Check in LLVM r95781.
diff --git a/lib/CodeGen/AsmPrinter/DwarfException.cpp b/lib/CodeGen/AsmPrinter/DwarfException.cpp
new file mode 100644
index 0000000..b6801dc
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/DwarfException.cpp
@@ -0,0 +1,1021 @@
+//===-- CodeGen/AsmPrinter/DwarfException.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 DWARF exception info into asm files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DwarfException.h"
+#include "llvm/Module.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#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/MC/MCSymbol.h"
+#include "llvm/Target/Mangler.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/FormattedStream.h"
+#include "llvm/Support/Timer.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Twine.h"
+using namespace llvm;
+
+DwarfException::DwarfException(raw_ostream &OS, AsmPrinter *A,
+ const MCAsmInfo *T)
+ : DwarfPrinter(OS, A, T, "eh"), shouldEmitTable(false),shouldEmitMoves(false),
+ shouldEmitTableModule(false), shouldEmitMovesModule(false),
+ ExceptionTimer(0) {
+ if (TimePassesIsEnabled)
+ ExceptionTimer = new Timer("DWARF Exception Writer");
+}
+
+DwarfException::~DwarfException() {
+ delete ExceptionTimer;
+}
+
+/// 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;
+}
+
+/// CreateLabelDiff - Emit a label and subtract it from the expression we
+/// already have. This is equivalent to emitting "foo - .", but we have to emit
+/// the label for "." directly.
+const MCExpr *DwarfException::CreateLabelDiff(const MCExpr *ExprRef,
+ const char *LabelName,
+ unsigned Index) {
+ SmallString<64> Name;
+ raw_svector_ostream(Name) << MAI->getPrivateGlobalPrefix()
+ << LabelName << Asm->getFunctionNumber()
+ << "_" << Index;
+ MCSymbol *DotSym = Asm->OutContext.GetOrCreateSymbol(Name.str());
+ Asm->OutStreamer.EmitLabel(DotSym);
+
+ return MCBinaryExpr::CreateSub(ExprRef,
+ MCSymbolRefExpr::Create(DotSym,
+ Asm->OutContext),
+ Asm->OutContext);
+}
+
+/// 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(TLOF.getEHFrameSection());
+
+ if (MAI->is_EHSymbolPrivate())
+ O << MAI->getPrivateGlobalPrefix();
+ O << "EH_frame" << Index << ":\n";
+
+ EmitLabel("section_eh_frame", Index);
+
+ // Define base labels.
+ EmitLabel("eh_frame_common", Index);
+
+ // Define the eh frame length.
+ EmitDifference("eh_frame_common_end", Index,
+ "eh_frame_common_begin", Index, true);
+ EOL("Length of Common Information Entry");
+
+ // EH frame header.
+ EmitLabel("eh_frame_common_begin", Index);
+ if (Asm->VerboseAsm) Asm->OutStreamer.AddComment("CIE Identifier Tag");
+ Asm->OutStreamer.EmitIntValue(0, 4/*size*/, 0/*addrspace*/);
+ if (Asm->VerboseAsm) Asm->OutStreamer.AddComment("DW_CIE_VERSION");
+ Asm->OutStreamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1/*size*/, 0/*addr*/);
+
+ // The personality presence indicates that language specific information will
+ // 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[6] = { 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->OutStreamer.EmitBytes(StringRef(Augmentation, strlen(Augmentation)+1),0);
+ EOL("CIE Augmentation");
+
+ // Round out reader.
+ EmitULEB128(1, "CIE Code Alignment Factor");
+ EmitSLEB128(stackGrowth, "CIE Data Alignment Factor");
+ Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), true));
+ EOL("CIE Return Address Column");
+
+ EmitULEB128(AugmentationSize, "Augmentation Size");
+ EmitEncodingByte(PerEncoding, "Personality");
+
+ // If there is a personality, we need to indicate the function's location.
+ if (PersonalityRef) {
+ if (!IsPersonalityPCRel)
+ PersonalityRef = CreateLabelDiff(PersonalityRef, "personalityref_addr",
+ Index);
+
+ O << MAI->getData32bitsDirective() << *PersonalityRef;
+ EOL("Personality");
+
+ EmitEncodingByte(LSDAEncoding, "LSDA");
+ EmitEncodingByte(FDEEncoding, "FDE");
+ }
+
+ // Indicate locations of general callee saved registers in frame.
