//
//===----------------------------------------------------------------------===//
//
-// This file contains support for writing dwarf exception info into asm files.
+// This file contains support for writing DWARF exception info into asm files.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineLocation.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/Target/TargetAsmInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/Dwarf.h"
+#include "llvm/Support/Mangler.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
using namespace llvm;
static TimerGroup &getDwarfTimerGroup() {
- static TimerGroup DwarfTimerGroup("Dwarf Exception");
+ static TimerGroup DwarfTimerGroup("DWARF Exception");
return DwarfTimerGroup;
}
DwarfException::DwarfException(raw_ostream &OS, AsmPrinter *A,
- const TargetAsmInfo *T)
+ const MCAsmInfo *T)
: Dwarf(OS, A, T, "eh"), shouldEmitTable(false), shouldEmitMoves(false),
shouldEmitTableModule(false), shouldEmitMovesModule(false),
ExceptionTimer(0) {
- if (TimePassesIsEnabled)
- ExceptionTimer = new Timer("Dwarf Exception Writer",
+ if (TimePassesIsEnabled)
+ ExceptionTimer = new Timer("DWARF Exception Writer",
getDwarfTimerGroup());
}
delete ExceptionTimer;
}
-void DwarfException::EmitCommonEHFrame(const Function *Personality,
- unsigned Index) {
+/// SizeOfEncodedValue - Return the size of the encoding in bytes.
+unsigned DwarfException::SizeOfEncodedValue(unsigned Encoding) {
+ if (Encoding == dwarf::DW_EH_PE_omit)
+ return 0;
+
+ switch (Encoding & 0x07) {
+ case dwarf::DW_EH_PE_absptr:
+ return TD->getPointerSize();
+ case dwarf::DW_EH_PE_udata2:
+ return 2;
+ case dwarf::DW_EH_PE_udata4:
+ return 4;
+ case dwarf::DW_EH_PE_udata8:
+ return 8;
+ }
+
+ assert(0 && "Invalid encoded value.");
+ return 0;
+}
+
+/// EmitCIE - Emit a Common Information Entry (CIE). This holds information that
+/// is shared among many Frame Description Entries. There is at least one CIE
+/// in every non-empty .debug_frame section.
+void DwarfException::EmitCIE(const Function *PersonalityFn, unsigned Index) {
// Size and sign of stack growth.
int stackGrowth =
Asm->TM.getFrameInfo()->getStackGrowthDirection() ==
TargetFrameInfo::StackGrowsUp ?
TD->getPointerSize() : -TD->getPointerSize();
+ const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
+
// Begin eh frame section.
- Asm->OutStreamer.SwitchSection(Asm->getObjFileLowering().getEHFrameSection());
-
- if (TAI->is_EHSymbolPrivate())
- O << TAI->getPrivateGlobalPrefix();
+ Asm->OutStreamer.SwitchSection(TLOF.getEHFrameSection());
+ if (MAI->is_EHSymbolPrivate())
+ O << MAI->getPrivateGlobalPrefix();
O << "EH_frame" << Index << ":\n";
+
EmitLabel("section_eh_frame", Index);
// Define base labels.
Asm->EOL("CIE Version");
// The personality presence indicates that language specific information will
- // show up in the eh frame.
- Asm->EmitString(Personality ? "zPLR" : "zR");
+ // show up in the eh frame. Find out how we are supposed to lower the
+ // personality function reference:
+ const MCExpr *PersonalityRef = 0;
+ bool IsPersonalityIndirect = false, IsPersonalityPCRel = false;
+ if (PersonalityFn) {
+ // FIXME: HANDLE STATIC CODEGEN MODEL HERE.
+
+ // In non-static mode, ask the object file how to represent this reference.
+ PersonalityRef =
+ TLOF.getSymbolForDwarfGlobalReference(PersonalityFn, Asm->Mang,
+ Asm->MMI,
+ IsPersonalityIndirect,
+ IsPersonalityPCRel);
+ }
+
+ unsigned PerEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
+ if (IsPersonalityIndirect)
+ PerEncoding |= dwarf::DW_EH_PE_indirect;
+ unsigned LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
+ unsigned FDEEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
+
+ char Augmentation[5] = { 0 };
+ unsigned AugmentationSize = 0;
+ char *APtr = Augmentation + 1;
+
+ if (PersonalityRef) {
+ // There is a personality function.
+ *APtr++ = 'P';
+ AugmentationSize += 1 + SizeOfEncodedValue(PerEncoding);
+ }
+
+ if (UsesLSDA[Index]) {
+ // An LSDA pointer is in the FDE augmentation.
+ *APtr++ = 'L';
+ ++AugmentationSize;
+ }
+
+ if (FDEEncoding != dwarf::DW_EH_PE_absptr) {
+ // A non-default pointer encoding for the FDE.
+ *APtr++ = 'R';
+ ++AugmentationSize;
+ }
+
+ if (APtr != Augmentation + 1)
+ Augmentation[0] = 'z';
+
+ Asm->EmitString(Augmentation);
Asm->EOL("CIE Augmentation");
// Round out reader.
Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), true));
Asm->EOL("CIE Return Address Column");
- // If there is a personality, we need to indicate the functions location.
- if (Personality) {
- Asm->EmitULEB128Bytes(7);
- Asm->EOL("Augmentation Size");
-
- if (TAI->getNeedsIndirectEncoding()) {
- Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4 |
- dwarf::DW_EH_PE_indirect);
- Asm->EOL("Personality (pcrel sdata4 indirect)");
- } else {
- Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
- Asm->EOL("Personality (pcrel sdata4)");
+ Asm->EmitULEB128Bytes(AugmentationSize);
+ Asm->EOL("Augmentation Size");
+
+ Asm->EmitInt8(PerEncoding);
+ Asm->EOL("Personality", PerEncoding);
+
+ // If there is a personality, we need to indicate the function's location.
+ if (PersonalityRef) {
+ // If the reference to the personality function symbol is not already
+ // pc-relative, then we need to subtract our current address from it. Do
+ // this by emitting a label and subtracting it from the expression we
+ // already have. This is equivalent to emitting "foo - .", but we have to
+ // emit the label for "." directly.
+ if (!IsPersonalityPCRel) {
+ SmallString<64> Name;
+ raw_svector_ostream(Name) << MAI->getPrivateGlobalPrefix()
+ << "personalityref_addr" << Asm->getFunctionNumber() << "_" << Index;
+ MCSymbol *DotSym = Asm->OutContext.GetOrCreateSymbol(Name.str());
+ Asm->OutStreamer.EmitLabel(DotSym);
+
+ PersonalityRef =
+ MCBinaryExpr::CreateSub(PersonalityRef,
+ MCSymbolRefExpr::Create(DotSym,Asm->OutContext),
+ Asm->OutContext);
}
-
- PrintRelDirective(true);
- O << TAI->getPersonalityPrefix();
- Asm->EmitExternalGlobal((const GlobalVariable *)(Personality));
- O << TAI->getPersonalitySuffix();
- if (strcmp(TAI->getPersonalitySuffix(), "+4@GOTPCREL"))
- O << "-" << TAI->getPCSymbol();
+
+ O << MAI->getData32bitsDirective();
+ PersonalityRef->print(O, MAI);
Asm->EOL("Personality");
- Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
- Asm->EOL("LSDA Encoding (pcrel sdata4)");
-
- Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
- Asm->EOL("FDE Encoding (pcrel sdata4)");
- } else {
- Asm->EmitULEB128Bytes(1);
- Asm->EOL("Augmentation Size");
+ Asm->EmitInt8(LSDAEncoding);
+ Asm->EOL("LSDA Encoding", LSDAEncoding);
- Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
- Asm->EOL("FDE Encoding (pcrel sdata4)");
+ Asm->EmitInt8(FDEEncoding);
+ Asm->EOL("FDE Encoding", FDEEncoding);
}
// Indicate locations of general callee saved registers in frame.
// On Darwin the linker honors the alignment of eh_frame, which means it must
// be 8-byte on 64-bit targets to match what gcc does. Otherwise you get
// holes which confuse readers of eh_frame.
- Asm->EmitAlignment(TD->getPointerSize() == sizeof(int32_t) ? 2 : 3,
- 0, 0, false);
+ Asm->EmitAlignment(TD->getPointerSize() == 4 ? 2 : 3, 0, 0, false);
EmitLabel("eh_frame_common_end", Index);
Asm->EOL();
}
-/// EmitEHFrame - Emit function exception frame information.
-///
-void DwarfException::EmitEHFrame(const FunctionEHFrameInfo &EHFrameInfo) {
- assert(!EHFrameInfo.function->hasAvailableExternallyLinkage() &&
+/// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
+void DwarfException::EmitFDE(const FunctionEHFrameInfo &EHFrameInfo) {
+ assert(!EHFrameInfo.function->hasAvailableExternallyLinkage() &&
"Should not emit 'available externally' functions at all");
const Function *TheFunc = EHFrameInfo.function;
-
+
Asm->OutStreamer.SwitchSection(Asm->getObjFileLowering().getEHFrameSection());
-
+
// Externally visible entry into the functions eh frame info. If the
// corresponding function is static, this should not be externally visible.
if (!TheFunc->hasLocalLinkage())
- if (const char *GlobalEHDirective = TAI->getGlobalEHDirective())
+ if (const char *GlobalEHDirective = MAI->getGlobalEHDirective())
O << GlobalEHDirective << EHFrameInfo.FnName << "\n";
// If corresponding function is weak definition, this should be too.
