createCanonicalLoop(
const LocationDescription &Loc, LoopBodyGenCallbackTy BodyGenCB,
Value *Start, Value *Stop, Value *Step, bool IsSigned, bool InclusiveStop,
InsertPointTy ComputeIP, const Twine &Name) {
// Consider the following difficulties (assuming 8-bit signed integers):
// * Adding \p Step to the loop counter which passes \p Stop may overflow:
// DO I = 1, 100, 50
/// * A \p Step of INT_MIN cannot not be normalized to a positive direction:
// DO I = 100, 0, -128
// Start, Stop and Step must be of the same integer type.
auto *IndVarTy = cast<IntegerType>(Start->getType());
assert(IndVarTy == Stop->getType() && "Stop type mismatch");
assert(IndVarTy == Step->getType() && "Step type mismatch");
LocationDescription ComputeLoc =
ComputeIP.isSet() ? LocationDescription(ComputeIP, Loc.DL) : Loc;
updateToLocation(ComputeLoc);
ConstantInt *Zero = ConstantInt::get(IndVarTy, 0);
ConstantInt *One = ConstantInt::get(IndVarTy, 1);
// Like Step, but always positive.
Value *Incr = Step;
// Distance between Start and Stop; always positive.
Value *Span;
// Condition whether there are no iterations are executed at all, e.g. because
// UB < LB.
Value *ZeroCmp;
if (IsSigned) {
// Ensure that increment is positive. If not, negate and invert LB and UB.
Value *IsNeg = Builder.CreateICmpSLT(Step, Zero);
Incr = Builder.CreateSelect(IsNeg, Builder.CreateNeg(Step), Step);
Value *LB = Builder.CreateSelect(IsNeg, Stop, Start);
Value *UB = Builder.CreateSelect(IsNeg, Start, Stop);
Span = Builder.CreateSub(UB, LB, "", false, true);
ZeroCmp = Builder.CreateICmp(
InclusiveStop ? CmpInst::ICMP_SLT : CmpInst::ICMP_SLE, UB, LB);
} else {
Span = Builder.CreateSub(Stop, Start, "", true);
ZeroCmp = Builder.CreateICmp(
InclusiveStop ? CmpInst::ICMP_ULT : CmpInst::ICMP_ULE, Stop, Start);
}
Value *CountIfLooping;
if (InclusiveStop) {
CountIfLooping = Builder.CreateAdd(Builder.CreateUDiv(Span, Incr), One);
} else {
// Avoid incrementing past stop since it could overflow.
Value *CountIfTwo = Builder.CreateAdd(
Builder.CreateUDiv(Builder.CreateSub(Span, One), Incr), One);
Value *OneCmp = Builder.CreateICmp(
InclusiveStop ? CmpInst::ICMP_ULT : CmpInst::ICMP_ULE, Span, Incr);
CountIfLooping = Builder.CreateSelect(OneCmp, One, CountIfTwo);
}
Value *TripCount = Builder.CreateSelect(ZeroCmp, Zero, CountIfLooping,
"omp_" + Name + ".tripcount");
auto BodyGen = [=](InsertPointTy CodeGenIP, Value *IV) {
Builder.restoreIP(CodeGenIP);
Value *Span = Builder.CreateMul(IV, Step);
Value *IndVar = Builder.CreateAdd(Span, Start);
BodyGenCB(Builder.saveIP(), IndVar);
};
LocationDescription LoopLoc = ComputeIP.isSet() ? Loc.IP : Builder.saveIP();
return createCanonicalLoop(LoopLoc, BodyGen, TripCount, Name);
}
// Returns an LLVM function to call for initializing loop bounds using OpenMP
// static scheduling depending on `type`. Only i32 and i64 are supported by the
// runtime. Always interpret integers as unsigned similarly to
// CanonicalLoopInfo.
static FunctionCallee getKmpcForStaticInitForType(Type *Ty, Module &M,
OpenMPIRBuilder &OMPBuilder) {
unsigned Bitwidth = Ty->getIntegerBitWidth();
if (Bitwidth == 32)
return OMPBuilder.getOrCreateRuntimeFunction(
M, omp::RuntimeFunction::OMPRTL___kmpc_for_static_init_4u);
if (Bitwidth == 64)
return OMPBuilder.getOrCreateRuntimeFunction(
M, omp::RuntimeFunction::OMPRTL___kmpc_for_static_init_8u);
llvm_unreachable("unknown OpenMP loop iterator bitwidth");
}
// Sets the number of loop iterations to the given value. This value must be
// valid in the condition block (i.e., defined in the preheader) and is
// interpreted as an unsigned integer.
void setCanonicalLoopTripCount(CanonicalLoopInfo *CLI, Value *TripCount) {
Instruction *CmpI = &CLI->getCond()->front();
assert(isa<CmpInst>(CmpI) && "First inst must compare IV with TripCount");
CmpI->setOperand(1, TripCount);
CLI->assertOK();
}
CanonicalLoopInfo *OpenMPIRBuilder::createStaticWorkshareLoop(
const LocationDescription &Loc, CanonicalLoopInfo *CLI,
InsertPointTy AllocaIP, bool NeedsBarrier, Value *Chunk) {
// Set up the source location value for OpenMP runtime.
if (!updateToLocation(Loc))
return nullptr;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *SrcLoc = getOrCreateIdent(SrcLocStr);
// Declare useful OpenMP runtime functions.
Value *IV = CLI->getIndVar();
Type *IVTy = IV->getType();
FunctionCallee StaticInit = getKmpcForStaticInitForType(IVTy, M, *this);
FunctionCallee StaticFini =
getOrCreateRuntimeFunction(M, omp::OMPRTL___kmpc_for_static_fini);
// Allocate space for computed loop bounds as expected by the "init" function.
Builder.restoreIP(AllocaIP);
Type *I32Type = Type::getInt32Ty(M.getContext());
Value *PLastIter = Builder.CreateAlloca(I32Type, nullptr, "p.lastiter");
Value *PLowerBound = Builder.CreateAlloca(IVTy, nullptr, "p.lowerbound");
Value *PUpperBound = Builder.CreateAlloca(IVTy, nullptr, "p.upperbound");
Value *PStride = Builder.CreateAlloca(IVTy, nullptr, "p.stride");
// At the end of the preheader, prepare for calling the "init" function by
// storing the current loop bounds into the allocated space. A canonical loop
// always iterates from 0 to trip-count with step 1. Note that "init" expects
// and produces an inclusive upper bound.
Builder.SetInsertPoint(CLI->getPreheader()->getTerminator());
Constant *Zero = ConstantInt::get(IVTy, 0);
Constant *One = ConstantInt::get(IVTy, 1);
Builder.CreateStore(Zero, PLowerBound);
Value *UpperBound = Builder.CreateSub(CLI->getTripCount(), One);
Builder.CreateStore(UpperBound, PUpperBound);
Builder.CreateStore(One, PStride);
if (!Chunk)
Chunk = One;
Value *ThreadNum = getOrCreateThreadID(SrcLoc);
Constant *SchedulingType =
ConstantInt::get(I32Type, static_cast<int>(OMPScheduleType::Static));
// Call the "init" function and update the trip count of the loop with the
// value it produced.
Builder.CreateCall(StaticInit,
{SrcLoc, ThreadNum, SchedulingType, PLastIter, PLowerBound,
PUpperBound, PStride, One, Chunk});
Value *LowerBound = Builder.CreateLoad(IVTy, PLowerBound);
Value *InclusiveUpperBound = Builder.CreateLoad(IVTy, PUpperBound);
Value *TripCountMinusOne = Builder.CreateSub(InclusiveUpperBound, LowerBound);
Value *TripCount = Builder.CreateAdd(TripCountMinusOne, One);
setCanonicalLoopTripCount(CLI, TripCount);
// Update all uses of the induction variable except the one in the condition
// block that compares it with the actual upper bound, and the increment in
// the latch block.
// TODO: this can eventually move to CanonicalLoopInfo or to a new
// CanonicalLoopInfoUpdater interface.
