//
//===----------------------------------------------------------------------===//
-#include "DwarfException.h"
+#include "Win64Exception.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineModuleInfo.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/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
-#include "llvm/Target/Mangler.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
Win64Exception::Win64Exception(AsmPrinter *A)
- : DwarfException(A),
- shouldEmitPersonality(false), shouldEmitLSDA(false), shouldEmitMoves(false)
- {}
+ : EHStreamer(A), shouldEmitPersonality(false), shouldEmitLSDA(false),
+ shouldEmitMoves(false) {}
Win64Exception::~Win64Exception() {}
void Win64Exception::endModule() {
}
-/// beginFunction - Gather pre-function exception information. Assumes it's
-/// being emitted immediately after the function entry point.
void Win64Exception::beginFunction(const MachineFunction *MF) {
shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
- const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
+ const Function *Per = MF->getMMI().getPersonality();
shouldEmitPersonality = hasLandingPads &&
PerEncoding != dwarf::DW_EH_PE_omit && Per;
shouldEmitLSDA = shouldEmitPersonality &&
LSDAEncoding != dwarf::DW_EH_PE_omit;
+
+ // If this was an outlined handler, we need to define the label corresponding
+ // to the offset of the parent frame relative to the stack pointer after the
+ // prologue.
+ const Function *F = MF->getFunction();
+ const Function *ParentF = MMI->getWinEHParent(F);
+ if (F != ParentF) {
+ WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
+ auto I = FuncInfo.CatchHandlerParentFrameObjOffset.find(F);
+ if (I != FuncInfo.CatchHandlerParentFrameObjOffset.end()) {
+ MCSymbol *HandlerTypeParentFrameOffset =
+ Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
+ GlobalValue::getRealLinkageName(F->getName()));
+
+ // Emit a symbol assignment.
+ Asm->OutStreamer.EmitAssignment(
+ HandlerTypeParentFrameOffset,
+ MCConstantExpr::Create(I->second, Asm->OutContext));
+ }
+ }
+
if (!shouldEmitPersonality && !shouldEmitMoves)
return;
- Asm->OutStreamer.EmitWin64EHStartProc(Asm->CurrentFnSym);
+ Asm->OutStreamer.EmitWinCFIStartProc(Asm->CurrentFnSym);
if (!shouldEmitPersonality)
return;
- MCSymbol *GCCHandlerSym =
- Asm->GetExternalSymbolSymbol("_GCC_specific_handler");
- Asm->OutStreamer.EmitWin64EHHandler(GCCHandlerSym, true, true);
-
- Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
- Asm->getFunctionNumber()));
+ const MCSymbol *PersHandlerSym =
+ TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
+ Asm->OutStreamer.EmitWinEHHandler(PersHandlerSym, true, true);
}
/// endFunction - Gather and emit post-function exception information.
///
-void Win64Exception::endFunction(const MachineFunction *) {
+void Win64Exception::endFunction(const MachineFunction *MF) {
if (!shouldEmitPersonality && !shouldEmitMoves)
return;
- Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
- Asm->getFunctionNumber()));
+ EHPersonality Per = MMI->getPersonalityType();
- // Map all labels and get rid of any dead landing pads.
- MMI->TidyLandingPads();
+ // Get rid of any dead landing pads if we're not using a Windows EH scheme. In
+ // Windows EH schemes, the landing pad is not actually reachable. It only
+ // exists so that we can emit the right table data.
+ if (!isMSVCEHPersonality(Per))
+ MMI->TidyLandingPads();
if (shouldEmitPersonality) {
- const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
- const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
- const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, Asm->Mang, MMI);
-
Asm->OutStreamer.PushSection();
- Asm->OutStreamer.EmitWin64EHHandlerData();
- Asm->OutStreamer.EmitValue(MCSymbolRefExpr::Create(Sym, Asm->OutContext),
- 4);
- EmitExceptionTable();
+
+ // Emit an UNWIND_INFO struct describing the prologue.
