| //===-- CodeGen/AsmPrinter/WinException.cpp - Dwarf Exception Impl ------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains support for writing Win64 exception info into asm files. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "WinException.h" |
| #include "llvm/ADT/Twine.h" |
| #include "llvm/BinaryFormat/COFF.h" |
| #include "llvm/BinaryFormat/Dwarf.h" |
| #include "llvm/CodeGen/AsmPrinter.h" |
| #include "llvm/CodeGen/MachineFrameInfo.h" |
| #include "llvm/CodeGen/MachineFunction.h" |
| #include "llvm/CodeGen/MachineModuleInfo.h" |
| #include "llvm/CodeGen/TargetFrameLowering.h" |
| #include "llvm/CodeGen/TargetLowering.h" |
| #include "llvm/CodeGen/TargetSubtargetInfo.h" |
| #include "llvm/CodeGen/WinEHFuncInfo.h" |
| #include "llvm/IR/DataLayout.h" |
| #include "llvm/IR/Mangler.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/MC/MCAsmInfo.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/MC/MCSection.h" |
| #include "llvm/MC/MCStreamer.h" |
| #include "llvm/MC/MCSymbol.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/FormattedStream.h" |
| #include "llvm/Target/TargetLoweringObjectFile.h" |
| #include "llvm/Target/TargetOptions.h" |
| using namespace llvm; |
| |
| WinException::WinException(AsmPrinter *A) : EHStreamer(A) { |
| // MSVC's EH tables are always composed of 32-bit words. All known 64-bit |
| // platforms use an imagerel32 relocation to refer to symbols. |
| useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64); |
| isAArch64 = Asm->TM.getTargetTriple().isAArch64(); |
| } |
| |
| WinException::~WinException() {} |
| |
| /// endModule - Emit all exception information that should come after the |
| /// content. |
| void WinException::endModule() { |
| auto &OS = *Asm->OutStreamer; |
| const Module *M = MMI->getModule(); |
| for (const Function &F : *M) |
| if (F.hasFnAttribute("safeseh")) |
| OS.EmitCOFFSafeSEH(Asm->getSymbol(&F)); |
| } |
| |
| void WinException::beginFunction(const MachineFunction *MF) { |
| shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false; |
| |
| // If any landing pads survive, we need an EH table. |
| bool hasLandingPads = !MF->getLandingPads().empty(); |
| bool hasEHFunclets = MF->hasEHFunclets(); |
| |
| const Function &F = MF->getFunction(); |
| |
| shouldEmitMoves = Asm->needsSEHMoves() && MF->hasWinCFI(); |
| |
| const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering(); |
| unsigned PerEncoding = TLOF.getPersonalityEncoding(); |
| |
| EHPersonality Per = EHPersonality::Unknown; |
| const Function *PerFn = nullptr; |
| if (F.hasPersonalityFn()) { |
| PerFn = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts()); |
| Per = classifyEHPersonality(PerFn); |
| } |
| |
| bool forceEmitPersonality = F.hasPersonalityFn() && |
| !isNoOpWithoutInvoke(Per) && |
| F.needsUnwindTableEntry(); |
| |
| shouldEmitPersonality = |
| forceEmitPersonality || ((hasLandingPads || hasEHFunclets) && |
| PerEncoding != dwarf::DW_EH_PE_omit && PerFn); |
| |
| unsigned LSDAEncoding = TLOF.getLSDAEncoding(); |
| shouldEmitLSDA = shouldEmitPersonality && |
| LSDAEncoding != dwarf::DW_EH_PE_omit; |
| |
| // If we're not using CFI, we don't want the CFI or the personality, but we |
| // might want EH tables if we had EH pads. |
| if (!Asm->MAI->usesWindowsCFI()) { |
| if (Per == EHPersonality::MSVC_X86SEH && !hasEHFunclets) { |
| // If this is 32-bit SEH and we don't have any funclets (really invokes), |
| // make sure we emit the parent offset label. Some unreferenced filter |
| // functions may still refer to it. |
| const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo(); |
| StringRef FLinkageName = |
| GlobalValue::dropLLVMManglingEscape(MF->getFunction().getName()); |
| emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName); |
| } |
| shouldEmitLSDA = hasEHFunclets; |
| shouldEmitPersonality = false; |
| return; |
| } |
| |
| beginFunclet(MF->front(), Asm->CurrentFnSym); |
| } |
| |
| void WinException::markFunctionEnd() { |
| if (isAArch64 && CurrentFuncletEntry && |
| (shouldEmitMoves || shouldEmitPersonality)) |
| Asm->OutStreamer->EmitWinCFIFuncletOrFuncEnd(); |
| } |
| |
| /// endFunction - Gather and emit post-function exception information. |
| /// |
| void WinException::endFunction(const MachineFunction *MF) { |
| if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA) |
| return; |
| |
| const Function &F = MF->getFunction(); |
| EHPersonality Per = EHPersonality::Unknown; |
| if (F.hasPersonalityFn()) |
| Per = classifyEHPersonality(F.getPersonalityFn()->stripPointerCasts()); |
| |
| // Get rid of any dead landing pads if we're not using funclets. In funclet |
| // schemes, the landing pad is not actually reachable. It only exists so |
| // that we can emit the right table data. |
| if (!isFuncletEHPersonality(Per)) { |
| MachineFunction *NonConstMF = const_cast<MachineFunction*>(MF); |
| NonConstMF->tidyLandingPads(); |
| } |
| |
| endFuncletImpl(); |
| |
| // endFunclet will emit the necessary .xdata tables for x64 SEH. |
| if (Per == EHPersonality::MSVC_Win64SEH && MF->hasEHFunclets()) |
| return; |
| |
| if (shouldEmitPersonality || shouldEmitLSDA) { |
| Asm->OutStreamer->PushSection(); |
| |
| // Just switch sections to the right xdata section. |
| MCSection *XData = Asm->OutStreamer->getAssociatedXDataSection( |
| Asm->OutStreamer->getCurrentSectionOnly()); |
| Asm->OutStreamer->SwitchSection(XData); |
| |
| // Emit the tables appropriate to the personality function in use. If we |
| // don't recognize the personality, assume it uses an Itanium-style LSDA. |
| if (Per == EHPersonality::MSVC_Win64SEH) |
| emitCSpecificHandlerTable(MF); |
| else if (Per == EHPersonality::MSVC_X86SEH) |
| emitExceptHandlerTable(MF); |
| else if (Per == EHPersonality::MSVC_CXX) |
| emitCXXFrameHandler3Table(MF); |
| else if (Per == EHPersonality::CoreCLR) |
| emitCLRExceptionTable(MF); |
| else |
| emitExceptionTable(); |
| |
| Asm->OutStreamer->PopSection(); |
| } |
| } |
| |
| /// Retrieve the MCSymbol for a GlobalValue or MachineBasicBlock. |
| static MCSymbol *getMCSymbolForMBB(AsmPrinter *Asm, |
| const MachineBasicBlock *MBB) { |
| if (!MBB) |
| return nullptr; |
| |
| assert(MBB->isEHFuncletEntry()); |
| |
| // Give catches and cleanups a name based off of their parent function and |
