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llvm-project/llvm/lib/CodeGen/WinEHPrepare.cpp

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//===-- WinEHPrepare - Prepare exception handling for code generation ---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass lowers LLVM IR exception handling into something closer to what the
// backend wants for functions using a personality function from a runtime
// provided by MSVC. Functions with other personality functions are left alone
// and may be prepared by other passes. In particular, all supported MSVC
// personality functions require cleanup code to be outlined, and the C++
// personality requires catch handler code to be outlined.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/LibCallSemantics.h"
#include "llvm/CodeGen/WinEHFuncInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
using namespace llvm;
#define DEBUG_TYPE "winehprepare"
static cl::opt<bool> DisableDemotion(
"disable-demotion", cl::Hidden,
cl::desc(
"Clone multicolor basic blocks but do not demote cross funclet values"),
cl::init(false));
static cl::opt<bool> DisableCleanups(
"disable-cleanups", cl::Hidden,
cl::desc("Do not remove implausible terminators or other similar cleanups"),
cl::init(false));
namespace {
class WinEHPrepare : public FunctionPass {
public:
static char ID; // Pass identification, replacement for typeid.
WinEHPrepare(const TargetMachine *TM = nullptr) : FunctionPass(ID) {}
bool runOnFunction(Function &Fn) override;
bool doFinalization(Module &M) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
const char *getPassName() const override {
return "Windows exception handling preparation";
}
private:
void insertPHIStores(PHINode *OriginalPHI, AllocaInst *SpillSlot);
void
insertPHIStore(BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist);
AllocaInst *insertPHILoads(PHINode *PN, Function &F);
void replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
DenseMap<BasicBlock *, Value *> &Loads, Function &F);
void demoteNonlocalUses(Value *V, SetVector<BasicBlock *> &ColorsForBB,
Function &F);
bool prepareExplicitEH(Function &F,
SmallVectorImpl<BasicBlock *> &EntryBlocks);
void replaceTerminatePadWithCleanup(Function &F);
void colorFunclets(Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks);
void resolveFuncletAncestry(Function &F,
SmallVectorImpl<BasicBlock *> &EntryBlocks);
void resolveFuncletAncestryForPath(
Function &F, SmallVectorImpl<BasicBlock *> &FuncletPath,
std::map<BasicBlock *, BasicBlock *> &IdentityMap);
void makeFuncletEdgeUnreachable(BasicBlock *Parent, BasicBlock *Child);
BasicBlock *cloneFuncletForParent(Function &F, BasicBlock *FuncletEntry,
BasicBlock *Parent);
void updateTerminatorsAfterFuncletClone(
Function &F, BasicBlock *OrigFunclet, BasicBlock *CloneFunclet,
BasicBlock *OrigBlock, BasicBlock *CloneBlock, BasicBlock *CloneParent,
ValueToValueMapTy &VMap,
std::map<BasicBlock *, BasicBlock *> &Orig2Clone);
void demotePHIsOnFunclets(Function &F);
void demoteUsesBetweenFunclets(Function &F);
void demoteArgumentUses(Function &F);
void cloneCommonBlocks(Function &F,
SmallVectorImpl<BasicBlock *> &EntryBlocks);
void removeImplausibleTerminators(Function &F);
void cleanupPreparedFunclets(Function &F);
void verifyPreparedFunclets(Function &F);
// All fields are reset by runOnFunction.
EHPersonality Personality = EHPersonality::Unknown;
std::map<BasicBlock *, SetVector<BasicBlock *>> BlockColors;
std::map<BasicBlock *, std::set<BasicBlock *>> FuncletBlocks;
std::map<BasicBlock *, std::vector<BasicBlock *>> FuncletChildren;
std::map<BasicBlock *, std::vector<BasicBlock *>> FuncletParents;
// This is a flag that indicates an uncommon situation where we need to
// clone funclets has been detected.
bool FuncletCloningRequired = false;
// When a funclet with multiple parents contains a catchret, the block to
// which it returns will be cloned so that there is a copy in each parent
// but one of the copies will not be properly linked to the catchret and
// in most cases will have no predecessors. This double map allows us
// to find these cloned blocks when we clone the child funclet.
std::map<BasicBlock *, std::map<BasicBlock *, BasicBlock*>> EstrangedBlocks;
};
} // end anonymous namespace
char WinEHPrepare::ID = 0;
INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions",
false, false)
FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) {
return new WinEHPrepare(TM);
}
static void findFuncletEntryPoints(Function &Fn,
SmallVectorImpl<BasicBlock *> &EntryBlocks) {
EntryBlocks.push_back(&Fn.getEntryBlock());
for (BasicBlock &BB : Fn) {
Instruction *First = BB.getFirstNonPHI();
if (!First->isEHPad())
continue;
assert(!isa<LandingPadInst>(First) &&
"landingpad cannot be used with funclet EH personality");
// Find EH pad blocks that represent funclet start points.
if (!isa<CatchEndPadInst>(First) && !isa<CleanupEndPadInst>(First))
EntryBlocks.push_back(&BB);
}
}
bool WinEHPrepare::runOnFunction(Function &Fn) {
if (!Fn.hasPersonalityFn())
return false;
// Classify the personality to see what kind of preparation we need.
Personality = classifyEHPersonality(Fn.getPersonalityFn());
// Do nothing if this is not a funclet-based personality.
if (!isFuncletEHPersonality(Personality))
return false;
// Remove unreachable blocks. It is not valuable to assign them a color and
// their existence can trick us into thinking values are alive when they are
// not.
removeUnreachableBlocks(Fn);
SmallVector<BasicBlock *, 4> EntryBlocks;
findFuncletEntryPoints(Fn, EntryBlocks);
return prepareExplicitEH(Fn, EntryBlocks);
}
bool WinEHPrepare::doFinalization(Module &M) { return false; }
void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {}
static int addUnwindMapEntry(WinEHFuncInfo &FuncInfo, int ToState,
const BasicBlock *BB) {
CxxUnwindMapEntry UME;
UME.ToState = ToState;
UME.Cleanup = BB;
FuncInfo.CxxUnwindMap.push_back(UME);
return FuncInfo.getLastStateNumber();
}
static void addTryBlockMapEntry(WinEHFuncInfo &FuncInfo, int TryLow,
int TryHigh, int CatchHigh,
ArrayRef<const CatchPadInst *> Handlers) {
WinEHTryBlockMapEntry TBME;
TBME.TryLow = TryLow;
TBME.TryHigh = TryHigh;
TBME.CatchHigh = CatchHigh;
assert(TBME.TryLow <= TBME.TryHigh);
for (const CatchPadInst *CPI : Handlers) {
WinEHHandlerType HT;
Constant *TypeInfo = cast<Constant>(CPI->getArgOperand(0));
if (TypeInfo->isNullValue())
HT.TypeDescriptor = nullptr;
else
HT.TypeDescriptor = cast<GlobalVariable>(TypeInfo->stripPointerCasts());
HT.Adjectives = cast<ConstantInt>(CPI->getArgOperand(1))->getZExtValue();
HT.Handler = CPI->getParent();
if (isa<ConstantPointerNull>(CPI->getArgOperand(2)))
HT.CatchObj.Alloca = nullptr;
else
HT.CatchObj.Alloca = cast<AllocaInst>(CPI->getArgOperand(2));
TBME.HandlerArray.push_back(HT);
}
FuncInfo.TryBlockMap.push_back(TBME);
}
static const CatchPadInst *getSingleCatchPadPredecessor(const BasicBlock *BB) {
for (const BasicBlock *PredBlock : predecessors(BB))
if (auto *CPI = dyn_cast<CatchPadInst>(PredBlock->getFirstNonPHI()))
return CPI;
return nullptr;
}
/// Find all the catchpads that feed directly into the catchendpad. Frontends
/// using this personality should ensure that each catchendpad and catchpad has
/// one or zero catchpad predecessors.
///
/// The following C++ generates the IR after it:
/// try {
/// } catch (A) {
/// } catch (B) {
/// }
///
/// IR:
/// %catchpad.A
/// catchpad [i8* A typeinfo]
/// to label %catch.A unwind label %catchpad.B
/// %catchpad.B
/// catchpad [i8* B typeinfo]
/// to label %catch.B unwind label %endcatches
/// %endcatches
/// catchendblock unwind to caller
static void
findCatchPadsForCatchEndPad(const BasicBlock *CatchEndBB,
SmallVectorImpl<const CatchPadInst *> &Handlers) {
const CatchPadInst *CPI = getSingleCatchPadPredecessor(CatchEndBB);
while (CPI) {
Handlers.push_back(CPI);
CPI = getSingleCatchPadPredecessor(CPI->getParent());
}
// We've pushed these back into reverse source order. Reverse them to get
// the list back into source order.
std::reverse(Handlers.begin(), Handlers.end());
}
// Given BB which ends in an unwind edge, return the EHPad that this BB belongs
// to. If the unwind edge came from an invoke, return null.
static const BasicBlock *getEHPadFromPredecessor(const BasicBlock *BB) {
const TerminatorInst *TI = BB->getTerminator();
if (isa<InvokeInst>(TI))
return nullptr;
if (TI->isEHPad())
return BB;
return cast<CleanupReturnInst>(TI)->getCleanupPad()->getParent();
}
static void calculateExplicitCXXStateNumbers(WinEHFuncInfo &FuncInfo,
const BasicBlock &BB,
int ParentState) {
assert(BB.isEHPad());
const Instruction *FirstNonPHI = BB.getFirstNonPHI();
// All catchpad instructions will be handled when we process their
// respective catchendpad instruction.
if (isa<CatchPadInst>(FirstNonPHI))
return;
if (isa<CatchEndPadInst>(FirstNonPHI)) {
SmallVector<const CatchPadInst *, 2> Handlers;
findCatchPadsForCatchEndPad(&BB, Handlers);
const BasicBlock *FirstTryPad = Handlers.front()->getParent();
int TryLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr);
FuncInfo.EHPadStateMap[Handlers.front()] = TryLow;
for (const BasicBlock *PredBlock : predecessors(FirstTryPad))
if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
calculateExplicitCXXStateNumbers(FuncInfo, *PredBlock, TryLow);
int CatchLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr);
// catchpads are separate funclets in C++ EH due to the way rethrow works.
// In SEH, they aren't, so no invokes will unwind to the catchendpad.
FuncInfo.EHPadStateMap[FirstNonPHI] = CatchLow;
int TryHigh = CatchLow - 1;
for (const BasicBlock *PredBlock : predecessors(&BB))
if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
calculateExplicitCXXStateNumbers(FuncInfo, *PredBlock, CatchLow);
int CatchHigh = FuncInfo.getLastStateNumber();
addTryBlockMapEntry(FuncInfo, TryLow, TryHigh, CatchHigh, Handlers);
DEBUG(dbgs() << "TryLow[" << FirstTryPad->getName() << "]: " << TryLow
<< '\n');
DEBUG(dbgs() << "TryHigh[" << FirstTryPad->getName() << "]: " << TryHigh
<< '\n');
DEBUG(dbgs() << "CatchHigh[" << FirstTryPad->getName() << "]: " << CatchHigh
<< '\n');
} else if (isa<CleanupPadInst>(FirstNonPHI)) {
// A cleanup can have multiple exits; don't re-process after the first.
if (FuncInfo.EHPadStateMap.count(FirstNonPHI))
return;
int CleanupState = addUnwindMapEntry(FuncInfo, ParentState, &BB);
FuncInfo.EHPadStateMap[FirstNonPHI] = CleanupState;
DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
<< BB.getName() << '\n');
for (const BasicBlock *PredBlock : predecessors(&BB))
if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
calculateExplicitCXXStateNumbers(FuncInfo, *PredBlock, CleanupState);
} else if (auto *CEPI = dyn_cast<CleanupEndPadInst>(FirstNonPHI)) {
// Propagate ParentState to the cleanuppad in case it doesn't have
// any cleanuprets.