+ Asm->OutStreamer.EmitWinEHHandlerData();
+
+ // 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();
+ else if (Per == EHPersonality::MSVC_CXX)
+ emitCXXFrameHandler3Table(MF);
+ else
+ emitExceptionTable();
+
Asm->OutStreamer.PopSection();
}
- Asm->OutStreamer.EmitWin64EHEndProc();
+ Asm->OutStreamer.EmitWinCFIEndProc();
+}
+
+const MCExpr *Win64Exception::createImageRel32(const MCSymbol *Value) {
+ if (!Value)
+ return MCConstantExpr::Create(0, Asm->OutContext);
+ return MCSymbolRefExpr::Create(Value, MCSymbolRefExpr::VK_COFF_IMGREL32,
+ Asm->OutContext);
+}
+
+const MCExpr *Win64Exception::createImageRel32(const GlobalValue *GV) {
+ if (!GV)
+ return MCConstantExpr::Create(0, Asm->OutContext);
+ return createImageRel32(Asm->getSymbol(GV));
+}
+
+/// 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 Win64Exception::emitCSpecificHandlerTable() {
+ const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
+
+ // Simplifying assumptions for first implementation:
+ // - Cleanups are not implemented.
+ // - Filters are not implemented.
+
+ // The Itanium LSDA table sorts similar landing pads together to simplify the
+ // actions table, but we don't need that.
+ SmallVector<const LandingPadInfo *, 64> LandingPads;
+ LandingPads.reserve(PadInfos.size());
+ for (const auto &LP : PadInfos)
+ LandingPads.push_back(&LP);
+
+ // Compute label ranges for call sites as we would for the Itanium LSDA, but
+ // use an all zero action table because we aren't using these actions.
+ SmallVector<unsigned, 64> FirstActions;
+ FirstActions.resize(LandingPads.size());
+ SmallVector<CallSiteEntry, 64> CallSites;
+ computeCallSiteTable(CallSites, LandingPads, FirstActions);
+
+ MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
+ MCSymbol *EHFuncEndSym = Asm->getFunctionEnd();
+
+ // Emit the number of table entries.
+ unsigned NumEntries = 0;
+ for (const CallSiteEntry &CSE : CallSites) {
+ if (!CSE.LPad)
+ continue; // Ignore gaps.
+ NumEntries += CSE.LPad->SEHHandlers.size();
+ }
+ Asm->OutStreamer.EmitIntValue(NumEntries, 4);
+
+ // If there are no actions, we don't need to iterate again.
+ if (NumEntries == 0)
+ return;
+
+ // Emit the four-label records for each call site entry. The table has to be
+ // sorted in layout order, and the call sites should already be sorted.
+ for (const CallSiteEntry &CSE : CallSites) {
+ // Ignore gaps. Unlike the Itanium model, unwinding through a frame without
+ // an EH table entry will propagate the exception rather than terminating
+ // the program.
+ if (!CSE.LPad)
+ continue;
+ const LandingPadInfo *LPad = CSE.LPad;
+
+ // Compute the label range. We may reuse the function begin and end labels
+ // rather than forming new ones.
+ const MCExpr *Begin =
+ createImageRel32(CSE.BeginLabel ? CSE.BeginLabel : EHFuncBeginSym);
+ const MCExpr *End;
+ if (CSE.EndLabel) {
+ // The interval is half-open, so we have to add one to include the return
+ // address of the last invoke in the range.
+ End = MCBinaryExpr::CreateAdd(createImageRel32(CSE.EndLabel),
+ MCConstantExpr::Create(1, Asm->OutContext),
+ Asm->OutContext);
+ } else {
+ End = createImageRel32(EHFuncEndSym);
+ }
+
+ // Emit an entry for each action.
+ for (SEHHandler Handler : LPad->SEHHandlers) {
+ Asm->OutStreamer.EmitValue(Begin, 4);
+ Asm->OutStreamer.EmitValue(End, 4);
+
+ // Emit the filter or finally function pointer, if present. Otherwise,
+ // emit '1' to indicate a catch-all.
+ const Function *F = Handler.FilterOrFinally;
+ if (F)
+ Asm->OutStreamer.EmitValue(createImageRel32(Asm->getSymbol(F)), 4);
+ else
+ Asm->OutStreamer.EmitIntValue(1, 4);
+
+ // Emit the recovery address, if present. Otherwise, this must be a
+ // finally.
