//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/Passes.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/EHPersonalities.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
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;
+ if (auto *AI =
+ dyn_cast<AllocaInst>(CPI->getArgOperand(2)->stripPointerCasts()))
+ HT.CatchObj.Alloca = AI;
else
- HT.CatchObj.Alloca = cast<AllocaInst>(CPI->getArgOperand(2));
+ HT.CatchObj.Alloca = nullptr;
TBME.HandlerArray.push_back(HT);
}
FuncInfo.TryBlockMap.push_back(TBME);
if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI))
if (InnerCatchSwitch->getUnwindDest() == CatchSwitch->getUnwindDest())
calculateCXXStateNumbers(FuncInfo, UserI, CatchLow);
- if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI))
- if (getCleanupRetUnwindDest(InnerCleanupPad) ==
- CatchSwitch->getUnwindDest())
+ if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI)) {
+ BasicBlock *UnwindDest = getCleanupRetUnwindDest(InnerCleanupPad);
+ // If a nested cleanup pad reports a null unwind destination and the
+ // enclosing catch pad doesn't it must be post-dominated by an
+ // unreachable instruction.
+ if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
calculateCXXStateNumbers(FuncInfo, UserI, CatchLow);
+ }
}
}
int CatchHigh = FuncInfo.getLastStateNumber();
if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI))
if (InnerCatchSwitch->getUnwindDest() == CatchSwitch->getUnwindDest())
calculateSEHStateNumbers(FuncInfo, UserI, ParentState);
- if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI))
- if (getCleanupRetUnwindDest(InnerCleanupPad) ==
- CatchSwitch->getUnwindDest())
+ if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI)) {
+ BasicBlock *UnwindDest = getCleanupRetUnwindDest(InnerCleanupPad);
+ // If a nested cleanup pad reports a null unwind destination and the
+ // enclosing catch pad doesn't it must be post-dominated by an
+ // unreachable instruction.
+ if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
calculateSEHStateNumbers(FuncInfo, UserI, ParentState);
+ }
}
} else {
auto *CleanupPad = cast<CleanupPadInst>(FirstNonPHI);
calculateStateNumbersForInvokes(Fn, FuncInfo);
}
-static int addClrEHHandler(WinEHFuncInfo &FuncInfo, int ParentState,
- ClrHandlerType HandlerType, uint32_t TypeToken,
- const BasicBlock *Handler) {
+static int addClrEHHandler(WinEHFuncInfo &FuncInfo, int HandlerParentState,
+ int TryParentState, ClrHandlerType HandlerType,
+ uint32_t TypeToken, const BasicBlock *Handler) {
ClrEHUnwindMapEntry Entry;
- Entry.Parent = ParentState;
+ Entry.HandlerParentState = HandlerParentState;
+ Entry.TryParentState = TryParentState;
Entry.Handler = Handler;
Entry.HandlerType = HandlerType;
Entry.TypeToken = TypeToken;
if (!FuncInfo.EHPadStateMap.empty())
return;
+ // This numbering assigns one state number to each catchpad and cleanuppad.
+ // It also computes two tree-like relations over states:
+ // 1) Each state has a "HandlerParentState", which is the state of the next
+ // outer handler enclosing this state's handler (same as nearest ancestor
+ // per the ParentPad linkage on EH pads, but skipping over catchswitches).
+ // 2) Each state has a "TryParentState", which:
+ // a) for a catchpad that's not the last handler on its catchswitch, is
+ // the state of the next catchpad on that catchswitch
+ // b) for all other pads, is the state of the pad whose try region is the
+ // next outer try region enclosing this state's try region. The "try
+ // regions are not present as such in the IR, but will be inferred
+ // based on the placement of invokes and pads which reach each other
+ // by exceptional exits
+ // Catchswitches do not get their own states, but each gets mapped to the
+ // state of its first catchpad.
