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be diced into atoms, and adjust getAtom() to take this into account. - This fixes relocations to symbols in fixed size literal sections, for example. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103532 91177308-0d34-0410-b5e6-96231b3b80d8
976 lines
31 KiB
C++
976 lines
31 KiB
C++
//===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
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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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#define DEBUG_TYPE "assembler"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCAsmLayout.h"
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#include "llvm/MC/MCCodeEmitter.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCObjectWriter.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/ADT/OwningPtr.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/ADT/Twine.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/raw_ostream.h"
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#include "llvm/Target/TargetRegistry.h"
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#include "llvm/Target/TargetAsmBackend.h"
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#include <vector>
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using namespace llvm;
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namespace {
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namespace stats {
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STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
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STATISTIC(EvaluateFixup, "Number of evaluated fixups");
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STATISTIC(FragmentLayouts, "Number of fragment layouts");
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STATISTIC(ObjectBytes, "Number of emitted object file bytes");
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STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
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STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
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STATISTIC(SectionLayouts, "Number of section layouts");
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}
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}
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// FIXME FIXME FIXME: There are number of places in this file where we convert
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// what is a 64-bit assembler value used for computation into a value in the
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// object file, which may truncate it. We should detect that truncation where
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// invalid and report errors back.
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/* *** */
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void MCAsmLayout::UpdateForSlide(MCFragment *F, int SlideAmount) {
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// We shouldn't have to do anything special to support negative slides, and it
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// is a perfectly valid thing to do as long as other parts of the system can
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// guarantee convergence.
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assert(SlideAmount >= 0 && "Negative slides not yet supported");
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// Update the layout by simply recomputing the layout for the entire
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// file. This is trivially correct, but very slow.
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//
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// FIXME-PERF: This is O(N^2), but will be eliminated once we get smarter.
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// Layout the concrete sections and fragments.
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MCAssembler &Asm = getAssembler();
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uint64_t Address = 0;
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for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) {
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// Skip virtual sections.
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if (Asm.getBackend().isVirtualSection(it->getSection()))
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continue;
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// Layout the section fragments and its size.
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Address = Asm.LayoutSection(*it, *this, Address);
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}
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// Layout the virtual sections.
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for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) {
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if (!Asm.getBackend().isVirtualSection(it->getSection()))
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continue;
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// Layout the section fragments and its size.
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Address = Asm.LayoutSection(*it, *this, Address);
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}
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}
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uint64_t MCAsmLayout::getFragmentAddress(const MCFragment *F) const {
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assert(F->getParent() && "Missing section()!");
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return getSectionAddress(F->getParent()) + getFragmentOffset(F);
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}
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uint64_t MCAsmLayout::getFragmentEffectiveSize(const MCFragment *F) const {
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assert(F->EffectiveSize != ~UINT64_C(0) && "Address not set!");
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return F->EffectiveSize;
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}
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void MCAsmLayout::setFragmentEffectiveSize(MCFragment *F, uint64_t Value) {
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F->EffectiveSize = Value;
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}
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uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
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assert(F->Offset != ~UINT64_C(0) && "Address not set!");
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return F->Offset;
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}
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void MCAsmLayout::setFragmentOffset(MCFragment *F, uint64_t Value) {
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F->Offset = Value;
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}
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uint64_t MCAsmLayout::getSymbolAddress(const MCSymbolData *SD) const {
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assert(SD->getFragment() && "Invalid getAddress() on undefined symbol!");
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return getFragmentAddress(SD->getFragment()) + SD->getOffset();
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}
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uint64_t MCAsmLayout::getSectionAddress(const MCSectionData *SD) const {
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assert(SD->Address != ~UINT64_C(0) && "Address not set!");
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return SD->Address;
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}
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void MCAsmLayout::setSectionAddress(MCSectionData *SD, uint64_t Value) {
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SD->Address = Value;
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}
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uint64_t MCAsmLayout::getSectionSize(const MCSectionData *SD) const {
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assert(SD->Size != ~UINT64_C(0) && "File size not set!");
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return SD->Size;
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}
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void MCAsmLayout::setSectionSize(MCSectionData *SD, uint64_t Value) {
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SD->Size = Value;
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}
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uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
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assert(SD->FileSize != ~UINT64_C(0) && "File size not set!");
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return SD->FileSize;
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}
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void MCAsmLayout::setSectionFileSize(MCSectionData *SD, uint64_t Value) {
