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Give the symbol's name and disengage the enchanced crash reporting. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191344 91177308-0d34-0410-b5e6-96231b3b80d8
959 lines
34 KiB
C++
959 lines
34 KiB
C++
//===- lib/MC/MachObjectWriter.cpp - Mach-O File Writer -------------------===//
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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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#include "llvm/MC/MCMachObjectWriter.h"
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#include "llvm/ADT/StringMap.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAsmLayout.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCFixupKindInfo.h"
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#include "llvm/MC/MCMachOSymbolFlags.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCSectionMachO.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/MachO.h"
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#include <vector>
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using namespace llvm;
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void MachObjectWriter::reset() {
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Relocations.clear();
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IndirectSymBase.clear();
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StringTable.clear();
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LocalSymbolData.clear();
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ExternalSymbolData.clear();
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UndefinedSymbolData.clear();
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MCObjectWriter::reset();
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}
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bool MachObjectWriter::
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doesSymbolRequireExternRelocation(const MCSymbolData *SD) {
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// Undefined symbols are always extern.
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if (SD->Symbol->isUndefined())
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return true;
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// References to weak definitions require external relocation entries; the
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// definition may not always be the one in the same object file.
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if (SD->getFlags() & SF_WeakDefinition)
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return true;
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// Otherwise, we can use an internal relocation.
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return false;
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}
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bool MachObjectWriter::
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MachSymbolData::operator<(const MachSymbolData &RHS) const {
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return SymbolData->getSymbol().getName() <
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RHS.SymbolData->getSymbol().getName();
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}
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bool MachObjectWriter::isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
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const MCFixupKindInfo &FKI = Asm.getBackend().getFixupKindInfo(
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(MCFixupKind) Kind);
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return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
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}
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uint64_t MachObjectWriter::getFragmentAddress(const MCFragment *Fragment,
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const MCAsmLayout &Layout) const {
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return getSectionAddress(Fragment->getParent()) +
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Layout.getFragmentOffset(Fragment);
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}
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uint64_t MachObjectWriter::getSymbolAddress(const MCSymbolData* SD,
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const MCAsmLayout &Layout) const {
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const MCSymbol &S = SD->getSymbol();
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// If this is a variable, then recursively evaluate now.
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if (S.isVariable()) {
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if (const MCConstantExpr *C =
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dyn_cast<const MCConstantExpr>(S.getVariableValue()))
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return C->getValue();
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MCValue Target;
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if (!S.getVariableValue()->EvaluateAsRelocatable(Target, Layout))
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report_fatal_error("unable to evaluate offset for variable '" +
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S.getName() + "'");
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// Verify that any used symbols are defined.
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if (Target.getSymA() && Target.getSymA()->getSymbol().isUndefined())
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report_fatal_error("unable to evaluate offset to undefined symbol '" +
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Target.getSymA()->getSymbol().getName() + "'");
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if (Target.getSymB() && Target.getSymB()->getSymbol().isUndefined())
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report_fatal_error("unable to evaluate offset to undefined symbol '" +
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Target.getSymB()->getSymbol().getName() + "'");
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uint64_t Address = Target.getConstant();
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if (Target.getSymA())
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Address += getSymbolAddress(&Layout.getAssembler().getSymbolData(
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Target.getSymA()->getSymbol()), Layout);
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if (Target.getSymB())
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Address += getSymbolAddress(&Layout.getAssembler().getSymbolData(
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Target.getSymB()->getSymbol()), Layout);
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return Address;
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}
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return getSectionAddress(SD->getFragment()->getParent()) +
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Layout.getSymbolOffset(SD);
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}
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uint64_t MachObjectWriter::getPaddingSize(const MCSectionData *SD,
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const MCAsmLayout &Layout) const {
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uint64_t EndAddr = getSectionAddress(SD) + Layout.getSectionAddressSize(SD);
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unsigned Next = SD->getLayoutOrder() + 1;
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if (Next >= Layout.getSectionOrder().size())
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return 0;
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const MCSectionData &NextSD = *Layout.getSectionOrder()[Next];
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if (NextSD.getSection().isVirtualSection())
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return 0;
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return OffsetToAlignment(EndAddr, NextSD.getAlignment());
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}
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void MachObjectWriter::WriteHeader(unsigned NumLoadCommands,
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unsigned LoadCommandsSize,
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bool SubsectionsViaSymbols) {
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uint32_t Flags = 0;
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if (SubsectionsViaSymbols)
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Flags |= MachO::MH_SUBSECTIONS_VIA_SYMBOLS;
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// struct mach_header (28 bytes) or
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// struct mach_header_64 (32 bytes)
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uint64_t Start = OS.tell();
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(void) Start;
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Write32(is64Bit() ? MachO::MH_MAGIC_64 : MachO::MH_MAGIC);
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Write32(TargetObjectWriter->getCPUType());
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Write32(TargetObjectWriter->getCPUSubtype());
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Write32(MachO::MH_OBJECT);
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Write32(NumLoadCommands);
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Write32(LoadCommandsSize);
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Write32(Flags);
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if (is64Bit())
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Write32(0); // reserved
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assert(OS.tell() - Start ==
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(is64Bit()?sizeof(MachO::mach_header_64): sizeof(MachO::mach_header)));
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}
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/// WriteSegmentLoadCommand - Write a segment load command.
