mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-30 05:29:47 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92206 91177308-0d34-0410-b5e6-96231b3b80d8
1029 lines
38 KiB
C++
1029 lines
38 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/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/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/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/Mangler.h"
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#include "llvm/Support/Timer.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringExtras.h"
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using namespace llvm;
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DwarfException::DwarfException(raw_ostream &OS, AsmPrinter *A,
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const MCAsmInfo *T)
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: Dwarf(OS, A, T, "eh"), shouldEmitTable(false), shouldEmitMoves(false),
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shouldEmitTableModule(false), shouldEmitMovesModule(false),
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ExceptionTimer(0) {
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if (TimePassesIsEnabled)
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ExceptionTimer = new Timer("DWARF Exception Writer");
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}
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DwarfException::~DwarfException() {
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delete ExceptionTimer;
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}
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/// SizeOfEncodedValue - Return the size of the encoding in bytes.
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unsigned DwarfException::SizeOfEncodedValue(unsigned Encoding) {
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if (Encoding == dwarf::DW_EH_PE_omit)
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return 0;
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switch (Encoding & 0x07) {
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case dwarf::DW_EH_PE_absptr:
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return TD->getPointerSize();
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case dwarf::DW_EH_PE_udata2:
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return 2;
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case dwarf::DW_EH_PE_udata4:
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return 4;
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case dwarf::DW_EH_PE_udata8:
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return 8;
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}
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assert(0 && "Invalid encoded value.");
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return 0;
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}
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/// CreateLabelDiff - Emit a label and subtract it from the expression we
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/// already have. This is equivalent to emitting "foo - .", but we have to emit
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/// the label for "." directly.
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const MCExpr *DwarfException::CreateLabelDiff(const MCExpr *ExprRef,
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const char *LabelName,
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unsigned Index) {
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SmallString<64> Name;
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raw_svector_ostream(Name) << MAI->getPrivateGlobalPrefix()
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<< LabelName << Asm->getFunctionNumber()
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<< "_" << Index;
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MCSymbol *DotSym = Asm->OutContext.GetOrCreateSymbol(Name.str());
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Asm->OutStreamer.EmitLabel(DotSym);
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return MCBinaryExpr::CreateSub(ExprRef,
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MCSymbolRefExpr::Create(DotSym,
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Asm->OutContext),
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Asm->OutContext);
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}
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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 =
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Asm->TM.getFrameInfo()->getStackGrowthDirection() ==
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TargetFrameInfo::StackGrowsUp ?
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TD->getPointerSize() : -TD->getPointerSize();
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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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if (MAI->is_EHSymbolPrivate())
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O << MAI->getPrivateGlobalPrefix();
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O << "EH_frame" << Index << ":\n";
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EmitLabel("section_eh_frame", Index);
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// Define base labels.
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EmitLabel("eh_frame_common", Index);
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// Define the eh frame length.
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EmitDifference("eh_frame_common_end", Index,
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"eh_frame_common_begin", Index, true);
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Asm->EOL("Length of Common Information Entry");
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// EH frame header.
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EmitLabel("eh_frame_common_begin", Index);
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Asm->EmitInt32((int)0);
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Asm->EOL("CIE Identifier Tag");
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Asm->EmitInt8(dwarf::DW_CIE_VERSION);
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Asm->EOL("CIE Version");
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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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const MCExpr *PersonalityRef = 0;
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bool IsPersonalityIndirect = false, IsPersonalityPCRel = false;
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if (PersonalityFn) {
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// FIXME: HANDLE STATIC CODEGEN MODEL HERE.
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// In non-static mode, ask the object file how to represent this reference.
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PersonalityRef =
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TLOF.getSymbolForDwarfGlobalReference(PersonalityFn, Asm->Mang,
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Asm->MMI,
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IsPersonalityIndirect,
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IsPersonalityPCRel);
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}
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unsigned PerEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
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if (IsPersonalityIndirect)
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PerEncoding |= dwarf::DW_EH_PE_indirect;
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unsigned LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
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unsigned FDEEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
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char Augmentation[5] = { 0 };
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unsigned AugmentationSize = 0;
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char *APtr = Augmentation + 1;
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if (PersonalityRef) {
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// There is a personality function.
