mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-17 18:31:04 +00:00
57dba1cf53
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109966 91177308-0d34-0410-b5e6-96231b3b80d8
961 lines
39 KiB
C++
961 lines
39 KiB
C++
//===-- CodeGen/AsmPrinter/DwarfException.cpp - Dwarf Exception Impl ------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains support for writing DWARF exception info into asm files.
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//
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//===----------------------------------------------------------------------===//
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#include "DwarfException.h"
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#include "llvm/Module.h"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineLocation.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/Target/Mangler.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Target/TargetFrameInfo.h"
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#include "llvm/Target/TargetLoweringObjectFile.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetOptions.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/Support/Dwarf.h"
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#include "llvm/Support/FormattedStream.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/ADT/Twine.h"
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using namespace llvm;
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DwarfException::DwarfException(AsmPrinter *A)
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: Asm(A), MMI(Asm->MMI), shouldEmitTable(false), shouldEmitMoves(false),
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shouldEmitTableModule(false), shouldEmitMovesModule(false) {}
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DwarfException::~DwarfException() {}
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/// EmitCIE - Emit a Common Information Entry (CIE). This holds information that
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/// is shared among many Frame Description Entries. There is at least one CIE
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/// in every non-empty .debug_frame section.
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void DwarfException::EmitCIE(const Function *PersonalityFn, unsigned Index) {
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// Size and sign of stack growth.
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int stackGrowth = Asm->getTargetData().getPointerSize();
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if (Asm->TM.getFrameInfo()->getStackGrowthDirection() ==
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TargetFrameInfo::StackGrowsDown)
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stackGrowth *= -1;
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const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
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// Begin eh frame section.
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Asm->OutStreamer.SwitchSection(TLOF.getEHFrameSection());
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MCSymbol *EHFrameSym;
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if (TLOF.isFunctionEHFrameSymbolPrivate())
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EHFrameSym = Asm->GetTempSymbol("EH_frame", Index);
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else
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EHFrameSym = Asm->OutContext.GetOrCreateSymbol(Twine("EH_frame") +
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Twine(Index));
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Asm->OutStreamer.EmitLabel(EHFrameSym);
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Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("section_eh_frame", Index));
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// Define base labels.
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Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_common", Index));
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// Define the eh frame length.
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Asm->OutStreamer.AddComment("Length of Common Information Entry");
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Asm->EmitLabelDifference(Asm->GetTempSymbol("eh_frame_common_end", Index),
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Asm->GetTempSymbol("eh_frame_common_begin", Index),
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4);
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// EH frame header.
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Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_common_begin",Index));
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Asm->OutStreamer.AddComment("CIE Identifier Tag");
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Asm->OutStreamer.EmitIntValue(0, 4/*size*/, 0/*addrspace*/);
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Asm->OutStreamer.AddComment("DW_CIE_VERSION");
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Asm->OutStreamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1/*size*/, 0/*addr*/);
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// The personality presence indicates that language specific information will
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// show up in the eh frame. Find out how we are supposed to lower the
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// personality function reference:
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unsigned LSDAEncoding = TLOF.getLSDAEncoding();
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unsigned FDEEncoding = TLOF.getFDEEncoding();
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unsigned PerEncoding = TLOF.getPersonalityEncoding();
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char Augmentation[6] = { 0 };
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unsigned AugmentationSize = 0;
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char *APtr = Augmentation + 1;
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if (PersonalityFn) {
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// There is a personality function.
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*APtr++ = 'P';
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AugmentationSize += 1 + Asm->GetSizeOfEncodedValue(PerEncoding);
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}
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if (UsesLSDA[Index]) {
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// An LSDA pointer is in the FDE augmentation.
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*APtr++ = 'L';
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++AugmentationSize;
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}
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if (FDEEncoding != dwarf::DW_EH_PE_absptr) {
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// A non-default pointer encoding for the FDE.
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*APtr++ = 'R';
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++AugmentationSize;
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}
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if (APtr != Augmentation + 1)
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Augmentation[0] = 'z';
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Asm->OutStreamer.AddComment("CIE Augmentation");
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Asm->OutStreamer.EmitBytes(StringRef(Augmentation, strlen(Augmentation)+1),0);
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// Round out reader.