- if (TheFunc->isWeakForLinker() && TAI->getWeakDefDirective())
- O << TAI->getWeakDefDirective() << EHFrameInfo.FnName << "\n";
+ if (TheFunc->isWeakForLinker() && MAI->getWeakDefDirective())
+ O << MAI->getWeakDefDirective() << EHFrameInfo.FnName << "\n";
// If there are no calls then you can't unwind. This may mean we can omit the
// EH Frame, but some environments do not handle weak absolute symbols. If
// info is to be available for non-EH uses.
if (!EHFrameInfo.hasCalls && !UnwindTablesMandatory &&
(!TheFunc->isWeakForLinker() ||
- !TAI->getWeakDefDirective() ||
- TAI->getSupportsWeakOmittedEHFrame())) {
+ !MAI->getWeakDefDirective() ||
+ MAI->getSupportsWeakOmittedEHFrame())) {
O << EHFrameInfo.FnName << " = 0\n";
// This name has no connection to the function, so it might get
// dead-stripped when the function is not, erroneously. Prohibit
// dead-stripping unconditionally.
- if (const char *UsedDirective = TAI->getUsedDirective())
+ if (const char *UsedDirective = MAI->getUsedDirective())
O << UsedDirective << EHFrameInfo.FnName << "\n\n";
} else {
O << EHFrameInfo.FnName << ":\n";
// If there is a personality and landing pads then point to the language
// specific data area in the exception table.
- if (EHFrameInfo.PersonalityIndex) {
- Asm->EmitULEB128Bytes(4);
+ if (MMI->getPersonalities()[0] != NULL) {
+ bool is4Byte = TD->getPointerSize() == sizeof(int32_t);
+
+ Asm->EmitULEB128Bytes(is4Byte ? 4 : 8);
Asm->EOL("Augmentation size");
if (EHFrameInfo.hasLandingPads)
- EmitReference("exception", EHFrameInfo.Number, true, true);
- else
- Asm->EmitInt32((int)0);
+ EmitReference("exception", EHFrameInfo.Number, true, false);
+ else {
+ if (is4Byte)
+ Asm->EmitInt32((int)0);
+ else
+ Asm->EmitInt64((int)0);
+ }
Asm->EOL("Language Specific Data Area");
} else {
Asm->EmitULEB128Bytes(0);
}
// Indicate locations of function specific callee saved registers in frame.
- EmitFrameMoves("eh_func_begin", EHFrameInfo.Number, EHFrameInfo.Moves,
+ EmitFrameMoves("eh_func_begin", EHFrameInfo.Number, EHFrameInfo.Moves,
true);
// On Darwin the linker honors the alignment of eh_frame, which means it
// on unused functions (calling undefined externals) being dead-stripped to
// link correctly. Yes, there really is.
if (MMI->isUsedFunction(EHFrameInfo.function))
- if (const char *UsedDirective = TAI->getUsedDirective())
+ if (const char *UsedDirective = MAI->getUsedDirective())
O << UsedDirective << EHFrameInfo.FnName << "\n\n";
}
+
+ Asm->EOL();
}
/// SharedTypeIds - How many leading type ids two landing pads have in common.
ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*> &LandingPads,
SmallVectorImpl<ActionEntry> &Actions,
SmallVectorImpl<unsigned> &FirstActions) {
+
+ // The action table follows the call-site table in the LSDA. The individual
+ // records are of two types:
+ //
+ // * Catch clause
+ // * Exception specification
+ //
+ // The two record kinds have the same format, with only small differences.
+ // They are distinguished by the "switch value" field: Catch clauses
+ // (TypeInfos) have strictly positive switch values, and exception
+ // specifications (FilterIds) have strictly negative switch values. Value 0
+ // indicates a catch-all clause.
+ //
// Negative type IDs index into FilterIds. Positive type IDs index into
// TypeInfos. The value written for a positive type ID is just the type ID
// itself. For a negative type ID, however, the value written is the
for (std::vector<unsigned>::const_iterator
I = FilterIds.begin(), E = FilterIds.end(); I != E; ++I) {
FilterOffsets.push_back(Offset);
- Offset -= TargetAsmInfo::getULEB128Size(*I);
+ Offset -= MCAsmInfo::getULEB128Size(*I);
}
FirstActions.reserve(LandingPads.size());
const unsigned SizePrevIds = PrevLPI->TypeIds.size();
assert(Actions.size());
PrevAction = &Actions.back();
- SizeAction = TargetAsmInfo::getSLEB128Size(PrevAction->NextAction) +
- TargetAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
+ SizeAction = MCAsmInfo::getSLEB128Size(PrevAction->NextAction) +
+ MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
for (unsigned j = NumShared; j != SizePrevIds; ++j) {
SizeAction -=
- TargetAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
+ MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
SizeAction += -PrevAction->NextAction;
PrevAction = PrevAction->Previous;
}
int TypeID = TypeIds[J];
assert(-1 - TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
- unsigned SizeTypeID = TargetAsmInfo::getSLEB128Size(ValueForTypeID);
+ unsigned SizeTypeID = MCAsmInfo::getSLEB128Size(ValueForTypeID);
int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
- SizeAction = SizeTypeID + TargetAsmInfo::getSLEB128Size(NextAction);
+ SizeAction = SizeTypeID + MCAsmInfo::getSLEB128Size(NextAction);
SizeSiteActions += SizeAction;
- ActionEntry Action = {ValueForTypeID, NextAction, PrevAction};
+ ActionEntry Action = { ValueForTypeID, NextAction, PrevAction };
Actions.push_back(Action);
PrevAction = &Actions.back();
}
FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
} // else identical - re-use previous FirstAction
+ // Information used when created the call-site table. The action record
+ // field of the call site record is the offset of the first associated
+ // action record, relative to the start of the actions table. This value is
+ // biased by 1 (1 in dicating the start of the actions table), and 0
+ // indicates that there are no actions.