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SD->FileSize = Value;
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}
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/* *** */
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MCFragment::MCFragment() : Kind(FragmentType(~0)) {
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}
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MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
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: Kind(_Kind), Parent(_Parent), Atom(0), EffectiveSize(~UINT64_C(0))
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{
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if (Parent)
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Parent->getFragmentList().push_back(this);
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}
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MCFragment::~MCFragment() {
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}
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/* *** */
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MCSectionData::MCSectionData() : Section(0) {}
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MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
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: Section(&_Section),
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Alignment(1),
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Address(~UINT64_C(0)),
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Size(~UINT64_C(0)),
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FileSize(~UINT64_C(0)),
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HasInstructions(false)
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{
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if (A)
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A->getSectionList().push_back(this);
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}
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/* *** */
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MCSymbolData::MCSymbolData() : Symbol(0) {}
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MCSymbolData::MCSymbolData(const MCSymbol &_Symbol, MCFragment *_Fragment,
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uint64_t _Offset, MCAssembler *A)
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: Symbol(&_Symbol), Fragment(_Fragment), Offset(_Offset),
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IsExternal(false), IsPrivateExtern(false),
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CommonSize(0), CommonAlign(0), Flags(0), Index(0)
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{
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if (A)
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A->getSymbolList().push_back(this);
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}
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/* *** */
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MCAssembler::MCAssembler(MCContext &_Context, TargetAsmBackend &_Backend,
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MCCodeEmitter &_Emitter, raw_ostream &_OS)
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: Context(_Context), Backend(_Backend), Emitter(_Emitter),
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OS(_OS), RelaxAll(false), SubsectionsViaSymbols(false)
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{
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}
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MCAssembler::~MCAssembler() {
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}
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static bool isScatteredFixupFullyResolvedSimple(const MCAssembler &Asm,
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const MCAsmFixup &Fixup,
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const MCValue Target,
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const MCSection *BaseSection) {
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// The effective fixup address is
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// addr(atom(A)) + offset(A)
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// - addr(atom(B)) - offset(B)
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// - addr(<base symbol>) + <fixup offset from base symbol>
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// and the offsets are not relocatable, so the fixup is fully resolved when
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// addr(atom(A)) - addr(atom(B)) - addr(<base symbol>)) == 0.
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//
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// The simple (Darwin, except on x86_64) way of dealing with this was to
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// assume that any reference to a temporary symbol *must* be a temporary
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// symbol in the same atom, unless the sections differ. Therefore, any PCrel
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// relocation to a temporary symbol (in the same section) is fully
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// resolved. This also works in conjunction with absolutized .set, which
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// requires the compiler to use .set to absolutize the differences between
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// symbols which the compiler knows to be assembly time constants, so we don't
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// need to worry about considering symbol differences fully resolved.
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// Non-relative fixups are only resolved if constant.
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if (!BaseSection)
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return Target.isAbsolute();
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// Otherwise, relative fixups are only resolved if not a difference and the
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// target is a temporary in the same section.
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if (Target.isAbsolute() || Target.getSymB())
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return false;
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const MCSymbol *A = &Target.getSymA()->getSymbol();
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if (!A->isTemporary() || !A->isInSection() ||
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&A->getSection() != BaseSection)
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return false;
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return true;
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}
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static bool isScatteredFixupFullyResolved(const MCAssembler &Asm,
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const MCAsmLayout &Layout,
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const MCAsmFixup &Fixup,
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const MCValue Target,
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const MCSymbolData *BaseSymbol) {
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// The effective fixup address is
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// addr(atom(A)) + offset(A)
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// - addr(atom(B)) - offset(B)
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// - addr(BaseSymbol) + <fixup offset from base symbol>
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// and the offsets are not relocatable, so the fixup is fully resolved when
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// addr(atom(A)) - addr(atom(B)) - addr(BaseSymbol) == 0.
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//
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// Note that "false" is almost always conservatively correct (it means we emit
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// a relocation which is unnecessary), except when it would force us to emit a
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// relocation which the target cannot encode.
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const MCSymbolData *A_Base = 0, *B_Base = 0;
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if (const MCSymbolRefExpr *A = Target.getSymA()) {
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// Modified symbol references cannot be resolved.
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if (A->getKind() != MCSymbolRefExpr::VK_None)
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return false;
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A_Base = Asm.getAtom(Layout, &Asm.getSymbolData(A->getSymbol()));
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if (!A_Base)
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return false;
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}
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if (const MCSymbolRefExpr *B = Target.getSymB()) {
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// Modified symbol references cannot be resolved.