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Asm->EmitULEB128(1, "CIE Code Alignment Factor");
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Asm->EmitSLEB128(stackGrowth, "CIE Data Alignment Factor");
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Asm->OutStreamer.AddComment("CIE Return Address Column");
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const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
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Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), true));
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if (Augmentation[0]) {
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Asm->EmitULEB128(AugmentationSize, "Augmentation Size");
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// If there is a personality, we need to indicate the function's location.
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if (PersonalityFn) {
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Asm->EmitEncodingByte(PerEncoding, "Personality");
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Asm->OutStreamer.AddComment("Personality");
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Asm->EmitReference(PersonalityFn, PerEncoding);
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}
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if (UsesLSDA[Index])
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Asm->EmitEncodingByte(LSDAEncoding, "LSDA");
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if (FDEEncoding != dwarf::DW_EH_PE_absptr)
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Asm->EmitEncodingByte(FDEEncoding, "FDE");
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}
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// Indicate locations of general callee saved registers in frame.
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std::vector<MachineMove> Moves;
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RI->getInitialFrameState(Moves);
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Asm->EmitFrameMoves(Moves, 0, true);
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// On Darwin the linker honors the alignment of eh_frame, which means it must
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// be 8-byte on 64-bit targets to match what gcc does. Otherwise you get
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// holes which confuse readers of eh_frame.
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Asm->EmitAlignment(Asm->getTargetData().getPointerSize() == 4 ? 2 : 3);
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Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_common_end", Index));
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}
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/// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
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void DwarfException::EmitFDE(const FunctionEHFrameInfo &EHFrameInfo) {
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assert(!EHFrameInfo.function->hasAvailableExternallyLinkage() &&
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"Should not emit 'available externally' functions at all");
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const Function *TheFunc = EHFrameInfo.function;
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const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
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unsigned LSDAEncoding = TLOF.getLSDAEncoding();
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unsigned FDEEncoding = TLOF.getFDEEncoding();
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Asm->OutStreamer.SwitchSection(TLOF.getEHFrameSection());
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// Externally visible entry into the functions eh frame info. If the
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// corresponding function is static, this should not be externally visible.
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if (!TheFunc->hasLocalLinkage() && TLOF.isFunctionEHSymbolGlobal())
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Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,MCSA_Global);
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// If corresponding function is weak definition, this should be too.
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if (TheFunc->isWeakForLinker() && Asm->MAI->getWeakDefDirective())
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Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
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MCSA_WeakDefinition);
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// If corresponding function is hidden, this should be too.
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if (TheFunc->hasHiddenVisibility())
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if (MCSymbolAttr HiddenAttr = Asm->MAI->getHiddenVisibilityAttr())
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Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
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HiddenAttr);
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// If there are no calls then you can't unwind. This may mean we can omit the
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// EH Frame, but some environments do not handle weak absolute symbols. If
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// UnwindTablesMandatory is set we cannot do this optimization; the unwind
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// info is to be available for non-EH uses.
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if (!EHFrameInfo.adjustsStack && !UnwindTablesMandatory &&
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(!TheFunc->isWeakForLinker() ||
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!Asm->MAI->getWeakDefDirective() ||
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TLOF.getSupportsWeakOmittedEHFrame())) {
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Asm->OutStreamer.EmitAssignment(EHFrameInfo.FunctionEHSym,
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MCConstantExpr::Create(0, Asm->OutContext));
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// This name has no connection to the function, so it might get
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// dead-stripped when the function is not, erroneously. Prohibit
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// dead-stripping unconditionally.
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if (Asm->MAI->hasNoDeadStrip())
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Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
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MCSA_NoDeadStrip);
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} else {
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Asm->OutStreamer.EmitLabel(EHFrameInfo.FunctionEHSym);
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// EH frame header.