+
+ // Step one: walk down from outermost to innermost funclets, assigning each
+ // catchpad and cleanuppad a state number. Add an entry to the
+ // ClrEHUnwindMap for each state, recording its HandlerParentState and
+ // handler attributes. Record the TryParentState as well for each catchpad
+ // that's not the last on its catchswitch, but initialize all other entries'
+ // TryParentStates to a sentinel -1 value that the next pass will update.
+
+ // Seed a worklist with pads that have no parent.
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 (!isTopLevelPadForMSVC(FirstNonPHI))
+ const Value *ParentPad;
+ if (const auto *CPI = dyn_cast<CleanupPadInst>(FirstNonPHI))
+ ParentPad = CPI->getParentPad();
+ else if (const auto *CSI = dyn_cast<CatchSwitchInst>(FirstNonPHI))
+ ParentPad = CSI->getParentPad();
+ else
continue;
- // queue this with sentinel parent state -1 to mean unwind to caller.
- Worklist.emplace_back(FirstNonPHI, -1);
+ if (isa<ConstantTokenNone>(ParentPad))
+ Worklist.emplace_back(FirstNonPHI, -1);
}
+ // Use the worklist to visit all pads, from outer to inner. Record
+ // HandlerParentState for all pads. Record TryParentState only for catchpads
+ // that aren't the last on their catchswitch (setting all other entries'
+ // TryParentStates to an initial value of -1). This loop is also responsible
+ // for setting the EHPadStateMap entry for all catchpads, cleanuppads, and
+ // catchswitches.
while (!Worklist.empty()) {
const Instruction *Pad;
- int ParentState;
- std::tie(Pad, ParentState) = Worklist.pop_back_val();
-
- Value *ParentPad;
- int PredState;
- 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(Cleanup))
- continue;
- // CoreCLR personality uses arity to distinguish faults from finallies.
- const BasicBlock *PadBlock = Cleanup->getParent();
+ int HandlerParentState;
+ std::tie(Pad, HandlerParentState) = Worklist.pop_back_val();
+
+ if (const auto *Cleanup = dyn_cast<CleanupPadInst>(Pad)) {
+ // Create the entry for this cleanup with the appropriate handler
+ // properties. Finaly and fault handlers are distinguished by arity.
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
- ParentPad = Cleanup->getParentPad();
- PredState = NewState;
- } else if (const auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Pad)) {
- SmallVector<const CatchPadInst *, 1> Handlers;
- for (const BasicBlock *CatchPadBB : CatchSwitch->handlers()) {
- const auto *Catch = cast<CatchPadInst>(CatchPadBB->getFirstNonPHI());
- Handlers.push_back(Catch);
- }
- FuncInfo.EHPadStateMap[CatchSwitch] = ParentState;
- int NewState = ParentState;
- for (auto HandlerI = Handlers.rbegin(), HandlerE = Handlers.rend();
- HandlerI != HandlerE; ++HandlerI) {
- const CatchPadInst *Catch = *HandlerI;
- const BasicBlock *PadBlock = Catch->getParent();
+ (Cleanup->getNumArgOperands() ? ClrHandlerType::Fault
+ : ClrHandlerType::Finally);
+ int CleanupState = addClrEHHandler(FuncInfo, HandlerParentState, -1,
+ HandlerType, 0, Pad->getParent());
+ // Queue any child EH pads on the worklist.
+ for (const User *U : Cleanup->users())
+ if (const auto *I = dyn_cast<Instruction>(U))
+ if (I->isEHPad())
+ Worklist.emplace_back(I, CleanupState);
+ // Remember this pad's state.
+ FuncInfo.EHPadStateMap[Cleanup] = CleanupState;
+ } else {
+ // Walk the handlers of this catchswitch in reverse order since all but
+ // the last need to set the following one as its TryParentState.
+ const auto *CatchSwitch = cast<CatchSwitchInst>(Pad);
+ int CatchState = -1, FollowerState = -1;
+ SmallVector<const BasicBlock *, 4> CatchBlocks(CatchSwitch->handlers());
+ for (auto CBI = CatchBlocks.rbegin(), CBE = CatchBlocks.rend();
+ CBI != CBE; ++CBI, FollowerState = CatchState) {
+ const BasicBlock *CatchBlock = *CBI;
+ // Create the entry for this catch with the appropriate handler
+ // properties.