Builder.SetInsertPoint(CLI->getBody(), CLI->getBody()->getFirstInsertionPt());
Value *UpdatedIV = Builder.CreateAdd(IV, LowerBound);
IV->replaceUsesWithIf(UpdatedIV, [&](Use &U) {
auto *Instr = dyn_cast<Instruction>(U.getUser());
return !Instr ||
(Instr->getParent() != CLI->getCond() &&
Instr->getParent() != CLI->getLatch() && Instr != UpdatedIV);
});
// In the "exit" block, call the "fini" function.
Builder.SetInsertPoint(CLI->getExit(),
CLI->getExit()->getTerminator()->getIterator());
Builder.CreateCall(StaticFini, {SrcLoc, ThreadNum});
// Add the barrier if requested.
if (NeedsBarrier)
createBarrier(LocationDescription(Builder.saveIP(), Loc.DL),
omp::Directive::OMPD_for, /* ForceSimpleCall */ false,
/* CheckCancelFlag */ false);
CLI->assertOK();
return CLI;
}
CanonicalLoopInfo *OpenMPIRBuilder::createWorkshareLoop(
const LocationDescription &Loc, CanonicalLoopInfo *CLI,
InsertPointTy AllocaIP, bool NeedsBarrier) {
// Currently only supports static schedules.
return createStaticWorkshareLoop(Loc, CLI, AllocaIP, NeedsBarrier);
}
/// Returns an LLVM function to call for initializing loop bounds using OpenMP
/// dynamic scheduling depending on `type`. Only i32 and i64 are supported by
/// the runtime. Always interpret integers as unsigned similarly to
/// CanonicalLoopInfo.
static FunctionCallee
getKmpcForDynamicInitForType(Type *Ty, Module &M, OpenMPIRBuilder &OMPBuilder) {
unsigned Bitwidth = Ty->getIntegerBitWidth();
if (Bitwidth == 32)
return OMPBuilder.getOrCreateRuntimeFunction(
M, omp::RuntimeFunction::OMPRTL___kmpc_dispatch_init_4u);
if (Bitwidth == 64)
return OMPBuilder.getOrCreateRuntimeFunction(
M, omp::RuntimeFunction::OMPRTL___kmpc_dispatch_init_8u);
llvm_unreachable("unknown OpenMP loop iterator bitwidth");
}
/// Returns an LLVM function to call for updating the next loop using OpenMP
/// dynamic scheduling depending on `type`. Only i32 and i64 are supported by
/// the runtime. Always interpret integers as unsigned similarly to
/// CanonicalLoopInfo.
static FunctionCallee
getKmpcForDynamicNextForType(Type *Ty, Module &M, OpenMPIRBuilder &OMPBuilder) {
unsigned Bitwidth = Ty->getIntegerBitWidth();
if (Bitwidth == 32)
return OMPBuilder.getOrCreateRuntimeFunction(
M, omp::RuntimeFunction::OMPRTL___kmpc_dispatch_next_4u);
if (Bitwidth == 64)
return OMPBuilder.getOrCreateRuntimeFunction(
M, omp::RuntimeFunction::OMPRTL___kmpc_dispatch_next_8u);
llvm_unreachable("unknown OpenMP loop iterator bitwidth");
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::createDynamicWorkshareLoop(
const LocationDescription &Loc, CanonicalLoopInfo *CLI,
InsertPointTy AllocaIP, OMPScheduleType SchedType, bool NeedsBarrier,
Value *Chunk) {
// Set up the source location value for OpenMP runtime.
Builder.SetCurrentDebugLocation(Loc.DL);
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *SrcLoc = getOrCreateIdent(SrcLocStr);
// Declare useful OpenMP runtime functions.
Value *IV = CLI->getIndVar();
Type *IVTy = IV->getType();
FunctionCallee DynamicInit = getKmpcForDynamicInitForType(IVTy, M, *this);
FunctionCallee DynamicNext = getKmpcForDynamicNextForType(IVTy, M, *this);
// Allocate space for computed loop bounds as expected by the "init" function.
Builder.restoreIP(AllocaIP);
Type *I32Type = Type::getInt32Ty(M.getContext());
Value *PLastIter = Builder.CreateAlloca(I32Type, nullptr, "p.lastiter");
Value *PLowerBound = Builder.CreateAlloca(IVTy, nullptr, "p.lowerbound");
Value *PUpperBound = Builder.CreateAlloca(IVTy, nullptr, "p.upperbound");
Value *PStride = Builder.CreateAlloca(IVTy, nullptr, "p.stride");
// At the end of the preheader, prepare for calling the "init" function by
// storing the current loop bounds into the allocated space. A canonical loop
// always iterates from 0 to trip-count with step 1. Note that "init" expects
// and produces an inclusive upper bound.
BasicBlock *PreHeader = CLI->getPreheader();
Builder.SetInsertPoint(PreHeader->getTerminator());
Constant *One = ConstantInt::get(IVTy, 1);
Builder.CreateStore(One, PLowerBound);
Value *UpperBound = CLI->getTripCount();
Builder.CreateStore(UpperBound, PUpperBound);
Builder.CreateStore(One, PStride);
BasicBlock *Header = CLI->getHeader();
BasicBlock *Exit = CLI->getExit();
BasicBlock *Cond = CLI->getCond();
InsertPointTy AfterIP = CLI->getAfterIP();
// The CLI will be "broken" in the code below, as the loop is no longer
// a valid canonical loop.
if (!Chunk)
Chunk = One;
Value *ThreadNum = getOrCreateThreadID(SrcLoc);
Constant *SchedulingType =
ConstantInt::get(I32Type, static_cast<int>(SchedType));
// Call the "init" function.
Builder.CreateCall(DynamicInit,
{SrcLoc, ThreadNum, SchedulingType, /* LowerBound */ One,
UpperBound, /* step */ One, Chunk});
// An outer loop around the existing one.
BasicBlock *OuterCond = BasicBlock::Create(
PreHeader->getContext(), Twine(PreHeader->getName()) + ".outer.cond",
PreHeader->getParent());
// This needs to be 32-bit always, so can't use the IVTy Zero above.
Builder.SetInsertPoint(OuterCond, OuterCond->getFirstInsertionPt());
Value *Res =
Builder.CreateCall(DynamicNext, {SrcLoc, ThreadNum, PLastIter,
PLowerBound, PUpperBound, PStride});
Constant *Zero32 = ConstantInt::get(I32Type, 0);
Value *MoreWork = Builder.CreateCmp(CmpInst::ICMP_NE, Res, Zero32);
Value *LowerBound =
Builder.CreateSub(Builder.CreateLoad(IVTy, PLowerBound), One, "lb");
Builder.CreateCondBr(MoreWork, Header, Exit);
// Change PHI-node in loop header to use outer cond rather than preheader,
// and set IV to the LowerBound.
Instruction *Phi = &Header->front();
auto *PI = cast<PHINode>(Phi);
PI->setIncomingBlock(0, OuterCond);
PI->setIncomingValue(0, LowerBound);
// Then set the pre-header to jump to the OuterCond
Instruction *Term = PreHeader->getTerminator();
auto *Br = cast<BranchInst>(Term);
Br->setSuccessor(0, OuterCond);
// Modify the inner condition:
// * Use the UpperBound returned from the DynamicNext call.
// * jump to the loop outer loop when done with one of the inner loops.
Builder.SetInsertPoint(Cond, Cond->getFirstInsertionPt());
UpperBound = Builder.CreateLoad(IVTy, PUpperBound, "ub");
Instruction *Comp = &*Builder.GetInsertPoint();
auto *CI = cast<CmpInst>(Comp);
CI->setOperand(1, UpperBound);
// Redirect the inner exit to branch to outer condition.
Instruction *Branch = &Cond->back();
auto *BI = cast<BranchInst>(Branch);
assert(BI->getSuccessor(1) == Exit);
BI->setSuccessor(1, OuterCond);
// Add the barrier if requested.
if (NeedsBarrier) {
Builder.SetInsertPoint(&Exit->back());
createBarrier(LocationDescription(Builder.saveIP(), Loc.DL),
omp::Directive::OMPD_for, /* ForceSimpleCall */ false,
/* CheckCancelFlag */ false);
}
return AfterIP;
}
/// Make \p Source branch to \p Target.