FirstActions.push_back(FirstAction);
// Compute this sites contribution to size.
}
/// ComputeCallSiteTable - Compute the call-site table. The entry for an invoke
-/// has a try-range containing the call, a non-zero landing pad and an
+/// has a try-range containing the call, a non-zero landing pad, and an
/// appropriate action. The entry for an ordinary call has a try-range
/// containing the call and zero for the landing pad and the action. Calls
/// marked 'nounwind' have no entry and must not be contained in the try-range
// Nope, it was just some random label.
continue;
- PadRange P = L->second;
+ const PadRange &P = L->second;
const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
"Inconsistent landing pad map!");
- // For Dwarf exception handling (SjLj handling doesn't use this)
- // If some instruction between the previous try-range and this one may
- // throw, create a call-site entry with no landing pad for the region
- // between the try-ranges.
+ // For Dwarf exception handling (SjLj handling doesn't use this). If some
+ // instruction between the previous try-range and this one may throw,
+ // create a call-site entry with no landing pad for the region between the
+ // try-ranges.
if (SawPotentiallyThrowing &&
- TAI->getExceptionHandlingType() == ExceptionHandling::Dwarf) {
- CallSiteEntry Site = {LastLabel, BeginLabel, 0, 0};
+ MAI->getExceptionHandlingType() == ExceptionHandling::Dwarf) {
+ CallSiteEntry Site = { LastLabel, BeginLabel, 0, 0 };
CallSites.push_back(Site);
PreviousIsInvoke = false;
}
if (LandingPad->LandingPadLabel) {
// This try-range is for an invoke.
- CallSiteEntry Site = {BeginLabel, LastLabel,
- LandingPad->LandingPadLabel,
- FirstActions[P.PadIndex]};
-
- // Try to merge with the previous call-site.
- if (PreviousIsInvoke) {
+ CallSiteEntry Site = {
+ BeginLabel,
+ LastLabel,
+ LandingPad->LandingPadLabel,
+ FirstActions[P.PadIndex]
+ };
+
+ // Try to merge with the previous call-site. SJLJ doesn't do this
+ if (PreviousIsInvoke &&
+ MAI->getExceptionHandlingType() == ExceptionHandling::Dwarf) {
CallSiteEntry &Prev = CallSites.back();
if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
// Extend the range of the previous entry.
// function may throw, create a call-site entry with no landing pad for the
// region following the try-range.
if (SawPotentiallyThrowing &&
- TAI->getExceptionHandlingType() == ExceptionHandling::Dwarf) {
- CallSiteEntry Site = {LastLabel, 0, 0, 0};
+ MAI->getExceptionHandlingType() == ExceptionHandling::Dwarf) {
+ CallSiteEntry Site = { LastLabel, 0, 0, 0 };
CallSites.push_back(Site);
}
}
/// The general organization of the table is complex, but the basic concepts are
/// easy. First there is a header which describes the location and organization
/// of the three components that follow.
-///
+///
/// 1. The landing pad site information describes the range of code covered by
/// the try. In our case it's an accumulation of the ranges covered by the
/// invokes in the try. There is also a reference to the landing pad that
/// handles the exception once processed. Finally an index into the actions
/// table.
-/// 2. The action table, in our case, is composed of pairs of type ids and next
+/// 2. The action table, in our case, is composed of pairs of type IDs and next
/// action offset. Starting with the action index from the landing pad
-/// site, each type Id is checked for a match to the current exception. If
+/// site, each type ID is checked for a match to the current exception. If
/// it matches then the exception and type id are passed on to the landing
/// pad. Otherwise the next action is looked up. This chain is terminated
-/// with a next action of zero. If no type id is found the the frame is
+/// with a next action of zero. If no type id is found then the frame is
/// unwound and handling continues.
-/// 3. Type id table contains references to all the C++ typeinfo for all
-/// catches in the function. This tables is reversed indexed base 1.
+/// 3. Type ID table contains references to all the C++ typeinfo for all
+/// catches in the function. This tables is reverse indexed base 1.
void DwarfException::EmitExceptionTable() {
const std::vector<GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
// landing pad site.
SmallVector<ActionEntry, 32> Actions;
SmallVector<unsigned, 64> FirstActions;
- unsigned SizeActions = ComputeActionsTable(LandingPads, Actions, FirstActions);
+ unsigned SizeActions = ComputeActionsTable(LandingPads, Actions,
+ FirstActions);
// Invokes and nounwind calls have entries in PadMap (due to being bracketed
// by try-range labels when lowered). Ordinary calls do not, so appropriate
- // try-ranges for them need be deduced when using Dwarf exception handling.
+ // try-ranges for them need be deduced when using DWARF exception handling.
