RPCS3/llvm
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm.git synced 2025-04-14 20:10:58 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity
llvm/lib/CodeGen/AsmPrinter/WinException.cpp
David Majnemer 0ba86faae2 [WinEH] Teach AsmPrinter about funclets 
Summary:
Funclets have been turned into functions by the time they hit the object
file.  Make sure that they have decent names for the symbol table and
CFI directives explaining how to reason about their prologues.

Differential Revision: http://reviews.llvm.org/D13261

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248824 91177308-0d34-0410-b5e6-96231b3b80d8
2015-09-29 20:12:33 +00:00

778 lines
31 KiB
C++
Raw Blame History

//===-- CodeGen/AsmPrinter/WinException.cpp - Dwarf Exception Impl ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing Win64 exception info into asm files.
//
//===----------------------------------------------------------------------===//
#include "WinException.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/AsmPrinter.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/MC/MCExpr.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCWin64EH.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.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);
}
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 = !MMI->getLandingPads().empty();
bool hasEHFunclets = MMI->hasEHFunclets();
const Function *F = MF->getFunction();
const Function *ParentF = MMI->getWinEHParent(F);
shouldEmitMoves = Asm->needsSEHMoves();
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
const Function *Per = nullptr;
if (F->hasPersonalityFn())
Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
bool forceEmitPersonality =
F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
F->needsUnwindTableEntry();
shouldEmitPersonality =
forceEmitPersonality || ((hasLandingPads || hasEHFunclets) &&
PerEncoding != dwarf::DW_EH_PE_omit && Per);
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.
// FIXME: If WinEHPrepare outlined something, we should emit the LSDA. Remove
// this once WinEHPrepare stops doing that.
if (!Asm->MAI->usesWindowsCFI()) {
shouldEmitLSDA =
hasEHFunclets || (F->hasFnAttribute("wineh-parent") && F == ParentF);
shouldEmitPersonality = false;
return;
}
beginFunclet(MF->front(), Asm->CurrentFnSym);
}
/// 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());
// 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();
endFunclet();
if (shouldEmitPersonality || shouldEmitLSDA) {
Asm->OutStreamer->PushSection();
// Just switch sections to the right xdata section. This use of CurrentFnSym
// assumes that we only emit the LSDA when ending the parent function.
MCSection *XData = WinEH::UnwindEmitter::getXDataSection(Asm->CurrentFnSym,
Asm->OutContext);
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
emitExceptionTable();
Asm->OutStreamer->PopSection();
}
}
/// Retreive the MCSymbol for a GlobalValue or MachineBasicBlock. GlobalValues
/// are used in the old WinEH scheme, and they will be removed eventually.
static MCSymbol *getMCSymbolForMBBOrGV(AsmPrinter *Asm, ValueOrMBB Handler) {
if (!Handler)
return nullptr;
if (Handler.is<const MachineBasicBlock *>()) {
auto *MBB = Handler.get<const MachineBasicBlock *>();
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::getRealLinkageName(F->getName());
MCContext &Ctx = MF->getContext();
StringRef HandlerPrefix = MBB->isCleanupFuncletEntry() ? "dtor" : "catch";
return Ctx.getOrCreateSymbol("?" + HandlerPrefix + "$" +
Twine(MBB->getNumber()) + "@?0?" +
FuncLinkageName + "@4HA");
}
return Asm->getSymbol(cast<GlobalValue>(Handler.get<const Value *>()));
}
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 = getMCSymbolForMBBOrGV(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)
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->Mang, Asm->TM, MMI);
// Classify the personality routine so that we may reason about it.
EHPersonality Per = EHPersonality::Unknown;
if (F->hasPersonalityFn())
Per = classifyEHPersonality(F->getPersonalityFn());
// Do not emit a .seh_handler directive if it is a C++ cleanup funclet.
if (Per != EHPersonality::MSVC_CXX ||
!CurrentFuncletEntry->isCleanupFuncletEntry())
Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
}
}
void WinException::endFunclet() {
// No funclet to process? Great, we have nothing to do.
if (!CurrentFuncletEntry)
return;
if (shouldEmitMoves || shouldEmitPersonality) {
const Function *F = Asm->MF->getFunction();
EHPersonality Per = EHPersonality::Unknown;
if (F->hasPersonalityFn())
Per = classifyEHPersonality(F->getPersonalityFn());
// The .seh_handlerdata directive implicitly switches section, push the
// current section so that we may return to it.
Asm->OutStreamer->PushSection();
// 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.
if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
!CurrentFuncletEntry->isCleanupFuncletEntry()) {
StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
Twine("$cppxdata$", FuncLinkageName));
Asm->OutStreamer->EmitValue(create32bitRef(FuncInfoXData), 4);
}
// Switch back to the previous section now that we are done writing to
// .xdata.
Asm->OutStreamer->PopSection();
// Emit a .seh_endproc directive to mark the end of the function.