BasicBlock *CleanupBlock = CEPI->getCleanupPad()->getParent();
calculateExplicitCXXStateNumbers(FuncInfo, *CleanupBlock, ParentState);
// Anything unwinding through CleanupEndPadInst is in ParentState.
FuncInfo.EHPadStateMap[FirstNonPHI] = ParentState;
for (const BasicBlock *PredBlock : predecessors(&BB))
if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
calculateExplicitCXXStateNumbers(FuncInfo, *PredBlock, ParentState);
} else if (isa<TerminatePadInst>(FirstNonPHI)) {
report_fatal_error("Not yet implemented!");
} else {
llvm_unreachable("unexpected EH Pad!");
}
}
static int addSEHExcept(WinEHFuncInfo &FuncInfo, int ParentState,
const Function *Filter, const BasicBlock *Handler) {
SEHUnwindMapEntry Entry;
Entry.ToState = ParentState;
Entry.IsFinally = false;
Entry.Filter = Filter;
Entry.Handler = Handler;
FuncInfo.SEHUnwindMap.push_back(Entry);
return FuncInfo.SEHUnwindMap.size() - 1;
}
static int addSEHFinally(WinEHFuncInfo &FuncInfo, int ParentState,
const BasicBlock *Handler) {
SEHUnwindMapEntry Entry;
Entry.ToState = ParentState;
Entry.IsFinally = true;
Entry.Filter = nullptr;
Entry.Handler = Handler;
FuncInfo.SEHUnwindMap.push_back(Entry);
return FuncInfo.SEHUnwindMap.size() - 1;
}
static void calculateExplicitSEHStateNumbers(WinEHFuncInfo &FuncInfo,
const BasicBlock &BB,
int ParentState) {
assert(BB.isEHPad());
const Instruction *FirstNonPHI = BB.getFirstNonPHI();
// All catchpad instructions will be handled when we process their
// respective catchendpad instruction.
if (isa<CatchPadInst>(FirstNonPHI))
return;
if (isa<CatchEndPadInst>(FirstNonPHI)) {
// Extract the filter function and the __except basic block and create a
// state for them.
SmallVector<const CatchPadInst *, 1> Handlers;
findCatchPadsForCatchEndPad(&BB, Handlers);
assert(Handlers.size() == 1 &&
"SEH doesn't have multiple handlers per __try");
const CatchPadInst *CPI = Handlers.front();
const BasicBlock *CatchPadBB = CPI->getParent();
const Constant *FilterOrNull =
cast<Constant>(CPI->getArgOperand(0)->stripPointerCasts());
const Function *Filter = dyn_cast<Function>(FilterOrNull);
assert((Filter || FilterOrNull->isNullValue()) &&
"unexpected filter value");
int TryState = addSEHExcept(FuncInfo, ParentState, Filter, CatchPadBB);
// Everything in the __try block uses TryState as its parent state.
FuncInfo.EHPadStateMap[CPI] = TryState;
DEBUG(dbgs() << "Assigning state #" << TryState << " to BB "
<< CatchPadBB->getName() << '\n');
for (const BasicBlock *PredBlock : predecessors(CatchPadBB))
if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
calculateExplicitSEHStateNumbers(FuncInfo, *PredBlock, TryState);
// Everything in the __except block unwinds to ParentState, just like code
// outside the __try.
FuncInfo.EHPadStateMap[FirstNonPHI] = ParentState;
DEBUG(dbgs() << "Assigning state #" << ParentState << " to BB "
<< BB.getName() << '\n');
for (const BasicBlock *PredBlock : predecessors(&BB))
if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
calculateExplicitSEHStateNumbers(FuncInfo, *PredBlock, ParentState);
} else if (isa<CleanupPadInst>(FirstNonPHI)) {
// A cleanup can have multiple exits; don't re-process after the first.
if (FuncInfo.EHPadStateMap.count(FirstNonPHI))
return;
int CleanupState = addSEHFinally(FuncInfo, ParentState, &BB);
FuncInfo.EHPadStateMap[FirstNonPHI] = CleanupState;
DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
<< BB.getName() << '\n');
for (const BasicBlock *PredBlock : predecessors(&BB))
if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
calculateExplicitSEHStateNumbers(FuncInfo, *PredBlock, CleanupState);
} else if (auto *CEPI = dyn_cast<CleanupEndPadInst>(FirstNonPHI)) {
// Propagate ParentState to the cleanuppad in case it doesn't have
// any cleanuprets.
BasicBlock *CleanupBlock = CEPI->getCleanupPad()->getParent();
calculateExplicitSEHStateNumbers(FuncInfo, *CleanupBlock, ParentState);
// Anything unwinding through CleanupEndPadInst is in ParentState.
FuncInfo.EHPadStateMap[FirstNonPHI] = ParentState;
DEBUG(dbgs() << "Assigning state #" << ParentState << " to BB "
<< BB.getName() << '\n');
for (const BasicBlock *PredBlock : predecessors(&BB))
if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
calculateExplicitSEHStateNumbers(FuncInfo, *PredBlock, ParentState);
} else if (isa<TerminatePadInst>(FirstNonPHI)) {
report_fatal_error("Not yet implemented!");
} else {
llvm_unreachable("unexpected EH Pad!");
}
}
/// Check if the EH Pad unwinds to caller. Cleanups are a little bit of a
/// special case because we have to look at the cleanupret instruction that uses
/// the cleanuppad.
static bool doesEHPadUnwindToCaller(const Instruction *EHPad) {
auto *CPI = dyn_cast<CleanupPadInst>(EHPad);
if (!CPI)
return EHPad->mayThrow();
// This cleanup does not return or unwind, so we say it unwinds to caller.
if (CPI->use_empty())
return true;
const Instruction *User = CPI->user_back();
if (auto *CRI = dyn_cast<CleanupReturnInst>(User))
return CRI->unwindsToCaller();
return cast<CleanupEndPadInst>(User)->unwindsToCaller();
}
void llvm::calculateSEHStateNumbers(const Function *Fn,
WinEHFuncInfo &FuncInfo) {
// Don't compute state numbers twice.
if (!FuncInfo.SEHUnwindMap.empty())
return;
for (const BasicBlock &BB : *Fn) {
if (!BB.isEHPad() || !doesEHPadUnwindToCaller(BB.getFirstNonPHI()))
continue;
calculateExplicitSEHStateNumbers(FuncInfo, BB, -1);
}
}
void llvm::calculateWinCXXEHStateNumbers(const Function *Fn,
WinEHFuncInfo &FuncInfo) {
// Return if it's already been done.
if (!FuncInfo.EHPadStateMap.empty())
return;
for (const BasicBlock &BB : *Fn) {
if (!BB.isEHPad())
continue;
if (BB.isLandingPad())
report_fatal_error("MSVC C++ EH cannot use landingpads");
const Instruction *FirstNonPHI = BB.getFirstNonPHI();
if (!doesEHPadUnwindToCaller(FirstNonPHI))
continue;
calculateExplicitCXXStateNumbers(FuncInfo, BB, -1);
}
}
static int addClrEHHandler(WinEHFuncInfo &FuncInfo, int ParentState,
ClrHandlerType HandlerType, uint32_t TypeToken,
const BasicBlock *Handler) {
ClrEHUnwindMapEntry Entry;
Entry.Parent = ParentState;
Entry.Handler = Handler;
Entry.HandlerType = HandlerType;
Entry.TypeToken = TypeToken;
FuncInfo.ClrEHUnwindMap.push_back(Entry);
return FuncInfo.ClrEHUnwindMap.size() - 1;
}
void llvm::calculateClrEHStateNumbers(const Function *Fn,
WinEHFuncInfo &FuncInfo) {
// Return if it's already been done.
if (!FuncInfo.EHPadStateMap.empty())
return;
SmallVector<std::pair<const Instruction *, int>, 8> Worklist;
// Each pad needs to be able to refer to its parent, so scan the function
// looking for top-level handlers and seed the worklist with them.
for (const BasicBlock &BB : *Fn) {
if (!BB.isEHPad())
continue;
if (BB.isLandingPad())
report_fatal_error("CoreCLR EH cannot use landingpads");
const Instruction *FirstNonPHI = BB.getFirstNonPHI();
if (!doesEHPadUnwindToCaller(FirstNonPHI))
continue;
// queue this with sentinel parent state -1 to mean unwind to caller.
Worklist.emplace_back(FirstNonPHI, -1);
}
while (!Worklist.empty()) {
const Instruction *Pad;
int ParentState;
std::tie(Pad, ParentState) = Worklist.pop_back_val();
int PredState;
if (const CleanupEndPadInst *EndPad = dyn_cast<CleanupEndPadInst>(Pad)) {
FuncInfo.EHPadStateMap[EndPad] = ParentState;
// Queue the cleanuppad, in case it doesn't have a cleanupret.
Worklist.emplace_back(EndPad->getCleanupPad(), ParentState);
// Preds of the endpad should get the parent state.
PredState = ParentState;
} else if (const CleanupPadInst *Cleanup = dyn_cast<CleanupPadInst>(Pad)) {
// A cleanup can have multiple exits; don't re-process after the first.
if (FuncInfo.EHPadStateMap.count(Pad))
continue;
// CoreCLR personality uses arity to distinguish faults from finallies.
const BasicBlock *PadBlock = Cleanup->getParent();
ClrHandlerType HandlerType =
(Cleanup->getNumOperands() ? ClrHandlerType::Fault
: ClrHandlerType::Finally);
int NewState =
addClrEHHandler(FuncInfo, ParentState, HandlerType, 0, PadBlock);
FuncInfo.EHPadStateMap[Cleanup] = NewState;
// Propagate the new state to all preds of the cleanup
PredState = NewState;
} else if (const CatchEndPadInst *EndPad = dyn_cast<CatchEndPadInst>(Pad)) {
FuncInfo.EHPadStateMap[EndPad] = ParentState;
// Preds of the endpad should get the parent state.
PredState = ParentState;
} else if (const CatchPadInst *Catch = dyn_cast<CatchPadInst>(Pad)) {
const BasicBlock *PadBlock = Catch->getParent();
uint32_t TypeToken = static_cast<uint32_t>(
cast<ConstantInt>(Catch->getArgOperand(0))->getZExtValue());
int NewState = addClrEHHandler(FuncInfo, ParentState,
ClrHandlerType::Catch, TypeToken, PadBlock);
FuncInfo.EHPadStateMap[Catch] = NewState;
// Preds of the catch get its state
PredState = NewState;
} else {
llvm_unreachable("Unexpected EH pad");
}
// Queue all predecessors with the given state
for (const BasicBlock *Pred : predecessors(Pad->getParent())) {
if ((Pred = getEHPadFromPredecessor(Pred)))
Worklist.emplace_back(Pred->getFirstNonPHI(), PredState);
}
}
}
void WinEHPrepare::replaceTerminatePadWithCleanup(Function &F) {
if (Personality != EHPersonality::MSVC_CXX)
return;
for (BasicBlock &BB : F) {
Instruction *First = BB.getFirstNonPHI();
auto *TPI = dyn_cast<TerminatePadInst>(First);
if (!TPI)
continue;
if (TPI->getNumArgOperands() != 1)
report_fatal_error(
"Expected a unary terminatepad for MSVC C++ personalities!");
auto *TerminateFn = dyn_cast<Function>(TPI->getArgOperand(0));
if (!TerminateFn)
report_fatal_error("Function operand expected in terminatepad for MSVC "
"C++ personalities!");
// Insert the cleanuppad instruction.
auto *CPI = CleanupPadInst::Create(
BB.getContext(), {}, Twine("terminatepad.for.", BB.getName()), &BB);
// Insert the call to the terminate instruction.
auto *CallTerminate = CallInst::Create(TerminateFn, {}, &BB);
CallTerminate->setDoesNotThrow();
CallTerminate->setDoesNotReturn();
CallTerminate->setCallingConv(TerminateFn->getCallingConv());
// Insert a new terminator for the cleanuppad using the same successor as
// the terminatepad.