| // their funclet entry block's number. |
| const MachineFunction *MF = MBB->getParent(); |
| const Function &F = MF->getFunction(); |
| StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName()); |
| MCContext &Ctx = MF->getContext(); |
| StringRef HandlerPrefix = MBB->isCleanupFuncletEntry() ? "dtor" : "catch"; |
| return Ctx.getOrCreateSymbol("?" + HandlerPrefix + "$" + |
| Twine(MBB->getNumber()) + "@?0?" + |
| FuncLinkageName + "@4HA"); |
| } |
| |
| void WinException::beginFunclet(const MachineBasicBlock &MBB, |
| MCSymbol *Sym) { |
| CurrentFuncletEntry = &MBB; |
| |
| const Function &F = Asm->MF->getFunction(); |
| // If a symbol was not provided for the funclet, invent one. |
| if (!Sym) { |
| Sym = getMCSymbolForMBB(Asm, &MBB); |
| |
| // Describe our funclet symbol as a function with internal linkage. |
| Asm->OutStreamer->BeginCOFFSymbolDef(Sym); |
| Asm->OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC); |
| Asm->OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION |
| << COFF::SCT_COMPLEX_TYPE_SHIFT); |
| Asm->OutStreamer->EndCOFFSymbolDef(); |
| |
| // We want our funclet's entry point to be aligned such that no nops will be |
| // present after the label. |
| Asm->EmitAlignment(std::max(Asm->MF->getAlignment(), MBB.getAlignment()), |
| &F); |
| |
| // Now that we've emitted the alignment directive, point at our funclet. |
| Asm->OutStreamer->EmitLabel(Sym); |
| } |
| |
| // Mark 'Sym' as starting our funclet. |
| if (shouldEmitMoves || shouldEmitPersonality) { |
| CurrentFuncletTextSection = Asm->OutStreamer->getCurrentSectionOnly(); |
| Asm->OutStreamer->EmitWinCFIStartProc(Sym); |
| } |
| |
| if (shouldEmitPersonality) { |
| const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering(); |
| const Function *PerFn = nullptr; |
| |
| // Determine which personality routine we are using for this funclet. |
| if (F.hasPersonalityFn()) |
| PerFn = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts()); |
| const MCSymbol *PersHandlerSym = |
| TLOF.getCFIPersonalitySymbol(PerFn, Asm->TM, MMI); |
| |
| // Do not emit a .seh_handler directives for cleanup funclets. |
| // FIXME: This means cleanup funclets cannot handle exceptions. Given that |
| // Clang doesn't produce EH constructs inside cleanup funclets and LLVM's |
| // inliner doesn't allow inlining them, this isn't a major problem in |
| // practice. |
| if (!CurrentFuncletEntry->isCleanupFuncletEntry()) |
| Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true); |
| } |
| } |
| |
| void WinException::endFunclet() { |
| if (isAArch64 && CurrentFuncletEntry && |
| (shouldEmitMoves || shouldEmitPersonality)) { |
| Asm->OutStreamer->SwitchSection(CurrentFuncletTextSection); |
| Asm->OutStreamer->EmitWinCFIFuncletOrFuncEnd(); |
| } |
| endFuncletImpl(); |
| } |
| |
| void WinException::endFuncletImpl() { |
| // No funclet to process? Great, we have nothing to do. |
| if (!CurrentFuncletEntry) |
| return; |
| |
| const MachineFunction *MF = Asm->MF; |
| if (shouldEmitMoves || shouldEmitPersonality) { |
| const Function &F = MF->getFunction(); |
| EHPersonality Per = EHPersonality::Unknown; |
| if (F.hasPersonalityFn()) |
| Per = classifyEHPersonality(F.getPersonalityFn()->stripPointerCasts()); |
| |
| // On funclet exit, we emit a fake "function" end marker, so that the call |
| // to EmitWinEHHandlerData below can calculate the size of the funclet or |
| // function. |
| if (isAArch64) { |
| MCSection *XData = Asm->OutStreamer->getAssociatedXDataSection( |
| Asm->OutStreamer->getCurrentSectionOnly()); |
| Asm->OutStreamer->SwitchSection(XData); |
| } |
| |
| // Emit an UNWIND_INFO struct describing the prologue. |
| Asm->OutStreamer->EmitWinEHHandlerData(); |
| |
| if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality && |
| !CurrentFuncletEntry->isCleanupFuncletEntry()) { |
| // If this is a C++ catch funclet (or the parent function), |
| // emit a reference to the LSDA for the parent function. |
| StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName()); |
| MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol( |
| Twine("$cppxdata$", FuncLinkageName)); |
| Asm->OutStreamer->EmitValue(create32bitRef(FuncInfoXData), 4); |
| } else if (Per == EHPersonality::MSVC_Win64SEH && MF->hasEHFunclets() && |
| !CurrentFuncletEntry->isEHFuncletEntry()) { |
| // If this is the parent function in Win64 SEH, emit the LSDA immediately |
| // following .seh_handlerdata. |
| emitCSpecificHandlerTable(MF); |
| } |
| |
| // Switch back to the funclet start .text section now that we are done |
| // writing to .xdata, and emit an .seh_endproc directive to mark the end of |
| // the function. |
| Asm->OutStreamer->SwitchSection(CurrentFuncletTextSection); |
| Asm->OutStreamer->EmitWinCFIEndProc(); |
| } |
| |
| // Let's make sure we don't try to end the same funclet twice. |
| CurrentFuncletEntry = nullptr; |
| } |
| |
| const MCExpr *WinException::create32bitRef(const MCSymbol *Value) { |
| if (!Value) |
| return MCConstantExpr::create(0, Asm->OutContext); |
| return MCSymbolRefExpr::create(Value, useImageRel32 |
| ? MCSymbolRefExpr::VK_COFF_IMGREL32 |
| : MCSymbolRefExpr::VK_None, |
| Asm->OutContext); |
| } |
| |
| const MCExpr *WinException::create32bitRef(const GlobalValue *GV) { |
| if (!GV) |
| return MCConstantExpr::create(0, Asm->OutContext); |
| return create32bitRef(Asm->getSymbol(GV)); |
| } |
| |
| const MCExpr *WinException::getLabel(const MCSymbol *Label) { |
| if (isAArch64) |
| return MCSymbolRefExpr::create(Label, MCSymbolRefExpr::VK_COFF_IMGREL32, |
| Asm->OutContext); |
| return MCBinaryExpr::createAdd(create32bitRef(Label), |
| MCConstantExpr::create(1, Asm->OutContext), |
| Asm->OutContext); |
| } |
| |
| const MCExpr *WinException::getOffset(const MCSymbol *OffsetOf, |
| const MCSymbol *OffsetFrom) { |
| return MCBinaryExpr::createSub( |
| MCSymbolRefExpr::create(OffsetOf, Asm->OutContext), |
| MCSymbolRefExpr::create(OffsetFrom, Asm->OutContext), Asm->OutContext); |
| } |
| |
| const MCExpr *WinException::getOffsetPlusOne(const MCSymbol *OffsetOf, |
| const MCSymbol *OffsetFrom) { |
| return MCBinaryExpr::createAdd(getOffset(OffsetOf, OffsetFrom), |
| MCConstantExpr::create(1, Asm->OutContext), |
| Asm->OutContext); |
| } |
| |
| int WinException::getFrameIndexOffset(int FrameIndex, |