+ std::vector<MachineMove> Moves;
+ RI->getInitialFrameState(Moves);
+ EmitFrameMoves(NULL, 0, Moves, true);
+
+ // 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() == 4 ? 2 : 3, 0, 0, false);
+ EmitLabel("eh_frame_common_end", Index);
+ Asm->O << '\n';
+}
+
+/// 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 = MAI->getGlobalEHDirective())
+ O << GlobalEHDirective << *EHFrameInfo.FunctionEHSym << '\n';
+
+ // If corresponding function is weak definition, this should be too.
+ if (TheFunc->isWeakForLinker() && MAI->getWeakDefDirective())
+ O << MAI->getWeakDefDirective() << *EHFrameInfo.FunctionEHSym << '\n';
+
+ // If corresponding function is hidden, this should be too.
+ if (TheFunc->hasHiddenVisibility())
+ if (MCSymbolAttr HiddenAttr = MAI->getHiddenVisibilityAttr())
+ Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
+ HiddenAttr);
+
+ // 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
+ // UnwindTablesMandatory is set we cannot do this optimization; the unwind
+ // info is to be available for non-EH uses.
+ if (!EHFrameInfo.hasCalls && !UnwindTablesMandatory &&
+ (!TheFunc->isWeakForLinker() ||
+ !MAI->getWeakDefDirective() ||
+ MAI->getSupportsWeakOmittedEHFrame())) {
+ O << *EHFrameInfo.FunctionEHSym << " = 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 (MAI->hasNoDeadStrip())
+ Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
+ MCSA_NoDeadStrip);
+ } else {
+ O << *EHFrameInfo.FunctionEHSym << ":\n";
+
+ // EH frame header.
+ EmitDifference("eh_frame_end", EHFrameInfo.Number,
+ "eh_frame_begin", EHFrameInfo.Number, true);
+ EOL("Length of Frame Information Entry");
+
+ EmitLabel("eh_frame_begin", EHFrameInfo.Number);
+
+ EmitSectionOffset("eh_frame_begin", "eh_frame_common",
+ EHFrameInfo.Number, EHFrameInfo.PersonalityIndex,
+ true, true, false);
+
+ EOL("FDE CIE offset");
+
+ EmitReference("eh_func_begin", EHFrameInfo.Number, true, true);
+ EOL("FDE initial location");
+ EmitDifference("eh_func_end", EHFrameInfo.Number,
+ "eh_func_begin", EHFrameInfo.Number, true);
+ EOL("FDE address range");
+
+ // If there is a personality and landing pads then point to the language
+ // specific data area in the exception table.
+ if (MMI->getPersonalities()[0] != NULL) {
+
+ if (Asm->TM.getLSDAEncoding() != DwarfLSDAEncoding::EightByte) {
+ EmitULEB128(4, "Augmentation size");
+
+ if (EHFrameInfo.hasLandingPads)
+ EmitReference("exception", EHFrameInfo.Number, true, true);
+ else
+ Asm->OutStreamer.EmitIntValue(0, 4/*size*/, 0/*addrspace*/);
+ } else {
+ EmitULEB128(TD->getPointerSize(), "Augmentation size");
+
+ if (EHFrameInfo.hasLandingPads) {
+ EmitReference("exception", EHFrameInfo.Number, true, false);
+ } else {
+ Asm->OutStreamer.EmitIntValue(0, TD->getPointerSize(),
+ 0/*addrspace*/);
+ }
+ }
+
+ EOL("Language Specific Data Area");
+ } else {
+ EmitULEB128(0, "Augmentation size");
+ }
+
+ // Indicate locations of function specific callee saved registers in frame.
+ EmitFrameMoves("eh_func_begin", EHFrameInfo.Number, EHFrameInfo.Moves,
+ true);
+
+ // 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);
+ EmitLabel("eh_frame_end", EHFrameInfo.Number);
+
+ // If the function is marked used, this table should be also. We cannot
+ // make the mark unconditional in this case, since retaining the table also
+ // retains the function in this case, and there is code around that depends
+ // on unused functions (calling undefined externals) being dead-stripped to
+ // link correctly. Yes, there really is.