RangeMapType PadMap;
for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
const LandingPadInfo *LandingPad = LandingPads[i];
// Final tallies.
// Call sites.
- const unsigned SiteStartSize = sizeof(int32_t); // DW_EH_PE_udata4
- const unsigned SiteLengthSize = sizeof(int32_t); // DW_EH_PE_udata4
- const unsigned LandingPadSize = sizeof(int32_t); // DW_EH_PE_udata4
+ const unsigned SiteStartSize = SizeOfEncodedValue(dwarf::DW_EH_PE_udata4);
+ const unsigned SiteLengthSize = SizeOfEncodedValue(dwarf::DW_EH_PE_udata4);
+ const unsigned LandingPadSize = SizeOfEncodedValue(dwarf::DW_EH_PE_udata4);
+ bool IsSJLJ = MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
+ bool HaveTTData = IsSJLJ ? (!TypeInfos.empty() || !FilterIds.empty()) : true;
unsigned SizeSites;
- bool HaveTTData = (TAI->getExceptionHandlingType() == ExceptionHandling::SjLj)
- ? (!TypeInfos.empty() || !FilterIds.empty()) : true;
-
-
- if (TAI->getExceptionHandlingType() == ExceptionHandling::SjLj) {
+ if (IsSJLJ)
SizeSites = 0;
- } else
+ else
SizeSites = CallSites.size() *
(SiteStartSize + SiteLengthSize + LandingPadSize);
+
for (unsigned i = 0, e = CallSites.size(); i < e; ++i) {
- SizeSites += TargetAsmInfo::getULEB128Size(CallSites[i].Action);
- if (TAI->getExceptionHandlingType() == ExceptionHandling::SjLj)
- SizeSites += TargetAsmInfo::getULEB128Size(i);
+ SizeSites += MCAsmInfo::getULEB128Size(CallSites[i].Action);
+ if (IsSJLJ)
+ SizeSites += MCAsmInfo::getULEB128Size(i);
}
- // Type infos.
- const unsigned TypeInfoSize = TD->getPointerSize(); // DW_EH_PE_absptr
- unsigned SizeTypes = TypeInfos.size() * TypeInfoSize;
- unsigned TypeOffset = sizeof(int8_t) + // Call site format
- TargetAsmInfo::getULEB128Size(SizeSites) + // Call-site table length
- SizeSites + SizeActions + SizeTypes;
-
- unsigned TotalSize = sizeof(int8_t) + // LPStart format
- sizeof(int8_t) + // TType format
- (HaveTTData ?
- TargetAsmInfo::getULEB128Size(TypeOffset) : 0) + // TType base offset
- TypeOffset;
-
- unsigned SizeAlign = (4 - TotalSize) & 3;
-
- // Begin the exception table.
+ // Type infos.
const MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
- Asm->OutStreamer.SwitchSection(LSDASection);
- Asm->EmitAlignment(2, 0, 0, false);
- O << "GCC_except_table" << SubprogramCount << ":\n";
-
- for (unsigned i = 0; i != SizeAlign; ++i) {
- Asm->EmitInt8(0);
- Asm->EOL("Padding");
- }
-
- EmitLabel("exception", SubprogramCount);
- if (TAI->getExceptionHandlingType() == ExceptionHandling::SjLj) {
- std::string SjLjName = "_lsda_";
- SjLjName += MF->getFunction()->getName().str();
- EmitLabel(SjLjName.c_str(), 0);
- }
+ unsigned TTypeFormat;
+ unsigned TypeFormatSize;
- // Emit the header.
- Asm->EmitInt8(dwarf::DW_EH_PE_omit);
- Asm->EOL("LPStart format (DW_EH_PE_omit)");
-
-#if 0
- if (TypeInfos.empty() && FilterIds.empty()) {
- // If there are no typeinfos or filters, there is nothing to emit, optimize
- // by specifying the "omit" encoding.
- Asm->EmitInt8(dwarf::DW_EH_PE_omit);
- Asm->EOL("TType format (DW_EH_PE_omit)");
+ if (!HaveTTData) {
+ // For SjLj exceptions, if there is no TypeInfo, then we just explicitly say
+ // that we're omitting that bit.
+ TTypeFormat = dwarf::DW_EH_PE_omit;
+ TypeFormatSize = SizeOfEncodedValue(dwarf::DW_EH_PE_absptr);
} else {
// Okay, we have actual filters or typeinfos to emit. As such, we need to
// pick a type encoding for them. We're about to emit a list of pointers to
// mode, this reference will require a relocation by the dynamic linker.
//
// Because of this, we have a couple of options:
+ //
// 1) If we are in -static mode, we can always use an absolute reference
// from the LSDA, because the static linker will resolve it.
+ //
// 2) Otherwise, if the LSDA section is writable, we can output the direct
// reference to the typeinfo and allow the dynamic linker to relocate
// it. Since it is in a writable section, the dynamic linker won't
// have a problem.
+ //
// 3) Finally, if we're in PIC mode and the LDSA section isn't writable,
// we need to use some form of indirection. For example, on Darwin,
// we can output a statically-relocatable reference to a dyld stub. The
// need to tell the personality function of the unwinder to indirect
// through the dyld stub.
