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llvm-for-llvmta/lib/CodeGen/AsmPrinter/WinException.cpp

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//===-- 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/TargetMachine.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 table-based SEH.
if (Per == EHPersonality::MSVC_TableSEH && 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_TableSEH)
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());
if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
!CurrentFuncletEntry->isCleanupFuncletEntry()) {
// Emit an UNWIND_INFO struct describing the prologue.
Asm->OutStreamer->EmitWinEHHandlerData();
// 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_TableSEH && MF->hasEHFunclets() &&
!CurrentFuncletEntry->isEHFuncletEntry()) {
// Emit an UNWIND_INFO struct describing the prologue.
Asm->OutStreamer->EmitWinEHHandlerData();
// If this is the parent function in Win64 SEH, emit the LSDA immediately
// following .seh_handlerdata.
emitCSpecificHandlerTable(MF);
} else if (shouldEmitPersonality || shouldEmitLSDA) {
// Emit an UNWIND_INFO struct describing the prologue.
Asm->OutStreamer->EmitWinEHHandlerData();
// In these cases, no further info is written to the .xdata section
// right here, but is written by e.g. emitExceptionTable in endFunction()
// above.
} else {
// No need to emit the EH handler data right here if nothing needs
// writing to the .xdata section; it will be emitted for all
// functions that need it in the end anyway.
}
// 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();
Register UnusedReg;
if (Asm->MAI->usesWindowsCFI()) {
StackOffset Offset =
TFI.getFrameIndexReferencePreferSP(*Asm->MF, FrameIndex, UnusedReg,
/*IgnoreSPUpdates*/ true);
assert(UnusedReg ==
Asm->MF->getSubtarget()
.getTargetLowering()
->getStackPointerRegisterToSaveRestore());
return Offset.getFixed();
}
// 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);
StackOffset Offset = TFI.getFrameIndexReference(*Asm->MF, FrameIndex, UnusedReg);
Offset += StackOffset::getFixed(FuncInfo.EHRegNodeEndOffset);
assert(!Offset.getScalable() &&
"Frame offsets with a scalable component are not supported");
return Offset.getFixed();
}
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.emitInt32(0x19930522);
AddComment("MaxState");
OS.emitInt32(FuncInfo.CxxUnwindMap.size());
AddComment("UnwindMap");
OS.emitValue(create32bitRef(UnwindMapXData), 4);
AddComment("NumTryBlocks");
OS.emitInt32(FuncInfo.TryBlockMap.size());
AddComment("TryBlockMap");
OS.emitValue(create32bitRef(TryBlockMapXData), 4);
AddComment("IPMapEntries");
OS.emitInt32(IPToStateTable.size());
AddComment("IPToStateXData");
OS.emitValue(create32bitRef(IPToStateXData), 4);
if (Asm->MAI->usesWindowsCFI()) {
AddComment("UnwindHelp");
OS.emitInt32(UnwindHelpOffset);
}
AddComment("ESTypeList");
OS.emitInt32(0);
AddComment("EHFlags");
OS.emitInt32(1);
// 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.emitInt32(UME.ToState);
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.emitInt32(TBME.TryLow);
AddComment("TryHigh");
OS.emitInt32(TBME.TryHigh);
AddComment("CatchHigh");
OS.emitInt32(TBME.CatchHigh);
AddComment("NumCatches");
OS.emitInt32(TBME.HandlerArray.size());
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.emitInt32(HT.Adjectives);
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.emitInt32(ParentFrameOffset);
}
}
}
}
// 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.emitInt32(IPStatePair.second);
}
}
}
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).getFixed();
}
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()) {
Register UnusedReg;
const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
int SSPIdx = MFI.getStackProtectorIndex();
GSCookieOffset =
TFI->getFrameIndexReference(*MF, SSPIdx, UnusedReg).getFixed();
}
// 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) {
Register UnusedReg;
const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
int EHGuardIdx = FuncInfo.EHGuardFrameIndex;
EHCookieOffset =
TFI->getFrameIndexReference(*MF, EHGuardIdx, UnusedReg).getFixed();
}
AddComment("GSCookieOffset");
OS.emitInt32(GSCookieOffset);
AddComment("GSCookieXOROffset");
OS.emitInt32(0);
AddComment("EHCookieOffset");
OS.emitInt32(EHCookieOffset);
AddComment("EHCookieXOROffset");
OS.emitInt32(0);
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.emitInt32(ToState);
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.emitInt32(0xffffffff);
// Write out the number of funclets
OS.emitInt32(NumStates);
// 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.emitInt32(Clauses.size());
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.emitInt32(Flags);
// 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.emitInt32(Entry.TypeToken);
}
}
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