+ if (MMI->isUsedFunction(EHFrameInfo.function))
+ if (MAI->hasNoDeadStrip())
+ Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
+ MCSA_NoDeadStrip);
+ }
+ Asm->O << '\n';
+}
+
+/// SharedTypeIds - How many leading type ids two landing pads have in common.
+unsigned DwarfException::SharedTypeIds(const LandingPadInfo *L,
+ const LandingPadInfo *R) {
+ const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
+ unsigned LSize = LIds.size(), RSize = RIds.size();
+ unsigned MinSize = LSize < RSize ? LSize : RSize;
+ unsigned Count = 0;
+
+ for (; Count != MinSize; ++Count)
+ if (LIds[Count] != RIds[Count])
+ return Count;
+
+ return Count;
+}
+
+/// PadLT - Order landing pads lexicographically by type id.
+bool DwarfException::PadLT(const LandingPadInfo *L, const LandingPadInfo *R) {
+ const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
+ unsigned LSize = LIds.size(), RSize = RIds.size();
+ unsigned MinSize = LSize < RSize ? LSize : RSize;
+
+ for (unsigned i = 0; i != MinSize; ++i)
+ if (LIds[i] != RIds[i])
+ return LIds[i] < RIds[i];
+
+ return LSize < RSize;
+}
+
+/// ComputeActionsTable - Compute the actions table and gather the first action
+/// index for each landing pad site.
+unsigned DwarfException::
+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
+ // (negative) byte offset of the corresponding FilterIds entry. The byte
+ // offset is usually equal to the type ID (because the FilterIds entries are
+ // written using a variable width encoding, which outputs one byte per entry
+ // as long as the value written is not too large) but can differ. This kind
+ // of complication does not occur for positive type IDs because type infos are
+ // output using a fixed width encoding. FilterOffsets[i] holds the byte
+ // offset corresponding to FilterIds[i].
+
+ const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
+ SmallVector<int, 16> FilterOffsets;
+ FilterOffsets.reserve(FilterIds.size());
+ int Offset = -1;
+
+ for (std::vector<unsigned>::const_iterator
+ I = FilterIds.begin(), E = FilterIds.end(); I != E; ++I) {
+ FilterOffsets.push_back(Offset);
+ Offset -= MCAsmInfo::getULEB128Size(*I);
+ }
+
+ FirstActions.reserve(LandingPads.size());
+
+ int FirstAction = 0;
+ unsigned SizeActions = 0;
+ const LandingPadInfo *PrevLPI = 0;
+
+ for (SmallVectorImpl<const LandingPadInfo *>::const_iterator
+ I = LandingPads.begin(), E = LandingPads.end(); I != E; ++I) {
+ const LandingPadInfo *LPI = *I;
+ const std::vector<int> &TypeIds = LPI->TypeIds;
+ const unsigned NumShared = PrevLPI ? SharedTypeIds(LPI, PrevLPI) : 0;
+ unsigned SizeSiteActions = 0;
+
+ if (NumShared < TypeIds.size()) {
+ unsigned SizeAction = 0;
+ ActionEntry *PrevAction = 0;
+
+ if (NumShared) {
+ const unsigned SizePrevIds = PrevLPI->TypeIds.size();
+ assert(Actions.size());
+ PrevAction = &Actions.back();
+ SizeAction = MCAsmInfo::getSLEB128Size(PrevAction->NextAction) +
+ MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
+
+ for (unsigned j = NumShared; j != SizePrevIds; ++j) {
+ SizeAction -=
+ MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
+ SizeAction += -PrevAction->NextAction;
+ PrevAction = PrevAction->Previous;
+ }
+ }
+
+ // Compute the actions.
+ for (unsigned J = NumShared, M = TypeIds.size(); J != M; ++J) {
+ int TypeID = TypeIds[J];
+ assert(-1 - TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
+ int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
+ unsigned SizeTypeID = MCAsmInfo::getSLEB128Size(ValueForTypeID);
+
+ int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
+ SizeAction = SizeTypeID + MCAsmInfo::getSLEB128Size(NextAction);
+ SizeSiteActions += SizeAction;
+
+ ActionEntry Action = { ValueForTypeID, NextAction, PrevAction };
+ Actions.push_back(Action);
+ PrevAction = &Actions.back();
+ }
+
+ // Record the first action of the landing pad site.