+ const BlockAddress *BA = Handler.RecoverBA;
+ if (BA)
+ Asm->OutStreamer.EmitValue(
+ createImageRel32(Asm->GetBlockAddressSymbol(BA)), 4);
+ else
+ Asm->OutStreamer.EmitIntValue(0, 4);
+ }
+ }
+}
+
+void Win64Exception::emitCXXFrameHandler3Table(const MachineFunction *MF) {
+ const Function *F = MF->getFunction();
+ const Function *ParentF = MMI->getWinEHParent(F);
+ auto &OS = Asm->OutStreamer;
+ WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
+
+ StringRef ParentLinkageName =
+ GlobalValue::getRealLinkageName(ParentF->getName());
+
+ MCSymbol *FuncInfoXData =
+ Asm->OutContext.GetOrCreateSymbol(Twine("$cppxdata$", ParentLinkageName));
+ OS.EmitValue(createImageRel32(FuncInfoXData), 4);
+
+ // The Itanium LSDA table sorts similar landing pads together to simplify the
+ // actions table, but we don't need that.
+ SmallVector<const LandingPadInfo *, 64> LandingPads;
+ const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
+ LandingPads.reserve(PadInfos.size());
+ for (const auto &LP : PadInfos)
+ LandingPads.push_back(&LP);
+
+ RangeMapType PadMap;
+ computePadMap(LandingPads, PadMap);
+
+ // The end label of the previous invoke or nounwind try-range.
+ MCSymbol *LastLabel = Asm->getFunctionBegin();
+
+ // Whether there is a potentially throwing instruction (currently this means
+ // an ordinary call) between the end of the previous try-range and now.
+ bool SawPotentiallyThrowing = false;
+
+ int LastEHState = -2;
+
+ // The parent function and the catch handlers contribute to the 'ip2state'
+ // table.
+ for (const auto &MBB : *MF) {
+ for (const auto &MI : MBB) {
+ if (!MI.isEHLabel()) {
+ if (MI.isCall())
+ SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
+ continue;
+ }
+
+ // End of the previous try-range?
+ MCSymbol *BeginLabel = MI.getOperand(0).getMCSymbol();
+ if (BeginLabel == LastLabel)
+ SawPotentiallyThrowing = false;
+
+ // Beginning of a new try-range?
+ RangeMapType::const_iterator L = PadMap.find(BeginLabel);
+ if (L == PadMap.end())
+ // Nope, it was just some random label.
+ continue;
+
+ const PadRange &P = L->second;
+ const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
+ assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
+ "Inconsistent landing pad map!");
+
+ if (SawPotentiallyThrowing) {
+ FuncInfo.IPToStateList.push_back(std::make_pair(LastLabel, -1));
+ SawPotentiallyThrowing = false;
+ LastEHState = -1;
+ }
+
+ if (LandingPad->WinEHState != LastEHState)
+ FuncInfo.IPToStateList.push_back(
+ std::make_pair(BeginLabel, LandingPad->WinEHState));
+ LastEHState = LandingPad->WinEHState;
+ LastLabel = LandingPad->EndLabels[P.RangeIndex];
+ }
+ }
+
+ // Defer emission until we've visited the parent function and all the catch
+ // handlers. Cleanups don't contribute to the ip2state table yet, so don't
+ // count them.
+ if (ParentF != F && !FuncInfo.CatchHandlerMaxState.count(F))
+ return;
+ ++FuncInfo.NumIPToStateFuncsVisited;
+ if (FuncInfo.NumIPToStateFuncsVisited != FuncInfo.CatchHandlerMaxState.size())
+ return;
+
+ MCSymbol *UnwindMapXData = nullptr;
+ MCSymbol *TryBlockMapXData = nullptr;
+ MCSymbol *IPToStateXData = nullptr;
+ if (!FuncInfo.UnwindMap.empty())
+ UnwindMapXData = Asm->OutContext.GetOrCreateSymbol(
+ Twine("$stateUnwindMap$", ParentLinkageName));
+ if (!FuncInfo.TryBlockMap.empty())
+ TryBlockMapXData = Asm->OutContext.GetOrCreateSymbol(
+ Twine("$tryMap$", ParentLinkageName));
+ if (!FuncInfo.IPToStateList.empty())
+ IPToStateXData = Asm->OutContext.GetOrCreateSymbol(
+ Twine("$ip2state$", ParentLinkageName));
+
+ // FuncInfo {
+ // uint32_t MagicNumber
+ // int32_t MaxState;
+ // UnwindMapEntry *UnwindMap;
+ // uint32_t NumTryBlocks;