///
/// Handles two situations:
/// * \p Source already has an unconditional branch.
/// * \p Source is a degenerate block (no terminator because the BB is
/// the current head of the IR construction).
static void redirectTo(BasicBlock *Source, BasicBlock *Target, DebugLoc DL) {
if (Instruction *Term = Source->getTerminator()) {
auto *Br = cast<BranchInst>(Term);
assert(!Br->isConditional() &&
"BB's terminator must be an unconditional branch (or degenerate)");
BasicBlock *Succ = Br->getSuccessor(0);
Succ->removePredecessor(Source, /*KeepOneInputPHIs=*/true);
Br->setSuccessor(0, Target);
return;
}
auto *NewBr = BranchInst::Create(Target, Source);
NewBr->setDebugLoc(DL);
}
/// Redirect all edges that branch to \p OldTarget to \p NewTarget. That is,
/// after this \p OldTarget will be orphaned.
static void redirectAllPredecessorsTo(BasicBlock *OldTarget,
BasicBlock *NewTarget, DebugLoc DL) {
for (BasicBlock *Pred : make_early_inc_range(predecessors(OldTarget)))
redirectTo(Pred, NewTarget, DL);
}
/// Determine which blocks in \p BBs are reachable from outside and remove the
/// ones that are not reachable from the function.
static void removeUnusedBlocksFromParent(ArrayRef<BasicBlock *> BBs) {
SmallPtrSet<BasicBlock *, 6> BBsToErase{BBs.begin(), BBs.end()};
auto HasRemainingUses = [&BBsToErase](BasicBlock *BB) {
for (Use &U : BB->uses()) {
auto *UseInst = dyn_cast<Instruction>(U.getUser());
if (!UseInst)
continue;
if (BBsToErase.count(UseInst->getParent()))
continue;
return true;
}
return false;
};
while (true) {
bool Changed = false;
for (BasicBlock *BB : make_early_inc_range(BBsToErase)) {
if (HasRemainingUses(BB)) {
BBsToErase.erase(BB);
Changed = true;
}
}
if (!Changed)
break;
}
SmallVector<BasicBlock *, 7> BBVec(BBsToErase.begin(), BBsToErase.end());
DeleteDeadBlocks(BBVec);
}
CanonicalLoopInfo *
OpenMPIRBuilder::collapseLoops(DebugLoc DL, ArrayRef<CanonicalLoopInfo *> Loops,
InsertPointTy ComputeIP) {
assert(Loops.size() >= 1 && "At least one loop required");
size_t NumLoops = Loops.size();
// Nothing to do if there is already just one loop.
if (NumLoops == 1)
return Loops.front();
CanonicalLoopInfo *Outermost = Loops.front();
CanonicalLoopInfo *Innermost = Loops.back();
BasicBlock *OrigPreheader = Outermost->getPreheader();
BasicBlock *OrigAfter = Outermost->getAfter();
Function *F = OrigPreheader->getParent();
// Setup the IRBuilder for inserting the trip count computation.
Builder.SetCurrentDebugLocation(DL);
if (ComputeIP.isSet())
Builder.restoreIP(ComputeIP);
else
Builder.restoreIP(Outermost->getPreheaderIP());
// Derive the collapsed' loop trip count.
// TODO: Find common/largest indvar type.
Value *CollapsedTripCount = nullptr;
for (CanonicalLoopInfo *L : Loops) {
Value *OrigTripCount = L->getTripCount();
if (!CollapsedTripCount) {
CollapsedTripCount = OrigTripCount;
continue;
}
// TODO: Enable UndefinedSanitizer to diagnose an overflow here.
CollapsedTripCount = Builder.CreateMul(CollapsedTripCount, OrigTripCount,
{}, /*HasNUW=*/true);
}
// Create the collapsed loop control flow.
CanonicalLoopInfo *Result =
createLoopSkeleton(DL, CollapsedTripCount, F,
OrigPreheader->getNextNode(), OrigAfter, "collapsed");
// Build the collapsed loop body code.
// Start with deriving the input loop induction variables from the collapsed
// one, using a divmod scheme. To preserve the original loops' order, the
// innermost loop use the least significant bits.
Builder.restoreIP(Result->getBodyIP());
Value *Leftover = Result->getIndVar();
SmallVector<Value *> NewIndVars;
NewIndVars.set_size(NumLoops);
for (int i = NumLoops - 1; i >= 1; --i) {
Value *OrigTripCount = Loops[i]->getTripCount();
Value *NewIndVar = Builder.CreateURem(Leftover, OrigTripCount);
NewIndVars[i] = NewIndVar;
Leftover = Builder.CreateUDiv(Leftover, OrigTripCount);
}
// Outermost loop gets all the remaining bits.
NewIndVars[0] = Leftover;
// Construct the loop body control flow.
// We progressively construct the branch structure following in direction of
// the control flow, from the leading in-between code, the loop nest body, the
// trailing in-between code, and rejoining the collapsed loop's latch.
// ContinueBlock and ContinuePred keep track of the source(s) of next edge. If
// the ContinueBlock is set, continue with that block. If ContinuePred, use
// its predecessors as sources.
BasicBlock *ContinueBlock = Result->getBody();
BasicBlock *ContinuePred = nullptr;
auto ContinueWith = [&ContinueBlock, &ContinuePred, DL](BasicBlock *Dest,
BasicBlock *NextSrc) {
if (ContinueBlock)
redirectTo(ContinueBlock, Dest, DL);
else
redirectAllPredecessorsTo(ContinuePred, Dest, DL);
ContinueBlock = nullptr;
ContinuePred = NextSrc;
};
// The code before the nested loop of each level.
// Because we are sinking it into the nest, it will be executed more often
// that the original loop. More sophisticated schemes could keep track of what
// the in-between code is and instantiate it only once per thread.
for (size_t i = 0; i < NumLoops - 1; ++i)
ContinueWith(Loops[i]->getBody(), Loops[i + 1]->getHeader());
// Connect the loop nest body.
ContinueWith(Innermost->getBody(), Innermost->getLatch());
// The code after the nested loop at each level.
for (size_t i = NumLoops - 1; i > 0; --i)
ContinueWith(Loops[i]->getAfter(), Loops[i - 1]->getLatch());
// Connect the finished loop to the collapsed loop latch.
ContinueWith(Result->getLatch(), nullptr);
// Replace the input loops with the new collapsed loop.
redirectTo(Outermost->getPreheader(), Result->getPreheader(), DL);
redirectTo(Result->getAfter(), Outermost->getAfter(), DL);
// Replace the input loop indvars with the derived ones.
for (size_t i = 0; i < NumLoops; ++i)
Loops[i]->getIndVar()->replaceAllUsesWith(NewIndVars[i]);
// Remove unused parts of the input loops.
SmallVector<BasicBlock *, 12> OldControlBBs;
OldControlBBs.reserve(6 * Loops.size());
for (CanonicalLoopInfo *Loop : Loops)
Loop->collectControlBlocks(OldControlBBs);
removeUnusedBlocksFromParent(OldControlBBs);
#ifndef NDEBUG
Result->assertOK();
#endif
return Result;
}
std::vector<CanonicalLoopInfo *>
OpenMPIRBuilder::tileLoops(DebugLoc DL, ArrayRef<CanonicalLoopInfo *> Loops,
ArrayRef<Value *> TileSizes) {
assert(TileSizes.size() == Loops.size() &&
"Must pass as many tile sizes as there are loops");
int NumLoops = Loops.size();
assert(NumLoops >= 1 && "At least one loop to tile required");
CanonicalLoopInfo *OutermostLoop = Loops.front();
CanonicalLoopInfo *InnermostLoop = Loops.back();
Function *F = OutermostLoop->getBody()->getParent();
BasicBlock *InnerEnter = InnermostLoop->getBody();
BasicBlock *InnerLatch = InnermostLoop->getLatch();
// Collect original trip counts and induction variable to be accessible by
// index. Also, the structure of the original loops is not preserved during
// the construction of the tiled loops, so do it before we scavenge the BBs of
// any original CanonicalLoopInfo.