+ 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.
+ SizeActions += SizeSiteActions;
+
+ PrevLPI = LPI;
+ }
+
+ return SizeActions;
+}
+
+/// CallToNoUnwindFunction - Return `true' if this is a call to a function
+/// marked `nounwind'. Return `false' otherwise.
+bool DwarfException::CallToNoUnwindFunction(const MachineInstr *MI) {
+ assert(MI->getDesc().isCall() && "This should be a call instruction!");
+
+ bool MarkedNoUnwind = false;
+ bool SawFunc = false;
+
+ for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) {
+ const MachineOperand &MO = MI->getOperand(I);
+
+ if (MO.isGlobal()) {
+ if (Function *F = dyn_cast<Function>(MO.getGlobal())) {
+ if (SawFunc) {
+ // Be conservative. If we have more than one function operand for this
+ // call, then we can't make the assumption that it's the callee and
+ // not a parameter to the call.
+ //
+ // FIXME: Determine if there's a way to say that `F' is the callee or
+ // parameter.
+ MarkedNoUnwind = false;
+ break;
+ }
+
+ MarkedNoUnwind = F->doesNotThrow();
+ SawFunc = true;
+ }
+ }
+ }
+
+ return MarkedNoUnwind;
+}
+
+/// 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
+/// 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
+/// of any entry - they form gaps in the table. Entries must be ordered by
+/// try-range address.
+void DwarfException::
+ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
+ const RangeMapType &PadMap,
+ const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
+ const SmallVectorImpl<unsigned> &FirstActions) {
+ // The end label of the previous invoke or nounwind try-range.
+ unsigned LastLabel = 0;
+
+ // 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;
+
+ // Whether the last CallSite entry was for an invoke.
+ bool PreviousIsInvoke = false;
+
+ // Visit all instructions in order of address.
+ for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
+ I != E; ++I) {
+ for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
+ MI != E; ++MI) {
+ if (!MI->isLabel()) {
+ if (MI->getDesc().isCall())
+ SawPotentiallyThrowing |= !CallToNoUnwindFunction(MI);
+
+ continue;
+ }
+
+ unsigned BeginLabel = MI->getOperand(0).getImm();
+ assert(BeginLabel && "Invalid label!");
+
+ // End of the previous try-range?
+ 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!");
+
+ // 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 &&
+ MAI->getExceptionHandlingType() == ExceptionHandling::Dwarf) {
+ CallSiteEntry Site = { LastLabel, BeginLabel, 0, 0 };
+ CallSites.push_back(Site);
+ PreviousIsInvoke = false;
+ }
+
+ LastLabel = LandingPad->EndLabels[P.RangeIndex];
+ assert(BeginLabel && LastLabel && "Invalid landing pad!");
+
+ 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. 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.
+ Prev.EndLabel = Site.EndLabel;
+ continue;
+ }
+ }
+
+ // Otherwise, create a new call-site.
+ if (MAI->getExceptionHandlingType() == ExceptionHandling::Dwarf)
+ CallSites.push_back(Site);
+ else {
+ // SjLj EH must maintain the call sites in the order assigned
+ // to them by the SjLjPrepare pass.
+ unsigned SiteNo = MMI->getCallSiteBeginLabel(BeginLabel);
+ if (CallSites.size() < SiteNo)
+ CallSites.resize(SiteNo);
+ CallSites[SiteNo - 1] = Site;
+ }
+ PreviousIsInvoke = true;
+ } else {
+ // Create a gap.
+ PreviousIsInvoke = false;
+ }
+ }
+ }
+
+ // If some instruction between the previous try-range and the end of the
+ // function may throw, create a call-site entry with no landing pad for the
+ // region following the try-range.
+ if (SawPotentiallyThrowing &&
+ MAI->getExceptionHandlingType() == ExceptionHandling::Dwarf) {
+ CallSiteEntry Site = { LastLabel, 0, 0, 0 };
+ CallSites.push_back(Site);
+ }
+}
+
+/// EmitExceptionTable - Emit landing pads and actions.