//
- // FIXME: When this is actually implemented, we'll have to emit the stubs
+ // FIXME: When (3) is actually implemented, we'll have to emit the stubs
// somewhere. This predicate should be moved to a shared location that is
// in target-independent code.
//
- if (LSDASection->isWritable() ||
- Asm->TM.getRelocationModel() == Reloc::Static) {
- Asm->EmitInt8(DW_EH_PE_absptr);
- Asm->EOL("TType format (DW_EH_PE_absptr)");
- } else {
- Asm->EmitInt8(DW_EH_PE_pcrel | DW_EH_PE_indirect | DW_EH_PE_sdata4);
- Asm->EOL("TType format (DW_EH_PE_pcrel | DW_EH_PE_indirect"
- " | DW_EH_PE_sdata4)");
- }
- Asm->EmitULEB128Bytes(TypeOffset);
- Asm->EOL("TType base offset");
+ if (LSDASection->getKind().isWriteable() ||
+ Asm->TM.getRelocationModel() == Reloc::Static)
+ TTypeFormat = dwarf::DW_EH_PE_absptr;
+ else
+ TTypeFormat = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
+ dwarf::DW_EH_PE_sdata4;
+
+ TypeFormatSize = SizeOfEncodedValue(TTypeFormat);
}
-#else
- // For SjLj exceptions, if there is no TypeInfo, then we just explicitly
- // say that we're omitting that bit.
- // FIXME: does this apply to Dwarf also? The above #if 0 implies yes?
- if (!HaveTTData) {
- Asm->EmitInt8(dwarf::DW_EH_PE_omit);
- Asm->EOL("TType format (DW_EH_PE_omit)");
- } else {
- Asm->EmitInt8(dwarf::DW_EH_PE_absptr);
- Asm->EOL("TType format (DW_EH_PE_absptr)");
- Asm->EmitULEB128Bytes(TypeOffset);
- Asm->EOL("TType base offset");
+
+ // Begin the exception table.
+ Asm->OutStreamer.SwitchSection(LSDASection);
+ Asm->EmitAlignment(2, 0, 0, false);
+
+ O << "GCC_except_table" << SubprogramCount << ":\n";
+
+ // The type infos need to be aligned. GCC does this by inserting padding just
+ // before the type infos. However, this changes the size of the exception
+ // table, so you need to take this into account when you output the exception
+ // table size. However, the size is output using a variable length encoding.
+ // So by increasing the size by inserting padding, you may increase the number
+ // of bytes used for writing the size. If it increases, say by one byte, then
+ // you now need to output one less byte of padding to get the type infos
+ // aligned. However this decreases the size of the exception table. This
+ // changes the value you have to output for the exception table size. Due to
+ // the variable length encoding, the number of bytes used for writing the
+ // length may decrease. If so, you then have to increase the amount of
+ // padding. And so on. If you look carefully at the GCC code you will see that
+ // it indeed does this in a loop, going on and on until the values stabilize.
+ // We chose another solution: don't output padding inside the table like GCC
+ // does, instead output it before the table.
+ unsigned SizeTypes = TypeInfos.size() * TypeFormatSize;
+ unsigned TyOffset = sizeof(int8_t) + // Call site format
+ MCAsmInfo::getULEB128Size(SizeSites) + // Call-site table length
+ SizeSites + SizeActions + SizeTypes;
+ unsigned TotalSize = sizeof(int8_t) + // LPStart format
+ sizeof(int8_t) + // TType format
+ (HaveTTData ?
+ MCAsmInfo::getULEB128Size(TyOffset) : 0) + // TType base offset
+ TyOffset;
+ unsigned SizeAlign = (4 - TotalSize) & 3;
+
+ for (unsigned i = 0; i != SizeAlign; ++i) {
+ Asm->EmitInt8(0);
+ Asm->EOL("Padding");
+ }
+
+ EmitLabel("exception", SubprogramCount);
+
+ if (IsSJLJ) {
+ SmallString<16> LSDAName;
+ raw_svector_ostream(LSDAName) << MAI->getPrivateGlobalPrefix() <<
+ "_LSDA_" << Asm->getFunctionNumber();
+ O << LSDAName.str() << ":\n";
}
-#endif
- // SjLj Exception handilng
- if (TAI->getExceptionHandlingType() == ExceptionHandling::SjLj) {
+ // Emit the header.