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 Value *V) {
if (!V)
return MCConstantExpr::create(0, Asm->OutContext);
// FIXME: Delete the GlobalValue case once the new IR is fully functional.
if (const auto *GV = dyn_cast<GlobalValue>(V))
return create32bitRef(Asm->getSymbol(GV));
return create32bitRef(MMI->getAddrLabelSymbol(cast<BasicBlock>(V)));
}
const MCExpr *WinException::getLabelPlusOne(MCSymbol *Label) {
return MCBinaryExpr::createAdd(create32bitRef(Label),
MCConstantExpr::create(1, Asm->OutContext),
Asm->OutContext);
}
/// 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) {
const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(MF->getFunction());
if (!FuncInfo.SEHUnwindMap.empty())
report_fatal_error("x64 SEH tables not yet implemented");
// 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 =
create32bitRef(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 = getLabelPlusOne(CSE.EndLabel);
} else {
End = create32bitRef(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(create32bitRef(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(
create32bitRef(Asm->GetBlockAddressSymbol(BA)), 4);
else
Asm->OutStreamer->EmitIntValue(0, 4);
}
}
}
void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
const Function *F = MF->getFunction();
auto &OS = *Asm->OutStreamer;
WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
StringRef FuncLinkageName = GlobalValue::getRealLinkageName(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$", FuncLinkageName));
computeIP2StateTable(MF, FuncInfo, IPToStateTable);
} else {
FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
emitEHRegistrationOffsetLabel(FuncInfo, FuncLinkageName);
}
MCSymbol *UnwindMapXData = nullptr;
MCSymbol *TryBlockMapXData = nullptr;
MCSymbol *IPToStateXData = nullptr;
if (!FuncInfo.UnwindMap.empty())
UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
Twine("$stateUnwindMap$", FuncLinkageName));
if (!FuncInfo.TryBlockMap.empty())
TryBlockMapXData =
Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
if (!IPToStateTable.empty())
IPToStateXData =
Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
// 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);
OS.EmitIntValue(0x19930522, 4); // MagicNumber
OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
OS.EmitIntValue(IPToStateTable.size(), 4); // IPMapEntries
OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
if (Asm->MAI->usesWindowsCFI())
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) {
MCSymbol *CleanupSym = getMCSymbolForMBBOrGV(Asm, UME.Cleanup);
OS.EmitIntValue(UME.ToState, 4); // ToState
OS.EmitValue(create32bitRef(CleanupSym), 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(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.UnwindMap.size()) &&
"bad trymap interval");
OS.EmitIntValue(TBME.TryLow, 4); // TryLow
OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
OS.EmitIntValue(TBME.CatchHigh, 4); // CatchHigh
OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
OS.EmitValue(create32bitRef(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) {
// 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(
FuncLinkageName, HT.CatchObjRecoverIdx);
FrameAllocOffsetRef = MCSymbolRefExpr::create(
FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
} else if (HT.CatchObj.FrameOffset != INT_MAX) {
int Offset = HT.CatchObj.FrameOffset;
// For 32-bit, the catch object offset is relative to the end of the
// EH registration node. For 64-bit, it's relative to SP at the end of
// the prologue.
if (!shouldEmitPersonality) {
assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
Offset += FuncInfo.EHRegNodeEndOffset;
}
FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
} else {
FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
}
MCSymbol *HandlerSym = getMCSymbolForMBBOrGV(Asm, HT.Handler);
OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
OS.EmitValue(create32bitRef(HandlerSym), 4); // Handler
if (shouldEmitPersonality) {
// With the new IR, this is always 16 + 8 + getMaxCallFrameSize().
// Keep this in sync with X86FrameLowering::emitPrologue.
int ParentFrameOffset =
16 + 8 + MF->getFrameInfo()->getMaxCallFrameSize();
OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
}
}
}
}
// IPToStateMapEntry {
// void *IP;
// int32_t State;
// };
if (IPToStateXData) {
OS.EmitLabel(IPToStateXData);
for (auto &IPStatePair : IPToStateTable) {
OS.EmitValue(IPStatePair.first, 4); // IP
OS.EmitIntValue(IPStatePair.second, 4); // State
}
}
}
void WinException::computeIP2StateTable(
const MachineFunction *MF, WinEHFuncInfo &FuncInfo,
SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
// 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 = true;
// Remember what state we were in the last time we found a begin try label.
// This allows us to coalesce many nearby invokes with the same state into one
// entry.
int LastEHState = -1;
MCSymbol *LastEndLabel = Asm->getFunctionBegin();
assert(LastEndLabel && "need local function start label");
// Indicate that all calls from the prologue to the first invoke unwind to
// caller. We handle this as a special case since other ranges starting at end
// labels need to use LtmpN+1.