CleanupReturnInst::Create(CPI, TPI->getUnwindDest(), &BB);
// Let's remove the terminatepad now that we've inserted the new
// instructions.
TPI->eraseFromParent();
}
}
static void
colorFunclets(Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks,
std::map<BasicBlock *, SetVector<BasicBlock *>> &BlockColors,
std::map<BasicBlock *, std::set<BasicBlock *>> &FuncletBlocks) {
SmallVector<std::pair<BasicBlock *, BasicBlock *>, 16> Worklist;
BasicBlock *EntryBlock = &F.getEntryBlock();
// Build up the color map, which maps each block to its set of 'colors'.
// For any block B, the "colors" of B are the set of funclets F (possibly
// including a root "funclet" representing the main function), such that
// F will need to directly contain B or a copy of B (where the term "directly
// contain" is used to distinguish from being "transitively contained" in
// a nested funclet).
// Use a CFG walk driven by a worklist of (block, color) pairs. The "color"
// sets attached during this processing to a block which is the entry of some
// funclet F is actually the set of F's parents -- i.e. the union of colors
// of all predecessors of F's entry. For all other blocks, the color sets
// are as defined above. A post-pass fixes up the block color map to reflect
// the same sense of "color" for funclet entries as for other blocks.
DEBUG_WITH_TYPE("winehprepare-coloring", dbgs() << "\nColoring funclets for "
<< F.getName() << "\n");
Worklist.push_back({EntryBlock, EntryBlock});
while (!Worklist.empty()) {
BasicBlock *Visiting;
BasicBlock *Color;
std::tie(Visiting, Color) = Worklist.pop_back_val();
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << "Visiting " << Visiting->getName() << ", "
<< Color->getName() << "\n");
Instruction *VisitingHead = Visiting->getFirstNonPHI();
if (VisitingHead->isEHPad() && !isa<CatchEndPadInst>(VisitingHead) &&
!isa<CleanupEndPadInst>(VisitingHead)) {
// Mark this as a funclet head as a member of itself.
FuncletBlocks[Visiting].insert(Visiting);
// Queue exits (i.e. successors of rets/endpads) with the parent color.
// Skip any exits that are catchendpads, since the parent color must then
// represent one of the catches chained to that catchendpad, but the
// catchendpad should get the color of the common parent of all its
// chained catches (i.e. the grandparent color of the current pad).
// We don't need to worry abou catchendpads going unvisited, since the
// catches chained to them must have unwind edges to them by which we will
// visit them.
for (User *U : VisitingHead->users()) {
if (auto *Exit = dyn_cast<TerminatorInst>(U)) {
for (BasicBlock *Succ : successors(Exit->getParent()))
if (!isa<CatchEndPadInst>(*Succ->getFirstNonPHI()))
if (BlockColors[Succ].insert(Color)) {
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Assigned color \'"
<< Color->getName() << "\' to block \'"
<< Succ->getName() << "\'.\n");
Worklist.push_back({Succ, Color});
}
}
}
// Handle CatchPad specially since its successors need different colors.
if (CatchPadInst *CatchPad = dyn_cast<CatchPadInst>(VisitingHead)) {
// Visit the normal successor with the color of the new EH pad, and
// visit the unwind successor with the color of the parent.
BasicBlock *NormalSucc = CatchPad->getNormalDest();
if (BlockColors[NormalSucc].insert(Visiting)) {
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Assigned color \'" << Visiting->getName()
<< "\' to block \'" << NormalSucc->getName()
<< "\'.\n");
Worklist.push_back({NormalSucc, Visiting});
}
BasicBlock *UnwindSucc = CatchPad->getUnwindDest();
if (BlockColors[UnwindSucc].insert(Color)) {
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Assigned color \'" << Color->getName()
<< "\' to block \'" << UnwindSucc->getName()
<< "\'.\n");
Worklist.push_back({UnwindSucc, Color});
}
continue;
}
// Switch color to the current node, except for terminate pads which
// have no bodies and only unwind successors and so need their successors
// visited with the color of the parent.
if (!isa<TerminatePadInst>(VisitingHead))
Color = Visiting;
} else {
// Note that this is a member of the given color.
FuncletBlocks[Color].insert(Visiting);
}
TerminatorInst *Terminator = Visiting->getTerminator();
if (isa<CleanupReturnInst>(Terminator) ||
isa<CatchReturnInst>(Terminator) ||
isa<CleanupEndPadInst>(Terminator)) {
// These blocks' successors have already been queued with the parent
// color.
continue;
}
for (BasicBlock *Succ : successors(Visiting)) {
if (isa<CatchEndPadInst>(Succ->getFirstNonPHI())) {
// The catchendpad needs to be visited with the parent's color, not
// the current color. This will happen in the code above that visits
// any catchpad unwind successor with the parent color, so we can
// safely skip this successor here.
continue;
}
if (BlockColors[Succ].insert(Color)) {
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Assigned color \'" << Color->getName()
<< "\' to block \'" << Succ->getName()
<< "\'.\n");
Worklist.push_back({Succ, Color});
}
}
}
}
static BasicBlock *getEndPadForCatch(CatchPadInst *Catch) {
// The catch may have sibling catches. Follow the unwind chain until we get
// to the catchendpad.
BasicBlock *NextUnwindDest = Catch->getUnwindDest();
auto *UnwindTerminator = NextUnwindDest->getTerminator();
while (auto *NextCatch = dyn_cast<CatchPadInst>(UnwindTerminator)) {
NextUnwindDest = NextCatch->getUnwindDest();
UnwindTerminator = NextUnwindDest->getTerminator();
}
// The last catch in the chain must unwind to a catchendpad.
assert(isa<CatchEndPadInst>(UnwindTerminator));
return NextUnwindDest;
}
static void updateClonedEHPadUnwindToParent(
BasicBlock *UnwindDest, BasicBlock *OrigBlock, BasicBlock *CloneBlock,
std::vector<BasicBlock *> &OrigParents, BasicBlock *CloneParent) {
auto updateUnwindTerminator = [](BasicBlock *BB) {
auto *Terminator = BB->getTerminator();
if (isa<CatchEndPadInst>(Terminator) ||
isa<CleanupEndPadInst>(Terminator)) {
removeUnwindEdge(BB);
} else {
// If the block we're updating has a cleanupendpad or cleanupret
// terminator, we just want to replace that terminator with an
// unreachable instruction.
assert(isa<CleanupEndPadInst>(Terminator) ||
isa<CleanupReturnInst>(Terminator));
// Loop over all of the successors, removing the block's entry from any
// PHI nodes.
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
(*SI)->removePredecessor(BB);
// Remove the terminator and replace it with an unreachable instruction.
BB->getTerminator()->eraseFromParent();
new UnreachableInst(BB->getContext(), BB);
}
};
assert(UnwindDest->isEHPad());
// There are many places to which this EH terminator can unwind and each has
// slightly different rules for whether or not it fits with the given
// location.
auto *EHPadInst = UnwindDest->getFirstNonPHI();
if (isa<CatchEndPadInst>(EHPadInst)) {
auto *CloneParentCatch =
dyn_cast<CatchPadInst>(CloneParent->getFirstNonPHI());
if (!CloneParentCatch ||
getEndPadForCatch(CloneParentCatch) != UnwindDest) {
DEBUG_WITH_TYPE(
"winehprepare-coloring",
dbgs() << " removing unwind destination of clone block \'"
<< CloneBlock->getName() << "\'.\n");
updateUnwindTerminator(CloneBlock);
}
// It's possible that the catch end pad is a legal match for both the clone
// and the original, so they must be checked separately. If the original
// funclet will still have multiple parents after the current clone parent
// is removed, we'll leave its unwind terminator until later.
assert(OrigParents.size() >= 2);
if (OrigParents.size() != 2)
return;
// If the original funclet will have a single parent after the clone parent
// is removed, check that parent's unwind destination.
assert(OrigParents.front() == CloneParent ||
OrigParents.back() == CloneParent);
BasicBlock *OrigParent;
if (OrigParents.front() == CloneParent)
OrigParent = OrigParents.back();
else
OrigParent = OrigParents.front();
auto *OrigParentCatch =
dyn_cast<CatchPadInst>(OrigParent->getFirstNonPHI());
if (!OrigParentCatch || getEndPadForCatch(OrigParentCatch) != UnwindDest) {
DEBUG_WITH_TYPE(
"winehprepare-coloring",
dbgs() << " removing unwind destination of original block \'"
<< OrigBlock << "\'.\n");
updateUnwindTerminator(OrigBlock);
}
} else if (auto *CleanupEnd = dyn_cast<CleanupEndPadInst>(EHPadInst)) {
// If the EH terminator unwinds to a cleanupendpad, that cleanupendpad
// must be ending a cleanuppad of either our clone parent or one
// one of the parents of the original funclet.
auto *CloneParentCP =
dyn_cast<CleanupPadInst>(CloneParent->getFirstNonPHI());
auto *EndedCP = CleanupEnd->getCleanupPad();
if (EndedCP == CloneParentCP) {
// If it is ending the cleanuppad of our cloned parent, then we
// want to remove the unwind destination of the EH terminator that
// we associated with the original funclet.
assert(isa<CatchEndPadInst>(OrigBlock->getFirstNonPHI()));
DEBUG_WITH_TYPE(
"winehprepare-coloring",
dbgs() << " removing unwind destination of original block \'"
<< OrigBlock->getName() << "\'.\n");
updateUnwindTerminator(OrigBlock);
} else {
// If it isn't ending the cleanuppad of our clone parent, then we
// want to remove the unwind destination of the EH terminator that
// associated with our cloned funclet.
assert(isa<CatchEndPadInst>(CloneBlock->getFirstNonPHI()));
DEBUG_WITH_TYPE(
"winehprepare-coloring",
dbgs() << " removing unwind destination of clone block \'"
<< CloneBlock->getName() << "\'.\n");
updateUnwindTerminator(CloneBlock);
}
} else {
// If the EH terminator unwinds to a catchpad, cleanuppad or
// terminatepad that EH pad must be a sibling of the funclet we're
// cloning. We'll clone it later and update one of the catchendpad
// instrunctions that unwinds to it at that time.
assert(isa<CatchPadInst>(EHPadInst) || isa<CleanupPadInst>(EHPadInst) ||
isa<TerminatePadInst>(EHPadInst));
}
}
// If the terminator is a catchpad, we must also clone the catchendpad to which
// it unwinds and add this to the clone parent's block list. The catchendpad
// unwinds to either its caller, a sibling EH pad, a cleanup end pad in its
// parent funclet or a catch end pad in its grandparent funclet (which must be
// coupled with the parent funclet). If it has no unwind destination
// (i.e. unwind to caller), there is nothing to be done. If the unwind
// destination is a sibling EH pad, we will update the terminators later (in
// resolveFuncletAncestryForPath). If it unwinds to a cleanup end pad or a
// catch end pad and this end pad corresponds to the clone parent, we will
// remove the unwind destination in the original catchendpad. If it unwinds to
// a cleanup end pad or a catch end pad that does not correspond to the clone
// parent, we will remove the unwind destination in the cloned catchendpad.
static void updateCatchTerminators(
Function &F, CatchPadInst *OrigCatch, CatchPadInst *CloneCatch,
std::vector<BasicBlock *> &OrigParents, BasicBlock *CloneParent,
ValueToValueMapTy &VMap,
std::map<BasicBlock *, SetVector<BasicBlock *>> &BlockColors,
std::map<BasicBlock *, std::set<BasicBlock *>> &FuncletBlocks) {
// If we're cloning a catch pad that unwinds to a catchendpad, we also
// need to clone the catchendpad. The coloring algorithm associates
// the catchendpad block with the funclet's parent, so we have some work
// to do here to figure out whether the original belongs to the clone
// parent or one of the original funclets other parents (it might have
// more than one at this point). In either case, we might also need to
// remove the unwind edge if the catchendpad doesn't unwind to a block
// in the right grandparent funclet.