SmallVector<Value *, 4> OrigTripCounts, OrigIndVars;
for (CanonicalLoopInfo *L : Loops) {
OrigTripCounts.push_back(L->getTripCount());
OrigIndVars.push_back(L->getIndVar());
}
// Collect the code between loop headers. These may contain SSA definitions
// that are used in the loop nest body. To be usable with in the innermost
// body, these BasicBlocks will be sunk into the loop nest body. That is,
// these instructions may be executed more often than before the tiling.
// TODO: It would be sufficient to only sink them into body of the
// corresponding tile loop.
SmallVector<std::pair<BasicBlock *, BasicBlock *>, 4> InbetweenCode;
for (int i = 0; i < NumLoops - 1; ++i) {
CanonicalLoopInfo *Surrounding = Loops[i];
CanonicalLoopInfo *Nested = Loops[i + 1];
BasicBlock *EnterBB = Surrounding->getBody();
BasicBlock *ExitBB = Nested->getHeader();
InbetweenCode.emplace_back(EnterBB, ExitBB);
}
// Compute the trip counts of the floor loops.
Builder.SetCurrentDebugLocation(DL);
Builder.restoreIP(OutermostLoop->getPreheaderIP());
SmallVector<Value *, 4> FloorCount, FloorRems;
for (int i = 0; i < NumLoops; ++i) {
Value *TileSize = TileSizes[i];
Value *OrigTripCount = OrigTripCounts[i];
Type *IVType = OrigTripCount->getType();
Value *FloorTripCount = Builder.CreateUDiv(OrigTripCount, TileSize);
Value *FloorTripRem = Builder.CreateURem(OrigTripCount, TileSize);
// 0 if tripcount divides the tilesize, 1 otherwise.
// 1 means we need an additional iteration for a partial tile.
//
// Unfortunately we cannot just use the roundup-formula
// (tripcount + tilesize - 1)/tilesize
// because the summation might overflow. We do not want introduce undefined
// behavior when the untiled loop nest did not.
Value *FloorTripOverflow =
Builder.CreateICmpNE(FloorTripRem, ConstantInt::get(IVType, 0));
FloorTripOverflow = Builder.CreateZExt(FloorTripOverflow, IVType);
FloorTripCount =
Builder.CreateAdd(FloorTripCount, FloorTripOverflow,
"omp_floor" + Twine(i) + ".tripcount", true);
// Remember some values for later use.
FloorCount.push_back(FloorTripCount);
FloorRems.push_back(FloorTripRem);
}
// Generate the new loop nest, from the outermost to the innermost.
std::vector<CanonicalLoopInfo *> Result;
Result.reserve(NumLoops * 2);
// The basic block of the surrounding loop that enters the nest generated
// loop.
BasicBlock *Enter = OutermostLoop->getPreheader();
// The basic block of the surrounding loop where the inner code should
// continue.
BasicBlock *Continue = OutermostLoop->getAfter();
// Where the next loop basic block should be inserted.
BasicBlock *OutroInsertBefore = InnermostLoop->getExit();
auto EmbeddNewLoop =
[this, DL, F, InnerEnter, &Enter, &Continue, &OutroInsertBefore](
Value *TripCount, const Twine &Name) -> CanonicalLoopInfo * {
CanonicalLoopInfo *EmbeddedLoop = createLoopSkeleton(
DL, TripCount, F, InnerEnter, OutroInsertBefore, Name);
redirectTo(Enter, EmbeddedLoop->getPreheader(), DL);
redirectTo(EmbeddedLoop->getAfter(), Continue, DL);
// Setup the position where the next embedded loop connects to this loop.
Enter = EmbeddedLoop->getBody();
Continue = EmbeddedLoop->getLatch();
OutroInsertBefore = EmbeddedLoop->getLatch();
return EmbeddedLoop;
};
auto EmbeddNewLoops = [&Result, &EmbeddNewLoop](ArrayRef<Value *> TripCounts,
const Twine &NameBase) {
for (auto P : enumerate(TripCounts)) {
CanonicalLoopInfo *EmbeddedLoop =
EmbeddNewLoop(P.value(), NameBase + Twine(P.index()));
Result.push_back(EmbeddedLoop);
}
};
EmbeddNewLoops(FloorCount, "floor");
// Within the innermost floor loop, emit the code that computes the tile
// sizes.
Builder.SetInsertPoint(Enter->getTerminator());
SmallVector<Value *, 4> TileCounts;
for (int i = 0; i < NumLoops; ++i) {
CanonicalLoopInfo *FloorLoop = Result[i];
Value *TileSize = TileSizes[i];
Value *FloorIsEpilogue =
Builder.CreateICmpEQ(FloorLoop->getIndVar(), FloorCount[i]);
Value *TileTripCount =
Builder.CreateSelect(FloorIsEpilogue, FloorRems[i], TileSize);
TileCounts.push_back(TileTripCount);
}
// Create the tile loops.
EmbeddNewLoops(TileCounts, "tile");
// Insert the inbetween code into the body.
BasicBlock *BodyEnter = Enter;
BasicBlock *BodyEntered = nullptr;
for (std::pair<BasicBlock *, BasicBlock *> P : InbetweenCode) {
BasicBlock *EnterBB = P.first;
BasicBlock *ExitBB = P.second;
if (BodyEnter)
redirectTo(BodyEnter, EnterBB, DL);
else
redirectAllPredecessorsTo(BodyEntered, EnterBB, DL);
BodyEnter = nullptr;
BodyEntered = ExitBB;
}
// Append the original loop nest body into the generated loop nest body.
if (BodyEnter)
redirectTo(BodyEnter, InnerEnter, DL);
else
redirectAllPredecessorsTo(BodyEntered, InnerEnter, DL);
redirectAllPredecessorsTo(InnerLatch, Continue, DL);
// Replace the original induction variable with an induction variable computed
// from the tile and floor induction variables.
Builder.restoreIP(Result.back()->getBodyIP());
for (int i = 0; i < NumLoops; ++i) {
CanonicalLoopInfo *FloorLoop = Result[i];
CanonicalLoopInfo *TileLoop = Result[NumLoops + i];
Value *OrigIndVar = OrigIndVars[i];
Value *Size = TileSizes[i];
Value *Scale =
Builder.CreateMul(Size, FloorLoop->getIndVar(), {}, /*HasNUW=*/true);
Value *Shift =
Builder.CreateAdd(Scale, TileLoop->getIndVar(), {}, /*HasNUW=*/true);
OrigIndVar->replaceAllUsesWith(Shift);
}
// Remove unused parts of the original loops.
SmallVector<BasicBlock *, 12> OldControlBBs;
OldControlBBs.reserve(6 * Loops.size());
for (CanonicalLoopInfo *Loop : Loops)
Loop->collectControlBlocks(OldControlBBs);
removeUnusedBlocksFromParent(OldControlBBs);
#ifndef NDEBUG
for (CanonicalLoopInfo *GenL : Result)
GenL->assertOK();
#endif
return Result;
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::createCopyPrivate(const LocationDescription &Loc,
llvm::Value *BufSize, llvm::Value *CpyBuf,
llvm::Value *CpyFn, llvm::Value *DidIt) {
if (!updateToLocation(Loc))
return Loc.IP;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadId = getOrCreateThreadID(Ident);
llvm::Value *DidItLD = Builder.CreateLoad(Builder.getInt32Ty(), DidIt);
Value *Args[] = {Ident, ThreadId, BufSize, CpyBuf, CpyFn, DidItLD};
Function *Fn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_copyprivate);
Builder.CreateCall(Fn, Args);
return Builder.saveIP();
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::createSingle(const LocationDescription &Loc,
BodyGenCallbackTy BodyGenCB,
FinalizeCallbackTy FiniCB, llvm::Value *DidIt) {
if (!updateToLocation(Loc))
return Loc.IP;
// If needed (i.e. not null), initialize `DidIt` with 0
if (DidIt) {
Builder.CreateStore(Builder.getInt32(0), DidIt);
}
Directive OMPD = Directive::OMPD_single;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadId = getOrCreateThreadID(Ident);
Value *Args[] = {Ident, ThreadId};
Function *EntryRTLFn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_single);
Instruction *EntryCall = Builder.CreateCall(EntryRTLFn, Args);
Function *ExitRTLFn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_end_single);
Instruction *ExitCall = Builder.CreateCall(ExitRTLFn, Args);
// generates the following:
// if (__kmpc_single()) {
// .... single region ...