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Asm->OutStreamer.AddComment("Length of Frame Information Entry");
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Asm->EmitLabelDifference(
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Asm->GetTempSymbol("eh_frame_end", EHFrameInfo.Number),
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Asm->GetTempSymbol("eh_frame_begin", EHFrameInfo.Number), 4);
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Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_begin",
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EHFrameInfo.Number));
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Asm->OutStreamer.AddComment("FDE CIE offset");
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Asm->EmitLabelDifference(
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Asm->GetTempSymbol("eh_frame_begin", EHFrameInfo.Number),
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Asm->GetTempSymbol("eh_frame_common",
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EHFrameInfo.PersonalityIndex), 4);
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MCSymbol *EHFuncBeginSym =
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Asm->GetTempSymbol("eh_func_begin", EHFrameInfo.Number);
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Asm->OutStreamer.AddComment("FDE initial location");
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Asm->EmitReference(EHFuncBeginSym, FDEEncoding);
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Asm->OutStreamer.AddComment("FDE address range");
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Asm->EmitLabelDifference(Asm->GetTempSymbol("eh_func_end",
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EHFrameInfo.Number),
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EHFuncBeginSym,
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Asm->GetSizeOfEncodedValue(FDEEncoding));
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// If there is a personality and landing pads then point to the language
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// specific data area in the exception table.
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if (MMI->getPersonalities()[0] != NULL) {
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unsigned Size = Asm->GetSizeOfEncodedValue(LSDAEncoding);
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Asm->EmitULEB128(Size, "Augmentation size");
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Asm->OutStreamer.AddComment("Language Specific Data Area");
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if (EHFrameInfo.hasLandingPads)
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Asm->EmitReference(Asm->GetTempSymbol("exception", EHFrameInfo.Number),
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LSDAEncoding);
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else
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Asm->OutStreamer.EmitIntValue(0, Size/*size*/, 0/*addrspace*/);
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} else {
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Asm->EmitULEB128(0, "Augmentation size");
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}
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// Indicate locations of function specific callee saved registers in frame.
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Asm->EmitFrameMoves(EHFrameInfo.Moves, EHFuncBeginSym, true);
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// On Darwin the linker honors the alignment of eh_frame, which means it
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// must be 8-byte on 64-bit targets to match what gcc does. Otherwise you
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// get holes which confuse readers of eh_frame.
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Asm->EmitAlignment(Asm->getTargetData().getPointerSize() == 4 ? 2 : 3);
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Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_end",
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EHFrameInfo.Number));
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// If the function is marked used, this table should be also. We cannot
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// make the mark unconditional in this case, since retaining the table also
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// retains the function in this case, and there is code around that depends
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// on unused functions (calling undefined externals) being dead-stripped to
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// link correctly. Yes, there really is.
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if (MMI->isUsedFunction(EHFrameInfo.function))
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if (Asm->MAI->hasNoDeadStrip())
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Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
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MCSA_NoDeadStrip);
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}
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Asm->OutStreamer.AddBlankLine();
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}
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/// SharedTypeIds - How many leading type ids two landing pads have in common.
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unsigned DwarfException::SharedTypeIds(const LandingPadInfo *L,
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const LandingPadInfo *R) {
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const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
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unsigned LSize = LIds.size(), RSize = RIds.size();
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unsigned MinSize = LSize < RSize ? LSize : RSize;
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unsigned Count = 0;
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for (; Count != MinSize; ++Count)
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if (LIds[Count] != RIds[Count])
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return Count;
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return Count;
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}
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/// PadLT - Order landing pads lexicographically by type id.
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bool DwarfException::PadLT(const LandingPadInfo *L, const LandingPadInfo *R) {
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const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
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unsigned LSize = LIds.size(), RSize = RIds.size();
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unsigned MinSize = LSize < RSize ? LSize : RSize;
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for (unsigned i = 0; i != MinSize; ++i)
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if (LIds[i] != RIds[i])
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return LIds[i] < RIds[i];
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return LSize < RSize;
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}
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/// ComputeActionsTable - Compute the actions table and gather the first action
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/// index for each landing pad site.
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unsigned DwarfException::
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ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*> &LandingPads,
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SmallVectorImpl<ActionEntry> &Actions,
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SmallVectorImpl<unsigned> &FirstActions) {
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// The action table follows the call-site table in the LSDA. The individual
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// records are of two types:
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//
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// * Catch clause
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// * Exception specification
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//
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// The two record kinds have the same format, with only small differences.
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// They are distinguished by the "switch value" field: Catch clauses
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// (TypeInfos) have strictly positive switch values, and exception
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// specifications (FilterIds) have strictly negative switch values. Value 0
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// indicates a catch-all clause.