Instruction *I = CloneCatch->getUnwindDest()->getFirstNonPHI();
if (auto *CEP = dyn_cast<CatchEndPadInst>(I)) {
assert(BlockColors[CEP->getParent()].size() == 1);
BasicBlock *CEPFunclet = *(BlockColors[CEP->getParent()].begin());
BasicBlock *CEPCloneParent = nullptr;
CatchPadInst *PredCatch = nullptr;
if (CEPFunclet == CloneParent) {
// The catchendpad is in the clone parent, so we need to clone it
// and associate the clone with the original funclet's parent. If
// the original funclet had multiple parents, we'll add it to the
// first parent that isn't the clone parent. The logic in
// updateClonedEHPadUnwindToParent() will only remove the unwind edge
// if there is only one parent other than the clone parent, so we don't
// need to verify the ancestry. The catchendpad will eventually be
// cloned into the correct parent and all invalid unwind edges will be
// removed.
for (auto *Parent : OrigParents) {
if (Parent != CloneParent) {
CEPCloneParent = Parent;
break;
}
}
PredCatch = OrigCatch;
} else {
CEPCloneParent = CloneParent;
PredCatch = CloneCatch;
}
assert(CEPCloneParent && PredCatch);
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Cloning catchendpad \'"
<< CEP->getParent()->getName() << "\' for funclet \'"
<< CEPCloneParent->getName() << "\'.\n");
BasicBlock *ClonedCEP = CloneBasicBlock(
CEP->getParent(), VMap, Twine(".from.", CEPCloneParent->getName()));
// Insert the clone immediately after the original to ensure determinism
// and to keep the same relative ordering of any funclet's blocks.
ClonedCEP->insertInto(&F, CEP->getParent()->getNextNode());
PredCatch->setUnwindDest(ClonedCEP);
FuncletBlocks[CEPCloneParent].insert(ClonedCEP);
BlockColors[ClonedCEP].insert(CEPCloneParent);
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Assigning color \'"
<< CEPCloneParent->getName() << "\' to block \'"
<< ClonedCEP->getName() << "\'.\n");
auto *ClonedCEPInst = cast<CatchEndPadInst>(ClonedCEP->getTerminator());
if (auto *Dest = ClonedCEPInst->getUnwindDest())
updateClonedEHPadUnwindToParent(Dest, OrigCatch->getUnwindDest(),
CloneCatch->getUnwindDest(), OrigParents,
CloneParent);
}
}
// While we are cloning a funclet because it has multiple parents, we will call
// this routine to update the terminators for the original and cloned copies
// of each basic block. All blocks in the funclet have been clone by this time.
// OrigBlock and CloneBlock will be identical except for their block label.
//
// If the terminator is a catchpad, we must also clone the catchendpad to which
// it unwinds and in most cases update either the original catchendpad or the
// clone. See the updateCatchTerminators() helper routine for details.
//
// If the terminator is a catchret its successor is a block in its parent
// funclet. If the instruction returns to a block in the parent for which the
// cloned funclet was created, the terminator in the original block must be
// replaced by an unreachable instruction. Otherwise the terminator in the
// clone block must be replaced by an unreachable instruction.
//
// If the terminator is a cleanupret or cleanupendpad it either unwinds to
// caller or unwinds to a sibling EH pad, a cleanup end pad in its parent
// funclet or a catch end pad in its grandparent funclet (which must be
// coupled with the parent funclet). If it unwinds to caller there is
// nothing to be done. If the unwind destination is a sibling EH pad, we will
// update the terminators later (in resolveFuncletAncestryForPath). If it
// unwinds to a cleanup end pad or a catch end pad and this end pad corresponds
// to the clone parent, we will replace the terminator in the original block
// with an unreachable instruction. If it unwinds to a cleanup end pad or a
// catch end pad that does not correspond to the clone parent, we will replace
// the terminator in the clone block with an unreachable instruction.
//
// If the terminator is an invoke instruction, we will handle it after all
// siblings of the current funclet have been cloned.
void WinEHPrepare::updateTerminatorsAfterFuncletClone(
Function &F, BasicBlock *OrigFunclet, BasicBlock *CloneFunclet,
BasicBlock *OrigBlock, BasicBlock *CloneBlock, BasicBlock *CloneParent,
ValueToValueMapTy &VMap, std::map<BasicBlock *, BasicBlock *> &Orig2Clone) {
// If the cloned block doesn't have an exceptional terminator, there is
// nothing to be done here.
TerminatorInst *CloneTerminator = CloneBlock->getTerminator();
if (!CloneTerminator->isExceptional())
return;
if (auto *CloneCatch = dyn_cast<CatchPadInst>(CloneTerminator)) {
// A cloned catch pad has a lot of wrinkles, so we'll call a helper function
// to update this case.
auto *OrigCatch = cast<CatchPadInst>(OrigBlock->getTerminator());
updateCatchTerminators(F, OrigCatch, CloneCatch,
FuncletParents[OrigFunclet], CloneParent, VMap,
BlockColors, FuncletBlocks);
} else if (auto *CRI = dyn_cast<CatchReturnInst>(CloneTerminator)) {
if (FuncletBlocks[CloneParent].count(CRI->getSuccessor())) {
BasicBlock *OrigParent;
// The original funclet may have more than two parents, but that's OK.
// We just need to remap the original catchret to any of the parents.
// All of the parents should have an entry in the EstrangedBlocks map
// if any of them do.
if (FuncletParents[OrigFunclet].front() == CloneParent)
OrigParent = FuncletParents[OrigFunclet].back();
else
OrigParent = FuncletParents[OrigFunclet].front();
for (succ_iterator SI = succ_begin(OrigBlock), SE = succ_end(OrigBlock);
SI != SE; ++SI)
(*SI)->removePredecessor(OrigBlock);
BasicBlock *LostBlock = EstrangedBlocks[OrigParent][CRI->getSuccessor()];
auto *OrigCatchRet = cast<CatchReturnInst>(OrigBlock->getTerminator());
if (LostBlock) {
OrigCatchRet->setSuccessor(LostBlock);
} else {
OrigCatchRet->eraseFromParent();
new UnreachableInst(OrigBlock->getContext(), OrigBlock);
}
} else {
for (succ_iterator SI = succ_begin(CloneBlock), SE = succ_end(CloneBlock);
SI != SE; ++SI)
(*SI)->removePredecessor(CloneBlock);
BasicBlock *LostBlock = EstrangedBlocks[CloneParent][CRI->getSuccessor()];
if (LostBlock) {
CRI->setSuccessor(LostBlock);
} else {
CRI->eraseFromParent();
new UnreachableInst(CloneBlock->getContext(), CloneBlock);
}
}
} else if (isa<CleanupReturnInst>(CloneTerminator) ||
isa<CleanupEndPadInst>(CloneTerminator)) {
BasicBlock *UnwindDest = nullptr;
// A cleanup pad can unwind through either a cleanupret or a cleanupendpad
// but both are handled the same way.
if (auto *CRI = dyn_cast<CleanupReturnInst>(CloneTerminator))
UnwindDest = CRI->getUnwindDest();
else if (auto *CEI = dyn_cast<CleanupEndPadInst>(CloneTerminator))
UnwindDest = CEI->getUnwindDest();
// If the instruction has no local unwind destination, there is nothing
// to be done.
if (!UnwindDest)
return;
// The unwind destination may be a sibling EH pad, a catchendpad in
// a grandparent funclet (ending a catchpad in the parent) or a cleanup
// cleanupendpad in the parent. Call a helper routine to diagnose this
// and remove either the clone or original terminator as needed.
updateClonedEHPadUnwindToParent(UnwindDest, OrigBlock, CloneBlock,
FuncletParents[OrigFunclet], CloneParent);
}
}
// Clones all blocks used by the specified funclet to avoid the funclet having
// multiple parent funclets. All terminators in the parent that unwind to the
// original funclet are remapped to unwind to the clone. Any terminator in the
// original funclet which returned to this parent is converted to an unreachable
// instruction. Likewise, any terminator in the cloned funclet which returns to
// a parent funclet other than the specified parent is converted to an
// unreachable instruction.
BasicBlock *WinEHPrepare::cloneFuncletForParent(Function &F,
BasicBlock *FuncletEntry,
BasicBlock *Parent) {
std::set<BasicBlock *> &BlocksInFunclet = FuncletBlocks[FuncletEntry];
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << "Cloning funclet \'" << FuncletEntry->getName()
<< "\' for parent \'" << Parent->getName() << "\'.\n");
std::map<BasicBlock *, BasicBlock *> Orig2Clone;
ValueToValueMapTy VMap;
for (BasicBlock *BB : BlocksInFunclet) {
// Create a new basic block and copy instructions into it.
BasicBlock *CBB =
CloneBasicBlock(BB, VMap, Twine(".from.", Parent->getName()));
// Insert the clone immediately after the original to ensure determinism
// and to keep the same relative ordering of any funclet's blocks.
CBB->insertInto(&F, BB->getNextNode());
// Add basic block mapping.
VMap[BB] = CBB;
// Record delta operations that we need to perform to our color mappings.
Orig2Clone[BB] = CBB;
} // end for (BasicBlock *BB : BlocksInFunclet)
BasicBlock *ClonedFunclet = Orig2Clone[FuncletEntry];
assert(ClonedFunclet);
// Set the coloring for the blocks we just cloned.
std::set<BasicBlock *> &ClonedBlocks = FuncletBlocks[ClonedFunclet];
for (auto &BBMapping : Orig2Clone) {
BasicBlock *NewBlock = BBMapping.second;
ClonedBlocks.insert(NewBlock);
BlockColors[NewBlock].insert(ClonedFunclet);
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Assigning color \'" << ClonedFunclet->getName()
<< "\' to block \'" << NewBlock->getName()
<< "\'.\n");
// Use the VMap to remap the instructions in this cloned block.
for (Instruction &I : *NewBlock)
RemapInstruction(&I, VMap, RF_IgnoreMissingEntries);
}
// All the cloned blocks have to be colored in the loop above before we can
// update the terminators because doing so can require checking the color of
// other blocks in the cloned funclet.
for (auto &BBMapping : Orig2Clone) {
BasicBlock *OldBlock = BBMapping.first;
BasicBlock *NewBlock = BBMapping.second;
// Update the terminator, if necessary, in both the original block and the
// cloned so that the original funclet never returns to a block in the
// clone parent and the clone funclet never returns to a block in any other
// of the original funclet's parents.
updateTerminatorsAfterFuncletClone(F, FuncletEntry, ClonedFunclet, OldBlock,
NewBlock, Parent, VMap, Orig2Clone);
// Check to see if the cloned block successor has PHI nodes. If so, we need
// to add entries to the PHI nodes for the cloned block now.
for (BasicBlock *SuccBB : successors(NewBlock)) {
for (Instruction &SuccI : *SuccBB) {
auto *SuccPN = dyn_cast<PHINode>(&SuccI);
if (!SuccPN)
break;
// Ok, we have a PHI node. Figure out what the incoming value was for
// the OldBlock.