+ Asm->EmitInt8(dwarf::DW_EH_PE_omit);
+ Asm->EOL("@LPStart format", dwarf::DW_EH_PE_omit);
+
+ Asm->EmitInt8(TTypeFormat);
+ Asm->EOL("@TType format", TTypeFormat);
+
+ if (HaveTTData) {
+ Asm->EmitULEB128Bytes(TyOffset);
+ Asm->EOL("@TType base offset");
+ }
+
+ // SjLj Exception handling
+ if (IsSJLJ) {
Asm->EmitInt8(dwarf::DW_EH_PE_udata4);
- Asm->EOL("Call site format (DW_EH_PE_udata4)");
+ Asm->EOL("Call site format", dwarf::DW_EH_PE_udata4);
Asm->EmitULEB128Bytes(SizeSites);
- Asm->EOL("Call-site table length");
+ Asm->EOL("Call site table length");
// Emit the landing pad site information.
unsigned idx = 0;
for (SmallVectorImpl<CallSiteEntry>::const_iterator
I = CallSites.begin(), E = CallSites.end(); I != E; ++I, ++idx) {
const CallSiteEntry &S = *I;
+
+ // Offset of the landing pad, counted in 16-byte bundles relative to the
+ // @LPStart address.
Asm->EmitULEB128Bytes(idx);
Asm->EOL("Landing pad");
+
+ // Offset of the first associated action record, relative to the start of
+ // the action table. This value is biased by 1 (1 indicates the start of
+ // the action table), and 0 indicates that there are no actions.
Asm->EmitULEB128Bytes(S.Action);
Asm->EOL("Action");
}
} else {
// DWARF Exception handling
- assert(TAI->getExceptionHandlingType() == ExceptionHandling::Dwarf);
+ assert(MAI->getExceptionHandlingType() == ExceptionHandling::Dwarf);
+
+ // The call-site table is a list of all call sites that may throw an
+ // exception (including C++ 'throw' statements) in the procedure
+ // fragment. It immediately follows the LSDA header. Each entry indicates,
+ // for a given call, the first corresponding action record and corresponding
+ // landing pad.
+ //
+ // The table begins with the number of bytes, stored as an LEB128
+ // compressed, unsigned integer. The records immediately follow the record
+ // count. They are sorted in increasing call-site address. Each record
+ // indicates:
+ //
+ // * The position of the call-site.
+ // * The position of the landing pad.
+ // * The first action record for that call site.
+ //
+ // A missing entry in the call-site table indicates that a call is not
+ // supposed to throw.
+ // Emit the landing pad call site table.
Asm->EmitInt8(dwarf::DW_EH_PE_udata4);
- Asm->EOL("Call site format (DW_EH_PE_udata4)");
+ Asm->EOL("Call site format", dwarf::DW_EH_PE_udata4);
Asm->EmitULEB128Bytes(SizeSites);
- Asm->EOL("Call-site table length");
+ Asm->EOL("Call site table size");
- // Emit the landing pad site information.
for (SmallVectorImpl<CallSiteEntry>::const_iterator
I = CallSites.begin(), E = CallSites.end(); I != E; ++I) {
const CallSiteEntry &S = *I;
BeginNumber = S.BeginLabel;
}
+ // Offset of the call site relative to the previous call site, counted in
+ // number of 16-byte bundles. The first call site is counted relative to
+ // the start of the procedure fragment.
EmitSectionOffset(BeginTag, "eh_func_begin", BeginNumber, SubprogramCount,
true, true);
Asm->EOL("Region start");
Asm->EOL("Region length");
+ // Offset of the landing pad, counted in 16-byte bundles relative to the
+ // @LPStart address.
if (!S.PadLabel)
Asm->EmitInt32(0);
else
Asm->EOL("Landing pad");
+ // Offset of the first associated action record, relative to the start of
+ // the action table. This value is biased by 1 (1 indicates the start of
+ // the action table), and 0 indicates that there are no actions.
Asm->EmitULEB128Bytes(S.Action);
Asm->EOL("Action");
}
}
- // Emit the actions.
+ // Emit the Action Table.
for (SmallVectorImpl<ActionEntry>::const_iterator
I = Actions.begin(), E = Actions.end(); I != E; ++I) {
const ActionEntry &Action = *I;
+
+ // Type Filter
+ //
+ // Used by the runtime to match the type of the thrown exception to the
+ // type of the catch clauses or the types in the exception specification.
+
Asm->EmitSLEB128Bytes(Action.ValueForTypeID);
Asm->EOL("TypeInfo index");
+
+ // Action Record
+ //
+ // Self-relative signed displacement in bytes of the next action record,
+ // or 0 if there is no next action record.
+
Asm->EmitSLEB128Bytes(Action.NextAction);
Asm->EOL("Next action");
}
- // Emit the type ids.
+ // Emit the Catch TypeInfos.
for (std::vector<GlobalVariable *>::const_reverse_iterator
I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
- GlobalVariable *GV = *I;
+ const GlobalVariable *GV = *I;
PrintRelDirective();
if (GV) {
- std::string GLN;
- O << Asm->getGlobalLinkName(GV, GLN);
+ O << Asm->Mang->getMangledName(GV);
} else {
- O << "0";
+ O << "0x0";
}
Asm->EOL("TypeInfo");
}
- // Emit the filter typeids.