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//
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// Negative type IDs index into FilterIds. Positive type IDs index into
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// TypeInfos. The value written for a positive type ID is just the type ID
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// itself. For a negative type ID, however, the value written is the
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// (negative) byte offset of the corresponding FilterIds entry. The byte
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// offset is usually equal to the type ID (because the FilterIds entries are
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// written using a variable width encoding, which outputs one byte per entry
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// as long as the value written is not too large) but can differ. This kind
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// of complication does not occur for positive type IDs because type infos are
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// output using a fixed width encoding. FilterOffsets[i] holds the byte
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// offset corresponding to FilterIds[i].
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const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
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SmallVector<int, 16> FilterOffsets;
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FilterOffsets.reserve(FilterIds.size());
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int Offset = -1;
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for (std::vector<unsigned>::const_iterator
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I = FilterIds.begin(), E = FilterIds.end(); I != E; ++I) {
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FilterOffsets.push_back(Offset);
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Offset -= MCAsmInfo::getULEB128Size(*I);
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}
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FirstActions.reserve(LandingPads.size());
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int FirstAction = 0;
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unsigned SizeActions = 0;
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const LandingPadInfo *PrevLPI = 0;
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for (SmallVectorImpl<const LandingPadInfo *>::const_iterator
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I = LandingPads.begin(), E = LandingPads.end(); I != E; ++I) {
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const LandingPadInfo *LPI = *I;
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const std::vector<int> &TypeIds = LPI->TypeIds;
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unsigned NumShared = PrevLPI ? SharedTypeIds(LPI, PrevLPI) : 0;
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unsigned SizeSiteActions = 0;
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if (NumShared < TypeIds.size()) {
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unsigned SizeAction = 0;
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unsigned PrevAction = (unsigned)-1;
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if (NumShared) {
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unsigned SizePrevIds = PrevLPI->TypeIds.size();
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assert(Actions.size());
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PrevAction = Actions.size() - 1;
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SizeAction =
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MCAsmInfo::getSLEB128Size(Actions[PrevAction].NextAction) +
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MCAsmInfo::getSLEB128Size(Actions[PrevAction].ValueForTypeID);
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for (unsigned j = NumShared; j != SizePrevIds; ++j) {
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assert(PrevAction != (unsigned)-1 && "PrevAction is invalid!");
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SizeAction -=
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MCAsmInfo::getSLEB128Size(Actions[PrevAction].ValueForTypeID);
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SizeAction += -Actions[PrevAction].NextAction;
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PrevAction = Actions[PrevAction].Previous;
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}
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}
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// Compute the actions.
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for (unsigned J = NumShared, M = TypeIds.size(); J != M; ++J) {
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int TypeID = TypeIds[J];
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assert(-1 - TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
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int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
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unsigned SizeTypeID = MCAsmInfo::getSLEB128Size(ValueForTypeID);
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int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
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SizeAction = SizeTypeID + MCAsmInfo::getSLEB128Size(NextAction);
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SizeSiteActions += SizeAction;
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ActionEntry Action = { ValueForTypeID, NextAction, PrevAction };
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Actions.push_back(Action);
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PrevAction = Actions.size() - 1;
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}
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// Record the first action of the landing pad site.
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FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
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} // else identical - re-use previous FirstAction
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// Information used when created the call-site table. The action record
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// field of the call site record is the offset of the first associated
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// action record, relative to the start of the actions table. This value is
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// biased by 1 (1 indicating the start of the actions table), and 0
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// indicates that there are no actions.
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FirstActions.push_back(FirstAction);
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// Compute this sites contribution to size.
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SizeActions += SizeSiteActions;
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PrevLPI = LPI;
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}
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return SizeActions;
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}
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/// CallToNoUnwindFunction - Return `true' if this is a call to a function
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/// marked `nounwind'. Return `false' otherwise.
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bool DwarfException::CallToNoUnwindFunction(const MachineInstr *MI) {
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assert(MI->getDesc().isCall() && "This should be a call instruction!");
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bool MarkedNoUnwind = false;
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bool SawFunc = false;
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for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) {
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const MachineOperand &MO = MI->getOperand(I);
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if (!MO.isGlobal()) continue;
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const Function *F = dyn_cast<Function>(MO.getGlobal());
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if (F == 0) continue;
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if (SawFunc) {
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// Be conservative. If we have more than one function operand for this
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// call, then we can't make the assumption that it's the callee and
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// not a parameter to the call.