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*APtr++ = 'P';
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AugmentationSize += 1 + SizeOfEncodedValue(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->EmitString(Augmentation);
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Asm->EOL("CIE Augmentation");
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// Round out reader.
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Asm->EmitULEB128Bytes(1);
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Asm->EOL("CIE Code Alignment Factor");
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Asm->EmitSLEB128Bytes(stackGrowth);
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Asm->EOL("CIE Data Alignment Factor");
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Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), true));
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Asm->EOL("CIE Return Address Column");
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Asm->EmitULEB128Bytes(AugmentationSize);
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Asm->EOL("Augmentation Size");
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Asm->EmitInt8(PerEncoding);
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Asm->EOL("Personality", PerEncoding);
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// If there is a personality, we need to indicate the function's location.
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if (PersonalityRef) {
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if (!IsPersonalityPCRel)
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PersonalityRef = CreateLabelDiff(PersonalityRef, "personalityref_addr",
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Index);
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O << MAI->getData32bitsDirective();
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PersonalityRef->print(O, MAI);
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Asm->EOL("Personality");
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Asm->EmitInt8(LSDAEncoding);
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Asm->EOL("LSDA Encoding", LSDAEncoding);
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Asm->EmitInt8(FDEEncoding);
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Asm->EOL("FDE Encoding", FDEEncoding);
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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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EmitFrameMoves(NULL, 0, Moves, 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(TD->getPointerSize() == 4 ? 2 : 3, 0, 0, false);
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EmitLabel("eh_frame_common_end", Index);
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Asm->EOL();
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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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Asm->OutStreamer.SwitchSection(Asm->getObjFileLowering().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())
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if (const char *GlobalEHDirective = MAI->getGlobalEHDirective())
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O << GlobalEHDirective << EHFrameInfo.FnName << '\n';
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// If corresponding function is weak definition, this should be too.
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if (TheFunc->isWeakForLinker() && MAI->getWeakDefDirective())
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O << MAI->getWeakDefDirective() << EHFrameInfo.FnName << '\n';
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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 (const char *HiddenDirective = MAI->getHiddenDirective())
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O << HiddenDirective << EHFrameInfo.FnName << '\n' ;
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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.hasCalls && !UnwindTablesMandatory &&
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(!TheFunc->isWeakForLinker() ||
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!MAI->getWeakDefDirective() ||
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MAI->getSupportsWeakOmittedEHFrame())) {
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O << EHFrameInfo.FnName << " = 0\n";
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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 (const char *UsedDirective = MAI->getUsedDirective())
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O << UsedDirective << EHFrameInfo.FnName << "\n\n";
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} else {
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O << EHFrameInfo.FnName << ":\n";
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// EH frame header.
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EmitDifference("eh_frame_end", EHFrameInfo.Number,
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"eh_frame_begin", EHFrameInfo.Number, true);
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Asm->EOL("Length of Frame Information Entry");
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EmitLabel("eh_frame_begin", EHFrameInfo.Number);
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EmitSectionOffset("eh_frame_begin", "eh_frame_common",
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EHFrameInfo.Number, EHFrameInfo.PersonalityIndex,
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true, true, false);
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Asm->EOL("FDE CIE offset");
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EmitReference("eh_func_begin", EHFrameInfo.Number, true, true);
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Asm->EOL("FDE initial location");
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EmitDifference("eh_func_end", EHFrameInfo.Number,
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"eh_func_begin", EHFrameInfo.Number, true);
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Asm->EOL("FDE address range");
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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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bool is4Byte = TD->getPointerSize() == sizeof(int32_t);
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Asm->EmitULEB128Bytes(is4Byte ? 4 : 8);
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Asm->EOL("Augmentation size");
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if (EHFrameInfo.hasLandingPads)
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EmitReference("exception", EHFrameInfo.Number, true, false);
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else {
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if (is4Byte)
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Asm->EmitInt32((int)0);
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else
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Asm->EmitInt64((int)0);
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}
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Asm->EOL("Language Specific Data Area");
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} else {
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Asm->EmitULEB128Bytes(0);
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Asm->EOL("Augmentation size");
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}
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// Indicate locations of function specific callee saved registers in frame.