+ const auto *Catch = cast<CatchPadInst>(CatchBlock->getFirstNonPHI());
uint32_t TypeToken = static_cast<uint32_t>(
cast<ConstantInt>(Catch->getArgOperand(0))->getZExtValue());
- NewState = addClrEHHandler(FuncInfo, NewState, ClrHandlerType::Catch,
- TypeToken, PadBlock);
- FuncInfo.EHPadStateMap[Catch] = NewState;
+ CatchState =
+ addClrEHHandler(FuncInfo, HandlerParentState, FollowerState,
+ ClrHandlerType::Catch, TypeToken, CatchBlock);
+ // Queue any child EH pads on the worklist.
+ for (const User *U : Catch->users())
+ if (const auto *I = dyn_cast<Instruction>(U))
+ if (I->isEHPad())
+ Worklist.emplace_back(I, CatchState);
+ // Remember this catch's state.
+ FuncInfo.EHPadStateMap[Catch] = CatchState;
}
- for (const auto *CatchPad : Handlers) {
- for (const User *U : CatchPad->users()) {
- const auto *UserI = cast<Instruction>(U);
- if (UserI->isEHPad())
- Worklist.emplace_back(UserI, ParentState);
+ // Associate the catchswitch with the state of its first catch.
+ assert(CatchSwitch->getNumHandlers());
+ FuncInfo.EHPadStateMap[CatchSwitch] = CatchState;
+ }
+ }
+
+ // Step two: record the TryParentState of each state. For cleanuppads that
+ // don't have cleanuprets, we may need to infer this from their child pads,
+ // so visit pads in descendant-most to ancestor-most order.
+ for (auto Entry = FuncInfo.ClrEHUnwindMap.rbegin(),
+ End = FuncInfo.ClrEHUnwindMap.rend();
+ Entry != End; ++Entry) {
+ const Instruction *Pad =
+ Entry->Handler.get<const BasicBlock *>()->getFirstNonPHI();
+ // For most pads, the TryParentState is the state associated with the
+ // unwind dest of exceptional exits from it.
+ const BasicBlock *UnwindDest;
+ if (const auto *Catch = dyn_cast<CatchPadInst>(Pad)) {
+ // If a catch is not the last in its catchswitch, its TryParentState is
+ // the state associated with the next catch in the switch, even though
+ // that's not the unwind dest of exceptions escaping the catch. Those
+ // cases were already assigned a TryParentState in the first pass, so
+ // skip them.
+ if (Entry->TryParentState != -1)
+ continue;
+ // Otherwise, get the unwind dest from the catchswitch.
+ UnwindDest = Catch->getCatchSwitch()->getUnwindDest();
+ } else {
+ const auto *Cleanup = cast<CleanupPadInst>(Pad);
+ UnwindDest = nullptr;
+ for (const User *U : Cleanup->users()) {
+ if (auto *CleanupRet = dyn_cast<CleanupReturnInst>(U)) {
+ // Common and unambiguous case -- cleanupret indicates cleanup's
+ // unwind dest.
+ UnwindDest = CleanupRet->getUnwindDest();
+ break;
}
+
+ // Get an unwind dest for the user
+ const BasicBlock *UserUnwindDest = nullptr;
+ if (auto *Invoke = dyn_cast<InvokeInst>(U)) {
+ UserUnwindDest = Invoke->getUnwindDest();
+ } else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(U)) {
+ UserUnwindDest = CatchSwitch->getUnwindDest();
+ } else if (auto *ChildCleanup = dyn_cast<CleanupPadInst>(U)) {
+ int UserState = FuncInfo.EHPadStateMap[ChildCleanup];
+ int UserUnwindState =
+ FuncInfo.ClrEHUnwindMap[UserState].TryParentState;
+ if (UserUnwindState != -1)
+ UserUnwindDest = FuncInfo.ClrEHUnwindMap[UserUnwindState]
+ .Handler.get<const BasicBlock *>();
+ }
+
+ // Not having an unwind dest for this user might indicate that it
+ // doesn't unwind, so can't be taken as proof that the cleanup itself
+ // may unwind to caller (see e.g. SimplifyUnreachable and
+ // RemoveUnwindEdge).