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//
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// FIXME: Determine if there's a way to say that `F' is the callee or
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// parameter.
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MarkedNoUnwind = false;
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break;
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}
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MarkedNoUnwind = F->doesNotThrow();
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|
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.
|
|
MCSymbol *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 = Asm->MF->begin(), E = Asm->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;
|
|
}
|
|
|
|
// End of the previous try-range?
|
|
MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
|
|
if (BeginLabel == LastLabel)
|
|
SawPotentiallyThrowing = false;
|
|
|
|
// Beginning of a new try-range?
|
|
RangeMapType::const_iterator L = PadMap.find(BeginLabel);
|
|
if (L == PadMap.end())
|
|
// Nope, it was just some random label.
|
|
continue;
|
|
|
|
const PadRange &P = L->second;
|
|
const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
|
|
assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
|
|
"Inconsistent landing pad map!");
|
|
|
|
// 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 &&
|
|
Asm->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) {
|
|
// Create a gap.
|
|
PreviousIsInvoke = false;
|
|
} else {
|
|
// 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 &&
|
|
Asm->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 (Asm->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;
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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 &&
|
|
Asm->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<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
|
|
const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
|
|
const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
|
|
|
|
// 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) {
|
|
MCSymbol *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.
|
|
bool IsSJLJ = Asm->MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
|
|
bool HaveTTData = IsSJLJ ? (!TypeInfos.empty() || !FilterIds.empty()) : true;
|
|
|
|
unsigned CallSiteTableLength;
|
|
if (IsSJLJ)
|
|
CallSiteTableLength = 0;
|
|
else {
|
|
unsigned SiteStartSize = 4; // dwarf::DW_EH_PE_udata4
|
|
unsigned SiteLengthSize = 4; // dwarf::DW_EH_PE_udata4
|
|
unsigned LandingPadSize = 4; // dwarf::DW_EH_PE_udata4
|
|
CallSiteTableLength =
|
|
CallSites.size() * (SiteStartSize + SiteLengthSize + LandingPadSize);
|
|
}
|
|
|
|
for (unsigned i = 0, e = CallSites.size(); i < e; ++i) {
|
|
CallSiteTableLength += MCAsmInfo::getULEB128Size(CallSites[i].Action);
|
|
if (IsSJLJ)
|
|
CallSiteTableLength += MCAsmInfo::getULEB128Size(i);
|
|
}
|
|
|
|
// Type infos.
|
|
const MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
|
|
unsigned TTypeEncoding;
|
|
unsigned TypeFormatSize;
|
|
|
|
if (!HaveTTData) {
|
|
// For SjLj exceptions, if there is no TypeInfo, then we just explicitly say
|
|
// that we're omitting that bit.
|
|
TTypeEncoding = dwarf::DW_EH_PE_omit;
|
|
// dwarf::DW_EH_PE_absptr
|
|
TypeFormatSize = Asm->getTargetData().getPointerSize();
|
|
} 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.
|
|
//
|
|
TTypeEncoding = Asm->getObjFileLowering().getTTypeEncoding();
|
|
TypeFormatSize = Asm->GetSizeOfEncodedValue(TTypeEncoding);
|
|
}
|
|
|
|
// Begin the exception table.
|
|
Asm->OutStreamer.SwitchSection(LSDASection);
|
|
Asm->EmitAlignment(2);
|
|
|
|
// Emit the LSDA.
|
|
MCSymbol *GCCETSym =
|
|
Asm->OutContext.GetOrCreateSymbol(Twine("GCC_except_table")+
|
|
Twine(Asm->getFunctionNumber()));
|
|
Asm->OutStreamer.EmitLabel(GCCETSym);
|
|
Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("exception",
|
|
Asm->getFunctionNumber()));
|
|
|
|
if (IsSJLJ)
|
|
Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("_LSDA_",
|
|
Asm->getFunctionNumber()));
|
|
|
|
// Emit the LSDA header.