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///
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/// \param NumSections The number of sections in this segment.
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/// \param SectionDataSize The total size of the sections.
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void MachObjectWriter::WriteSegmentLoadCommand(unsigned NumSections,
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uint64_t VMSize,
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uint64_t SectionDataStartOffset,
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uint64_t SectionDataSize) {
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// struct segment_command (56 bytes) or
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// struct segment_command_64 (72 bytes)
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uint64_t Start = OS.tell();
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(void) Start;
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unsigned SegmentLoadCommandSize =
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is64Bit() ? sizeof(MachO::segment_command_64):
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sizeof(MachO::segment_command);
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Write32(is64Bit() ? MachO::LC_SEGMENT_64 : MachO::LC_SEGMENT);
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Write32(SegmentLoadCommandSize +
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NumSections * (is64Bit() ? sizeof(MachO::section_64) :
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sizeof(MachO::section)));
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WriteBytes("", 16);
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if (is64Bit()) {
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Write64(0); // vmaddr
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Write64(VMSize); // vmsize
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Write64(SectionDataStartOffset); // file offset
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Write64(SectionDataSize); // file size
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} else {
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Write32(0); // vmaddr
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Write32(VMSize); // vmsize
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Write32(SectionDataStartOffset); // file offset
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Write32(SectionDataSize); // file size
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}
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// maxprot
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Write32(MachO::VM_PROT_READ | MachO::VM_PROT_WRITE | MachO::VM_PROT_EXECUTE);
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// initprot
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Write32(MachO::VM_PROT_READ | MachO::VM_PROT_WRITE | MachO::VM_PROT_EXECUTE);
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Write32(NumSections);
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Write32(0); // flags
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assert(OS.tell() - Start == SegmentLoadCommandSize);
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}
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void MachObjectWriter::WriteSection(const MCAssembler &Asm,
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const MCAsmLayout &Layout,
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const MCSectionData &SD,
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uint64_t FileOffset,
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uint64_t RelocationsStart,
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unsigned NumRelocations) {
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uint64_t SectionSize = Layout.getSectionAddressSize(&SD);
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// The offset is unused for virtual sections.
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if (SD.getSection().isVirtualSection()) {
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assert(Layout.getSectionFileSize(&SD) == 0 && "Invalid file size!");
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FileOffset = 0;
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}
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// struct section (68 bytes) or
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// struct section_64 (80 bytes)
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uint64_t Start = OS.tell();
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(void) Start;
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const MCSectionMachO &Section = cast<MCSectionMachO>(SD.getSection());
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WriteBytes(Section.getSectionName(), 16);
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WriteBytes(Section.getSegmentName(), 16);
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if (is64Bit()) {
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Write64(getSectionAddress(&SD)); // address
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Write64(SectionSize); // size
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} else {
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Write32(getSectionAddress(&SD)); // address
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Write32(SectionSize); // size
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}
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Write32(FileOffset);
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unsigned Flags = Section.getTypeAndAttributes();
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if (SD.hasInstructions())
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Flags |= MCSectionMachO::S_ATTR_SOME_INSTRUCTIONS;
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assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!");
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Write32(Log2_32(SD.getAlignment()));
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Write32(NumRelocations ? RelocationsStart : 0);
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Write32(NumRelocations);
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Write32(Flags);
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Write32(IndirectSymBase.lookup(&SD)); // reserved1
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Write32(Section.getStubSize()); // reserved2
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if (is64Bit())
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Write32(0); // reserved3
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assert(OS.tell() - Start == (is64Bit() ? sizeof(MachO::section_64) :
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sizeof(MachO::section)));
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}
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void MachObjectWriter::WriteSymtabLoadCommand(uint32_t SymbolOffset,
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uint32_t NumSymbols,
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uint32_t StringTableOffset,
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uint32_t StringTableSize) {
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// struct symtab_command (24 bytes)
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uint64_t Start = OS.tell();
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(void) Start;
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Write32(MachO::LC_SYMTAB);
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Write32(sizeof(MachO::symtab_command));
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Write32(SymbolOffset);
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Write32(NumSymbols);
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Write32(StringTableOffset);
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Write32(StringTableSize);
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assert(OS.tell() - Start == sizeof(MachO::symtab_command));
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}
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void MachObjectWriter::WriteDysymtabLoadCommand(uint32_t FirstLocalSymbol,
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uint32_t NumLocalSymbols,
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uint32_t FirstExternalSymbol,
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uint32_t NumExternalSymbols,
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uint32_t FirstUndefinedSymbol,
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uint32_t NumUndefinedSymbols,
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uint32_t IndirectSymbolOffset,
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uint32_t NumIndirectSymbols) {
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// struct dysymtab_command (80 bytes)