int OldBlockIdx = SuccPN->getBasicBlockIndex(OldBlock);
if (OldBlockIdx == -1)
break;
Value *IV = SuccPN->getIncomingValue(OldBlockIdx);
// Remap the value if necessary.
if (auto *Inst = dyn_cast<Instruction>(IV)) {
ValueToValueMapTy::iterator I = VMap.find(Inst);
if (I != VMap.end())
IV = I->second;
}
SuccPN->addIncoming(IV, NewBlock);
}
}
}
// Erase the clone's parent from the original funclet's parent list.
std::vector<BasicBlock *> &Parents = FuncletParents[FuncletEntry];
Parents.erase(std::remove(Parents.begin(), Parents.end(), Parent),
Parents.end());
// Store the cloned funclet's parent.
assert(std::find(FuncletParents[ClonedFunclet].begin(),
FuncletParents[ClonedFunclet].end(),
Parent) == std::end(FuncletParents[ClonedFunclet]));
FuncletParents[ClonedFunclet].push_back(Parent);
// Copy any children of the original funclet to the clone. We'll either
// clone them too or make that path unreachable when we take the next step
// in resolveFuncletAncestryForPath().
for (auto *Child : FuncletChildren[FuncletEntry]) {
assert(std::find(FuncletChildren[ClonedFunclet].begin(),
FuncletChildren[ClonedFunclet].end(),
Child) == std::end(FuncletChildren[ClonedFunclet]));
FuncletChildren[ClonedFunclet].push_back(Child);
assert(std::find(FuncletParents[Child].begin(), FuncletParents[Child].end(),
ClonedFunclet) == std::end(FuncletParents[Child]));
FuncletParents[Child].push_back(ClonedFunclet);
}
// Find any blocks that unwound to the original funclet entry from the
// clone parent block and remap them to the clone.
for (auto *U : FuncletEntry->users()) {
auto *UT = dyn_cast<TerminatorInst>(U);
if (!UT)
continue;
BasicBlock *UBB = UT->getParent();
assert(BlockColors[UBB].size() == 1);
BasicBlock *UFunclet = *(BlockColors[UBB].begin());
// Funclets shouldn't be able to loop back on themselves.
assert(UFunclet != FuncletEntry);
// If this instruction unwinds to the original funclet from the clone
// parent, remap the terminator so that it unwinds to the clone instead.
// We will perform a similar transformation for siblings after all
// the siblings have been cloned.
if (UFunclet == Parent) {
// We're about to break the path from this block to the uncloned funclet
// entry, so remove it as a predeccessor to clean up the PHIs.
FuncletEntry->removePredecessor(UBB);
TerminatorInst *Terminator = UBB->getTerminator();
RemapInstruction(Terminator, VMap, RF_IgnoreMissingEntries);
}
}
// This asserts a condition that is relied upon inside the loop below,
// namely that no predecessors of the original funclet entry block
// are also predecessors of the cloned funclet entry block.
assert(std::all_of(pred_begin(FuncletEntry), pred_end(FuncletEntry),
[&ClonedFunclet](BasicBlock *Pred) {
return std::find(pred_begin(ClonedFunclet),
pred_end(ClonedFunclet),
Pred) == pred_end(ClonedFunclet);
}));
// Remove any invalid PHI node entries in the cloned funclet.cl
std::vector<PHINode *> PHIsToErase;
for (Instruction &I : *ClonedFunclet) {
auto *PN = dyn_cast<PHINode>(&I);
if (!PN)
break;
// Predecessors of the original funclet do not reach the cloned funclet,
// but the cloning process assumes they will. Remove them now.
for (auto *Pred : predecessors(FuncletEntry))
PN->removeIncomingValue(Pred, false);
}
for (auto *PN : PHIsToErase)
PN->eraseFromParent();
// Replace the original funclet in the parent's children vector with the
// cloned funclet.
for (auto &It : FuncletChildren[Parent]) {
if (It == FuncletEntry) {
It = ClonedFunclet;
break;
}
}
return ClonedFunclet;
}
// Removes the unwind edge for any exceptional terminators within the specified
// parent funclet that previously unwound to the specified child funclet.
void WinEHPrepare::makeFuncletEdgeUnreachable(BasicBlock *Parent,
BasicBlock *Child) {
for (BasicBlock *BB : FuncletBlocks[Parent]) {
TerminatorInst *Terminator = BB->getTerminator();
if (!Terminator->isExceptional())
continue;
// Look for terninators that unwind to the child funclet.
BasicBlock *UnwindDest = nullptr;
if (auto *I = dyn_cast<InvokeInst>(Terminator))
UnwindDest = I->getUnwindDest();
else if (auto *I = dyn_cast<CatchEndPadInst>(Terminator))
UnwindDest = I->getUnwindDest();
else if (auto *I = dyn_cast<TerminatePadInst>(Terminator))
UnwindDest = I->getUnwindDest();
// cleanupendpad, catchret and cleanupret don't represent a parent-to-child
// funclet transition, so we don't need to consider them here.
// If the child funclet is the unwind destination, replace the terminator
// with an unreachable instruction.
if (UnwindDest == Child)
removeUnwindEdge(BB);
}
// The specified parent is no longer a parent of the specified child.
std::vector<BasicBlock *> &Children = FuncletChildren[Parent];
Children.erase(std::remove(Children.begin(), Children.end(), Child),
Children.end());
}
// This routine is called after funclets with multiple parents are cloned for
// a specific parent. Here we look for children of the specified funclet that
// unwind to other children of that funclet and update the unwind destinations
// to ensure that each sibling is connected to the correct clone of the sibling
// to which it unwinds.
//
// If the terminator is an invoke instruction, it unwinds either to a child
// EH pad, a cleanup end pad in the current funclet, or a catch end pad in a
// parent funclet (which ends either the current catch pad or a sibling
// catch pad). If it unwinds to a child EH pad, the child will have multiple
// parents after this funclet is cloned and this case will be handled later in
// the resolveFuncletAncestryForPath processing. If it unwinds to a
// cleanup end pad in the current funclet, the instruction remapping during
// the cloning process should have already mapped the unwind destination to
// the cloned copy of the cleanup end pad. If it unwinds to a catch end pad
// there are two possibilities: either the catch end pad is the unwind
// destination for the catch pad we are currently cloning or it is the unwind
// destination for a sibling catch pad. If it it the unwind destination of the
// catch pad we are cloning, we need to update the cloned invoke instruction
// to unwind to the cloned catch end pad. Otherwise, we will handle this
// later (in resolveFuncletAncestryForPath).
static void updateSiblingToSiblingUnwind(
BasicBlock *CurFunclet,
std::map<BasicBlock *, SetVector<BasicBlock *>> &BlockColors,
std::map<BasicBlock *, std::set<BasicBlock *>> &FuncletBlocks,
std::map<BasicBlock *, std::vector<BasicBlock *>> &FuncletParents,
std::map<BasicBlock *, std::vector<BasicBlock *>> &FuncletChildren,
std::map<BasicBlock *, BasicBlock *> &Funclet2Orig) {
// Remap any bad sibling-to-sibling transitions for funclets that
// we just cloned.
for (BasicBlock *ChildFunclet : FuncletChildren[CurFunclet]) {
for (auto *BB : FuncletBlocks[ChildFunclet]) {
TerminatorInst *Terminator = BB->getTerminator();
if (!Terminator->isExceptional())
continue;
// See if this terminator has an unwind destination.
// Note that catchendpads are handled when the associated catchpad
// is cloned. They don't fit the pattern we're looking for here.
BasicBlock *UnwindDest = nullptr;
if (auto *I = dyn_cast<CatchPadInst>(Terminator)) {
UnwindDest = I->getUnwindDest();
// The catchendpad is not a sibling destination. This case should
// have been handled in cloneFuncletForParent().
if (isa<CatchEndPadInst>(Terminator)) {
assert(BlockColors[UnwindDest].size() == 1 &&
"Cloned catchpad unwinds to an pad with multiple parents.");
assert(FuncletParents[UnwindDest].front() == CurFunclet &&
"Cloned catchpad unwinds to the wrong parent.");
continue;
}
} else {
if (auto *I = dyn_cast<CleanupReturnInst>(Terminator))
UnwindDest = I->getUnwindDest();
else if (auto *I = dyn_cast<CleanupEndPadInst>(Terminator))
UnwindDest = I->getUnwindDest();
// If the cleanup unwinds to caller, there is nothing to be done.
if (!UnwindDest)
continue;
}
// If the destination is not a cleanup pad, catch pad or terminate pad
// we don't need to handle it here.
Instruction *EHPad = UnwindDest->getFirstNonPHI();
if (!isa<CleanupPadInst>(EHPad) && !isa<CatchPadInst>(EHPad) &&
!isa<TerminatePadInst>(EHPad))
continue;
// If it is one of these, then it is either a sibling of the current
// child funclet or a clone of one of those siblings.
// If it is a sibling, no action is needed.
if (FuncletParents[UnwindDest].size() == 1 &&
FuncletParents[UnwindDest].front() == CurFunclet)
continue;
// If the unwind destination is a clone of a sibling, we need to figure
// out which sibling it is a clone of and use that sibling as the
// unwind destination.
BasicBlock *DestOrig = Funclet2Orig[UnwindDest];
BasicBlock *TargetSibling = nullptr;
for (auto &Mapping : Funclet2Orig) {
if (Mapping.second != DestOrig)
continue;
BasicBlock *MappedFunclet = Mapping.first;
if (FuncletParents[MappedFunclet].size() == 1 &&
FuncletParents[MappedFunclet].front() == CurFunclet) {
TargetSibling = MappedFunclet;
}
}
// If we didn't find the sibling we were looking for then the
// unwind destination is not a clone of one of child's siblings.
// That's unexpected.
assert(TargetSibling && "Funclet unwinds to unexpected destination.");
// Update the terminator instruction to unwind to the correct sibling.
if (auto *I = dyn_cast<CatchPadInst>(Terminator))
I->setUnwindDest(TargetSibling);
else if (auto *I = dyn_cast<CleanupReturnInst>(Terminator))
I->setUnwindDest(TargetSibling);
else if (auto *I = dyn_cast<CleanupEndPadInst>(Terminator))
I->setUnwindDest(TargetSibling);
}
}
// Invoke remapping can't be done correctly until after all of their
// other sibling-to-sibling unwinds have been remapped.
for (BasicBlock *ChildFunclet : FuncletChildren[CurFunclet]) {
bool NeedOrigInvokeRemapping = false;
for (auto *BB : FuncletBlocks[ChildFunclet]) {
TerminatorInst *Terminator = BB->getTerminator();
auto *II = dyn_cast<InvokeInst>(Terminator);
if (!II)
continue;
BasicBlock *UnwindDest = II->getUnwindDest();
assert(UnwindDest && "Invoke unwinds to a null destination.");
assert(UnwindDest->isEHPad() && "Invoke does not unwind to an EH pad.");
auto *EHPadInst = UnwindDest->getFirstNonPHI();
if (isa<CleanupEndPadInst>(EHPadInst)) {
// An invoke that unwinds to a cleanup end pad must be in a cleanup pad.
assert(isa<CleanupPadInst>(ChildFunclet->getFirstNonPHI()) &&
"Unwinding to cleanup end pad from a non cleanup pad funclet.");
// The funclet cloning should have remapped the destination to the cloned
// cleanup end pad.
assert(FuncletBlocks[ChildFunclet].count(UnwindDest) &&
"Unwind destination for invoke was not updated during cloning.");
} else if (isa<CatchEndPadInst>(EHPadInst)) {
// If the invoke unwind destination is the unwind destination for
// the current child catch pad funclet, there is nothing to be done.