// __kmpc_end_single
// }
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 = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_critical_with_hint);
} else {
RTFn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_critical);
}
Instruction *EntryCall = Builder.CreateCall(RTFn, EnterArgs);
Function *ExitRTLFn =
getOrCreateRuntimeFunctionPtr(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, bool IsCancellable) {
if (HasFinalize)
FinalizationStack.push_back({FiniCB, OMPD, IsCancellable});
// 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 || !EntryCall)
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);
}
if (!ExitCall)
return Builder.saveIP();
// place the Exitcall as last instruction before Finalization block terminator
ExitCall->removeFromParent();
Builder.Insert(ExitCall);
return IRBuilder<>::InsertPoint(ExitCall->getParent(),
ExitCall->getIterator());
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::createCopyinClauseBlocks(
InsertPointTy IP, Value *MasterAddr, Value *PrivateAddr,
llvm::IntegerType *IntPtrTy, bool BranchtoEnd) {
if (!IP.isSet())
return IP;
IRBuilder<>::InsertPointGuard IPG(Builder);
// creates the following CFG structure
// OMP_Entry : (MasterAddr != PrivateAddr)?
// F T
// | \
// | copin.not.master
// | /
// v /
// copyin.not.master.end
// |
// v
// OMP.Entry.Next
BasicBlock *OMP_Entry = IP.getBlock();
Function *CurFn = OMP_Entry->getParent();
BasicBlock *CopyBegin =
BasicBlock::Create(M.getContext(), "copyin.not.master", CurFn);
BasicBlock *CopyEnd = nullptr;
// If entry block is terminated, split to preserve the branch to following
// basic block (i.e. OMP.Entry.Next), otherwise, leave everything as is.
if (isa_and_nonnull<BranchInst>(OMP_Entry->getTerminator())) {
CopyEnd = OMP_Entry->splitBasicBlock(OMP_Entry->getTerminator(),
"copyin.not.master.end");
OMP_Entry->getTerminator()->eraseFromParent();
} else {
CopyEnd =
BasicBlock::Create(M.getContext(), "copyin.not.master.end", CurFn);
}
Builder.SetInsertPoint(OMP_Entry);
Value *MasterPtr = Builder.CreatePtrToInt(MasterAddr, IntPtrTy);
Value *PrivatePtr = Builder.CreatePtrToInt(PrivateAddr, IntPtrTy);
Value *cmp = Builder.CreateICmpNE(MasterPtr, PrivatePtr);
Builder.CreateCondBr(cmp, CopyBegin, CopyEnd);
Builder.SetInsertPoint(CopyBegin);
if (BranchtoEnd)
Builder.SetInsertPoint(Builder.CreateBr(CopyEnd));
return Builder.saveIP();
}
CallInst *OpenMPIRBuilder::createOMPAlloc(const LocationDescription &Loc,
Value *Size, Value *Allocator,
std::string Name) {
IRBuilder<>::InsertPointGuard IPG(Builder);
Builder.restoreIP(Loc.IP);
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadId = getOrCreateThreadID(Ident);
Value *Args[] = {ThreadId, Size, Allocator};
Function *Fn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_alloc);
return Builder.CreateCall(Fn, Args, Name);
}
CallInst *OpenMPIRBuilder::createOMPFree(const LocationDescription &Loc,
Value *Addr, Value *Allocator,
std::string Name) {
IRBuilder<>::InsertPointGuard IPG(Builder);
Builder.restoreIP(Loc.IP);
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadId = getOrCreateThreadID(Ident);
Value *Args[] = {ThreadId, Addr, Allocator};
Function *Fn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_free);
return Builder.CreateCall(Fn, Args, Name);
}
CallInst *OpenMPIRBuilder::createCachedThreadPrivate(
const LocationDescription &Loc, llvm::Value *Pointer,
llvm::ConstantInt *Size, const llvm::Twine &Name) {
IRBuilder<>::InsertPointGuard IPG(Builder);
Builder.restoreIP(Loc.IP);
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
Value *ThreadId = getOrCreateThreadID(Ident);
Constant *ThreadPrivateCache =
getOrCreateOMPInternalVariable(Int8PtrPtr, Name);
llvm::Value *Args[] = {Ident, ThreadId, Pointer, Size, ThreadPrivateCache};
Function *Fn =
getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_threadprivate_cached);
return Builder.CreateCall(Fn, Args);
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::createTargetInit(const LocationDescription &Loc, bool IsSPMD, bool RequiresFullRuntime) {
if (!updateToLocation(Loc))
return Loc.IP;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
ConstantInt *IsSPMDVal = ConstantInt::getBool(Int32->getContext(), IsSPMD);
ConstantInt *UseGenericStateMachine =
ConstantInt::getBool(Int32->getContext(), !IsSPMD);
ConstantInt *RequiresFullRuntimeVal = ConstantInt::getBool(Int32->getContext(), RequiresFullRuntime);
Function *Fn = getOrCreateRuntimeFunctionPtr(
omp::RuntimeFunction::OMPRTL___kmpc_target_init);
CallInst *ThreadKind =
Builder.CreateCall(Fn, {Ident, IsSPMDVal, UseGenericStateMachine, RequiresFullRuntimeVal});
Value *ExecUserCode = Builder.CreateICmpEQ(
ThreadKind, ConstantInt::get(ThreadKind->getType(), -1), "exec_user_code");
// ThreadKind = __kmpc_target_init(...)
// if (ThreadKind == -1)
// user_code
// else
// return;
auto *UI = Builder.CreateUnreachable();
BasicBlock *CheckBB = UI->getParent();
BasicBlock *UserCodeEntryBB = CheckBB->splitBasicBlock(UI, "user_code.entry");
BasicBlock *WorkerExitBB = BasicBlock::Create(
CheckBB->getContext(), "worker.exit", CheckBB->getParent());
Builder.SetInsertPoint(WorkerExitBB);
Builder.CreateRetVoid();
auto *CheckBBTI = CheckBB->getTerminator();
Builder.SetInsertPoint(CheckBBTI);
Builder.CreateCondBr(ExecUserCode, UI->getParent(), WorkerExitBB);
CheckBBTI->eraseFromParent();
UI->eraseFromParent();
// Continue in the "user_code" block, see diagram above and in
// openmp/libomptarget/deviceRTLs/common/include/target.h .