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uint64_t Start = OS.tell();
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(void) Start;
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Write32(MachO::LC_DYSYMTAB);
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Write32(sizeof(MachO::dysymtab_command));
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Write32(FirstLocalSymbol);
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Write32(NumLocalSymbols);
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Write32(FirstExternalSymbol);
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Write32(NumExternalSymbols);
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Write32(FirstUndefinedSymbol);
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Write32(NumUndefinedSymbols);
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Write32(0); // tocoff
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Write32(0); // ntoc
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Write32(0); // modtaboff
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Write32(0); // nmodtab
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Write32(0); // extrefsymoff
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Write32(0); // nextrefsyms
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Write32(IndirectSymbolOffset);
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Write32(NumIndirectSymbols);
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Write32(0); // extreloff
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Write32(0); // nextrel
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Write32(0); // locreloff
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Write32(0); // nlocrel
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assert(OS.tell() - Start == sizeof(MachO::dysymtab_command));
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}
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void MachObjectWriter::WriteNlist(MachSymbolData &MSD,
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const MCAsmLayout &Layout) {
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MCSymbolData &Data = *MSD.SymbolData;
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const MCSymbol &Symbol = Data.getSymbol();
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uint8_t Type = 0;
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uint16_t Flags = Data.getFlags();
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uint64_t Address = 0;
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// Set the N_TYPE bits. See <mach-o/nlist.h>.
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//
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// FIXME: Are the prebound or indirect fields possible here?
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if (Symbol.isUndefined())
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Type = MachO::N_UNDF;
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else if (Symbol.isAbsolute())
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Type = MachO::N_ABS;
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else
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Type = MachO::N_SECT;
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// FIXME: Set STAB bits.
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if (Data.isPrivateExtern())
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Type |= MachO::N_PEXT;
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// Set external bit.
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if (Data.isExternal() || Symbol.isUndefined())
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Type |= MachO::N_EXT;
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// Compute the symbol address.
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if (Symbol.isDefined()) {
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Address = getSymbolAddress(&Data, Layout);
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} else if (Data.isCommon()) {
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// Common symbols are encoded with the size in the address
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// field, and their alignment in the flags.
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Address = Data.getCommonSize();
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// Common alignment is packed into the 'desc' bits.
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if (unsigned Align = Data.getCommonAlignment()) {
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unsigned Log2Size = Log2_32(Align);
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assert((1U << Log2Size) == Align && "Invalid 'common' alignment!");
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if (Log2Size > 15)
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report_fatal_error("invalid 'common' alignment '" +
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Twine(Align) + "' for '" + Symbol.getName() + "'",
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false);
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// FIXME: Keep this mask with the SymbolFlags enumeration.
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Flags = (Flags & 0xF0FF) | (Log2Size << 8);
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}
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}
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// struct nlist (12 bytes)
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Write32(MSD.StringIndex);
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Write8(Type);
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Write8(MSD.SectionIndex);
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// The Mach-O streamer uses the lowest 16-bits of the flags for the 'desc'
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// value.
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Write16(Flags);
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if (is64Bit())
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Write64(Address);
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else
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Write32(Address);
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}
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void MachObjectWriter::WriteLinkeditLoadCommand(uint32_t Type,
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uint32_t DataOffset,
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uint32_t DataSize) {
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uint64_t Start = OS.tell();
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(void) Start;
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Write32(Type);
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Write32(sizeof(MachO::linkedit_data_command));
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Write32(DataOffset);
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Write32(DataSize);
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assert(OS.tell() - Start == sizeof(MachO::linkedit_data_command));
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}
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static unsigned ComputeLinkerOptionsLoadCommandSize(
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const std::vector<std::string> &Options, bool is64Bit)
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{
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unsigned Size = sizeof(MachO::linker_options_command);
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for (unsigned i = 0, e = Options.size(); i != e; ++i)
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Size += Options[i].size() + 1;
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return RoundUpToAlignment(Size, is64Bit ? 8 : 4);
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}
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void MachObjectWriter::WriteLinkerOptionsLoadCommand(
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const std::vector<std::string> &Options)
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{
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unsigned Size = ComputeLinkerOptionsLoadCommandSize(Options, is64Bit());
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uint64_t Start = OS.tell();
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(void) Start;
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Write32(MachO::LC_LINKER_OPTIONS);
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Write32(Size);
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Write32(Options.size());
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uint64_t BytesWritten = sizeof(MachO::linker_options_command);
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for (unsigned i = 0, e = Options.size(); i != e; ++i) {
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// Write each string, including the null byte.