| const WinEHFuncInfo &FuncInfo) { |
| const TargetFrameLowering &TFI = *Asm->MF->getSubtarget().getFrameLowering(); |
| unsigned UnusedReg; |
| if (Asm->MAI->usesWindowsCFI()) { |
| int Offset = |
| TFI.getFrameIndexReferencePreferSP(*Asm->MF, FrameIndex, UnusedReg, |
| /*IgnoreSPUpdates*/ true); |
| assert(UnusedReg == |
| Asm->MF->getSubtarget() |
| .getTargetLowering() |
| ->getStackPointerRegisterToSaveRestore()); |
| return Offset; |
| } |
| |
| // For 32-bit, offsets should be relative to the end of the EH registration |
| // node. For 64-bit, it's relative to SP at the end of the prologue. |
| assert(FuncInfo.EHRegNodeEndOffset != INT_MAX); |
| int Offset = TFI.getFrameIndexReference(*Asm->MF, FrameIndex, UnusedReg); |
| Offset += FuncInfo.EHRegNodeEndOffset; |
| return Offset; |
| } |
| |
| namespace { |
| |
| /// Top-level state used to represent unwind to caller |
| const int NullState = -1; |
| |
| struct InvokeStateChange { |
| /// EH Label immediately after the last invoke in the previous state, or |
| /// nullptr if the previous state was the null state. |
| const MCSymbol *PreviousEndLabel; |
| |
| /// EH label immediately before the first invoke in the new state, or nullptr |
| /// if the new state is the null state. |
| const MCSymbol *NewStartLabel; |
| |
| /// State of the invoke following NewStartLabel, or NullState to indicate |
| /// the presence of calls which may unwind to caller. |
| int NewState; |
| }; |
| |
| /// Iterator that reports all the invoke state changes in a range of machine |
| /// basic blocks. Changes to the null state are reported whenever a call that |
| /// may unwind to caller is encountered. The MBB range is expected to be an |
| /// entire function or funclet, and the start and end of the range are treated |
| /// as being in the NullState even if there's not an unwind-to-caller call |
| /// before the first invoke or after the last one (i.e., the first state change |
| /// reported is the first change to something other than NullState, and a |
| /// change back to NullState is always reported at the end of iteration). |
| class InvokeStateChangeIterator { |
| InvokeStateChangeIterator(const WinEHFuncInfo &EHInfo, |
| MachineFunction::const_iterator MFI, |
| MachineFunction::const_iterator MFE, |
| MachineBasicBlock::const_iterator MBBI, |
| int BaseState) |
| : EHInfo(EHInfo), MFI(MFI), MFE(MFE), MBBI(MBBI), BaseState(BaseState) { |
| LastStateChange.PreviousEndLabel = nullptr; |
| LastStateChange.NewStartLabel = nullptr; |
| LastStateChange.NewState = BaseState; |
| scan(); |
| } |
| |
| public: |
| static iterator_range<InvokeStateChangeIterator> |
| range(const WinEHFuncInfo &EHInfo, MachineFunction::const_iterator Begin, |
| MachineFunction::const_iterator End, int BaseState = NullState) { |
| // Reject empty ranges to simplify bookkeeping by ensuring that we can get |
| // the end of the last block. |
| assert(Begin != End); |
| auto BlockBegin = Begin->begin(); |
| auto BlockEnd = std::prev(End)->end(); |
| return make_range( |
| InvokeStateChangeIterator(EHInfo, Begin, End, BlockBegin, BaseState), |
| InvokeStateChangeIterator(EHInfo, End, End, BlockEnd, BaseState)); |
| } |
| |
| // Iterator methods. |
| bool operator==(const InvokeStateChangeIterator &O) const { |
| assert(BaseState == O.BaseState); |
| // Must be visiting same block. |
| if (MFI != O.MFI) |
| return false; |
| // Must be visiting same isntr. |
| if (MBBI != O.MBBI) |
| return false; |
| // At end of block/instr iteration, we can still have two distinct states: |
| // one to report the final EndLabel, and another indicating the end of the |
| // state change iteration. Check for CurrentEndLabel equality to |
| // distinguish these. |
| return CurrentEndLabel == O.CurrentEndLabel; |
| } |
| |
| bool operator!=(const InvokeStateChangeIterator &O) const { |
| return !operator==(O); |
| } |
| InvokeStateChange &operator*() { return LastStateChange; } |
| InvokeStateChange *operator->() { return &LastStateChange; } |
| InvokeStateChangeIterator &operator++() { return scan(); } |
| |
| private: |
| InvokeStateChangeIterator &scan(); |
| |
| const WinEHFuncInfo &EHInfo; |
| const MCSymbol *CurrentEndLabel = nullptr; |
| MachineFunction::const_iterator MFI; |
| MachineFunction::const_iterator MFE; |
| MachineBasicBlock::const_iterator MBBI; |
| InvokeStateChange LastStateChange; |
| bool VisitingInvoke = false; |
| int BaseState; |
| }; |
| |
| } // end anonymous namespace |
| |
| InvokeStateChangeIterator &InvokeStateChangeIterator::scan() { |
| bool IsNewBlock = false; |
| for (; MFI != MFE; ++MFI, IsNewBlock = true) { |
| if (IsNewBlock) |
| MBBI = MFI->begin(); |
| for (auto MBBE = MFI->end(); MBBI != MBBE; ++MBBI) { |
| const MachineInstr &MI = *MBBI; |
| if (!VisitingInvoke && LastStateChange.NewState != BaseState && |
| MI.isCall() && !EHStreamer::callToNoUnwindFunction(&MI)) { |
| // Indicate a change of state to the null state. We don't have |
| // start/end EH labels handy but the caller won't expect them for |
| // null state regions. |
| LastStateChange.PreviousEndLabel = CurrentEndLabel; |
| LastStateChange.NewStartLabel = nullptr; |
| LastStateChange.NewState = BaseState; |
| CurrentEndLabel = nullptr; |
| // Don't re-visit this instr on the next scan |
| ++MBBI; |
| return *this; |
| } |
| |
| // All other state changes are at EH labels before/after invokes. |
| if (!MI.isEHLabel()) |
| continue; |
| MCSymbol *Label = MI.getOperand(0).getMCSymbol(); |
| if (Label == CurrentEndLabel) { |
| VisitingInvoke = false; |
| continue; |
| } |
| auto InvokeMapIter = EHInfo.LabelToStateMap.find(Label); |
| // Ignore EH labels that aren't the ones inserted before an invoke |
| if (InvokeMapIter == EHInfo.LabelToStateMap.end()) |
| continue; |
| auto &StateAndEnd = InvokeMapIter->second; |
| int NewState = StateAndEnd.first; |
| // Keep track of the fact that we're between EH start/end labels so |
| // we know not to treat the inoke we'll see as unwinding to caller. |
| VisitingInvoke = true; |
| if (NewState == LastStateChange.NewState) { |
| // The state isn't actually changing here. Record the new end and |
| // keep going. |
| CurrentEndLabel = StateAndEnd.second; |
| continue; |
| } |
| // Found a state change to report |