+ // Emit the Exception Specifications.
for (std::vector<unsigned>::const_iterator
I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
unsigned TypeID = *I;
Asm->EmitULEB128Bytes(TypeID);
- Asm->EOL("Filter TypeInfo index");
+ if (TypeID != 0)
+ Asm->EOL("Exception specification");
+ else
+ Asm->EOL();
}
Asm->EmitAlignment(2, 0, 0, false);
/// EndModule - Emit all exception information that should come after the
/// content.
void DwarfException::EndModule() {
- if (TAI->getExceptionHandlingType() != ExceptionHandling::Dwarf)
+ if (MAI->getExceptionHandlingType() != ExceptionHandling::Dwarf)
return;
+
+ if (!shouldEmitMovesModule && !shouldEmitTableModule)
+ return;
+
if (TimePassesIsEnabled)
ExceptionTimer->startTimer();
- if (shouldEmitMovesModule || shouldEmitTableModule) {
- const std::vector<Function *> Personalities = MMI->getPersonalities();
- for (unsigned i = 0; i < Personalities.size(); ++i)
- EmitCommonEHFrame(Personalities[i], i);
+ const std::vector<Function *> Personalities = MMI->getPersonalities();
- for (std::vector<FunctionEHFrameInfo>::iterator I = EHFrames.begin(),
- E = EHFrames.end(); I != E; ++I)
- EmitEHFrame(*I);
- }
+ for (unsigned I = 0, E = Personalities.size(); I < E; ++I)
+ EmitCIE(Personalities[I], I);
+
+ for (std::vector<FunctionEHFrameInfo>::iterator
+ I = EHFrames.begin(), E = EHFrames.end(); I != E; ++I)
+ EmitFDE(*I);
if (TimePassesIsEnabled)
ExceptionTimer->stopTimer();
}
-/// BeginFunction - Gather pre-function exception information. Assumes being
-/// emitted immediately after the function entry point.
+/// BeginFunction - Gather pre-function exception information. Assumes it's
+/// being emitted immediately after the function entry point.
void DwarfException::BeginFunction(MachineFunction *MF) {
+ if (!MMI || !MAI->doesSupportExceptionHandling()) return;
+
if (TimePassesIsEnabled)
ExceptionTimer->startTimer();
this->MF = MF;
shouldEmitTable = shouldEmitMoves = false;
- if (MMI && TAI->doesSupportExceptionHandling()) {
- // Map all labels and get rid of any dead landing pads.
- MMI->TidyLandingPads();
+ // Map all labels and get rid of any dead landing pads.
+ MMI->TidyLandingPads();
- // If any landing pads survive, we need an EH table.
- if (MMI->getLandingPads().size())
- shouldEmitTable = true;
+ // If any landing pads survive, we need an EH table.
+ if (!MMI->getLandingPads().empty())
+ shouldEmitTable = true;
- // See if we need frame move info.
- if (!MF->getFunction()->doesNotThrow() || UnwindTablesMandatory)
- shouldEmitMoves = true;
+ // See if we need frame move info.
+ if (!MF->getFunction()->doesNotThrow() || UnwindTablesMandatory)
+ shouldEmitMoves = true;
- if (shouldEmitMoves || shouldEmitTable)
- // Assumes in correct section after the entry point.
- EmitLabel("eh_func_begin", ++SubprogramCount);
- }
+ if (shouldEmitMoves || shouldEmitTable)
+ // Assumes in correct section after the entry point.
+ EmitLabel("eh_func_begin", ++SubprogramCount);
shouldEmitTableModule |= shouldEmitTable;
shouldEmitMovesModule |= shouldEmitMoves;
/// EndFunction - Gather and emit post-function exception information.
///
void DwarfException::EndFunction() {
- if (TimePassesIsEnabled)
+ if (!shouldEmitMoves && !shouldEmitTable) return;
+
+ if (TimePassesIsEnabled)
ExceptionTimer->startTimer();
- if (shouldEmitMoves || shouldEmitTable) {
- EmitLabel("eh_func_end", SubprogramCount);
- EmitExceptionTable();
-
- // Save EH frame information
- EHFrames.push_back(
- FunctionEHFrameInfo(getAsm()->getCurrentFunctionEHName(MF),
- SubprogramCount,
- MMI->getPersonalityIndex(),
- MF->getFrameInfo()->hasCalls(),
- !MMI->getLandingPads().empty(),
- MMI->getFrameMoves(),
- MF->getFunction()));
- }
+ EmitLabel("eh_func_end", SubprogramCount);
+ EmitExceptionTable();
- if (TimePassesIsEnabled)
+ std::string FunctionEHName =
+ Asm->Mang->getMangledName(MF->getFunction(), ".eh",
+ Asm->MAI->is_EHSymbolPrivate());
+
+ // Save EH frame information
+ EHFrames.push_back(FunctionEHFrameInfo(FunctionEHName, SubprogramCount,
+ MMI->getPersonalityIndex(),
+ MF->getFrameInfo()->hasCalls(),
+ !MMI->getLandingPads().empty(),
+ MMI->getFrameMoves(),
+ MF->getFunction()));
+
+ // Record if this personality index uses a landing pad.
+ UsesLSDA[MMI->getPersonalityIndex()] |= !MMI->getLandingPads().empty();
+
+ if (TimePassesIsEnabled)
ExceptionTimer->stopTimer();
}
projects / oota-llvm.git / blobdiff