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const std::string &Option = Options[i];
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WriteBytes(Option.c_str(), Option.size() + 1);
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BytesWritten += Option.size() + 1;
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}
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// Pad to a multiple of the pointer size.
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WriteBytes("", OffsetToAlignment(BytesWritten, is64Bit() ? 8 : 4));
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assert(OS.tell() - Start == Size);
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}
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void MachObjectWriter::RecordRelocation(const MCAssembler &Asm,
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const MCAsmLayout &Layout,
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const MCFragment *Fragment,
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const MCFixup &Fixup,
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MCValue Target,
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uint64_t &FixedValue) {
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TargetObjectWriter->RecordRelocation(this, Asm, Layout, Fragment, Fixup,
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Target, FixedValue);
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}
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void MachObjectWriter::BindIndirectSymbols(MCAssembler &Asm) {
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// This is the point where 'as' creates actual symbols for indirect symbols
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// (in the following two passes). It would be easier for us to do this sooner
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// when we see the attribute, but that makes getting the order in the symbol
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// table much more complicated than it is worth.
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//
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// FIXME: Revisit this when the dust settles.
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// Report errors for use of .indirect_symbol not in a symbol pointer section
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// or stub section.
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for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
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ie = Asm.indirect_symbol_end(); it != ie; ++it) {
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const MCSectionMachO &Section =
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cast<MCSectionMachO>(it->SectionData->getSection());
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if (Section.getType() != MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS &&
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Section.getType() != MCSectionMachO::S_LAZY_SYMBOL_POINTERS &&
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Section.getType() != MCSectionMachO::S_SYMBOL_STUBS) {
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MCSymbol &Symbol = *it->Symbol;
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report_fatal_error("indirect symbol '" + Symbol.getName() +
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"' not in a symbol pointer or stub section");
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}
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}
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// Bind non lazy symbol pointers first.
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unsigned IndirectIndex = 0;
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for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
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ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
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const MCSectionMachO &Section =
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cast<MCSectionMachO>(it->SectionData->getSection());
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if (Section.getType() != MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS)
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continue;
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// Initialize the section indirect symbol base, if necessary.
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IndirectSymBase.insert(std::make_pair(it->SectionData, IndirectIndex));
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Asm.getOrCreateSymbolData(*it->Symbol);
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}
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// Then lazy symbol pointers and symbol stubs.
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IndirectIndex = 0;
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for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
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ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
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const MCSectionMachO &Section =
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cast<MCSectionMachO>(it->SectionData->getSection());
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if (Section.getType() != MCSectionMachO::S_LAZY_SYMBOL_POINTERS &&
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Section.getType() != MCSectionMachO::S_SYMBOL_STUBS)
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continue;
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// Initialize the section indirect symbol base, if necessary.
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IndirectSymBase.insert(std::make_pair(it->SectionData, IndirectIndex));
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// Set the symbol type to undefined lazy, but only on construction.
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//
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// FIXME: Do not hardcode.
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bool Created;
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MCSymbolData &Entry = Asm.getOrCreateSymbolData(*it->Symbol, &Created);
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if (Created)
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Entry.setFlags(Entry.getFlags() | 0x0001);
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}
|
|
}
|
|
|
|
/// ComputeSymbolTable - Compute the symbol table data
|
|
///
|
|
/// \param StringTable [out] - The string table data.
|
|
/// \param StringIndexMap [out] - Map from symbol names to offsets in the
|
|
/// string table.
|
|
void MachObjectWriter::
|
|
ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable,
|
|
std::vector<MachSymbolData> &LocalSymbolData,
|
|
std::vector<MachSymbolData> &ExternalSymbolData,
|
|
std::vector<MachSymbolData> &UndefinedSymbolData) {
|
|
// Build section lookup table.
|
|
DenseMap<const MCSection*, uint8_t> SectionIndexMap;
|
|
unsigned Index = 1;
|
|
for (MCAssembler::iterator it = Asm.begin(),
|
|
ie = Asm.end(); it != ie; ++it, ++Index)
|
|
SectionIndexMap[&it->getSection()] = Index;
|
|
assert(Index <= 256 && "Too many sections!");
|
|
|
|
// Index 0 is always the empty string.
|
|
StringMap<uint64_t> StringIndexMap;
|
|
StringTable += '\x00';
|
|
|
|
// Build the symbol arrays and the string table, but only for non-local
|
|
// symbols.
|
|
//
|
|
// The particular order that we collect the symbols and create the string
|
|
// table, then sort the symbols is chosen to match 'as'. Even though it
|
|
// doesn't matter for correctness, this is important for letting us diff .o
|
|
// files.
|
|
for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
|
|
ie = Asm.symbol_end(); it != ie; ++it) {
|
|
const MCSymbol &Symbol = it->getSymbol();
|
|
|
|
// Ignore non-linker visible symbols.