BasicBlock *OrigFunclet = Funclet2Orig[ChildFunclet];
auto *CurCatch = cast<CatchPadInst>(ChildFunclet->getFirstNonPHI());
auto *OrigCatch = cast<CatchPadInst>(OrigFunclet->getFirstNonPHI());
if (OrigCatch->getUnwindDest() == UnwindDest) {
// If the invoke unwinds to a catch end pad that is the unwind
// destination for the original catch pad, the cloned invoke should
// unwind to the cloned catch end pad.
II->setUnwindDest(CurCatch->getUnwindDest());
} else if (CurCatch->getUnwindDest() == UnwindDest) {
// If the invoke unwinds to a catch end pad that is the unwind
// destination for the clone catch pad, the original invoke should
// unwind to the unwind destination of the original catch pad.
// This happens when the catch end pad is matched to the clone
// parent when the catchpad instruction is cloned and the original
// invoke instruction unwinds to the original catch end pad (which
// is now the unwind destination of the cloned catch pad).
NeedOrigInvokeRemapping = true;
} else {
// Otherwise, the invoke unwinds to a catch end pad that is the unwind
// destination another catch pad in the unwind chain from either the
// current catch pad or one of its clones. If it is already the
// catch end pad at the end unwind chain from the current catch pad,
// we'll need to check the invoke instructions in the original funclet
// later. Otherwise, we need to remap this invoke now.
assert((getEndPadForCatch(OrigCatch) == UnwindDest ||
getEndPadForCatch(CurCatch) == UnwindDest) &&
"Invoke within catch pad unwinds to an invalid catch end pad.");
BasicBlock *CurCatchEnd = getEndPadForCatch(CurCatch);
if (CurCatchEnd == UnwindDest)
NeedOrigInvokeRemapping = true;
else
II->setUnwindDest(CurCatchEnd);
}
}
}
if (NeedOrigInvokeRemapping) {
// To properly remap invoke instructions that unwind to catch end pads
// that are not the unwind destination of the catch pad funclet in which
// the invoke appears, we must also look at the uncloned invoke in the
// original funclet. If we saw an invoke that was already properly
// unwinding to a sibling's catch end pad, we need to check the invokes
// in the original funclet.
BasicBlock *OrigFunclet = Funclet2Orig[ChildFunclet];
for (auto *BB : FuncletBlocks[OrigFunclet]) {
auto *II = dyn_cast<InvokeInst>(BB->getTerminator());
if (!II)
continue;
BasicBlock *UnwindDest = II->getUnwindDest();
assert(UnwindDest && "Invoke unwinds to a null destination.");
assert(UnwindDest->isEHPad() && "Invoke does not unwind to an EH pad.");
auto *CEP = dyn_cast<CatchEndPadInst>(UnwindDest->getFirstNonPHI());
if (!CEP)
continue;
// If the invoke unwind destination is the unwind destination for
// the original catch pad funclet, there is nothing to be done.
auto *OrigCatch = cast<CatchPadInst>(OrigFunclet->getFirstNonPHI());
// If the invoke unwinds to a catch end pad that is neither the unwind
// destination of OrigCatch or the destination another catch pad in the
// unwind chain from current catch pad, we need to remap the invoke.
BasicBlock *OrigCatchEnd = getEndPadForCatch(OrigCatch);
if (OrigCatchEnd != UnwindDest)
II->setUnwindDest(OrigCatchEnd);
}
}
}
}
void WinEHPrepare::resolveFuncletAncestry(
Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks) {
// Most of the time this will be unnecessary. If the conditions arise that
// require this work, this flag will be set.
if (!FuncletCloningRequired)
return;
// Funclet2Orig is used to map any cloned funclets back to the original
// funclet from which they were cloned. The map is seeded with the
// original funclets mapping to themselves.
std::map<BasicBlock *, BasicBlock *> Funclet2Orig;
for (auto *Funclet : EntryBlocks)
Funclet2Orig[Funclet] = Funclet;
// Start with the entry funclet and walk the funclet parent-child tree.
SmallVector<BasicBlock *, 4> FuncletPath;
FuncletPath.push_back(&(F.getEntryBlock()));
resolveFuncletAncestryForPath(F, FuncletPath, Funclet2Orig);
}
// Walks the funclet control flow, cloning any funclets that have more than one
// parent funclet and breaking any cyclic unwind chains so that the path becomes
// unreachable at the point where a funclet would have unwound to a funclet that
// was already in the chain.
void WinEHPrepare::resolveFuncletAncestryForPath(
Function &F, SmallVectorImpl<BasicBlock *> &FuncletPath,
std::map<BasicBlock *, BasicBlock *> &Funclet2Orig) {
bool ClonedAnyChildren = false;
BasicBlock *CurFunclet = FuncletPath.back();
// Copy the children vector because we might changing it.
std::vector<BasicBlock *> Children(FuncletChildren[CurFunclet]);
for (BasicBlock *ChildFunclet : Children) {
// Don't allow the funclet chain to unwind back on itself.
// If this funclet is already in the current funclet chain, make the
// path to it through the current funclet unreachable.
bool IsCyclic = false;
BasicBlock *ChildIdentity = Funclet2Orig[ChildFunclet];
for (BasicBlock *Ancestor : FuncletPath) {
BasicBlock *AncestorIdentity = Funclet2Orig[Ancestor];
if (AncestorIdentity == ChildIdentity) {
IsCyclic = true;
break;
}
}
// If the unwind chain wraps back on itself, break the chain.
if (IsCyclic) {
makeFuncletEdgeUnreachable(CurFunclet, ChildFunclet);
continue;
}
// If this child funclet has other parents, clone the entire funclet.
if (FuncletParents[ChildFunclet].size() > 1) {
ChildFunclet = cloneFuncletForParent(F, ChildFunclet, CurFunclet);
Funclet2Orig[ChildFunclet] = ChildIdentity;
ClonedAnyChildren = true;
}
FuncletPath.push_back(ChildFunclet);
resolveFuncletAncestryForPath(F, FuncletPath, Funclet2Orig);
FuncletPath.pop_back();
}
// If we didn't clone any children, we can return now.
if (!ClonedAnyChildren)
return;
updateSiblingToSiblingUnwind(CurFunclet, BlockColors, FuncletBlocks,
FuncletParents, FuncletChildren, Funclet2Orig);
}
void WinEHPrepare::colorFunclets(Function &F,
SmallVectorImpl<BasicBlock *> &EntryBlocks) {
::colorFunclets(F, EntryBlocks, BlockColors, FuncletBlocks);
// The processing above actually accumulated the parent set for this
// funclet into the color set for its entry; use the parent set to
// populate the children map, and reset the color set to include just
// the funclet itself (no instruction can target a funclet entry except on
// that transitions to the child funclet).
for (BasicBlock *FuncletEntry : EntryBlocks) {
SetVector<BasicBlock *> &ColorMapItem = BlockColors[FuncletEntry];
// It will be rare for funclets to have multiple parents, but if any
// do we need to clone the funclet later to address that. Here we
// set a flag indicating that this case has arisen so that we don't
// have to do a lot of checking later to handle the more common case.
if (ColorMapItem.size() > 1)
FuncletCloningRequired = true;
for (BasicBlock *Parent : ColorMapItem) {
assert(std::find(FuncletChildren[Parent].begin(),
FuncletChildren[Parent].end(),
FuncletEntry) == std::end(FuncletChildren[Parent]));
FuncletChildren[Parent].push_back(FuncletEntry);
assert(std::find(FuncletParents[FuncletEntry].begin(),
FuncletParents[FuncletEntry].end(),
Parent) == std::end(FuncletParents[FuncletEntry]));
FuncletParents[FuncletEntry].push_back(Parent);
}
ColorMapItem.clear();
ColorMapItem.insert(FuncletEntry);
}
}
void llvm::calculateCatchReturnSuccessorColors(const Function *Fn,
WinEHFuncInfo &FuncInfo) {
SmallVector<BasicBlock *, 4> EntryBlocks;
// colorFunclets needs the set of EntryBlocks, get them using
// findFuncletEntryPoints.
findFuncletEntryPoints(const_cast<Function &>(*Fn), EntryBlocks);
std::map<BasicBlock *, SetVector<BasicBlock *>> BlockColors;
std::map<BasicBlock *, std::set<BasicBlock *>> FuncletBlocks;
// Figure out which basic blocks belong to which funclets.
colorFunclets(const_cast<Function &>(*Fn), EntryBlocks, BlockColors,
FuncletBlocks);
// The static colorFunclets routine assigns multiple colors to funclet entries
// because that information is needed to calculate funclets' parent-child
// relationship, but we don't need those relationship here and ultimately the
// entry blocks should have the color of the funclet they begin.
for (BasicBlock *FuncletEntry : EntryBlocks) {
BlockColors[FuncletEntry].clear();
BlockColors[FuncletEntry].insert(FuncletEntry);
}
// We need to find the catchret successors. To do this, we must first find
// all the catchpad funclets.
for (auto &Funclet : FuncletBlocks) {
// Figure out what kind of funclet we are looking at; We only care about
// catchpads.
BasicBlock *FuncletPadBB = Funclet.first;
Instruction *FirstNonPHI = FuncletPadBB->getFirstNonPHI();
auto *CatchPad = dyn_cast<CatchPadInst>(FirstNonPHI);
if (!CatchPad)
continue;
// The users of a catchpad are always catchrets.
for (User *Exit : CatchPad->users()) {
auto *CatchReturn = dyn_cast<CatchReturnInst>(Exit);
if (!CatchReturn)
continue;
BasicBlock *CatchRetSuccessor = CatchReturn->getSuccessor();
SetVector<BasicBlock *> &SuccessorColors = BlockColors[CatchRetSuccessor];
assert(SuccessorColors.size() == 1 && "Expected BB to be monochrome!");
BasicBlock *Color = *SuccessorColors.begin();
// Record the catchret successor's funclet membership.
FuncInfo.CatchRetSuccessorColorMap[CatchReturn] = Color;
}
}
}
void WinEHPrepare::demotePHIsOnFunclets(Function &F) {
// Strip PHI nodes off of EH pads.
SmallVector<PHINode *, 16> PHINodes;
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
BasicBlock *BB = &*FI++;
if (!BB->isEHPad())
continue;
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
Instruction *I = &*BI++;
auto *PN = dyn_cast<PHINode>(I);
// Stop at the first non-PHI.
if (!PN)
break;
AllocaInst *SpillSlot = insertPHILoads(PN, F);
if (SpillSlot)
insertPHIStores(PN, SpillSlot);
PHINodes.push_back(PN);
}
}
for (auto *PN : PHINodes) {
// There may be lingering uses on other EH PHIs being removed
PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
PN->eraseFromParent();
}
}
void WinEHPrepare::demoteUsesBetweenFunclets(Function &F) {
// Turn all inter-funclet uses of a Value into loads and stores.
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
BasicBlock *BB = &*FI++;
SetVector<BasicBlock *> &ColorsForBB = BlockColors[BB];
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
Instruction *I = &*BI++;
// Funclets are permitted to use static allocas.
if (auto *AI = dyn_cast<AllocaInst>(I))
if (AI->isStaticAlloca())
continue;
demoteNonlocalUses(I, ColorsForBB, F);
}
}
}
void WinEHPrepare::demoteArgumentUses(Function &F) {
// Also demote function parameters used in funclets.