| LastStateChange.PreviousEndLabel = CurrentEndLabel; |
| LastStateChange.NewStartLabel = Label; |
| LastStateChange.NewState = NewState; |
| // Start keeping track of the new current end |
| CurrentEndLabel = StateAndEnd.second; |
| // Don't re-visit this instr on the next scan |
| ++MBBI; |
| return *this; |
| } |
| } |
| // Iteration hit the end of the block range. |
| if (LastStateChange.NewState != BaseState) { |
| // Report the end of the last new state |
| LastStateChange.PreviousEndLabel = CurrentEndLabel; |
| LastStateChange.NewStartLabel = nullptr; |
| LastStateChange.NewState = BaseState; |
| // Leave CurrentEndLabel non-null to distinguish this state from end. |
| assert(CurrentEndLabel != nullptr); |
| return *this; |
| } |
| // We've reported all state changes and hit the end state. |
| CurrentEndLabel = nullptr; |
| return *this; |
| } |
| |
| /// Emit the language-specific data that __C_specific_handler expects. This |
| /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning |
| /// up after faults with __try, __except, and __finally. The typeinfo values |
| /// are not really RTTI data, but pointers to filter functions that return an |
| /// integer (1, 0, or -1) indicating how to handle the exception. For __finally |
| /// blocks and other cleanups, the landing pad label is zero, and the filter |
| /// function is actually a cleanup handler with the same prototype. A catch-all |
| /// entry is modeled with a null filter function field and a non-zero landing |
| /// pad label. |
| /// |
| /// Possible filter function return values: |
| /// EXCEPTION_EXECUTE_HANDLER (1): |
| /// Jump to the landing pad label after cleanups. |
| /// EXCEPTION_CONTINUE_SEARCH (0): |
| /// Continue searching this table or continue unwinding. |
| /// EXCEPTION_CONTINUE_EXECUTION (-1): |
| /// Resume execution at the trapping PC. |
| /// |
| /// Inferred table structure: |
| /// struct Table { |
| /// int NumEntries; |
| /// struct Entry { |
| /// imagerel32 LabelStart; |
| /// imagerel32 LabelEnd; |
| /// imagerel32 FilterOrFinally; // One means catch-all. |
| /// imagerel32 LabelLPad; // Zero means __finally. |
| /// } Entries[NumEntries]; |
| /// }; |
| void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) { |
| auto &OS = *Asm->OutStreamer; |
| MCContext &Ctx = Asm->OutContext; |
| const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo(); |
| |
| bool VerboseAsm = OS.isVerboseAsm(); |
| auto AddComment = [&](const Twine &Comment) { |
| if (VerboseAsm) |
| OS.AddComment(Comment); |
| }; |
| |
| if (!isAArch64) { |
| // Emit a label assignment with the SEH frame offset so we can use it for |
| // llvm.eh.recoverfp. |
| StringRef FLinkageName = |
| GlobalValue::dropLLVMManglingEscape(MF->getFunction().getName()); |
| MCSymbol *ParentFrameOffset = |
| Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName); |
| const MCExpr *MCOffset = |
| MCConstantExpr::create(FuncInfo.SEHSetFrameOffset, Ctx); |
| Asm->OutStreamer->EmitAssignment(ParentFrameOffset, MCOffset); |
| } |
| |
| // Use the assembler to compute the number of table entries through label |
| // difference and division. |
| MCSymbol *TableBegin = |
| Ctx.createTempSymbol("lsda_begin", /*AlwaysAddSuffix=*/true); |
| MCSymbol *TableEnd = |
| Ctx.createTempSymbol("lsda_end", /*AlwaysAddSuffix=*/true); |
| const MCExpr *LabelDiff = getOffset(TableEnd, TableBegin); |
| const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx); |
| const MCExpr *EntryCount = MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx); |
| AddComment("Number of call sites"); |
| OS.EmitValue(EntryCount, 4); |
| |
| OS.EmitLabel(TableBegin); |
| |
| // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only |
| // models exceptions from invokes. LLVM also allows arbitrary reordering of |
| // the code, so our tables end up looking a bit different. Rather than |
| // trying to match MSVC's tables exactly, we emit a denormalized table. For |
| // each range of invokes in the same state, we emit table entries for all |
| // the actions that would be taken in that state. This means our tables are |
| // slightly bigger, which is OK. |
| const MCSymbol *LastStartLabel = nullptr; |
| int LastEHState = -1; |
| // Break out before we enter into a finally funclet. |
| // FIXME: We need to emit separate EH tables for cleanups. |
| MachineFunction::const_iterator End = MF->end(); |
| MachineFunction::const_iterator Stop = std::next(MF->begin()); |
| while (Stop != End && !Stop->isEHFuncletEntry()) |
| ++Stop; |
| for (const auto &StateChange : |
| InvokeStateChangeIterator::range(FuncInfo, MF->begin(), Stop)) { |
| // Emit all the actions for the state we just transitioned out of |
| // if it was not the null state |
| if (LastEHState != -1) |
| emitSEHActionsForRange(FuncInfo, LastStartLabel, |
| StateChange.PreviousEndLabel, LastEHState); |
| LastStartLabel = StateChange.NewStartLabel; |
| LastEHState = StateChange.NewState; |
| } |
| |
| OS.EmitLabel(TableEnd); |
| } |
| |
| void WinException::emitSEHActionsForRange(const WinEHFuncInfo &FuncInfo, |
| const MCSymbol *BeginLabel, |
| const MCSymbol *EndLabel, int State) { |
| auto &OS = *Asm->OutStreamer; |
| MCContext &Ctx = Asm->OutContext; |
| bool VerboseAsm = OS.isVerboseAsm(); |
| auto AddComment = [&](const Twine &Comment) { |
| if (VerboseAsm) |
| OS.AddComment(Comment); |
| }; |
| |
| assert(BeginLabel && EndLabel); |
| while (State != -1) { |
| const SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State]; |
| const MCExpr *FilterOrFinally; |
| const MCExpr *ExceptOrNull; |
| auto *Handler = UME.Handler.get<MachineBasicBlock *>(); |
| if (UME.IsFinally) { |
| FilterOrFinally = create32bitRef(getMCSymbolForMBB(Asm, Handler)); |
| ExceptOrNull = MCConstantExpr::create(0, Ctx); |
| } else { |
| // For an except, the filter can be 1 (catch-all) or a function |
| // label. |
| FilterOrFinally = UME.Filter ? create32bitRef(UME.Filter) |
| : MCConstantExpr::create(1, Ctx); |
| ExceptOrNull = create32bitRef(Handler->getSymbol()); |
| } |
| |
| AddComment("LabelStart"); |
| OS.EmitValue(getLabel(BeginLabel), 4); |
| AddComment("LabelEnd"); |
| OS.EmitValue(getLabel(EndLabel), 4); |
| AddComment(UME.IsFinally ? "FinallyFunclet" : UME.Filter ? "FilterFunction" |
| : "CatchAll"); |
| OS.EmitValue(FilterOrFinally, 4); |