|
|
if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
|
|
continue;
|
|
|
|
if (!it->isExternal() && !Symbol.isUndefined())
|
|
continue;
|
|
|
|
uint64_t &Entry = StringIndexMap[Symbol.getName()];
|
|
if (!Entry) {
|
|
Entry = StringTable.size();
|
|
StringTable += Symbol.getName();
|
|
StringTable += '\x00';
|
|
}
|
|
|
|
MachSymbolData MSD;
|
|
MSD.SymbolData = it;
|
|
MSD.StringIndex = Entry;
|
|
|
|
if (Symbol.isUndefined()) {
|
|
MSD.SectionIndex = 0;
|
|
UndefinedSymbolData.push_back(MSD);
|
|
} else if (Symbol.isAbsolute()) {
|
|
MSD.SectionIndex = 0;
|
|
ExternalSymbolData.push_back(MSD);
|
|
} else {
|
|
MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
|
|
assert(MSD.SectionIndex && "Invalid section index!");
|
|
ExternalSymbolData.push_back(MSD);
|
|
}
|
|
}
|
|
|
|
// Now add the data for local symbols.
|
|
for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
|
|
ie = Asm.symbol_end(); it != ie; ++it) {
|
|
const MCSymbol &Symbol = it->getSymbol();
|
|
|
|
// Ignore non-linker visible symbols.
|
|
if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
|
|
continue;
|
|
|
|
if (it->isExternal() || Symbol.isUndefined())
|
|
continue;
|
|
|
|
uint64_t &Entry = StringIndexMap[Symbol.getName()];
|
|
if (!Entry) {
|
|
Entry = StringTable.size();
|
|
StringTable += Symbol.getName();
|
|
StringTable += '\x00';
|
|
}
|
|
|
|
MachSymbolData MSD;
|
|
MSD.SymbolData = it;
|
|
MSD.StringIndex = Entry;
|
|
|
|
if (Symbol.isAbsolute()) {
|
|
MSD.SectionIndex = 0;
|
|
LocalSymbolData.push_back(MSD);
|
|
} else {
|
|
MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
|
|
assert(MSD.SectionIndex && "Invalid section index!");
|
|
LocalSymbolData.push_back(MSD);
|
|
}
|
|
}
|
|
|
|
// External and undefined symbols are required to be in lexicographic order.
|
|
std::sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
|
|
std::sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
|
|
|
|
// Set the symbol indices.
|
|
Index = 0;
|
|
for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
|
|
LocalSymbolData[i].SymbolData->setIndex(Index++);
|
|
for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
|
|
ExternalSymbolData[i].SymbolData->setIndex(Index++);
|
|
for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
|
|
UndefinedSymbolData[i].SymbolData->setIndex(Index++);
|
|
|
|
// The string table is padded to a multiple of 4.
|
|
while (StringTable.size() % 4)
|
|
StringTable += '\x00';
|
|
}
|
|
|
|
void MachObjectWriter::computeSectionAddresses(const MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
uint64_t StartAddress = 0;
|
|
const SmallVectorImpl<MCSectionData*> &Order = Layout.getSectionOrder();
|
|
for (int i = 0, n = Order.size(); i != n ; ++i) {
|
|
const MCSectionData *SD = Order[i];
|
|
StartAddress = RoundUpToAlignment(StartAddress, SD->getAlignment());
|
|
SectionAddress[SD] = StartAddress;
|
|
StartAddress += Layout.getSectionAddressSize(SD);
|
|
|
|
// Explicitly pad the section to match the alignment requirements of the
|
|
// following one. This is for 'gas' compatibility, it shouldn't
|
|
/// strictly be necessary.
|
|
StartAddress += getPaddingSize(SD, Layout);
|
|
}
|
|
}
|
|
|
|
void MachObjectWriter::markAbsoluteVariableSymbols(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
for (MCAssembler::symbol_iterator i = Asm.symbol_begin(),
|
|
e = Asm.symbol_end();
|
|
i != e; ++i) {
|
|
MCSymbolData &SD = *i;
|
|
if (!SD.getSymbol().isVariable())
|
|
continue;
|
|
|
|
// Is the variable is a symbol difference (SA - SB + C) expression,
|
|
// and neither symbol is external, mark the variable as absolute.
|
|
const MCExpr *Expr = SD.getSymbol().getVariableValue();
|
|
MCValue Value;
|
|
if (Expr->EvaluateAsRelocatable(Value, Layout)) {
|
|
if (Value.getSymA() && Value.getSymB())
|
|
const_cast<MCSymbol*>(&SD.getSymbol())->setAbsolute();
|
|
}
|
|
}
|
|
}
|
|
|
|
void MachObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
computeSectionAddresses(Asm, Layout);
|
|
|
|
// Create symbol data for any indirect symbols.