SetVector<BasicBlock *> &ColorsForEntry = BlockColors[&F.getEntryBlock()];
for (Argument &Arg : F.args())
demoteNonlocalUses(&Arg, ColorsForEntry, F);
}
void WinEHPrepare::cloneCommonBlocks(
Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks) {
// We need to clone all blocks which belong to multiple funclets. Values are
// remapped throughout the funclet to propogate both the new instructions
// *and* the new basic blocks themselves.
for (BasicBlock *FuncletPadBB : EntryBlocks) {
std::set<BasicBlock *> &BlocksInFunclet = FuncletBlocks[FuncletPadBB];
std::map<BasicBlock *, BasicBlock *> Orig2Clone;
ValueToValueMapTy VMap;
for (auto BlockIt = BlocksInFunclet.begin(),
BlockEnd = BlocksInFunclet.end();
BlockIt != BlockEnd;) {
// Increment the iterator inside the loop because we might be removing
// blocks from the set.
BasicBlock *BB = *BlockIt++;
SetVector<BasicBlock *> &ColorsForBB = BlockColors[BB];
// We don't need to do anything if the block is monochromatic.
size_t NumColorsForBB = ColorsForBB.size();
if (NumColorsForBB == 1)
continue;
// If this block is a catchendpad, it shouldn't be cloned.
// We will only see a catchendpad with multiple colors in the case where
// some funclet has multiple parents. In that case, the color will be
// resolved during the resolveFuncletAncestry processing.
// For now, find the catchpad that unwinds to this block and assign
// that catchpad's first parent to be the color for this block.
if (isa<CatchEndPadInst>(BB->getFirstNonPHI())) {
assert(
FuncletCloningRequired &&
"Found multi-colored catchendpad with no multi-parent funclets.");
BasicBlock *CatchParent = nullptr;
// There can only be one catchpad predecessor for a catchendpad.
for (BasicBlock *PredBB : predecessors(BB)) {
if (isa<CatchPadInst>(PredBB->getTerminator())) {
CatchParent = PredBB;
break;
}
}
// There must be one catchpad predecessor for a catchendpad.
assert(CatchParent && "No catchpad found for catchendpad.");
// If the catchpad has multiple parents, we'll clone the catchendpad
// when we clone the catchpad funclet and insert it into the correct
// funclet. For now, we just select the first parent of the catchpad
// and give the catchendpad that color.
BasicBlock *CorrectColor = FuncletParents[CatchParent].front();
assert(FuncletBlocks[CorrectColor].count(BB));
assert(BlockColors[BB].count(CorrectColor));
// Remove this block from the FuncletBlocks set of any funclet that
// isn't the funclet whose color we just selected.
for (BasicBlock *ContainingFunclet : BlockColors[BB])
if (ContainingFunclet != CorrectColor)
FuncletBlocks[ContainingFunclet].erase(BB);
BlockColors[BB].remove_if([&](BasicBlock *ContainingFunclet) {
return ContainingFunclet != CorrectColor;
});
// This should leave just one color for BB.
assert(BlockColors[BB].size() == 1);
continue;
}
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Cloning block \'" << BB->getName()
<< "\' for funclet \'" << FuncletPadBB->getName()
<< "\'.\n");
// Create a new basic block and copy instructions into it!
BasicBlock *CBB =
CloneBasicBlock(BB, VMap, Twine(".for.", FuncletPadBB->getName()));
// Insert the clone immediately after the original to ensure determinism
// and to keep the same relative ordering of any funclet's blocks.
CBB->insertInto(&F, BB->getNextNode());
// Add basic block mapping.
VMap[BB] = CBB;
// Record delta operations that we need to perform to our color mappings.
Orig2Clone[BB] = CBB;
}
// If nothing was cloned, we're done cloning in this funclet.
if (Orig2Clone.empty())
continue;
// Update our color mappings to reflect that one block has lost a color and
// another has gained a color.
for (auto &BBMapping : Orig2Clone) {
BasicBlock *OldBlock = BBMapping.first;
BasicBlock *NewBlock = BBMapping.second;
BlocksInFunclet.insert(NewBlock);
BlockColors[NewBlock].insert(FuncletPadBB);
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Assigned color \'" << FuncletPadBB->getName()
<< "\' to block \'" << NewBlock->getName()
<< "\'.\n");
BlocksInFunclet.erase(OldBlock);
BlockColors[OldBlock].remove(FuncletPadBB);
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Removed color \'" << FuncletPadBB->getName()
<< "\' from block \'" << OldBlock->getName()
<< "\'.\n");
// If we are cloning a funclet that might share a child funclet with
// another funclet, look to see if the cloned block is reached from a
// catchret instruction. If so, save this association so we can retrieve
// the possibly orphaned clone when we clone the child funclet.
if (FuncletCloningRequired) {
for (auto *Pred : predecessors(OldBlock)) {
auto *Terminator = Pred->getTerminator();
if (!isa<CatchReturnInst>(Terminator))
continue;
// If this block is reached from a catchret instruction in a funclet
// that has multiple parents, it will have a color for each of those
// parents. We just removed the color of one of the parents, but
// the cloned block will be unreachable until we clone the child
// funclet that contains the catchret instruction. In that case we
// need to create a mapping that will let us find the cloned block
// later and associate it with the cloned child funclet.
bool BlockWillBeEstranged = false;
for (auto *Color : BlockColors[Pred]) {
if (FuncletParents[Color].size() > 1) {
BlockWillBeEstranged = true;
break; // Breaks out of the color loop
}
}
if (BlockWillBeEstranged) {
EstrangedBlocks[FuncletPadBB][OldBlock] = NewBlock;
DEBUG_WITH_TYPE("winehprepare-coloring",
dbgs() << " Saved mapping of estranged block \'"
<< NewBlock->getName() << "\' for \'"
<< FuncletPadBB->getName() << "\'.\n");
break; // Breaks out of the predecessor loop
}
}
}
}
// Loop over all of the instructions in this funclet, fixing up operand
// references as we go. This uses VMap to do all the hard work.
for (BasicBlock *BB : BlocksInFunclet)
// Loop over all instructions, fixing each one as we find it...
for (Instruction &I : *BB)
RemapInstruction(&I, VMap,
RF_IgnoreMissingEntries | RF_NoModuleLevelChanges);
// Check to see if SuccBB has PHI nodes. If so, we need to add entries to
// the PHI nodes for NewBB now.
for (auto &BBMapping : Orig2Clone) {
BasicBlock *OldBlock = BBMapping.first;
BasicBlock *NewBlock = BBMapping.second;
for (BasicBlock *SuccBB : successors(NewBlock)) {
for (Instruction &SuccI : *SuccBB) {
auto *SuccPN = dyn_cast<PHINode>(&SuccI);
if (!SuccPN)
break;
// Ok, we have a PHI node. Figure out what the incoming value was for
// the OldBlock.
int OldBlockIdx = SuccPN->getBasicBlockIndex(OldBlock);
if (OldBlockIdx == -1)
break;
Value *IV = SuccPN->getIncomingValue(OldBlockIdx);
// Remap the value if necessary.
if (auto *Inst = dyn_cast<Instruction>(IV)) {
ValueToValueMapTy::iterator I = VMap.find(Inst);
if (I != VMap.end())
IV = I->second;
}
SuccPN->addIncoming(IV, NewBlock);
}
}
}
for (ValueToValueMapTy::value_type VT : VMap) {
// If there were values defined in BB that are used outside the funclet,
// then we now have to update all uses of the value to use either the
// original value, the cloned value, or some PHI derived value. This can
// require arbitrary PHI insertion, of which we are prepared to do, clean
// these up now.
SmallVector<Use *, 16> UsesToRename;
auto *OldI = dyn_cast<Instruction>(const_cast<Value *>(VT.first));
if (!OldI)
continue;
auto *NewI = cast<Instruction>(VT.second);
// Scan all uses of this instruction to see if it is used outside of its
// funclet, and if so, record them in UsesToRename.
for (Use &U : OldI->uses()) {
Instruction *UserI = cast<Instruction>(U.getUser());
BasicBlock *UserBB = UserI->getParent();
SetVector<BasicBlock *> &ColorsForUserBB = BlockColors[UserBB];
assert(!ColorsForUserBB.empty());
if (ColorsForUserBB.size() > 1 ||
*ColorsForUserBB.begin() != FuncletPadBB)
UsesToRename.push_back(&U);
}
// If there are no uses outside the block, we're done with this
// instruction.
if (UsesToRename.empty())
continue;
// We found a use of OldI outside of the funclet. Rename all uses of OldI
// that are outside its funclet to be uses of the appropriate PHI node
// etc.
SSAUpdater SSAUpdate;
SSAUpdate.Initialize(OldI->getType(), OldI->getName());
SSAUpdate.AddAvailableValue(OldI->getParent(), OldI);
SSAUpdate.AddAvailableValue(NewI->getParent(), NewI);
while (!UsesToRename.empty())
SSAUpdate.RewriteUseAfterInsertions(*UsesToRename.pop_back_val());
}
}
}
void WinEHPrepare::removeImplausibleTerminators(Function &F) {
// Remove implausible terminators and replace them with UnreachableInst.
for (auto &Funclet : FuncletBlocks) {
BasicBlock *FuncletPadBB = Funclet.first;
std::set<BasicBlock *> &BlocksInFunclet = Funclet.second;
Instruction *FirstNonPHI = FuncletPadBB->getFirstNonPHI();
auto *CatchPad = dyn_cast<CatchPadInst>(FirstNonPHI);
auto *CleanupPad = dyn_cast<CleanupPadInst>(FirstNonPHI);
for (BasicBlock *BB : BlocksInFunclet) {
TerminatorInst *TI = BB->getTerminator();
// CatchPadInst and CleanupPadInst can't transfer control to a ReturnInst.
bool IsUnreachableRet = isa<ReturnInst>(TI) && (CatchPad || CleanupPad);
// The token consumed by a CatchReturnInst must match the funclet token.
bool IsUnreachableCatchret = false;
if (auto *CRI = dyn_cast<CatchReturnInst>(TI))
IsUnreachableCatchret = CRI->getCatchPad() != CatchPad;
// The token consumed by a CleanupReturnInst must match the funclet token.
bool IsUnreachableCleanupret = false;
if (auto *CRI = dyn_cast<CleanupReturnInst>(TI))
IsUnreachableCleanupret = CRI->getCleanupPad() != CleanupPad;
// The token consumed by a CleanupEndPadInst must match the funclet token.
bool IsUnreachableCleanupendpad = false;
if (auto *CEPI = dyn_cast<CleanupEndPadInst>(TI))
IsUnreachableCleanupendpad = CEPI->getCleanupPad() != CleanupPad;
if (IsUnreachableRet || IsUnreachableCatchret ||
IsUnreachableCleanupret || IsUnreachableCleanupendpad) {
// Loop through all of our successors and make sure they know that one
// of their predecessors is going away.
for (BasicBlock *SuccBB : TI->successors())
SuccBB->removePredecessor(BB);
if (IsUnreachableCleanupendpad) {
// We can't simply replace a cleanupendpad with unreachable, because
// its predecessor edges are EH edges and unreachable is not an EH
// pad. Change all predecessors to the "unwind to caller" form.
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
PI != PE;) {
BasicBlock *Pred = *PI++;
removeUnwindEdge(Pred);
}
}
new UnreachableInst(BB->getContext(), TI);
TI->eraseFromParent();
}
// FIXME: Check for invokes/cleanuprets/cleanupendpads which unwind to
// implausible catchendpads (i.e. catchendpad not in immediate parent
// funclet).
}
}
}
void WinEHPrepare::cleanupPreparedFunclets(Function &F) {
// Clean-up some of the mess we made by removing useles PHI nodes, trivial
// branches, etc.