| AddComment(UME.IsFinally ? "Null" : "ExceptionHandler"); |
| OS.EmitValue(ExceptOrNull, 4); |
| |
| assert(UME.ToState < State && "states should decrease"); |
| State = UME.ToState; |
| } |
| } |
| |
| void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) { |
| const Function &F = MF->getFunction(); |
| auto &OS = *Asm->OutStreamer; |
| const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo(); |
| |
| StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName()); |
| |
| SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable; |
| MCSymbol *FuncInfoXData = nullptr; |
| if (shouldEmitPersonality) { |
| // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from |
| // IPs to state numbers. |
| FuncInfoXData = |
| Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName)); |
| computeIP2StateTable(MF, FuncInfo, IPToStateTable); |
| } else { |
| FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName); |
| } |
| |
| int UnwindHelpOffset = 0; |
| if (Asm->MAI->usesWindowsCFI()) |
| UnwindHelpOffset = |
| getFrameIndexOffset(FuncInfo.UnwindHelpFrameIdx, FuncInfo); |
| |
| MCSymbol *UnwindMapXData = nullptr; |
| MCSymbol *TryBlockMapXData = nullptr; |
| MCSymbol *IPToStateXData = nullptr; |
| if (!FuncInfo.CxxUnwindMap.empty()) |
| UnwindMapXData = Asm->OutContext.getOrCreateSymbol( |
| Twine("$stateUnwindMap$", FuncLinkageName)); |
| if (!FuncInfo.TryBlockMap.empty()) |
| TryBlockMapXData = |
| Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName)); |
| if (!IPToStateTable.empty()) |
| IPToStateXData = |
| Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName)); |
| |
| bool VerboseAsm = OS.isVerboseAsm(); |
| auto AddComment = [&](const Twine &Comment) { |
| if (VerboseAsm) |
| OS.AddComment(Comment); |
| }; |
| |
| // FuncInfo { |
| // uint32_t MagicNumber |
| // int32_t MaxState; |
| // UnwindMapEntry *UnwindMap; |
| // uint32_t NumTryBlocks; |
| // TryBlockMapEntry *TryBlockMap; |
| // uint32_t IPMapEntries; // always 0 for x86 |
| // IPToStateMapEntry *IPToStateMap; // always 0 for x86 |
| // uint32_t UnwindHelp; // non-x86 only |
| // ESTypeList *ESTypeList; |
| // int32_t EHFlags; |
| // } |
| // EHFlags & 1 -> Synchronous exceptions only, no async exceptions. |
| // EHFlags & 2 -> ??? |
| // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue. |
| OS.EmitValueToAlignment(4); |
| OS.EmitLabel(FuncInfoXData); |
| |
| AddComment("MagicNumber"); |
| OS.EmitIntValue(0x19930522, 4); |
| |
| AddComment("MaxState"); |
| OS.EmitIntValue(FuncInfo.CxxUnwindMap.size(), 4); |
| |
| AddComment("UnwindMap"); |
| OS.EmitValue(create32bitRef(UnwindMapXData), 4); |
| |
| AddComment("NumTryBlocks"); |
| OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); |
| |
| AddComment("TryBlockMap"); |
| OS.EmitValue(create32bitRef(TryBlockMapXData), 4); |
| |
| AddComment("IPMapEntries"); |
| OS.EmitIntValue(IPToStateTable.size(), 4); |
| |
| AddComment("IPToStateXData"); |
| OS.EmitValue(create32bitRef(IPToStateXData), 4); |
| |
| if (Asm->MAI->usesWindowsCFI()) { |
| AddComment("UnwindHelp"); |
| OS.EmitIntValue(UnwindHelpOffset, 4); |
| } |
| |
| AddComment("ESTypeList"); |
| OS.EmitIntValue(0, 4); |
| |
| AddComment("EHFlags"); |
| OS.EmitIntValue(1, 4); |
| |
| // UnwindMapEntry { |
| // int32_t ToState; |
| // void (*Action)(); |
| // }; |
| if (UnwindMapXData) { |
| OS.EmitLabel(UnwindMapXData); |
| for (const CxxUnwindMapEntry &UME : FuncInfo.CxxUnwindMap) { |
| MCSymbol *CleanupSym = |
| getMCSymbolForMBB(Asm, UME.Cleanup.dyn_cast<MachineBasicBlock *>()); |
| AddComment("ToState"); |
| OS.EmitIntValue(UME.ToState, 4); |
| |
| AddComment("Action"); |
| OS.EmitValue(create32bitRef(CleanupSym), 4); |
| } |
| } |
| |
| // TryBlockMap { |
| // int32_t TryLow; |
| // int32_t TryHigh; |
| // int32_t CatchHigh; |
| // int32_t NumCatches; |
| // HandlerType *HandlerArray; |
| // }; |
| if (TryBlockMapXData) { |
| OS.EmitLabel(TryBlockMapXData); |
| SmallVector<MCSymbol *, 1> HandlerMaps; |
| for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) { |
| const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I]; |
| |
| MCSymbol *HandlerMapXData = nullptr; |
| if (!TBME.HandlerArray.empty()) |
| HandlerMapXData = |
| Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$") |
| .concat(Twine(I)) |
| .concat("$") |
| .concat(FuncLinkageName)); |
| HandlerMaps.push_back(HandlerMapXData); |
| |
| // TBMEs should form intervals. |
| assert(0 <= TBME.TryLow && "bad trymap interval"); |
| assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval"); |
| assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval"); |
| assert(TBME.CatchHigh < int(FuncInfo.CxxUnwindMap.size()) && |
| "bad trymap interval"); |
| |
| AddComment("TryLow"); |
| OS.EmitIntValue(TBME.TryLow, 4); |
| |
| AddComment("TryHigh"); |
| OS.EmitIntValue(TBME.TryHigh, 4); |
| |
| AddComment("CatchHigh"); |
| OS.EmitIntValue(TBME.CatchHigh, 4); |
| |
| AddComment("NumCatches"); |
| OS.EmitIntValue(TBME.HandlerArray.size(), 4); |
| |
| AddComment("HandlerArray"); |
| OS.EmitValue(create32bitRef(HandlerMapXData), 4); |
| } |
| |
| // All funclets use the same parent frame offset currently. |
| unsigned ParentFrameOffset = 0; |
| if (shouldEmitPersonality) { |
| const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering(); |
| ParentFrameOffset = TFI->getWinEHParentFrameOffset(*MF); |
| } |
| |
| for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) { |
| const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I]; |
| MCSymbol *HandlerMapXData = HandlerMaps[I]; |
| if (!HandlerMapXData) |
| continue; |
| // HandlerType { |
| // int32_t Adjectives; |
| // TypeDescriptor *Type; |
| // int32_t CatchObjOffset; |
| // void (*Handler)(); |
| // int32_t ParentFrameOffset; // x64 and AArch64 only |
| // }; |
| OS.EmitLabel(HandlerMapXData); |
| for (const WinEHHandlerType &HT : TBME.HandlerArray) { |
| // Get the frame escape label with the offset of the catch object. If |
| // the index is INT_MAX, then there is no catch object, and we should |
| // emit an offset of zero, indicating that no copy will occur. |
| const MCExpr *FrameAllocOffsetRef = nullptr; |
| if (HT.CatchObj.FrameIndex != INT_MAX) { |
| int Offset = getFrameIndexOffset(HT.CatchObj.FrameIndex, FuncInfo); |