+ // TryBlockMapEntry *TryBlockMap;
+ // uint32_t IPMapEntries;
+ // IPToStateMapEntry *IPToStateMap;
+ // uint32_t UnwindHelp; // (x64/ARM 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.EmitLabel(FuncInfoXData);
+ OS.EmitIntValue(0x19930522, 4); // MagicNumber
+ OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
+ OS.EmitValue(createImageRel32(UnwindMapXData), 4); // UnwindMap
+ OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
+ OS.EmitValue(createImageRel32(TryBlockMapXData), 4); // TryBlockMap
+ OS.EmitIntValue(FuncInfo.IPToStateList.size(), 4); // IPMapEntries
+ OS.EmitValue(createImageRel32(IPToStateXData), 4); // IPToStateMap
+ OS.EmitIntValue(FuncInfo.UnwindHelpFrameOffset, 4); // UnwindHelp
+ OS.EmitIntValue(0, 4); // ESTypeList
+ OS.EmitIntValue(1, 4); // EHFlags
+
+ // UnwindMapEntry {
+ // int32_t ToState;
+ // void (*Action)();
+ // };
+ if (UnwindMapXData) {
+ OS.EmitLabel(UnwindMapXData);
+ for (const WinEHUnwindMapEntry &UME : FuncInfo.UnwindMap) {
+ OS.EmitIntValue(UME.ToState, 4); // ToState
+ OS.EmitValue(createImageRel32(UME.Cleanup), 4); // Action
+ }
+ }
+
+ // 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) {
+ WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
+ MCSymbol *HandlerMapXData = nullptr;
+
+ if (!TBME.HandlerArray.empty())
+ HandlerMapXData =
+ Asm->OutContext.GetOrCreateSymbol(Twine("$handlerMap$")
+ .concat(Twine(I))
+ .concat("$")
+ .concat(ParentLinkageName));
+
+ HandlerMaps.push_back(HandlerMapXData);
+
+ int CatchHigh = -1;
+ for (WinEHHandlerType &HT : TBME.HandlerArray)
+ CatchHigh =
+ std::max(CatchHigh, FuncInfo.CatchHandlerMaxState[HT.Handler]);
+
+ assert(TBME.TryLow <= TBME.TryHigh);
+ OS.EmitIntValue(TBME.TryLow, 4); // TryLow
+ OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
+ OS.EmitIntValue(CatchHigh, 4); // CatchHigh
+ OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
+ OS.EmitValue(createImageRel32(HandlerMapXData), 4); // HandlerArray
+ }
+
+ for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
+ 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 only
+ // };
+ OS.EmitLabel(HandlerMapXData);
+ for (const WinEHHandlerType &HT : TBME.HandlerArray) {
+ MCSymbol *ParentFrameOffset =
+ Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
+ GlobalValue::getRealLinkageName(HT.Handler->getName()));
+ const MCSymbolRefExpr *ParentFrameOffsetRef = MCSymbolRefExpr::Create(
+ ParentFrameOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
+
+ // Get the frame escape label with the offset of the catch object. If
+ // the index is -1, 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.CatchObjRecoverIdx >= 0) {
+ MCSymbol *FrameAllocOffset =
+ Asm->OutContext.getOrCreateFrameAllocSymbol(
+ GlobalValue::getRealLinkageName(ParentF->getName()),
+ HT.CatchObjRecoverIdx);
+ FrameAllocOffsetRef = MCSymbolRefExpr::Create(
+ FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
+ } else {
+ FrameAllocOffsetRef = MCConstantExpr::Create(0, Asm->OutContext);
+ }
+
+ OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
+ OS.EmitValue(createImageRel32(HT.TypeDescriptor), 4); // Type
+ OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
+ OS.EmitValue(createImageRel32(HT.Handler), 4); // Handler
+ OS.EmitValue(ParentFrameOffsetRef, 4); // ParentFrameOffset
+ }
+ }
+ }
+
+ // IPToStateMapEntry {
+ // void *IP;
+ // int32_t State;
+ // };
+ if (IPToStateXData) {
+ OS.EmitLabel(IPToStateXData);
+ for (auto &IPStatePair : FuncInfo.IPToStateList) {
+ OS.EmitValue(createImageRel32(IPStatePair.first), 4); // IP
+ OS.EmitIntValue(IPStatePair.second, 4); // State
+ }
+ }
}
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