|
|
BindIndirectSymbols(Asm);
|
|
|
|
// Mark symbol difference expressions in variables (from .set or = directives)
|
|
// as absolute.
|
|
markAbsoluteVariableSymbols(Asm, Layout);
|
|
|
|
// Compute symbol table information and bind symbol indices.
|
|
ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData,
|
|
UndefinedSymbolData);
|
|
}
|
|
|
|
bool MachObjectWriter::
|
|
IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
|
|
const MCSymbolData &DataA,
|
|
const MCFragment &FB,
|
|
bool InSet,
|
|
bool IsPCRel) const {
|
|
if (InSet)
|
|
return true;
|
|
|
|
// The effective address is
|
|
// addr(atom(A)) + offset(A)
|
|
// - addr(atom(B)) - offset(B)
|
|
// and the offsets are not relocatable, so the fixup is fully resolved when
|
|
// addr(atom(A)) - addr(atom(B)) == 0.
|
|
const MCSymbolData *A_Base = 0, *B_Base = 0;
|
|
|
|
const MCSymbol &SA = DataA.getSymbol().AliasedSymbol();
|
|
const MCSection &SecA = SA.getSection();
|
|
const MCSection &SecB = FB.getParent()->getSection();
|
|
|
|
if (IsPCRel) {
|
|
// The simple (Darwin, except on x86_64) way of dealing with this was to
|
|
// assume that any reference to a temporary symbol *must* be a temporary
|
|
// symbol in the same atom, unless the sections differ. Therefore, any PCrel
|
|
// relocation to a temporary symbol (in the same section) is fully
|
|
// resolved. This also works in conjunction with absolutized .set, which
|
|
// requires the compiler to use .set to absolutize the differences between
|
|
// symbols which the compiler knows to be assembly time constants, so we
|
|
// don't need to worry about considering symbol differences fully resolved.
|
|
//
|
|
// If the file isn't using sub-sections-via-symbols, we can make the
|
|
// same assumptions about any symbol that we normally make about
|
|
// assembler locals.
|
|
|
|
if (!Asm.getBackend().hasReliableSymbolDifference()) {
|
|
if (!SA.isInSection() || &SecA != &SecB ||
|
|
(!SA.isTemporary() &&
|
|
FB.getAtom() != Asm.getSymbolData(SA).getFragment()->getAtom() &&
|
|
Asm.getSubsectionsViaSymbols()))
|
|
return false;
|
|
return true;
|
|
}
|
|
// For Darwin x86_64, there is one special case when the reference IsPCRel.
|
|
// If the fragment with the reference does not have a base symbol but meets
|
|
// the simple way of dealing with this, in that it is a temporary symbol in
|
|
// the same atom then it is assumed to be fully resolved. This is needed so
|
|
// a relocation entry is not created and so the static linker does not
|
|
// mess up the reference later.
|
|
else if(!FB.getAtom() &&
|
|
SA.isTemporary() && SA.isInSection() && &SecA == &SecB){
|
|
return true;
|
|
}
|
|
} else {
|
|
if (!TargetObjectWriter->useAggressiveSymbolFolding())
|
|
return false;
|
|
}
|
|
|
|
const MCFragment *FA = Asm.getSymbolData(SA).getFragment();
|
|
|
|
// Bail if the symbol has no fragment.
|
|
if (!FA)
|
|
return false;
|
|
|
|
A_Base = FA->getAtom();
|
|
if (!A_Base)
|
|
return false;
|
|
|
|
B_Base = FB.getAtom();
|
|
if (!B_Base)
|
|
return false;
|
|
|
|
// If the atoms are the same, they are guaranteed to have the same address.
|
|
if (A_Base == B_Base)
|
|
return true;
|
|
|
|
// Otherwise, we can't prove this is fully resolved.
|
|
return false;
|
|
}
|
|
|
|
void MachObjectWriter::WriteObject(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
unsigned NumSections = Asm.size();
|
|
|
|
// The section data starts after the header, the segment load command (and
|
|
// section headers) and the symbol table.
|
|
unsigned NumLoadCommands = 1;
|
|
uint64_t LoadCommandsSize = is64Bit() ?
|
|
sizeof(MachO::segment_command_64) + NumSections * sizeof(MachO::section_64):
|
|
sizeof(MachO::segment_command) + NumSections * sizeof(MachO::section);
|
|
|
|
// Add the data-in-code load command size, if used.
|
|
unsigned NumDataRegions = Asm.getDataRegions().size();
|
|
if (NumDataRegions) {
|
|
++NumLoadCommands;
|
|
LoadCommandsSize += sizeof(MachO::linkedit_data_command);
|
|
}
|
|
|
|
// Add the symbol table load command sizes, if used.