| assert(Offset != 0 && "Illegal offset for catch object!"); |
| FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext); |
| } else { |
| FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext); |
| } |
| |
| MCSymbol *HandlerSym = |
| getMCSymbolForMBB(Asm, HT.Handler.dyn_cast<MachineBasicBlock *>()); |
| |
| AddComment("Adjectives"); |
| OS.EmitIntValue(HT.Adjectives, 4); |
| |
| AddComment("Type"); |
| OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); |
| |
| AddComment("CatchObjOffset"); |
| OS.EmitValue(FrameAllocOffsetRef, 4); |
| |
| AddComment("Handler"); |
| OS.EmitValue(create32bitRef(HandlerSym), 4); |
| |
| if (shouldEmitPersonality) { |
| AddComment("ParentFrameOffset"); |
| OS.EmitIntValue(ParentFrameOffset, 4); |
| } |
| } |
| } |
| } |
| |
| // IPToStateMapEntry { |
| // void *IP; |
| // int32_t State; |
| // }; |
| if (IPToStateXData) { |
| OS.EmitLabel(IPToStateXData); |
| for (auto &IPStatePair : IPToStateTable) { |
| AddComment("IP"); |
| OS.EmitValue(IPStatePair.first, 4); |
| AddComment("ToState"); |
| OS.EmitIntValue(IPStatePair.second, 4); |
| } |
| } |
| } |
| |
| void WinException::computeIP2StateTable( |
| const MachineFunction *MF, const WinEHFuncInfo &FuncInfo, |
| SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) { |
| |
| for (MachineFunction::const_iterator FuncletStart = MF->begin(), |
| FuncletEnd = MF->begin(), |
| End = MF->end(); |
| FuncletStart != End; FuncletStart = FuncletEnd) { |
| // Find the end of the funclet |
| while (++FuncletEnd != End) { |
| if (FuncletEnd->isEHFuncletEntry()) { |
| break; |
| } |
| } |
| |
| // Don't emit ip2state entries for cleanup funclets. Any interesting |
| // exceptional actions in cleanups must be handled in a separate IR |
| // function. |
| if (FuncletStart->isCleanupFuncletEntry()) |
| continue; |
| |
| MCSymbol *StartLabel; |
| int BaseState; |
| if (FuncletStart == MF->begin()) { |
| BaseState = NullState; |
| StartLabel = Asm->getFunctionBegin(); |
| } else { |
| auto *FuncletPad = |
| cast<FuncletPadInst>(FuncletStart->getBasicBlock()->getFirstNonPHI()); |
| assert(FuncInfo.FuncletBaseStateMap.count(FuncletPad) != 0); |
| BaseState = FuncInfo.FuncletBaseStateMap.find(FuncletPad)->second; |
| StartLabel = getMCSymbolForMBB(Asm, &*FuncletStart); |
| } |
| assert(StartLabel && "need local function start label"); |
| IPToStateTable.push_back( |
| std::make_pair(create32bitRef(StartLabel), BaseState)); |
| |
| for (const auto &StateChange : InvokeStateChangeIterator::range( |
| FuncInfo, FuncletStart, FuncletEnd, BaseState)) { |
| // Compute the label to report as the start of this entry; use the EH |
| // start label for the invoke if we have one, otherwise (this is a call |
| // which may unwind to our caller and does not have an EH start label, so) |
| // use the previous end label. |
| const MCSymbol *ChangeLabel = StateChange.NewStartLabel; |
| if (!ChangeLabel) |
| ChangeLabel = StateChange.PreviousEndLabel; |
| // Emit an entry indicating that PCs after 'Label' have this EH state. |
| IPToStateTable.push_back( |
| std::make_pair(getLabel(ChangeLabel), StateChange.NewState)); |
| // FIXME: assert that NewState is between CatchLow and CatchHigh. |
| } |
| } |
| } |
| |
| void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo, |
| StringRef FLinkageName) { |
| // Outlined helpers called by the EH runtime need to know the offset of the EH |
| // registration in order to recover the parent frame pointer. Now that we know |
| // we've code generated the parent, we can emit the label assignment that |
| // those helpers use to get the offset of the registration node. |
| |
| // Compute the parent frame offset. The EHRegNodeFrameIndex will be invalid if |
| // after optimization all the invokes were eliminated. We still need to emit |
| // the parent frame offset label, but it should be garbage and should never be |
| // used. |
| int64_t Offset = 0; |
| int FI = FuncInfo.EHRegNodeFrameIndex; |
| if (FI != INT_MAX) { |
| const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering(); |
| Offset = TFI->getNonLocalFrameIndexReference(*Asm->MF, FI); |
| } |
| |
| MCContext &Ctx = Asm->OutContext; |
| MCSymbol *ParentFrameOffset = |
| Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName); |
| Asm->OutStreamer->EmitAssignment(ParentFrameOffset, |
| MCConstantExpr::create(Offset, Ctx)); |
| } |
| |
| /// Emit the language-specific data that _except_handler3 and 4 expect. This is |
| /// functionally equivalent to the __C_specific_handler table, except it is |
| /// indexed by state number instead of IP. |
| void WinException::emitExceptHandlerTable(const MachineFunction *MF) { |
| MCStreamer &OS = *Asm->OutStreamer; |
| const Function &F = MF->getFunction(); |
| StringRef FLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName()); |
| |
| bool VerboseAsm = OS.isVerboseAsm(); |
| auto AddComment = [&](const Twine &Comment) { |
| if (VerboseAsm) |
| OS.AddComment(Comment); |
| }; |
| |
| const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo(); |
| emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName); |
| |
| // Emit the __ehtable label that we use for llvm.x86.seh.lsda. |
| MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName); |
| OS.EmitValueToAlignment(4); |
| OS.EmitLabel(LSDALabel); |
| |
| const auto *Per = cast<Function>(F.getPersonalityFn()->stripPointerCasts()); |
| StringRef PerName = Per->getName(); |
| int BaseState = -1; |
| if (PerName == "_except_handler4") { |
| // The LSDA for _except_handler4 starts with this struct, followed by the |
| // scope table: |
| // |
| // struct EH4ScopeTable { |
| // int32_t GSCookieOffset; |
| // int32_t GSCookieXOROffset; |
| // int32_t EHCookieOffset; |
| // int32_t EHCookieXOROffset; |
| // ScopeTableEntry ScopeRecord[]; |
| // }; |
| // |
| // Offsets are %ebp relative. |
| // |
| // The GS cookie is present only if the function needs stack protection. |
| // GSCookieOffset = -2 means that GS cookie is not used. |
| // |
| // The EH cookie is always present. |
| // |
| // Check is done the following way: |
| // (ebp+CookieXOROffset) ^ [ebp+CookieOffset] == _security_cookie |
| |
| // Retrieve the Guard Stack slot. |
| int GSCookieOffset = -2; |
| const MachineFrameInfo &MFI = MF->getFrameInfo(); |
| if (MFI.hasStackProtectorIndex()) { |