|
|
Asm->EmitEncodingByte(dwarf::DW_EH_PE_omit, "@LPStart");
|
|
Asm->EmitEncodingByte(TTypeEncoding, "@TType");
|
|
|
|
// 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 CallSiteTableLengthSize =
|
|
MCAsmInfo::getULEB128Size(CallSiteTableLength);
|
|
unsigned TTypeBaseOffset =
|
|
sizeof(int8_t) + // Call site format
|
|
CallSiteTableLengthSize + // Call site table length size
|
|
CallSiteTableLength + // Call site table length
|
|
SizeActions + // Actions size
|
|
SizeTypes;
|
|
unsigned TTypeBaseOffsetSize = MCAsmInfo::getULEB128Size(TTypeBaseOffset);
|
|
unsigned TotalSize =
|
|
sizeof(int8_t) + // LPStart format
|
|
sizeof(int8_t) + // TType format
|
|
(HaveTTData ? TTypeBaseOffsetSize : 0) + // TType base offset size
|
|
TTypeBaseOffset; // TType base offset
|
|
unsigned SizeAlign = (4 - TotalSize) & 3;
|
|
|
|
if (HaveTTData) {
|
|
// Account for any extra padding that will be added to the call site table
|
|
// length.
|
|
Asm->EmitULEB128(TTypeBaseOffset, "@TType base offset", SizeAlign);
|
|
SizeAlign = 0;
|
|
}
|
|
|
|
// SjLj Exception handling
|
|
if (IsSJLJ) {
|
|
Asm->EmitEncodingByte(dwarf::DW_EH_PE_udata4, "Call site");
|
|
|
|
// Add extra padding if it wasn't added to the TType base offset.
|
|
Asm->EmitULEB128(CallSiteTableLength, "Call site table length", SizeAlign);
|
|
|
|
// 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->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.
|
|
Asm->EmitULEB128(S.Action, "Action");
|
|
}
|
|
} else {
|
|
// DWARF Exception handling
|
|
assert(Asm->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->EmitEncodingByte(dwarf::DW_EH_PE_udata4, "Call site");
|
|
|
|
// Add extra padding if it wasn't added to the TType base offset.
|
|
Asm->EmitULEB128(CallSiteTableLength, "Call site table length", SizeAlign);
|
|
|
|
for (SmallVectorImpl<CallSiteEntry>::const_iterator
|
|
I = CallSites.begin(), E = CallSites.end(); I != E; ++I) {
|
|
const CallSiteEntry &S = *I;
|
|
|
|
MCSymbol *EHFuncBeginSym =
|
|
Asm->GetTempSymbol("eh_func_begin", Asm->getFunctionNumber());
|
|
|
|
MCSymbol *BeginLabel = S.BeginLabel;
|
|
if (BeginLabel == 0)
|
|
BeginLabel = EHFuncBeginSym;
|
|
MCSymbol *EndLabel = S.EndLabel;
|
|
if (EndLabel == 0)
|
|
EndLabel = Asm->GetTempSymbol("eh_func_end", Asm->getFunctionNumber());
|
|
|
|
// 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.
|
|
Asm->OutStreamer.AddComment("Region start");
|
|
Asm->EmitLabelDifference(BeginLabel, EHFuncBeginSym, 4);
|
|
|
|
Asm->OutStreamer.AddComment("Region length");
|
|
Asm->EmitLabelDifference(EndLabel, BeginLabel, 4);
|
|
|
|
|
|
// Offset of the landing pad, counted in 16-byte bundles relative to the
|
|
// @LPStart address.
|
|
Asm->OutStreamer.AddComment("Landing pad");
|
|
if (!S.PadLabel)
|
|
Asm->OutStreamer.EmitIntValue(0, 4/*size*/, 0/*addrspace*/);
|
|
else
|
|
Asm->EmitLabelDifference(S.PadLabel, EHFuncBeginSym, 4);
|
|
|
|
// 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->EmitULEB128(S.Action, "Action");
|
|
}
|
|
}
|
|
|
|
// Emit the Action Table.
|
|
if (Actions.size() != 0) {
|
|
Asm->OutStreamer.AddComment("-- Action Record Table --");
|
|
Asm->OutStreamer.AddBlankLine();
|
|
}
|
|
|
|
for (SmallVectorImpl<ActionEntry>::const_iterator
|
|
I = Actions.begin(), E = Actions.end(); I != E; ++I) {
|
|
const ActionEntry &Action = *I;
|
|
Asm->OutStreamer.AddComment("Action Record");
|
|
Asm->OutStreamer.AddBlankLine();
|
|
|
|
// 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->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.