|
|
unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
|
|
UndefinedSymbolData.size();
|
|
if (NumSymbols) {
|
|
NumLoadCommands += 2;
|
|
LoadCommandsSize += (sizeof(MachO::symtab_command) +
|
|
sizeof(MachO::dysymtab_command));
|
|
}
|
|
|
|
// Add the linker option load commands sizes.
|
|
const std::vector<std::vector<std::string> > &LinkerOptions =
|
|
Asm.getLinkerOptions();
|
|
for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
|
|
++NumLoadCommands;
|
|
LoadCommandsSize += ComputeLinkerOptionsLoadCommandSize(LinkerOptions[i],
|
|
is64Bit());
|
|
}
|
|
|
|
// Compute the total size of the section data, as well as its file size and vm
|
|
// size.
|
|
uint64_t SectionDataStart = (is64Bit() ? sizeof(MachO::mach_header_64) :
|
|
sizeof(MachO::mach_header)) + LoadCommandsSize;
|
|
uint64_t SectionDataSize = 0;
|
|
uint64_t SectionDataFileSize = 0;
|
|
uint64_t VMSize = 0;
|
|
for (MCAssembler::const_iterator it = Asm.begin(),
|
|
ie = Asm.end(); it != ie; ++it) {
|
|
const MCSectionData &SD = *it;
|
|
uint64_t Address = getSectionAddress(&SD);
|
|
uint64_t Size = Layout.getSectionAddressSize(&SD);
|
|
uint64_t FileSize = Layout.getSectionFileSize(&SD);
|
|
FileSize += getPaddingSize(&SD, Layout);
|
|
|
|
VMSize = std::max(VMSize, Address + Size);
|
|
|
|
if (SD.getSection().isVirtualSection())
|
|
continue;
|
|
|
|
SectionDataSize = std::max(SectionDataSize, Address + Size);
|
|
SectionDataFileSize = std::max(SectionDataFileSize, Address + FileSize);
|
|
}
|
|
|
|
// The section data is padded to 4 bytes.
|
|
//
|
|
// FIXME: Is this machine dependent?
|
|
unsigned SectionDataPadding = OffsetToAlignment(SectionDataFileSize, 4);
|
|
SectionDataFileSize += SectionDataPadding;
|
|
|
|
// Write the prolog, starting with the header and load command...
|
|
WriteHeader(NumLoadCommands, LoadCommandsSize,
|
|
Asm.getSubsectionsViaSymbols());
|
|
WriteSegmentLoadCommand(NumSections, VMSize,
|
|
SectionDataStart, SectionDataSize);
|
|
|
|
// ... and then the section headers.
|
|
uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
|
|
for (MCAssembler::const_iterator it = Asm.begin(),
|
|
ie = Asm.end(); it != ie; ++it) {
|
|
std::vector<MachO::any_relocation_info> &Relocs = Relocations[it];
|
|
unsigned NumRelocs = Relocs.size();
|
|
uint64_t SectionStart = SectionDataStart + getSectionAddress(it);
|
|
WriteSection(Asm, Layout, *it, SectionStart, RelocTableEnd, NumRelocs);
|
|
RelocTableEnd += NumRelocs * sizeof(MachO::any_relocation_info);
|
|
}
|
|
|
|
// Write the data-in-code load command, if used.
|
|
uint64_t DataInCodeTableEnd = RelocTableEnd + NumDataRegions * 8;
|
|
if (NumDataRegions) {
|
|
uint64_t DataRegionsOffset = RelocTableEnd;
|
|
uint64_t DataRegionsSize = NumDataRegions * 8;
|
|
WriteLinkeditLoadCommand(MachO::LC_DATA_IN_CODE, DataRegionsOffset,
|
|
DataRegionsSize);
|
|
}
|
|
|
|
// Write the symbol table load command, if used.
|
|
if (NumSymbols) {
|
|
unsigned FirstLocalSymbol = 0;
|
|
unsigned NumLocalSymbols = LocalSymbolData.size();
|
|
unsigned FirstExternalSymbol = FirstLocalSymbol + NumLocalSymbols;
|
|
unsigned NumExternalSymbols = ExternalSymbolData.size();
|
|
unsigned FirstUndefinedSymbol = FirstExternalSymbol + NumExternalSymbols;
|
|
unsigned NumUndefinedSymbols = UndefinedSymbolData.size();
|
|
unsigned NumIndirectSymbols = Asm.indirect_symbol_size();
|
|
unsigned NumSymTabSymbols =
|
|
NumLocalSymbols + NumExternalSymbols + NumUndefinedSymbols;
|
|
uint64_t IndirectSymbolSize = NumIndirectSymbols * 4;
|
|
uint64_t IndirectSymbolOffset = 0;
|
|
|
|
// If used, the indirect symbols are written after the section data.
|
|
if (NumIndirectSymbols)
|
|
IndirectSymbolOffset = DataInCodeTableEnd;
|
|
|
|
// The symbol table is written after the indirect symbol data.