+///
+/// 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
+/// 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
+/// 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 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 reverse indexed base 1.
+void DwarfException::EmitExceptionTable() {
+ const std::vector<GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
+ const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
+ const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
+ if (PadInfos.empty()) return;
+
+ // Sort the landing pads in order of their type ids. This is used to fold
+ // duplicate actions.
+ SmallVector<const LandingPadInfo *, 64> LandingPads;
+ LandingPads.reserve(PadInfos.size());
+
+ for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
+ LandingPads.push_back(&PadInfos[i]);
+
+ std::sort(LandingPads.begin(), LandingPads.end(), PadLT);
+
+ // Compute the actions table and gather the first action index for each
+ // landing pad site.
+ SmallVector<ActionEntry, 32> Actions;
+ SmallVector<unsigned, 64> 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.
+ RangeMapType PadMap;
+ for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
+ const LandingPadInfo *LandingPad = LandingPads[i];
+ for (unsigned j = 0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
+ unsigned BeginLabel = LandingPad->BeginLabels[j];
+ assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
+ PadRange P = { i, j };
+ PadMap[BeginLabel] = P;
+ }
+ }
+
+ // Compute the call-site table.
+ SmallVector<CallSiteEntry, 64> CallSites;
+ ComputeCallSiteTable(CallSites, PadMap, LandingPads, FirstActions);
+
+ // Final tallies.
+
+ // Call sites.
+ 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;
+
+ if (IsSJLJ)
+ SizeSites = 0;
+ else
+ SizeSites = CallSites.size() *
+ (SiteStartSize + SiteLengthSize + LandingPadSize);
+
+ for (unsigned i = 0, e = CallSites.size(); i < e; ++i) {
+ SizeSites += MCAsmInfo::getULEB128Size(CallSites[i].Action);
+ if (IsSJLJ)
+ SizeSites += MCAsmInfo::getULEB128Size(i);
+ }
+
+ // Type infos.
+ const MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
+ unsigned TTypeFormat;
+ unsigned TypeFormatSize;
+
+ 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
+ // typeinfo objects at the end of the LSDA. However, unless we're in static
+ // 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
+ // offset to the stub is constant, but the contents are in a section
+ // that is updated by the dynamic linker. This is easy enough, but we
+ // need to tell the personality function of the unwinder to indirect
+ // through the dyld stub.
+ //
+ // 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->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);
+ }
+
+ // 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);
+ EOL("Padding");
+ }
+
+ EmitLabel("exception", SubprogramCount);
+
+ if (IsSJLJ) {
+ SmallString<16> LSDAName;
+ raw_svector_ostream(LSDAName) << MAI->getPrivateGlobalPrefix() <<
+ "_LSDA_" << Asm->getFunctionNumber();
+ O << LSDAName.str() << ":\n";
+ }
+
+ // Emit the header.
+ EmitEncodingByte(dwarf::DW_EH_PE_omit, "@LPStart");
+ EmitEncodingByte(TTypeFormat, "@TType");
+
+ if (HaveTTData)
+ EmitULEB128(TyOffset, "@TType base offset");
+
+ // SjLj Exception handling
+ if (IsSJLJ) {
+ EmitEncodingByte(dwarf::DW_EH_PE_udata4, "Call site");
+ EmitULEB128(SizeSites, "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.
+ EmitULEB128(idx, "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.
+ EmitULEB128(S.Action, "Action");
+ }
+ } else {
+ // DWARF Exception handling
+ 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.
+ EmitEncodingByte(dwarf::DW_EH_PE_udata4, "Call site");
+ EmitULEB128(SizeSites, "Call site table length");
+
+ for (SmallVectorImpl<CallSiteEntry>::const_iterator
+ I = CallSites.begin(), E = CallSites.end(); I != E; ++I) {
+ const CallSiteEntry &S = *I;
+ const char *BeginTag;
+ unsigned BeginNumber;
+
+ if (!S.BeginLabel) {
+ BeginTag = "eh_func_begin";
+ BeginNumber = SubprogramCount;
+ } else {
+ BeginTag = "label";
+ 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);
+ EOL("Region start");
+
+ if (!S.EndLabel)
+ EmitDifference("eh_func_end", SubprogramCount, BeginTag, BeginNumber,
+ true);
+ else
+ EmitDifference("label", S.EndLabel, BeginTag, BeginNumber, true);
+
+ EOL("Region length");
+
+ // Offset of the landing pad, counted in 16-byte bundles relative to the
+ // @LPStart address.