|
|
Asm->EmitSLEB128(Action.NextAction, " Next action");
|
|
}
|
|
|
|
// Emit the Catch TypeInfos.
|
|
if (!TypeInfos.empty()) {
|
|
Asm->OutStreamer.AddComment("-- Catch TypeInfos --");
|
|
Asm->OutStreamer.AddBlankLine();
|
|
}
|
|
for (std::vector<const GlobalVariable *>::const_reverse_iterator
|
|
I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
|
|
const GlobalVariable *GV = *I;
|
|
|
|
Asm->OutStreamer.AddComment("TypeInfo");
|
|
if (GV)
|
|
Asm->EmitReference(GV, TTypeEncoding);
|
|
else
|
|
Asm->OutStreamer.EmitIntValue(0,Asm->GetSizeOfEncodedValue(TTypeEncoding),
|
|
0);
|
|
}
|
|
|
|
// Emit the Exception Specifications.
|
|
if (!FilterIds.empty()) {
|
|
Asm->OutStreamer.AddComment("-- Filter IDs --");
|
|
Asm->OutStreamer.AddBlankLine();
|
|
}
|
|
for (std::vector<unsigned>::const_iterator
|
|
I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
|
|
unsigned TypeID = *I;
|
|
Asm->EmitULEB128(TypeID, TypeID != 0 ? "Exception specification" : 0);
|
|
}
|
|
|
|
Asm->EmitAlignment(2);
|
|
}
|
|
|
|
/// EndModule - Emit all exception information that should come after the
|
|
/// content.
|
|
void DwarfException::EndModule() {
|
|
if (Asm->MAI->getExceptionHandlingType() != ExceptionHandling::Dwarf)
|
|
return;
|
|
|
|
if (!shouldEmitMovesModule && !shouldEmitTableModule)
|
|
return;
|
|
|
|
const std::vector<const 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);
|
|
}
|
|
|
|
/// BeginFunction - Gather pre-function exception information. Assumes it's
|
|
/// being emitted immediately after the function entry point.
|
|
void DwarfException::BeginFunction(const MachineFunction *MF) {
|
|
shouldEmitTable = shouldEmitMoves = false;
|
|
|
|
// If any landing pads survive, we need an EH table.
|
|
shouldEmitTable = !MMI->getLandingPads().empty();
|
|
|
|
// See if we need frame move info.
|
|
shouldEmitMoves =
|
|
!Asm->MF->getFunction()->doesNotThrow() || UnwindTablesMandatory;
|
|
|
|
if (shouldEmitMoves || shouldEmitTable)
|
|
// Assumes in correct section after the entry point.
|
|
Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
|
|
Asm->getFunctionNumber()));
|
|
|
|
shouldEmitTableModule |= shouldEmitTable;
|
|
shouldEmitMovesModule |= shouldEmitMoves;
|
|
}
|
|
|
|
/// EndFunction - Gather and emit post-function exception information.
|
|
///
|
|
void DwarfException::EndFunction() {
|
|
if (!shouldEmitMoves && !shouldEmitTable) return;
|
|
|
|
Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
|
|
Asm->getFunctionNumber()));
|
|
|
|
// Record if this personality index uses a landing pad.
|
|
bool HasLandingPad = !MMI->getLandingPads().empty();
|
|
UsesLSDA[MMI->getPersonalityIndex()] |= HasLandingPad;
|
|
|
|
// Map all labels and get rid of any dead landing pads.
|
|
MMI->TidyLandingPads();
|
|
|
|
if (HasLandingPad)
|
|
EmitExceptionTable();
|
|
|
|
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
|
|
MCSymbol *FunctionEHSym =
|
|
Asm->GetSymbolWithGlobalValueBase(Asm->MF->getFunction(), ".eh",
|
|
TLOF.isFunctionEHFrameSymbolPrivate());
|
|
|
|
// Save EH frame information
|
|
EHFrames.
|
|
push_back(FunctionEHFrameInfo(FunctionEHSym,
|
|
Asm->getFunctionNumber(),
|
|
MMI->getPersonalityIndex(),
|
|
Asm->MF->getFrameInfo()->adjustsStack(),
|
|
!MMI->getLandingPads().empty(),
|
|
MMI->getFrameMoves(),
|
|
Asm->MF->getFunction()));
|
|
}
|