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if (B->getKind() != MCSymbolRefExpr::VK_None)
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return false;
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B_Base = Asm.getAtom(Layout, &Asm.getSymbolData(B->getSymbol()));
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if (!B_Base)
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return false;
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}
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// If there is no base, A and B have to be the same atom for this fixup to be
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// fully resolved.
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if (!BaseSymbol)
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return A_Base == B_Base;
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// Otherwise, B must be missing and A must be the base.
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return !B_Base && BaseSymbol == A_Base;
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}
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bool MCAssembler::isSymbolLinkerVisible(const MCSymbolData *SD) const {
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// Non-temporary labels should always be visible to the linker.
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if (!SD->getSymbol().isTemporary())
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return true;
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// Absolute temporary labels are never visible.
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if (!SD->getFragment())
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return false;
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// Otherwise, check if the section requires symbols even for temporary labels.
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return getBackend().doesSectionRequireSymbols(
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SD->getFragment()->getParent()->getSection());
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}
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const MCSymbolData *MCAssembler::getAtom(const MCAsmLayout &Layout,
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const MCSymbolData *SD) const {
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// Linker visible symbols define atoms.
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if (isSymbolLinkerVisible(SD))
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return SD;
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// Absolute and undefined symbols have no defining atom.
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if (!SD->getFragment())
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return 0;
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// Non-linker visible symbols in sections which can't be atomized have no
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// defining atom.
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if (!getBackend().isSectionAtomizable(
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SD->getFragment()->getParent()->getSection()))
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return 0;
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// Otherwise, return the atom for the containing fragment.
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return SD->getFragment()->getAtom();
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}
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bool MCAssembler::EvaluateFixup(const MCAsmLayout &Layout,
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const MCAsmFixup &Fixup, const MCFragment *DF,
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MCValue &Target, uint64_t &Value) const {
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++stats::EvaluateFixup;
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if (!Fixup.Value->EvaluateAsRelocatable(Target, &Layout))
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report_fatal_error("expected relocatable expression");
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// FIXME: How do non-scattered symbols work in ELF? I presume the linker
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// doesn't support small relocations, but then under what criteria does the
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// assembler allow symbol differences?
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Value = Target.getConstant();
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bool IsPCRel =
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Emitter.getFixupKindInfo(Fixup.Kind).Flags & MCFixupKindInfo::FKF_IsPCRel;
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bool IsResolved = true;
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if (const MCSymbolRefExpr *A = Target.getSymA()) {
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if (A->getSymbol().isDefined())
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Value += Layout.getSymbolAddress(&getSymbolData(A->getSymbol()));
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else
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IsResolved = false;
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}
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if (const MCSymbolRefExpr *B = Target.getSymB()) {
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if (B->getSymbol().isDefined())
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Value -= Layout.getSymbolAddress(&getSymbolData(B->getSymbol()));
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else
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IsResolved = false;
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}
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// If we are using scattered symbols, determine whether this value is actually
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// resolved; scattering may cause atoms to move.
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if (IsResolved && getBackend().hasScatteredSymbols()) {
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if (getBackend().hasReliableSymbolDifference()) {
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// If this is a PCrel relocation, find the base atom (identified by its
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// symbol) that the fixup value is relative to.
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const MCSymbolData *BaseSymbol = 0;
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if (IsPCRel) {
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BaseSymbol = DF->getAtom();
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if (!BaseSymbol)
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IsResolved = false;
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}
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if (IsResolved)
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IsResolved = isScatteredFixupFullyResolved(*this, Layout, Fixup, Target,
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BaseSymbol);
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} else {
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const MCSection *BaseSection = 0;
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if (IsPCRel)
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BaseSection = &DF->getParent()->getSection();
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IsResolved = isScatteredFixupFullyResolvedSimple(*this, Fixup, Target,
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BaseSection);
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}
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}
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if (IsPCRel)
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Value -= Layout.getFragmentAddress(DF) + Fixup.Offset;
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return IsResolved;
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}
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uint64_t MCAssembler::LayoutSection(MCSectionData &SD,
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MCAsmLayout &Layout,
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uint64_t StartAddress) {
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bool IsVirtual = getBackend().isVirtualSection(SD.getSection());
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++stats::SectionLayouts;
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// Align this section if necessary by adding padding bytes to the previous
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// section. It is safe to adjust this out-of-band, because no symbol or
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// fragment is allowed to point past the end of the section at any time.