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
BasicBlock *BB = &*FI++;
SimplifyInstructionsInBlock(BB);
ConstantFoldTerminator(BB, /*DeleteDeadConditions=*/true);
MergeBlockIntoPredecessor(BB);
}
// We might have some unreachable blocks after cleaning up some impossible
// control flow.
removeUnreachableBlocks(F);
}
void WinEHPrepare::verifyPreparedFunclets(Function &F) {
// Recolor the CFG to verify that all is well.
for (BasicBlock &BB : F) {
size_t NumColors = BlockColors[&BB].size();
assert(NumColors == 1 && "Expected monochromatic BB!");
if (NumColors == 0)
report_fatal_error("Uncolored BB!");
if (NumColors > 1)
report_fatal_error("Multicolor BB!");
if (!DisableDemotion) {
bool EHPadHasPHI = BB.isEHPad() && isa<PHINode>(BB.begin());
assert(!EHPadHasPHI && "EH Pad still has a PHI!");
if (EHPadHasPHI)
report_fatal_error("EH Pad still has a PHI!");
}
}
}
bool WinEHPrepare::prepareExplicitEH(
Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks) {
replaceTerminatePadWithCleanup(F);
// Determine which blocks are reachable from which funclet entries.
colorFunclets(F, EntryBlocks);
if (!DisableDemotion) {
demotePHIsOnFunclets(F);
demoteUsesBetweenFunclets(F);
demoteArgumentUses(F);
}
cloneCommonBlocks(F, EntryBlocks);
resolveFuncletAncestry(F, EntryBlocks);
if (!DisableCleanups) {
removeImplausibleTerminators(F);
cleanupPreparedFunclets(F);
}
verifyPreparedFunclets(F);
BlockColors.clear();
FuncletBlocks.clear();
FuncletChildren.clear();
FuncletParents.clear();
EstrangedBlocks.clear();
FuncletCloningRequired = false;
return true;
}
// TODO: Share loads when one use dominates another, or when a catchpad exit
// dominates uses (needs dominators).
AllocaInst *WinEHPrepare::insertPHILoads(PHINode *PN, Function &F) {
BasicBlock *PHIBlock = PN->getParent();
AllocaInst *SpillSlot = nullptr;
if (isa<CleanupPadInst>(PHIBlock->getFirstNonPHI())) {
// Insert a load in place of the PHI and replace all uses.
SpillSlot = new AllocaInst(PN->getType(), nullptr,
Twine(PN->getName(), ".wineh.spillslot"),
&F.getEntryBlock().front());
Value *V = new LoadInst(SpillSlot, Twine(PN->getName(), ".wineh.reload"),
&*PHIBlock->getFirstInsertionPt());
PN->replaceAllUsesWith(V);
return SpillSlot;
}
DenseMap<BasicBlock *, Value *> Loads;
for (Value::use_iterator UI = PN->use_begin(), UE = PN->use_end();
UI != UE;) {
Use &U = *UI++;
auto *UsingInst = cast<Instruction>(U.getUser());
BasicBlock *UsingBB = UsingInst->getParent();
if (UsingBB->isEHPad()) {
// Use is on an EH pad phi. Leave it alone; we'll insert loads and
// stores for it separately.
assert(isa<PHINode>(UsingInst));
continue;
}
replaceUseWithLoad(PN, U, SpillSlot, Loads, F);
}
return SpillSlot;
}
// TODO: improve store placement. Inserting at def is probably good, but need
// to be careful not to introduce interfering stores (needs liveness analysis).
// TODO: identify related phi nodes that can share spill slots, and share them
// (also needs liveness).
void WinEHPrepare::insertPHIStores(PHINode *OriginalPHI,
AllocaInst *SpillSlot) {
// Use a worklist of (Block, Value) pairs -- the given Value needs to be
// stored to the spill slot by the end of the given Block.
SmallVector<std::pair<BasicBlock *, Value *>, 4> Worklist;
Worklist.push_back({OriginalPHI->getParent(), OriginalPHI});
while (!Worklist.empty()) {
BasicBlock *EHBlock;
Value *InVal;
std::tie(EHBlock, InVal) = Worklist.pop_back_val();
PHINode *PN = dyn_cast<PHINode>(InVal);
if (PN && PN->getParent() == EHBlock) {
// The value is defined by another PHI we need to remove, with no room to
// insert a store after the PHI, so each predecessor needs to store its
// incoming value.
for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i) {
Value *PredVal = PN->getIncomingValue(i);
// Undef can safely be skipped.
if (isa<UndefValue>(PredVal))
continue;
insertPHIStore(PN->getIncomingBlock(i), PredVal, SpillSlot, Worklist);
}
} else {
// We need to store InVal, which dominates EHBlock, but can't put a store
// in EHBlock, so need to put stores in each predecessor.
for (BasicBlock *PredBlock : predecessors(EHBlock)) {
insertPHIStore(PredBlock, InVal, SpillSlot, Worklist);
}
}
}
}
void WinEHPrepare::insertPHIStore(
BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist) {
if (PredBlock->isEHPad() &&
!isa<CleanupPadInst>(PredBlock->getFirstNonPHI())) {
// Pred is unsplittable, so we need to queue it on the worklist.
Worklist.push_back({PredBlock, PredVal});
return;
}
// Otherwise, insert the store at the end of the basic block.
new StoreInst(PredVal, SpillSlot, PredBlock->getTerminator());
}
// The SetVector == operator uses the std::vector == operator, so it doesn't
// actually tell us whether or not the two sets contain the same colors. This
// function does that.
// FIXME: Would it be better to add a isSetEquivalent() method to SetVector?
static bool isBlockColorSetEquivalent(SetVector<BasicBlock *> &SetA,
SetVector<BasicBlock *> &SetB) {
if (SetA.size() != SetB.size())
return false;
for (auto *Color : SetA)
if (!SetB.count(Color))
return false;
return true;
}
// TODO: Share loads for same-funclet uses (requires dominators if funclets
// aren't properly nested).
void WinEHPrepare::demoteNonlocalUses(Value *V,
SetVector<BasicBlock *> &ColorsForBB,
Function &F) {
// Tokens can only be used non-locally due to control flow involving
// unreachable edges. Don't try to demote the token usage, we'll simply
// delete the cloned user later.
if (isa<CatchPadInst>(V) || isa<CleanupPadInst>(V))
return;
DenseMap<BasicBlock *, Value *> Loads;
AllocaInst *SpillSlot = nullptr;
for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;) {
Use &U = *UI++;
auto *UsingInst = cast<Instruction>(U.getUser());
BasicBlock *UsingBB = UsingInst->getParent();
// Is the Use inside a block which is colored the same as the Def?
// If so, we don't need to escape the Def because we will clone
// ourselves our own private copy.
SetVector<BasicBlock *> &ColorsForUsingBB = BlockColors[UsingBB];
if (isBlockColorSetEquivalent(ColorsForUsingBB, ColorsForBB))
continue;
replaceUseWithLoad(V, U, SpillSlot, Loads, F);
}
if (SpillSlot) {
// Insert stores of the computed value into the stack slot.
// We have to be careful if I is an invoke instruction,
// because we can't insert the store AFTER the terminator instruction.
BasicBlock::iterator InsertPt;
if (isa<Argument>(V)) {
InsertPt = F.getEntryBlock().getTerminator()->getIterator();
} else if (isa<TerminatorInst>(V)) {
auto *II = cast<InvokeInst>(V);
// We cannot demote invoke instructions to the stack if their normal
// edge is critical. Therefore, split the critical edge and create a
// basic block into which the store can be inserted.
if (!II->getNormalDest()->getSinglePredecessor()) {
unsigned SuccNum =
GetSuccessorNumber(II->getParent(), II->getNormalDest());
assert(isCriticalEdge(II, SuccNum) && "Expected a critical edge!");
BasicBlock *NewBlock = SplitCriticalEdge(II, SuccNum);
assert(NewBlock && "Unable to split critical edge.");
// Update the color mapping for the newly split edge.
SetVector<BasicBlock *> &ColorsForUsingBB = BlockColors[II->getParent()];
BlockColors[NewBlock] = ColorsForUsingBB;
for (BasicBlock *FuncletPad : ColorsForUsingBB)
FuncletBlocks[FuncletPad].insert(NewBlock);
}
InsertPt = II->getNormalDest()->getFirstInsertionPt();
} else {
InsertPt = cast<Instruction>(V)->getIterator();
++InsertPt;
// Don't insert before PHI nodes or EH pad instrs.
for (; isa<PHINode>(InsertPt) || InsertPt->isEHPad(); ++InsertPt)
;
}
new StoreInst(V, SpillSlot, &*InsertPt);
}
}
void WinEHPrepare::replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
DenseMap<BasicBlock *, Value *> &Loads,
Function &F) {
// Lazilly create the spill slot.
if (!SpillSlot)
SpillSlot = new AllocaInst(V->getType(), nullptr,
Twine(V->getName(), ".wineh.spillslot"),
&F.getEntryBlock().front());
auto *UsingInst = cast<Instruction>(U.getUser());
if (auto *UsingPHI = dyn_cast<PHINode>(UsingInst)) {
// If this is a PHI node, we can't insert a load of the value before
// the use. Instead insert the load in the predecessor block
// corresponding to the incoming value.
//
// Note that if there are multiple edges from a basic block to this
// PHI node that we cannot have multiple loads. The problem is that
// the resulting PHI node will have multiple values (from each load)
// coming in from the same block, which is illegal SSA form.
// For this reason, we keep track of and reuse loads we insert.
BasicBlock *IncomingBlock = UsingPHI->getIncomingBlock(U);
if (auto *CatchRet =
dyn_cast<CatchReturnInst>(IncomingBlock->getTerminator())) {
// Putting a load above a catchret and use on the phi would still leave
// a cross-funclet def/use. We need to split the edge, change the
// catchret to target the new block, and put the load there.
BasicBlock *PHIBlock = UsingInst->getParent();
BasicBlock *NewBlock = SplitEdge(IncomingBlock, PHIBlock);
// SplitEdge gives us:
// IncomingBlock:
// ...
// br label %NewBlock
// NewBlock:
// catchret label %PHIBlock
// But we need:
// IncomingBlock:
// ...
// catchret label %NewBlock
// NewBlock:
// br label %PHIBlock
// So move the terminators to each others' blocks and swap their
// successors.
BranchInst *Goto = cast<BranchInst>(IncomingBlock->getTerminator());
Goto->removeFromParent();
CatchRet->removeFromParent();
IncomingBlock->getInstList().push_back(CatchRet);
NewBlock->getInstList().push_back(Goto);
Goto->setSuccessor(0, PHIBlock);
CatchRet->setSuccessor(NewBlock);
// Update the color mapping for the newly split edge.
SetVector<BasicBlock *> &ColorsForPHIBlock = BlockColors[PHIBlock];
BlockColors[NewBlock] = ColorsForPHIBlock;
for (BasicBlock *FuncletPad : ColorsForPHIBlock)
FuncletBlocks[FuncletPad].insert(NewBlock);
// Treat the new block as incoming for load insertion.
IncomingBlock = NewBlock;
}
Value *&Load = Loads[IncomingBlock];
// Insert the load into the predecessor block
if (!Load)
Load = new LoadInst(SpillSlot, Twine(V->getName(), ".wineh.reload"),
/*Volatile=*/false, IncomingBlock->getTerminator());
U.set(Load);
} else {
// Reload right before the old use.
auto *Load = new LoadInst(SpillSlot, Twine(V->getName(), ".wineh.reload"),
/*Volatile=*/false, UsingInst);
U.set(Load);
}
}
void WinEHFuncInfo::addIPToStateRange(const BasicBlock *PadBB,
MCSymbol *InvokeBegin,
MCSymbol *InvokeEnd) {
assert(PadBB->isEHPad() && EHPadStateMap.count(PadBB->getFirstNonPHI()) &&
"should get EH pad BB with precomputed state");
InvokeToStateMap[InvokeBegin] =
std::make_pair(EHPadStateMap[PadBB->getFirstNonPHI()], InvokeEnd);
}
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