+ if (!UserUnwindDest)
+ continue;
+
+ // Now we have an unwind dest for the user, but we need to see if it
+ // unwinds all the way out of the cleanup or if it stays within it.
+ const Instruction *UserUnwindPad = UserUnwindDest->getFirstNonPHI();
+ const Value *UserUnwindParent;
+ if (auto *CSI = dyn_cast<CatchSwitchInst>(UserUnwindPad))
+ UserUnwindParent = CSI->getParentPad();
+ else
+ UserUnwindParent =
+ cast<CleanupPadInst>(UserUnwindPad)->getParentPad();
+
+ // The unwind stays within the cleanup iff it targets a child of the
+ // cleanup.
+ if (UserUnwindParent == Cleanup)
+ continue;
+
+ // This unwind exits the cleanup, so its dest is the cleanup's dest.
+ UnwindDest = UserUnwindDest;
+ break;
}
- PredState = NewState;
- ParentPad = CatchSwitch->getParentPad();
- } else {
- llvm_unreachable("Unexpected EH pad");
}
- // Queue all predecessors with the given state
- for (const BasicBlock *Pred : predecessors(Pad->getParent())) {
- if ((Pred = getEHPadFromPredecessor(Pred, ParentPad)))
- Worklist.emplace_back(Pred->getFirstNonPHI(), PredState);
+ // Record the state of the unwind dest as the TryParentState.
+ int UnwindDestState;
+
+ // If UnwindDest is null at this point, either the pad in question can
+ // be exited by unwind to caller, or it cannot be exited by unwind. In
+ // either case, reporting such cases as unwinding to caller is correct.
+ // This can lead to EH tables that "look strange" -- if this pad's is in
+ // a parent funclet which has other children that do unwind to an enclosing
+ // pad, the try region for this pad will be missing the "duplicate" EH
+ // clause entries that you'd expect to see covering the whole parent. That
+ // should be benign, since the unwind never actually happens. If it were
+ // an issue, we could add a subsequent pass that pushes unwind dests down
+ // from parents that have them to children that appear to unwind to caller.
+ if (!UnwindDest) {
+ UnwindDestState = -1;
+ } else {
+ UnwindDestState = FuncInfo.EHPadStateMap[UnwindDest->getFirstNonPHI()];
}
+
+ Entry->TryParentState = UnwindDestState;
}
+ // Step three: transfer information from pads to invokes.
calculateStateNumbersForInvokes(Fn, FuncInfo);
}
}
}
-void llvm::calculateCatchReturnSuccessorColors(const Function *Fn,
- WinEHFuncInfo &FuncInfo) {
- for (const BasicBlock &BB : *Fn) {
- const auto *CatchRet = dyn_cast<CatchReturnInst>(BB.getTerminator());
- if (!CatchRet)
- continue;
- // A 'catchret' returns to the outer scope's color.
- Value *ParentPad = CatchRet->getParentPad();
- const BasicBlock *Color;
- if (isa<ConstantTokenNone>(ParentPad))
- Color = &Fn->getEntryBlock();
- else
- Color = cast<Instruction>(ParentPad)->getParent();
- // Record the catchret successor's funclet membership.
- FuncInfo.CatchRetSuccessorColorMap[CatchRet] = Color;
- }
-}
-
void WinEHPrepare::demotePHIsOnFunclets(Function &F) {
// Strip PHI nodes off of EH pads.
SmallVector<PHINode *, 16> PHINodes;
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!");
- }
+ assert((DisableDemotion || !(BB.isEHPad() && isa<PHINode>(BB.begin()))) &&
+ "EH Pad still has a PHI!");
}
}
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