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EmitFrameMoves("eh_func_begin", EHFrameInfo.Number, EHFrameInfo.Moves,
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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(TD->getPointerSize() == sizeof(int32_t) ? 2 : 3,
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0, 0, false);
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EmitLabel("eh_frame_end", 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 (const char *UsedDirective = MAI->getUsedDirective())
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O << UsedDirective << EHFrameInfo.FnName << "\n\n";
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}
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Asm->EOL();
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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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const 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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ActionEntry *PrevAction = 0;
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if (NumShared) {
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const unsigned SizePrevIds = PrevLPI->TypeIds.size();
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assert(Actions.size());
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PrevAction = &Actions.back();
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SizeAction = MCAsmInfo::getSLEB128Size(PrevAction->NextAction) +
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MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
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for (unsigned j = NumShared; j != SizePrevIds; ++j) {
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SizeAction -=
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MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
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SizeAction += -PrevAction->NextAction;
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PrevAction = 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.back();
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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 in dicating 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;
|
|
}
|
|
|
|
/// 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.
|
|
CallSites.push_back(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);
|
|
Asm->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.
|
|
Asm->EmitInt8(dwarf::DW_EH_PE_omit);
|
|
Asm->EOL("@LPStart format", dwarf::DW_EH_PE_omit);
|
|
|
|
Asm->EmitInt8(TTypeFormat);
|
|
Asm->EOL("@TType format", TTypeFormat);
|
|
|
|
if (HaveTTData) {
|
|
Asm->EmitULEB128Bytes(TyOffset);
|
|
Asm->EOL("@TType base offset");
|
|
}
|
|
|
|
// SjLj Exception handling
|
|
if (IsSJLJ) {
|
|
Asm->EmitInt8(dwarf::DW_EH_PE_udata4);
|
|
Asm->EOL("Call site format", dwarf::DW_EH_PE_udata4);
|
|
Asm->EmitULEB128Bytes(SizeSites);
|
|
Asm->EOL("Call site table length");
|
|
|
|
// Emit the landing pad site information.
|
|
unsigned idx = 0;
|
|
for (SmallVectorImpl<CallSiteEntry>::const_iterator
|
|
I = CallSites.begin(), E = CallSites.end(); I != E; ++I, ++idx) {
|
|
const CallSiteEntry &S = *I;
|
|
|
|
// Offset of the landing pad, counted in 16-byte bundles relative to the
|
|
// @LPStart address.
|
|
Asm->EmitULEB128Bytes(idx);
|
|
Asm->EOL("Landing pad");
|
|
|
|
// Offset of the first associated action record, relative to the start of
|
|
// the action table. This value is biased by 1 (1 indicates the start of
|
|
// the action table), and 0 indicates that there are no actions.
|
|
Asm->EmitULEB128Bytes(S.Action);
|
|
Asm->EOL("Action");
|
|
}
|
|
} else {
|
|
// DWARF Exception handling
|
|
assert(MAI->getExceptionHandlingType() == ExceptionHandling::Dwarf);
|
|
|
|
// The call-site table is a list of all call sites that may throw an
|
|
// exception (including C++ 'throw' statements) in the procedure
|
|
// fragment. It immediately follows the LSDA header. Each entry indicates,
|
|
// for a given call, the first corresponding action record and corresponding
|
|
// landing pad.
|
|
//
|
|
// The table begins with the number of bytes, stored as an LEB128
|
|
// compressed, unsigned integer. The records immediately follow the record
|
|
// count. They are sorted in increasing call-site address. Each record
|
|
// indicates:
|
|
//
|
|
// * The position of the call-site.
|
|
// * The position of the landing pad.
|
|
// * The first action record for that call site.
|
|
//
|
|
// A missing entry in the call-site table indicates that a call is not
|
|
// supposed to throw.
|
|
|
|
// Emit the landing pad call site table.