return InsertPointTy(UserCodeEntryBB, UserCodeEntryBB->getFirstInsertionPt());
}
void OpenMPIRBuilder::createTargetDeinit(const LocationDescription &Loc,
bool IsSPMD, bool RequiresFullRuntime) {
if (!updateToLocation(Loc))
return;
Constant *SrcLocStr = getOrCreateSrcLocStr(Loc);
Value *Ident = getOrCreateIdent(SrcLocStr);
ConstantInt *IsSPMDVal = ConstantInt::getBool(Int32->getContext(), IsSPMD);
ConstantInt *RequiresFullRuntimeVal = ConstantInt::getBool(Int32->getContext(), RequiresFullRuntime);
Function *Fn = getOrCreateRuntimeFunctionPtr(
omp::RuntimeFunction::OMPRTL___kmpc_target_deinit);
Builder.CreateCall(Fn, {Ident, IsSPMDVal, RequiresFullRuntimeVal});
}
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);
}
GlobalVariable *
OpenMPIRBuilder::createOffloadMaptypes(SmallVectorImpl<uint64_t> &Mappings,
std::string VarName) {
llvm::Constant *MaptypesArrayInit =
llvm::ConstantDataArray::get(M.getContext(), Mappings);
auto *MaptypesArrayGlobal = new llvm::GlobalVariable(
M, MaptypesArrayInit->getType(),
/*isConstant=*/true, llvm::GlobalValue::PrivateLinkage, MaptypesArrayInit,
VarName);
MaptypesArrayGlobal->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
return MaptypesArrayGlobal;
}
void OpenMPIRBuilder::createMapperAllocas(const LocationDescription &Loc,
InsertPointTy AllocaIP,
unsigned NumOperands,
struct MapperAllocas &MapperAllocas) {
if (!updateToLocation(Loc))
return;
auto *ArrI8PtrTy = ArrayType::get(Int8Ptr, NumOperands);
auto *ArrI64Ty = ArrayType::get(Int64, NumOperands);
Builder.restoreIP(AllocaIP);
AllocaInst *ArgsBase = Builder.CreateAlloca(ArrI8PtrTy);
AllocaInst *Args = Builder.CreateAlloca(ArrI8PtrTy);
AllocaInst *ArgSizes = Builder.CreateAlloca(ArrI64Ty);
Builder.restoreIP(Loc.IP);
MapperAllocas.ArgsBase = ArgsBase;
MapperAllocas.Args = Args;
MapperAllocas.ArgSizes = ArgSizes;
}
void OpenMPIRBuilder::emitMapperCall(const LocationDescription &Loc,
Function *MapperFunc, Value *SrcLocInfo,
Value *MaptypesArg, Value *MapnamesArg,
struct MapperAllocas &MapperAllocas,
int64_t DeviceID, unsigned NumOperands) {
if (!updateToLocation(Loc))
return;
auto *ArrI8PtrTy = ArrayType::get(Int8Ptr, NumOperands);
auto *ArrI64Ty = ArrayType::get(Int64, NumOperands);
Value *ArgsBaseGEP =
Builder.CreateInBoundsGEP(ArrI8PtrTy, MapperAllocas.ArgsBase,
{Builder.getInt32(0), Builder.getInt32(0)});
Value *ArgsGEP =
Builder.CreateInBoundsGEP(ArrI8PtrTy, MapperAllocas.Args,
{Builder.getInt32(0), Builder.getInt32(0)});
Value *ArgSizesGEP =
Builder.CreateInBoundsGEP(ArrI64Ty, MapperAllocas.ArgSizes,
{Builder.getInt32(0), Builder.getInt32(0)});
Value *NullPtr = Constant::getNullValue(Int8Ptr->getPointerTo());
Builder.CreateCall(MapperFunc,
{SrcLocInfo, Builder.getInt64(DeviceID),
Builder.getInt32(NumOperands), ArgsBaseGEP, ArgsGEP,
ArgSizesGEP, MaptypesArg, MapnamesArg, NullPtr});
}
bool OpenMPIRBuilder::checkAndEmitFlushAfterAtomic(
const LocationDescription &Loc, llvm::AtomicOrdering AO, AtomicKind AK) {
assert(!(AO == AtomicOrdering::NotAtomic ||
AO == llvm::AtomicOrdering::Unordered) &&
"Unexpected Atomic Ordering.");
bool Flush = false;
llvm::AtomicOrdering FlushAO = AtomicOrdering::Monotonic;
switch (AK) {
case Read:
if (AO == AtomicOrdering::Acquire || AO == AtomicOrdering::AcquireRelease ||
AO == AtomicOrdering::SequentiallyConsistent) {
FlushAO = AtomicOrdering::Acquire;
Flush = true;
}
break;
case Write:
case Update:
if (AO == AtomicOrdering::Release || AO == AtomicOrdering::AcquireRelease ||
AO == AtomicOrdering::SequentiallyConsistent) {
FlushAO = AtomicOrdering::Release;
Flush = true;
}
break;
case Capture:
switch (AO) {
case AtomicOrdering::Acquire:
FlushAO = AtomicOrdering::Acquire;
Flush = true;
break;
case AtomicOrdering::Release:
FlushAO = AtomicOrdering::Release;
Flush = true;
break;
case AtomicOrdering::AcquireRelease:
case AtomicOrdering::SequentiallyConsistent:
FlushAO = AtomicOrdering::AcquireRelease;
Flush = true;
break;
default:
// do nothing - leave silently.
break;
}
}
if (Flush) {
// Currently Flush RT call still doesn't take memory_ordering, so for when
// that happens, this tries to do the resolution of which atomic ordering
// to use with but issue the flush call
// TODO: pass `FlushAO` after memory ordering support is added
(void)FlushAO;
emitFlush(Loc);
}
// for AO == AtomicOrdering::Monotonic and all other case combinations
// do nothing
return Flush;
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::createAtomicRead(const LocationDescription &Loc,
AtomicOpValue &X, AtomicOpValue &V,
AtomicOrdering AO) {
if (!updateToLocation(Loc))
return Loc.IP;
Type *XTy = X.Var->getType();
assert(XTy->isPointerTy() && "OMP Atomic expects a pointer to target memory");
Type *XElemTy = XTy->getPointerElementType();
assert((XElemTy->isFloatingPointTy() || XElemTy->isIntegerTy() ||
XElemTy->isPointerTy()) &&
"OMP atomic read expected a scalar type");
Value *XRead = nullptr;
if (XElemTy->isIntegerTy()) {
LoadInst *XLD =
Builder.CreateLoad(XElemTy, X.Var, X.IsVolatile, "omp.atomic.read");
XLD->setAtomic(AO);
XRead = cast<Value>(XLD);
} else {
// We need to bitcast and perform atomic op as integer
unsigned Addrspace = cast<PointerType>(XTy)->getAddressSpace();
IntegerType *IntCastTy =
IntegerType::get(M.getContext(), XElemTy->getScalarSizeInBits());
Value *XBCast = Builder.CreateBitCast(
X.Var, IntCastTy->getPointerTo(Addrspace), "atomic.src.int.cast");
LoadInst *XLoad =
Builder.CreateLoad(IntCastTy, XBCast, X.IsVolatile, "omp.atomic.load");
XLoad->setAtomic(AO);
if (XElemTy->isFloatingPointTy()) {
XRead = Builder.CreateBitCast(XLoad, XElemTy, "atomic.flt.cast");
} else {
XRead = Builder.CreateIntToPtr(XLoad, XElemTy, "atomic.ptr.cast");
}
}
checkAndEmitFlushAfterAtomic(Loc, AO, AtomicKind::Read);
Builder.CreateStore(XRead, V.Var, V.IsVolatile);
return Builder.saveIP();
}
OpenMPIRBuilder::InsertPointTy
OpenMPIRBuilder::createAtomicWrite(const LocationDescription &Loc,
AtomicOpValue &X, Value *Expr,
AtomicOrdering AO) {
if (!updateToLocation(Loc))
return Loc.IP;
Type *XTy = X.Var->getType();
assert(XTy->isPointerTy() && "OMP Atomic expects a pointer to target memory");
Type *XElemTy = XTy->getPointerElementType();
assert((XElemTy->isFloatingPointTy() || XElemTy->isIntegerTy() ||
XElemTy->isPointerTy()) &&
"OMP atomic write expected a scalar type");
if (XElemTy->isIntegerTy()) {
StoreInst *XSt = Builder.CreateStore(Expr, X.Var, X.IsVolatile);
XSt->setAtomic(AO);
} else {
// We need to bitcast and perform atomic op as integers
unsigned Addrspace = cast<PointerType>(XTy)->getAddressSpace();
IntegerType *IntCastTy =
IntegerType::get(M.getContext(), XElemTy->getScalarSizeInBits());