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if (uint64_t Pad = OffsetToAlignment(StartAddress, SD.getAlignment())) {
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// Unless this section is virtual (where we are allowed to adjust the offset
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// freely), the padding goes in the previous section.
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if (!IsVirtual) {
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// Find the previous non-virtual section.
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iterator it = &SD;
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assert(it != begin() && "Invalid initial section address!");
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for (--it; getBackend().isVirtualSection(it->getSection()); --it) ;
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Layout.setSectionFileSize(&*it, Layout.getSectionFileSize(&*it) + Pad);
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}
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StartAddress += Pad;
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}
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// Set the aligned section address.
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Layout.setSectionAddress(&SD, StartAddress);
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uint64_t Address = StartAddress;
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for (MCSectionData::iterator it = SD.begin(), ie = SD.end(); it != ie; ++it) {
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MCFragment &F = *it;
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++stats::FragmentLayouts;
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uint64_t FragmentOffset = Address - StartAddress;
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Layout.setFragmentOffset(&F, FragmentOffset);
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// Evaluate fragment size.
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uint64_t EffectiveSize = 0;
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switch (F.getKind()) {
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case MCFragment::FT_Align: {
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MCAlignFragment &AF = cast<MCAlignFragment>(F);
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EffectiveSize = OffsetToAlignment(Address, AF.getAlignment());
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if (EffectiveSize > AF.getMaxBytesToEmit())
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EffectiveSize = 0;
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break;
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}
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case MCFragment::FT_Data:
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EffectiveSize = cast<MCDataFragment>(F).getContents().size();
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break;
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case MCFragment::FT_Fill: {
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MCFillFragment &FF = cast<MCFillFragment>(F);
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EffectiveSize = FF.getValueSize() * FF.getCount();
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break;
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}
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case MCFragment::FT_Inst:
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EffectiveSize = cast<MCInstFragment>(F).getInstSize();
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break;
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case MCFragment::FT_Org: {
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MCOrgFragment &OF = cast<MCOrgFragment>(F);
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int64_t TargetLocation;
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if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, &Layout))
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report_fatal_error("expected assembly-time absolute expression");
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// FIXME: We need a way to communicate this error.
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int64_t Offset = TargetLocation - FragmentOffset;
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if (Offset < 0)
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report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
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"' (at offset '" + Twine(FragmentOffset) + "'");
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EffectiveSize = Offset;
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break;
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}
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case MCFragment::FT_ZeroFill: {
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MCZeroFillFragment &ZFF = cast<MCZeroFillFragment>(F);
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// Align the fragment offset; it is safe to adjust the offset freely since
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// this is only in virtual sections.
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//
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// FIXME: We shouldn't be doing this here.
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Address = RoundUpToAlignment(Address, ZFF.getAlignment());
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Layout.setFragmentOffset(&F, Address - StartAddress);
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EffectiveSize = ZFF.getSize();
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break;
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}
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}
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Layout.setFragmentEffectiveSize(&F, EffectiveSize);
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Address += EffectiveSize;
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}
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// Set the section sizes.
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Layout.setSectionSize(&SD, Address - StartAddress);
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if (IsVirtual)
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Layout.setSectionFileSize(&SD, 0);
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else
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Layout.setSectionFileSize(&SD, Address - StartAddress);
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return Address;
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}
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/// WriteFragmentData - Write the \arg F data to the output file.
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static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout,
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const MCFragment &F, MCObjectWriter *OW) {
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uint64_t Start = OW->getStream().tell();
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(void) Start;
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++stats::EmittedFragments;
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// FIXME: Embed in fragments instead?
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uint64_t FragmentSize = Layout.getFragmentEffectiveSize(&F);
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switch (F.getKind()) {
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case MCFragment::FT_Align: {
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|
MCAlignFragment &AF = cast<MCAlignFragment>(F);
|
|
uint64_t Count = FragmentSize / AF.getValueSize();
|
|
|
|
// FIXME: This error shouldn't actually occur (the front end should emit
|
|
// multiple .align directives to enforce the semantics it wants), but is
|
|
// severe enough that we want to report it. How to handle this?
|
|
if (Count * AF.getValueSize() != FragmentSize)
|
|
report_fatal_error("undefined .align directive, value size '" +
|
|
Twine(AF.getValueSize()) +
|
|
"' is not a divisor of padding size '" +
|
|
Twine(FragmentSize) + "'");
|
|
|
|
// See if we are aligning with nops, and if so do that first to try to fill
|
|
// the Count bytes. Then if that did not fill any bytes or there are any
|
|
// bytes left to fill use the the Value and ValueSize to fill the rest.