| unsigned UnusedReg; |
| const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering(); |
| int SSPIdx = MFI.getStackProtectorIndex(); |
| GSCookieOffset = TFI->getFrameIndexReference(*MF, SSPIdx, UnusedReg); |
| } |
| |
| // Retrieve the EH Guard slot. |
| // TODO(etienneb): Get rid of this value and change it for and assertion. |
| int EHCookieOffset = 9999; |
| if (FuncInfo.EHGuardFrameIndex != INT_MAX) { |
| unsigned UnusedReg; |
| const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering(); |
| int EHGuardIdx = FuncInfo.EHGuardFrameIndex; |
| EHCookieOffset = TFI->getFrameIndexReference(*MF, EHGuardIdx, UnusedReg); |
| } |
| |
| AddComment("GSCookieOffset"); |
| OS.EmitIntValue(GSCookieOffset, 4); |
| AddComment("GSCookieXOROffset"); |
| OS.EmitIntValue(0, 4); |
| AddComment("EHCookieOffset"); |
| OS.EmitIntValue(EHCookieOffset, 4); |
| AddComment("EHCookieXOROffset"); |
| OS.EmitIntValue(0, 4); |
| BaseState = -2; |
| } |
| |
| assert(!FuncInfo.SEHUnwindMap.empty()); |
| for (const SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) { |
| auto *Handler = UME.Handler.get<MachineBasicBlock *>(); |
| const MCSymbol *ExceptOrFinally = |
| UME.IsFinally ? getMCSymbolForMBB(Asm, Handler) : Handler->getSymbol(); |
| // -1 is usually the base state for "unwind to caller", but for |
| // _except_handler4 it's -2. Do that replacement here if necessary. |
| int ToState = UME.ToState == -1 ? BaseState : UME.ToState; |
| AddComment("ToState"); |
| OS.EmitIntValue(ToState, 4); |
| AddComment(UME.IsFinally ? "Null" : "FilterFunction"); |
| OS.EmitValue(create32bitRef(UME.Filter), 4); |
| AddComment(UME.IsFinally ? "FinallyFunclet" : "ExceptionHandler"); |
| OS.EmitValue(create32bitRef(ExceptOrFinally), 4); |
| } |
| } |
| |
| static int getTryRank(const WinEHFuncInfo &FuncInfo, int State) { |
| int Rank = 0; |
| while (State != -1) { |
| ++Rank; |
| State = FuncInfo.ClrEHUnwindMap[State].TryParentState; |
| } |
| return Rank; |
| } |
| |
| static int getTryAncestor(const WinEHFuncInfo &FuncInfo, int Left, int Right) { |
| int LeftRank = getTryRank(FuncInfo, Left); |
| int RightRank = getTryRank(FuncInfo, Right); |
| |
| while (LeftRank < RightRank) { |
| Right = FuncInfo.ClrEHUnwindMap[Right].TryParentState; |
| --RightRank; |
| } |
| |
| while (RightRank < LeftRank) { |
| Left = FuncInfo.ClrEHUnwindMap[Left].TryParentState; |
| --LeftRank; |
| } |
| |
| while (Left != Right) { |
| Left = FuncInfo.ClrEHUnwindMap[Left].TryParentState; |
| Right = FuncInfo.ClrEHUnwindMap[Right].TryParentState; |
| } |
| |
| return Left; |
| } |
| |
| void WinException::emitCLRExceptionTable(const MachineFunction *MF) { |
| // CLR EH "states" are really just IDs that identify handlers/funclets; |
| // states, handlers, and funclets all have 1:1 mappings between them, and a |
| // handler/funclet's "state" is its index in the ClrEHUnwindMap. |
| MCStreamer &OS = *Asm->OutStreamer; |
| const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo(); |
| MCSymbol *FuncBeginSym = Asm->getFunctionBegin(); |
| MCSymbol *FuncEndSym = Asm->getFunctionEnd(); |
| |
| // A ClrClause describes a protected region. |
| struct ClrClause { |
| const MCSymbol *StartLabel; // Start of protected region |
| const MCSymbol *EndLabel; // End of protected region |
| int State; // Index of handler protecting the protected region |
| int EnclosingState; // Index of funclet enclosing the protected region |
| }; |
| SmallVector<ClrClause, 8> Clauses; |
| |
| // Build a map from handler MBBs to their corresponding states (i.e. their |
| // indices in the ClrEHUnwindMap). |
| int NumStates = FuncInfo.ClrEHUnwindMap.size(); |
| assert(NumStates > 0 && "Don't need exception table!"); |
| DenseMap<const MachineBasicBlock *, int> HandlerStates; |
| for (int State = 0; State < NumStates; ++State) { |
| MachineBasicBlock *HandlerBlock = |
| FuncInfo.ClrEHUnwindMap[State].Handler.get<MachineBasicBlock *>(); |
| HandlerStates[HandlerBlock] = State; |
| // Use this loop through all handlers to verify our assumption (used in |
| // the MinEnclosingState computation) that enclosing funclets have lower |
| // state numbers than their enclosed funclets. |
| assert(FuncInfo.ClrEHUnwindMap[State].HandlerParentState < State && |
| "ill-formed state numbering"); |
| } |
| // Map the main function to the NullState. |
| HandlerStates[&MF->front()] = NullState; |
| |
| // Write out a sentinel indicating the end of the standard (Windows) xdata |
| // and the start of the additional (CLR) info. |
| OS.EmitIntValue(0xffffffff, 4); |
| // Write out the number of funclets |
| OS.EmitIntValue(NumStates, 4); |
| |
| // Walk the machine blocks/instrs, computing and emitting a few things: |
| // 1. Emit a list of the offsets to each handler entry, in lexical order. |
| // 2. Compute a map (EndSymbolMap) from each funclet to the symbol at its end. |
| // 3. Compute the list of ClrClauses, in the required order (inner before |
| // outer, earlier before later; the order by which a forward scan with |
| // early termination will find the innermost enclosing clause covering |
| // a given address). |
| // 4. A map (MinClauseMap) from each handler index to the index of the |
| // outermost funclet/function which contains a try clause targeting the |
| // key handler. This will be used to determine IsDuplicate-ness when |
| // emitting ClrClauses. The NullState value is used to indicate that the |
| // top-level function contains a try clause targeting the key handler. |
| // HandlerStack is a stack of (PendingStartLabel, PendingState) pairs for |
| // try regions we entered before entering the PendingState try but which |
| // we haven't yet exited. |
| SmallVector<std::pair<const MCSymbol *, int>, 4> HandlerStack; |
| // EndSymbolMap and MinClauseMap are maps described above. |
| std::unique_ptr<MCSymbol *[]> EndSymbolMap(new MCSymbol *[NumStates]); |
| SmallVector<int, 4> MinClauseMap((size_t)NumStates, NumStates); |
| |
| // Visit the root function and each funclet. |
| for (MachineFunction::const_iterator FuncletStart = MF->begin(), |
| FuncletEnd = MF->begin(), |
| End = MF->end(); |
| FuncletStart != End; FuncletStart = FuncletEnd) { |
| int FuncletState = HandlerStates[&*FuncletStart]; |
| // Find the end of the funclet |