|
|
uint64_t SymbolTableOffset = DataInCodeTableEnd + IndirectSymbolSize;
|
|
|
|
// The string table is written after symbol table.
|
|
uint64_t StringTableOffset =
|
|
SymbolTableOffset + NumSymTabSymbols * (is64Bit() ?
|
|
sizeof(MachO::nlist_64) :
|
|
sizeof(MachO::nlist));
|
|
WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
|
|
StringTableOffset, StringTable.size());
|
|
|
|
WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
|
|
FirstExternalSymbol, NumExternalSymbols,
|
|
FirstUndefinedSymbol, NumUndefinedSymbols,
|
|
IndirectSymbolOffset, NumIndirectSymbols);
|
|
}
|
|
|
|
// Write the linker options load commands.
|
|
for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
|
|
WriteLinkerOptionsLoadCommand(LinkerOptions[i]);
|
|
}
|
|
|
|
// Write the actual section data.
|
|
for (MCAssembler::const_iterator it = Asm.begin(),
|
|
ie = Asm.end(); it != ie; ++it) {
|
|
Asm.writeSectionData(it, Layout);
|
|
|
|
uint64_t Pad = getPaddingSize(it, Layout);
|
|
for (unsigned int i = 0; i < Pad; ++i)
|
|
Write8(0);
|
|
}
|
|
|
|
// Write the extra padding.
|
|
WriteZeros(SectionDataPadding);
|
|
|
|
// Write the relocation entries.
|
|
for (MCAssembler::const_iterator it = Asm.begin(),
|
|
ie = Asm.end(); it != ie; ++it) {
|
|
// Write the section relocation entries, in reverse order to match 'as'
|
|
// (approximately, the exact algorithm is more complicated than this).
|
|
std::vector<MachO::any_relocation_info> &Relocs = Relocations[it];
|
|
for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
|
|
Write32(Relocs[e - i - 1].r_word0);
|
|
Write32(Relocs[e - i - 1].r_word1);
|
|
}
|
|
}
|
|
|
|
// Write out the data-in-code region payload, if there is one.
|
|
for (MCAssembler::const_data_region_iterator
|
|
it = Asm.data_region_begin(), ie = Asm.data_region_end();
|
|
it != ie; ++it) {
|
|
const DataRegionData *Data = &(*it);
|
|
uint64_t Start =
|
|
getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->Start),
|
|
Layout);
|
|
uint64_t End =
|
|
getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->End),
|
|
Layout);
|
|
DEBUG(dbgs() << "data in code region-- kind: " << Data->Kind
|
|
<< " start: " << Start << "(" << Data->Start->getName() << ")"
|
|
<< " end: " << End << "(" << Data->End->getName() << ")"
|
|
<< " size: " << End - Start
|
|
<< "\n");
|
|
Write32(Start);
|
|
Write16(End - Start);
|
|
Write16(Data->Kind);
|
|
}
|
|
|
|
// Write the symbol table data, if used.
|
|
if (NumSymbols) {
|
|
// Write the indirect symbol entries.
|
|
for (MCAssembler::const_indirect_symbol_iterator
|
|
it = Asm.indirect_symbol_begin(),
|
|
ie = Asm.indirect_symbol_end(); it != ie; ++it) {
|
|
// Indirect symbols in the non lazy symbol pointer section have some
|
|
// special handling.
|
|
const MCSectionMachO &Section =
|
|
static_cast<const MCSectionMachO&>(it->SectionData->getSection());
|
|
if (Section.getType() == MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) {
|
|
// If this symbol is defined and internal, mark it as such.
|
|
if (it->Symbol->isDefined() &&
|
|
!Asm.getSymbolData(*it->Symbol).isExternal()) {
|
|
uint32_t Flags = MachO::INDIRECT_SYMBOL_LOCAL;
|
|
if (it->Symbol->isAbsolute())
|
|
Flags |= MachO::INDIRECT_SYMBOL_ABS;
|
|
Write32(Flags);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
Write32(Asm.getSymbolData(*it->Symbol).getIndex());
|
|
}
|
|
|
|
// FIXME: Check that offsets match computed ones.
|
|
|
|
// Write the symbol table entries.
|
|
for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
|
|
WriteNlist(LocalSymbolData[i], Layout);
|
|
for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
|
|
WriteNlist(ExternalSymbolData[i], Layout);
|
|
for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
|
|
WriteNlist(UndefinedSymbolData[i], Layout);
|
|
|
|
// Write the string table.
|
|
OS << StringTable.str();
|
|
}
|
|
}
|
|
|
|
MCObjectWriter *llvm::createMachObjectWriter(MCMachObjectTargetWriter *MOTW,
|
|
raw_ostream &OS,
|
|
bool IsLittleEndian) {
|
|
return new MachObjectWriter(MOTW, OS, IsLittleEndian);
|
|
}
|