Value *XBCast = Builder.CreateBitCast(
X.Var, IntCastTy->getPointerTo(Addrspace), "atomic.dst.int.cast");
Value *ExprCast =
Builder.CreateBitCast(Expr, IntCastTy, "atomic.src.int.cast");
StoreInst *XSt = Builder.CreateStore(ExprCast, XBCast, X.IsVolatile);
XSt->setAtomic(AO);
}
checkAndEmitFlushAfterAtomic(Loc, AO, AtomicKind::Write);
return Builder.saveIP();
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::createAtomicUpdate(
const LocationDescription &Loc, Instruction *AllocIP, AtomicOpValue &X,
Value *Expr, AtomicOrdering AO, AtomicRMWInst::BinOp RMWOp,
AtomicUpdateCallbackTy &UpdateOp, bool IsXLHSInRHSPart) {
if (!updateToLocation(Loc))
return Loc.IP;
LLVM_DEBUG({
Type *XTy = X.Var->getType();
assert(XTy->isPointerTy() &&
"OMP Atomic expects a pointer to target memory");
Type *XElemTy = XTy->getPointerElementType();
assert((XElemTy->isFloatingPointTy() || XElemTy->isIntegerTy() ||
XElemTy->isPointerTy()) &&
"OMP atomic update expected a scalar type");
assert((RMWOp != AtomicRMWInst::Max) && (RMWOp != AtomicRMWInst::Min) &&
(RMWOp != AtomicRMWInst::UMax) && (RMWOp != AtomicRMWInst::UMin) &&
"OpenMP atomic does not support LT or GT operations");
});
emitAtomicUpdate(AllocIP, X.Var, Expr, AO, RMWOp, UpdateOp, X.IsVolatile,
IsXLHSInRHSPart);
checkAndEmitFlushAfterAtomic(Loc, AO, AtomicKind::Update);
return Builder.saveIP();
}
Value *OpenMPIRBuilder::emitRMWOpAsInstruction(Value *Src1, Value *Src2,
AtomicRMWInst::BinOp RMWOp) {
switch (RMWOp) {
case AtomicRMWInst::Add:
return Builder.CreateAdd(Src1, Src2);
case AtomicRMWInst::Sub:
return Builder.CreateSub(Src1, Src2);
case AtomicRMWInst::And:
return Builder.CreateAnd(Src1, Src2);
case AtomicRMWInst::Nand:
return Builder.CreateNeg(Builder.CreateAnd(Src1, Src2));
case AtomicRMWInst::Or:
return Builder.CreateOr(Src1, Src2);
case AtomicRMWInst::Xor:
return Builder.CreateXor(Src1, Src2);
case AtomicRMWInst::Xchg:
case AtomicRMWInst::FAdd:
case AtomicRMWInst::FSub:
case AtomicRMWInst::BAD_BINOP:
case AtomicRMWInst::Max:
case AtomicRMWInst::Min:
case AtomicRMWInst::UMax:
case AtomicRMWInst::UMin:
llvm_unreachable("Unsupported atomic update operation");
}
llvm_unreachable("Unsupported atomic update operation");
}
std::pair<Value *, Value *>
OpenMPIRBuilder::emitAtomicUpdate(Instruction *AllocIP, Value *X, Value *Expr,
AtomicOrdering AO, AtomicRMWInst::BinOp RMWOp,
AtomicUpdateCallbackTy &UpdateOp,
bool VolatileX, bool IsXLHSInRHSPart) {
Type *XElemTy = X->getType()->getPointerElementType();
bool DoCmpExch =
((RMWOp == AtomicRMWInst::BAD_BINOP) || (RMWOp == AtomicRMWInst::FAdd)) ||
(RMWOp == AtomicRMWInst::FSub) ||
(RMWOp == AtomicRMWInst::Sub && !IsXLHSInRHSPart);
std::pair<Value *, Value *> Res;
if (XElemTy->isIntegerTy() && !DoCmpExch) {
Res.first = Builder.CreateAtomicRMW(RMWOp, X, Expr, llvm::MaybeAlign(), AO);
// not needed except in case of postfix captures. Generate anyway for
// consistency with the else part. Will be removed with any DCE pass.
Res.second = emitRMWOpAsInstruction(Res.first, Expr, RMWOp);
} else {
unsigned Addrspace = cast<PointerType>(X->getType())->getAddressSpace();
IntegerType *IntCastTy =
IntegerType::get(M.getContext(), XElemTy->getScalarSizeInBits());
Value *XBCast =
Builder.CreateBitCast(X, IntCastTy->getPointerTo(Addrspace));
LoadInst *OldVal =
Builder.CreateLoad(IntCastTy, XBCast, X->getName() + ".atomic.load");
OldVal->setAtomic(AO);
// CurBB
// | /---\
// ContBB |
// | \---/
// ExitBB
BasicBlock *CurBB = Builder.GetInsertBlock();
Instruction *CurBBTI = CurBB->getTerminator();
CurBBTI = CurBBTI ? CurBBTI : Builder.CreateUnreachable();
BasicBlock *ExitBB =
CurBB->splitBasicBlock(CurBBTI, X->getName() + ".atomic.exit");
BasicBlock *ContBB = CurBB->splitBasicBlock(CurBB->getTerminator(),
X->getName() + ".atomic.cont");
ContBB->getTerminator()->eraseFromParent();
Builder.SetInsertPoint(ContBB);
llvm::PHINode *PHI = Builder.CreatePHI(OldVal->getType(), 2);
PHI->addIncoming(OldVal, CurBB);
AllocaInst *NewAtomicAddr = Builder.CreateAlloca(XElemTy);
NewAtomicAddr->setName(X->getName() + "x.new.val");
NewAtomicAddr->moveBefore(AllocIP);
IntegerType *NewAtomicCastTy =
IntegerType::get(M.getContext(), XElemTy->getScalarSizeInBits());
bool IsIntTy = XElemTy->isIntegerTy();
Value *NewAtomicIntAddr =
(IsIntTy)
? NewAtomicAddr
: Builder.CreateBitCast(NewAtomicAddr,
NewAtomicCastTy->getPointerTo(Addrspace));
Value *OldExprVal = PHI;
if (!IsIntTy) {
if (XElemTy->isFloatingPointTy()) {
OldExprVal = Builder.CreateBitCast(PHI, XElemTy,
X->getName() + ".atomic.fltCast");
} else {
OldExprVal = Builder.CreateIntToPtr(PHI, XElemTy,
X->getName() + ".atomic.ptrCast");
}
}
Value *Upd = UpdateOp(OldExprVal, Builder);
Builder.CreateStore(Upd, NewAtomicAddr);
LoadInst *DesiredVal = Builder.CreateLoad(XElemTy, NewAtomicIntAddr);
Value *XAddr =
(IsIntTy)
? X
: Builder.CreateBitCast(X, IntCastTy->getPointerTo(Addrspace));
AtomicOrdering Failure =
llvm::AtomicCmpXchgInst::getStrongestFailureOrdering(AO);
AtomicCmpXchgInst *Result = Builder.CreateAtomicCmpXchg(
XAddr, OldExprVal, DesiredVal, llvm::MaybeAlign(), AO, Failure);
Result->setVolatile(VolatileX);
Value *PreviousVal = Builder.CreateExtractValue(Result, /*Idxs=*/0);
Value *SuccessFailureVal = Builder.CreateExtractValue(Result, /*Idxs=*/1);
PHI->addIncoming(PreviousVal, Builder.GetInsertBlock());
Builder.CreateCondBr(SuccessFailureVal, ExitBB, ContBB);
Res.first = OldExprVal;
Res.second = Upd;
// set Insertion point in exit block
if (UnreachableInst *ExitTI =
dyn_cast<UnreachableInst>(ExitBB->getTerminator())) {
CurBBTI->eraseFromParent();
Builder.SetInsertPoint(ExitBB);
} else {
Builder.SetInsertPoint(ExitTI);
}
}
return Res;
}
OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::createAtomicCapture(
const LocationDescription &Loc, Instruction *AllocIP, AtomicOpValue &X,
AtomicOpValue &V, Value *Expr, AtomicOrdering AO,
AtomicRMWInst::BinOp RMWOp, AtomicUpdateCallbackTy &UpdateOp,
bool UpdateExpr, bool IsPostfixUpdate, bool IsXLHSInRHSPart) {
if (!updateToLocation(Loc))
return Loc.IP;
LLVM_DEBUG({
Type *XTy = X.Var->getType();
assert(XTy->isPointerTy() &&
"OMP Atomic expects a pointer to target memory");
Type *XElemTy = XTy->getPointerElementType();
assert((XElemTy->isFloatingPointTy() || XElemTy->isIntegerTy() ||
XElemTy->isPointerTy()) &&
"OMP atomic capture expected a scalar type");
assert((RMWOp != AtomicRMWInst::Max) && (RMWOp != AtomicRMWInst::Min) &&
"OpenMP atomic does not support LT or GT operations");
});
// If UpdateExpr is 'x' updated with some `expr` not based on 'x',
// 'x' is simply atomically rewritten with 'expr'.