|
|
Asm->EmitInt8(dwarf::DW_EH_PE_udata4);
|
|
Asm->EOL("Call site format", dwarf::DW_EH_PE_udata4);
|
|
Asm->EmitULEB128Bytes(SizeSites);
|
|
Asm->EOL("Call site table size");
|
|
|
|
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);
|
|
Asm->EOL("Region start");
|
|
|
|
if (!S.EndLabel)
|
|
EmitDifference("eh_func_end", SubprogramCount, BeginTag, BeginNumber,
|
|
true);
|
|
else
|
|
EmitDifference("label", S.EndLabel, BeginTag, BeginNumber, true);
|
|
|
|
Asm->EOL("Region length");
|
|
|
|
// Offset of the landing pad, counted in 16-byte bundles relative to the
|
|
// @LPStart address.
|
|
if (!S.PadLabel)
|
|
Asm->EmitInt32(0);
|
|
else
|
|
EmitSectionOffset("label", "eh_func_begin", S.PadLabel, SubprogramCount,
|
|
true, true);
|
|
|
|
Asm->EOL("Landing pad");
|
|
|
|
// Offset of the first associated action record, relative to the start of
|
|
// the action table. This value is biased by 1 (1 indicates the start of
|
|
// the action table), and 0 indicates that there are no actions.
|
|
Asm->EmitULEB128Bytes(S.Action);
|
|
Asm->EOL("Action");
|
|
}
|
|
}
|
|
|
|
// Emit the Action Table.
|
|
for (SmallVectorImpl<ActionEntry>::const_iterator
|
|
I = Actions.begin(), E = Actions.end(); I != E; ++I) {
|
|
const ActionEntry &Action = *I;
|
|
|
|
// Type Filter
|
|
//
|
|
// Used by the runtime to match the type of the thrown exception to the
|
|
// type of the catch clauses or the types in the exception specification.
|
|
|
|
Asm->EmitSLEB128Bytes(Action.ValueForTypeID);
|
|
Asm->EOL("TypeInfo index");
|
|
|
|
// Action Record
|
|
//
|
|
// Self-relative signed displacement in bytes of the next action record,
|
|
// or 0 if there is no next action record.
|
|
|
|
Asm->EmitSLEB128Bytes(Action.NextAction);
|
|
Asm->EOL("Next action");
|
|
}
|
|
|
|
// Emit the 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->Mang->getMangledName(GV);
|
|
} else {
|
|
O << "0x0";
|
|
}
|
|
|
|
Asm->EOL("TypeInfo");
|
|
}
|
|
|
|
// Emit the Exception Specifications.
|
|
for (std::vector<unsigned>::const_iterator
|
|
I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
|
|
unsigned TypeID = *I;
|
|
Asm->EmitULEB128Bytes(TypeID);
|
|
if (TypeID != 0)
|
|
Asm->EOL("Exception specification");
|
|
else
|
|
Asm->EOL();
|
|
}
|
|
|
|
Asm->EmitAlignment(2, 0, 0, false);
|
|
}
|
|
|
|
/// EndModule - Emit all exception information that should come after the
|
|
/// content.
|
|
void DwarfException::EndModule() {
|
|
if (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(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();
|
|
|
|
std::string FunctionEHName =
|
|
Asm->Mang->getMangledName(MF->getFunction(), ".eh",
|
|
Asm->MAI->is_EHSymbolPrivate());
|
|
|
|
// Save EH frame information
|
|
EHFrames.push_back(FunctionEHFrameInfo(FunctionEHName, SubprogramCount,
|
|
MMI->getPersonalityIndex(),
|
|
MF->getFrameInfo()->hasCalls(),
|
|
!MMI->getLandingPads().empty(),
|
|
MMI->getFrameMoves(),
|
|
MF->getFunction()));
|
|
|
|
// Record if this personality index uses a landing pad.
|
|
UsesLSDA[MMI->getPersonalityIndex()] |= !MMI->getLandingPads().empty();
|
|
|
|
if (TimePassesIsEnabled)
|
|
ExceptionTimer->stopTimer();
|
|
}
|