IPToStateTable.push_back(std::make_pair(create32bitRef(LastEndLabel), -1));
for (const auto &MBB : *MF) {
// FIXME: Do we need to emit entries for funclet base states?
for (const auto &MI : MBB) {
// Find all the EH_LABEL instructions, tracking if we've crossed a
// potentially throwing call since the last label.
if (!MI.isEHLabel()) {
if (MI.isCall())
SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
continue;
}
// If this was an end label, return SawPotentiallyThrowing to the start
// state and keep going. Otherwise, we will consider the call between the
// begin/end labels to be a potentially throwing call and generate extra
// table entries.
MCSymbol *Label = MI.getOperand(0).getMCSymbol();
if (Label == LastEndLabel)
SawPotentiallyThrowing = false;
// Check if this was a begin label. Otherwise, it must be an end label or
// some random label, and we should continue.
auto StateAndEnd = FuncInfo.InvokeToStateMap.find(Label);
if (StateAndEnd == FuncInfo.InvokeToStateMap.end())
continue;
// Extract the state and end label.
int State;
MCSymbol *EndLabel;
std::tie(State, EndLabel) = StateAndEnd->second;
// If there was a potentially throwing call between this begin label and
// the last end label, we need an extra base state entry to indicate that
// those calls unwind directly to the caller.
if (SawPotentiallyThrowing && LastEHState != -1) {
IPToStateTable.push_back(
std::make_pair(getLabelPlusOne(LastEndLabel), -1));
SawPotentiallyThrowing = false;
LastEHState = -1;
}
// Emit an entry indicating that PCs after 'Label' have this EH state.
if (State != LastEHState)
IPToStateTable.push_back(std::make_pair(create32bitRef(Label), State));
LastEHState = State;
LastEndLabel = EndLabel;
}
}
if (LastEndLabel != Asm->getFunctionBegin()) {
// Indicate that all calls from the last invoke until the epilogue unwind to
// caller. This also ensures that we have at least one ip2state entry, if
// somehow all invokes were deleted during CodeGen.
IPToStateTable.push_back(std::make_pair(getLabelPlusOne(LastEndLabel), -1));
}
}
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.
assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
"no EH reg node localescape index");
MCSymbol *ParentFrameOffset =
Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
const MCExpr *RegistrationOffsetSymRef =
MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
}
/// 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::getRealLinkageName(F->getName());
WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
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 Function *Per =
dyn_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[];
// };
//
// Only the EHCookieOffset field appears to vary, and it appears to be the
// offset from the final saved SP value to the retaddr.
OS.EmitIntValue(-2, 4);
OS.EmitIntValue(0, 4);
// FIXME: Calculate.
OS.EmitIntValue(9999, 4);
OS.EmitIntValue(0, 4);
BaseState = -2;
}
if (!FuncInfo.SEHUnwindMap.empty()) {
for (SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
MCSymbol *ExceptOrFinally =
UME.Handler.get<MachineBasicBlock *>()->getSymbol();
OS.EmitIntValue(UME.ToState, 4); // ToState
OS.EmitValue(create32bitRef(UME.Filter), 4); // Filter
OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally
}
return;
}
// FIXME: The following code is for the old landingpad-based SEH
// implementation. Remove it when possible.
// Build a list of pointers to LandingPadInfos and then sort by WinEHState.
const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
SmallVector<const LandingPadInfo *, 4> LPads;
LPads.reserve((PadInfos.size()));
for (const LandingPadInfo &LPInfo : PadInfos)
LPads.push_back(&LPInfo);
std::sort(LPads.begin(), LPads.end(),
[](const LandingPadInfo *L, const LandingPadInfo *R) {
return L->WinEHState < R->WinEHState;
});
// For each action in each lpad, emit one of these:
// struct ScopeTableEntry {
// int32_t EnclosingLevel;
// int32_t (__cdecl *Filter)();
// void *HandlerOrFinally;
// };
//
// The "outermost" action will use BaseState as its enclosing level. Each
// other action will refer to the previous state as its enclosing level.
int CurState = 0;
for (const LandingPadInfo *LPInfo : LPads) {
int EnclosingLevel = BaseState;
assert(CurState + int(LPInfo->SEHHandlers.size()) - 1 ==
LPInfo->WinEHState &&
"gaps in the SEH scope table");
for (auto I = LPInfo->SEHHandlers.rbegin(), E = LPInfo->SEHHandlers.rend();
I != E; ++I) {
const SEHHandler &Handler = *I;
const BlockAddress *BA = Handler.RecoverBA;
const Function *F = Handler.FilterOrFinally;
assert(F && "cannot catch all in 32-bit SEH without filter function");
const MCExpr *FilterOrNull =
create32bitRef(BA ? Asm->getSymbol(F) : nullptr);
const MCExpr *ExceptOrFinally = create32bitRef(
BA ? Asm->GetBlockAddressSymbol(BA) : Asm->getSymbol(F));
OS.EmitIntValue(EnclosingLevel, 4);
OS.EmitValue(FilterOrNull, 4);
OS.EmitValue(ExceptOrFinally, 4);
// The next state unwinds to this state.
EnclosingLevel = CurState;
CurState++;
}
}
}
Reference in New Issue View Git Blame Copy Permalink