+ if (!S.PadLabel) {
+ Asm->OutStreamer.AddComment("Landing pad");
+ Asm->OutStreamer.EmitIntValue(0, 4/*size*/, 0/*addrspace*/);
+ } else {
+ EmitSectionOffset("label", "eh_func_begin", S.PadLabel, SubprogramCount,
+ true, true);
+ 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.
+ EmitULEB128(S.Action, "Action");
+ }
+ }
+
+ // Emit the Action Table.
+ if (Actions.size() != 0) EOL("-- Action Record Table --");
+ for (SmallVectorImpl<ActionEntry>::const_iterator
+ I = Actions.begin(), E = Actions.end(); I != E; ++I) {
+ const ActionEntry &Action = *I;
+ EOL("Action Record:");
+
+ // 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.
+ EmitSLEB128(Action.ValueForTypeID, " TypeInfo index");
+
+ // Action Record
+ //
+ // Self-relative signed displacement in bytes of the next action record,
+ // or 0 if there is no next action record.
+ EmitSLEB128(Action.NextAction, " Next action");
+ }
+
+ // Emit the Catch TypeInfos.
+ if (TypeInfos.size() != 0) EOL("-- Catch TypeInfos --");
+ for (std::vector<GlobalVariable *>::const_reverse_iterator
+ I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
+ const GlobalVariable *GV = *I;
+ PrintRelDirective();
+
+ if (GV) {
+ O << *Asm->GetGlobalValueSymbol(GV);
+ EOL("TypeInfo");
+ } else {
+ O << "0x0";
+ EOL("");
+ }
+ }
+
+ // Emit the Exception Specifications.
+ if (FilterIds.size() != 0) EOL("-- Filter IDs --");
+ for (std::vector<unsigned>::const_iterator
+ I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
+ unsigned TypeID = *I;
+ EmitULEB128(TypeID, TypeID != 0 ? "Exception specification" : 0);
+ }
+
+ Asm->EmitAlignment(2, 0, 0, false);
+}
+
+/// EndModule - Emit all exception information that should come after the
+/// content.
+void DwarfException::EndModule() {
+ if (MAI->getExceptionHandlingType() != ExceptionHandling::Dwarf)
+ return;
+
+ if (!shouldEmitMovesModule && !shouldEmitTableModule)
+ return;
+
+ if (TimePassesIsEnabled)
+ ExceptionTimer->startTimer();
+
+ const std::vector<Function *> Personalities = MMI->getPersonalities();
+
+ 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 it's
+/// being emitted immediately after the function entry point.
+void DwarfException::BeginFunction(const MachineFunction *MF) {
+ if (!MMI || !MAI->doesSupportExceptionHandling()) return;
+
+ if (TimePassesIsEnabled)
+ ExceptionTimer->startTimer();
+
+ this->MF = MF;
+ shouldEmitTable = shouldEmitMoves = false;
+
+ // 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().empty())
+ shouldEmitTable = 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);
+
+ shouldEmitTableModule |= shouldEmitTable;
+ shouldEmitMovesModule |= shouldEmitMoves;
+
+ if (TimePassesIsEnabled)
+ ExceptionTimer->stopTimer();
+}
+
+/// EndFunction - Gather and emit post-function exception information.
+///
+void DwarfException::EndFunction() {
+ if (!shouldEmitMoves && !shouldEmitTable) return;
+
+ if (TimePassesIsEnabled)
+ ExceptionTimer->startTimer();
+
+ EmitLabel("eh_func_end", SubprogramCount);
+ EmitExceptionTable();
+
+ MCSymbol *FunctionEHSym =
+ Asm->GetSymbolWithGlobalValueBase(MF->getFunction(), ".eh",
+ Asm->MAI->is_EHSymbolPrivate());
+
+ // Save EH frame information
+ EHFrames.push_back(FunctionEHFrameInfo(FunctionEHSym, 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();
+}