AtomicRMWInst::BinOp AtomicOp = (UpdateExpr ? RMWOp : AtomicRMWInst::Xchg);
std::pair<Value *, Value *> Result =
emitAtomicUpdate(AllocIP, X.Var, Expr, AO, AtomicOp, UpdateOp,
X.IsVolatile, IsXLHSInRHSPart);
Value *CapturedVal = (IsPostfixUpdate ? Result.first : Result.second);
Builder.CreateStore(CapturedVal, V.Var, V.IsVolatile);
checkAndEmitFlushAfterAtomic(Loc, AO, AtomicKind::Capture);
return Builder.saveIP();
}
GlobalVariable *
OpenMPIRBuilder::createOffloadMapnames(SmallVectorImpl<llvm::Constant *> &Names,
std::string VarName) {
llvm::Constant *MapNamesArrayInit = llvm::ConstantArray::get(
llvm::ArrayType::get(
llvm::Type::getInt8Ty(M.getContext())->getPointerTo(), Names.size()),
Names);
auto *MapNamesArrayGlobal = new llvm::GlobalVariable(
M, MapNamesArrayInit->getType(),
/*isConstant=*/true, llvm::GlobalValue::PrivateLinkage, MapNamesArrayInit,
VarName);
return MapNamesArrayGlobal;
}
// Create all simple and struct types exposed by the runtime and remember
// the llvm::PointerTypes of them for easy access later.
void OpenMPIRBuilder::initializeTypes(Module &M) {
LLVMContext &Ctx = M.getContext();
StructType *T;
#define OMP_TYPE(VarName, InitValue) VarName = InitValue;
#define OMP_ARRAY_TYPE(VarName, ElemTy, ArraySize) \
VarName##Ty = ArrayType::get(ElemTy, ArraySize); \
VarName##PtrTy = PointerType::getUnqual(VarName##Ty);
#define OMP_FUNCTION_TYPE(VarName, IsVarArg, ReturnType, ...) \
VarName = FunctionType::get(ReturnType, {__VA_ARGS__}, IsVarArg); \
VarName##Ptr = PointerType::getUnqual(VarName);
#define OMP_STRUCT_TYPE(VarName, StructName, ...) \
T = StructType::getTypeByName(Ctx, StructName); \
if (!T) \
T = StructType::create(Ctx, {__VA_ARGS__}, StructName); \
VarName = T; \
VarName##Ptr = PointerType::getUnqual(T);
#include "llvm/Frontend/OpenMP/OMPKinds.def"
}
void OpenMPIRBuilder::OutlineInfo::collectBlocks(
SmallPtrSetImpl<BasicBlock *> &BlockSet,
SmallVectorImpl<BasicBlock *> &BlockVector) {
SmallVector<BasicBlock *, 32> Worklist;
BlockSet.insert(EntryBB);
BlockSet.insert(ExitBB);
Worklist.push_back(EntryBB);
while (!Worklist.empty()) {
BasicBlock *BB = Worklist.pop_back_val();
BlockVector.push_back(BB);
for (BasicBlock *SuccBB : successors(BB))
if (BlockSet.insert(SuccBB).second)
Worklist.push_back(SuccBB);
}
}
void CanonicalLoopInfo::collectControlBlocks(
SmallVectorImpl<BasicBlock *> &BBs) {
// We only count those BBs as control block for which we do not need to
// reverse the CFG, i.e. not the loop body which can contain arbitrary control
// flow. For consistency, this also means we do not add the Body block, which
// is just the entry to the body code.
BBs.reserve(BBs.size() + 6);
BBs.append({Preheader, Header, Cond, Latch, Exit, After});
}
void CanonicalLoopInfo::assertOK() const {
#ifndef NDEBUG
if (!IsValid)
return;
// Verify standard control-flow we use for OpenMP loops.
assert(Preheader);
assert(isa<BranchInst>(Preheader->getTerminator()) &&
"Preheader must terminate with unconditional branch");
assert(Preheader->getSingleSuccessor() == Header &&
"Preheader must jump to header");
assert(Header);
assert(isa<BranchInst>(Header->getTerminator()) &&
"Header must terminate with unconditional branch");
assert(Header->getSingleSuccessor() == Cond &&
"Header must jump to exiting block");
assert(Cond);
assert(Cond->getSinglePredecessor() == Header &&
"Exiting block only reachable from header");
assert(isa<BranchInst>(Cond->getTerminator()) &&
"Exiting block must terminate with conditional branch");
assert(size(successors(Cond)) == 2 &&
"Exiting block must have two successors");
assert(cast<BranchInst>(Cond->getTerminator())->getSuccessor(0) == Body &&
"Exiting block's first successor jump to the body");
assert(cast<BranchInst>(Cond->getTerminator())->getSuccessor(1) == Exit &&
"Exiting block's second successor must exit the loop");
assert(Body);
assert(Body->getSinglePredecessor() == Cond &&
"Body only reachable from exiting block");
assert(!isa<PHINode>(Body->front()));
assert(Latch);
assert(isa<BranchInst>(Latch->getTerminator()) &&
"Latch must terminate with unconditional branch");
assert(Latch->getSingleSuccessor() == Header && "Latch must jump to header");
// TODO: To support simple redirecting of the end of the body code that has
// multiple; introduce another auxiliary basic block like preheader and after.
assert(Latch->getSinglePredecessor() != nullptr);
assert(!isa<PHINode>(Latch->front()));
assert(Exit);
assert(isa<BranchInst>(Exit->getTerminator()) &&
"Exit block must terminate with unconditional branch");
assert(Exit->getSingleSuccessor() == After &&
"Exit block must jump to after block");
assert(After);
assert(After->getSinglePredecessor() == Exit &&
"After block only reachable from exit block");
assert(After->empty() || !isa<PHINode>(After->front()));
Instruction *IndVar = getIndVar();
assert(IndVar && "Canonical induction variable not found?");
assert(isa<IntegerType>(IndVar->getType()) &&
"Induction variable must be an integer");
assert(cast<PHINode>(IndVar)->getParent() == Header &&
"Induction variable must be a PHI in the loop header");
assert(cast<PHINode>(IndVar)->getIncomingBlock(0) == Preheader);
assert(
cast<ConstantInt>(cast<PHINode>(IndVar)->getIncomingValue(0))->isZero());
assert(cast<PHINode>(IndVar)->getIncomingBlock(1) == Latch);
auto *NextIndVar = cast<PHINode>(IndVar)->getIncomingValue(1);
assert(cast<Instruction>(NextIndVar)->getParent() == Latch);
assert(cast<BinaryOperator>(NextIndVar)->getOpcode() == BinaryOperator::Add);
assert(cast<BinaryOperator>(NextIndVar)->getOperand(0) == IndVar);
assert(cast<ConstantInt>(cast<BinaryOperator>(NextIndVar)->getOperand(1))
->isOne());
Value *TripCount = getTripCount();
assert(TripCount && "Loop trip count not found?");
assert(IndVar->getType() == TripCount->getType() &&
"Trip count and induction variable must have the same type");
auto *CmpI = cast<CmpInst>(&Cond->front());
assert(CmpI->getPredicate() == CmpInst::ICMP_ULT &&
"Exit condition must be a signed less-than comparison");
assert(CmpI->getOperand(0) == IndVar &&
"Exit condition must compare the induction variable");
assert(CmpI->getOperand(1) == TripCount &&
"Exit condition must compare with the trip count");
#endif
}
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