| MCSymbol *EndSymbol = FuncEndSym; |
| while (++FuncletEnd != End) { |
| if (FuncletEnd->isEHFuncletEntry()) { |
| EndSymbol = getMCSymbolForMBB(Asm, &*FuncletEnd); |
| break; |
| } |
| } |
| // Emit the function/funclet end and, if this is a funclet (and not the |
| // root function), record it in the EndSymbolMap. |
| OS.EmitValue(getOffset(EndSymbol, FuncBeginSym), 4); |
| if (FuncletState != NullState) { |
| // Record the end of the handler. |
| EndSymbolMap[FuncletState] = EndSymbol; |
| } |
| |
| // Walk the state changes in this function/funclet and compute its clauses. |
| // Funclets always start in the null state. |
| const MCSymbol *CurrentStartLabel = nullptr; |
| int CurrentState = NullState; |
| assert(HandlerStack.empty()); |
| for (const auto &StateChange : |
| InvokeStateChangeIterator::range(FuncInfo, FuncletStart, FuncletEnd)) { |
| // Close any try regions we're not still under |
| int StillPendingState = |
| getTryAncestor(FuncInfo, CurrentState, StateChange.NewState); |
| while (CurrentState != StillPendingState) { |
| assert(CurrentState != NullState && |
| "Failed to find still-pending state!"); |
| // Close the pending clause |
| Clauses.push_back({CurrentStartLabel, StateChange.PreviousEndLabel, |
| CurrentState, FuncletState}); |
| // Now the next-outer try region is current |
| CurrentState = FuncInfo.ClrEHUnwindMap[CurrentState].TryParentState; |
| // Pop the new start label from the handler stack if we've exited all |
| // inner try regions of the corresponding try region. |
| if (HandlerStack.back().second == CurrentState) |
| CurrentStartLabel = HandlerStack.pop_back_val().first; |
| } |
| |
| if (StateChange.NewState != CurrentState) { |
| // For each clause we're starting, update the MinClauseMap so we can |
| // know which is the topmost funclet containing a clause targeting |
| // it. |
| for (int EnteredState = StateChange.NewState; |
| EnteredState != CurrentState; |
| EnteredState = |
| FuncInfo.ClrEHUnwindMap[EnteredState].TryParentState) { |
| int &MinEnclosingState = MinClauseMap[EnteredState]; |
| if (FuncletState < MinEnclosingState) |
| MinEnclosingState = FuncletState; |
| } |
| // Save the previous current start/label on the stack and update to |
| // the newly-current start/state. |
| HandlerStack.emplace_back(CurrentStartLabel, CurrentState); |
| CurrentStartLabel = StateChange.NewStartLabel; |
| CurrentState = StateChange.NewState; |
| } |
| } |
| assert(HandlerStack.empty()); |
| } |
| |
| // Now emit the clause info, starting with the number of clauses. |
| OS.EmitIntValue(Clauses.size(), 4); |
| for (ClrClause &Clause : Clauses) { |
| // Emit a CORINFO_EH_CLAUSE : |
| /* |
| struct CORINFO_EH_CLAUSE |
| { |
| CORINFO_EH_CLAUSE_FLAGS Flags; // actually a CorExceptionFlag |
| DWORD TryOffset; |
| DWORD TryLength; // actually TryEndOffset |
| DWORD HandlerOffset; |
| DWORD HandlerLength; // actually HandlerEndOffset |
| union |
| { |
| DWORD ClassToken; // use for catch clauses |
| DWORD FilterOffset; // use for filter clauses |
| }; |
| }; |
| |
| enum CORINFO_EH_CLAUSE_FLAGS |
| { |
| CORINFO_EH_CLAUSE_NONE = 0, |
| CORINFO_EH_CLAUSE_FILTER = 0x0001, // This clause is for a filter |
| CORINFO_EH_CLAUSE_FINALLY = 0x0002, // This clause is a finally clause |
| CORINFO_EH_CLAUSE_FAULT = 0x0004, // This clause is a fault clause |
| }; |
| typedef enum CorExceptionFlag |
| { |
| COR_ILEXCEPTION_CLAUSE_NONE, |
| COR_ILEXCEPTION_CLAUSE_FILTER = 0x0001, // This is a filter clause |
| COR_ILEXCEPTION_CLAUSE_FINALLY = 0x0002, // This is a finally clause |
| COR_ILEXCEPTION_CLAUSE_FAULT = 0x0004, // This is a fault clause |
| COR_ILEXCEPTION_CLAUSE_DUPLICATED = 0x0008, // duplicated clause. This |
| // clause was duplicated |
| // to a funclet which was |
| // pulled out of line |
| } CorExceptionFlag; |
| */ |
| // Add 1 to the start/end of the EH clause; the IP associated with a |
| // call when the runtime does its scan is the IP of the next instruction |
| // (the one to which control will return after the call), so we need |
| // to add 1 to the end of the clause to cover that offset. We also add |
| // 1 to the start of the clause to make sure that the ranges reported |
| // for all clauses are disjoint. Note that we'll need some additional |
| // logic when machine traps are supported, since in that case the IP |
| // that the runtime uses is the offset of the faulting instruction |
| // itself; if such an instruction immediately follows a call but the |
| // two belong to different clauses, we'll need to insert a nop between |
| // them so the runtime can distinguish the point to which the call will |
| // return from the point at which the fault occurs. |
| |
| const MCExpr *ClauseBegin = |
| getOffsetPlusOne(Clause.StartLabel, FuncBeginSym); |
| const MCExpr *ClauseEnd = getOffsetPlusOne(Clause.EndLabel, FuncBeginSym); |
| |
| const ClrEHUnwindMapEntry &Entry = FuncInfo.ClrEHUnwindMap[Clause.State]; |
| MachineBasicBlock *HandlerBlock = Entry.Handler.get<MachineBasicBlock *>(); |
| MCSymbol *BeginSym = getMCSymbolForMBB(Asm, HandlerBlock); |
| const MCExpr *HandlerBegin = getOffset(BeginSym, FuncBeginSym); |
| MCSymbol *EndSym = EndSymbolMap[Clause.State]; |
| const MCExpr *HandlerEnd = getOffset(EndSym, FuncBeginSym); |
| |
| uint32_t Flags = 0; |
| switch (Entry.HandlerType) { |
| case ClrHandlerType::Catch: |
| // Leaving bits 0-2 clear indicates catch. |
| break; |
| case ClrHandlerType::Filter: |
| Flags |= 1; |
| break; |
| case ClrHandlerType::Finally: |
| Flags |= 2; |
| break; |
| case ClrHandlerType::Fault: |
| Flags |= 4; |
| break; |
| } |
| if (Clause.EnclosingState != MinClauseMap[Clause.State]) { |
| // This is a "duplicate" clause; the handler needs to be entered from a |
| // frame above the one holding the invoke. |
| assert(Clause.EnclosingState > MinClauseMap[Clause.State]); |
| Flags |= 8; |
| } |
| OS.EmitIntValue(Flags, 4); |
| |
| // Write the clause start/end |
| OS.EmitValue(ClauseBegin, 4); |
| OS.EmitValue(ClauseEnd, 4); |
| |
| // Write out the handler start/end |
| OS.EmitValue(HandlerBegin, 4); |
| OS.EmitValue(HandlerEnd, 4); |
| |
| // Write out the type token or filter offset |
| assert(Entry.HandlerType != ClrHandlerType::Filter && "NYI: filters"); |
| OS.EmitIntValue(Entry.TypeToken, 4); |
| } |
| } |