|
|
// If we are aligning with nops, ask that target to emit the right data.
|
|
if (AF.getEmitNops()) {
|
|
if (!Asm.getBackend().WriteNopData(Count, OW))
|
|
report_fatal_error("unable to write nop sequence of " +
|
|
Twine(Count) + " bytes");
|
|
break;
|
|
}
|
|
|
|
// Otherwise, write out in multiples of the value size.
|
|
for (uint64_t i = 0; i != Count; ++i) {
|
|
switch (AF.getValueSize()) {
|
|
default:
|
|
assert(0 && "Invalid size!");
|
|
case 1: OW->Write8 (uint8_t (AF.getValue())); break;
|
|
case 2: OW->Write16(uint16_t(AF.getValue())); break;
|
|
case 4: OW->Write32(uint32_t(AF.getValue())); break;
|
|
case 8: OW->Write64(uint64_t(AF.getValue())); break;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
case MCFragment::FT_Data: {
|
|
MCDataFragment &DF = cast<MCDataFragment>(F);
|
|
assert(FragmentSize == DF.getContents().size() && "Invalid size!");
|
|
OW->WriteBytes(DF.getContents().str());
|
|
break;
|
|
}
|
|
|
|
case MCFragment::FT_Fill: {
|
|
MCFillFragment &FF = cast<MCFillFragment>(F);
|
|
for (uint64_t i = 0, e = FF.getCount(); i != e; ++i) {
|
|
switch (FF.getValueSize()) {
|
|
default:
|
|
assert(0 && "Invalid size!");
|
|
case 1: OW->Write8 (uint8_t (FF.getValue())); break;
|
|
case 2: OW->Write16(uint16_t(FF.getValue())); break;
|
|
case 4: OW->Write32(uint32_t(FF.getValue())); break;
|
|
case 8: OW->Write64(uint64_t(FF.getValue())); break;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
case MCFragment::FT_Inst:
|
|
llvm_unreachable("unexpected inst fragment after lowering");
|
|
break;
|
|
|
|
case MCFragment::FT_Org: {
|
|
MCOrgFragment &OF = cast<MCOrgFragment>(F);
|
|
|
|
for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
|
|
OW->Write8(uint8_t(OF.getValue()));
|
|
|
|
break;
|
|
}
|
|
|
|
case MCFragment::FT_ZeroFill: {
|
|
assert(0 && "Invalid zero fill fragment in concrete section!");
|
|
break;
|
|
}
|
|
}
|
|
|
|
assert(OW->getStream().tell() - Start == FragmentSize);
|
|
}
|
|
|
|
void MCAssembler::WriteSectionData(const MCSectionData *SD,
|
|
const MCAsmLayout &Layout,
|
|
MCObjectWriter *OW) const {
|
|
uint64_t SectionSize = Layout.getSectionSize(SD);
|
|
uint64_t SectionFileSize = Layout.getSectionFileSize(SD);
|
|
|
|
// Ignore virtual sections.
|
|
if (getBackend().isVirtualSection(SD->getSection())) {
|
|
assert(SectionFileSize == 0 && "Invalid size for section!");
|
|
return;
|
|
}
|
|
|
|
uint64_t Start = OW->getStream().tell();
|
|
(void) Start;
|
|
|
|
for (MCSectionData::const_iterator it = SD->begin(),
|
|
ie = SD->end(); it != ie; ++it)
|
|
WriteFragmentData(*this, Layout, *it, OW);
|
|
|
|
// Add section padding.
|
|
assert(SectionFileSize >= SectionSize && "Invalid section sizes!");
|
|
OW->WriteZeros(SectionFileSize - SectionSize);
|
|
|
|
assert(OW->getStream().tell() - Start == SectionFileSize);
|
|
}
|
|
|
|
void MCAssembler::Finish() {
|
|
DEBUG_WITH_TYPE("mc-dump", {
|
|
llvm::errs() << "assembler backend - pre-layout\n--\n";
|
|
dump(); });
|
|
|
|
// Assign section and fragment ordinals, all subsequent backend code is
|
|
// responsible for updating these in place.
|
|
unsigned SectionIndex = 0;
|
|
unsigned FragmentIndex = 0;
|
|
for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
it->setOrdinal(SectionIndex++);
|
|
|
|
for (MCSectionData::iterator it2 = it->begin(),
|
|
ie2 = it->end(); it2 != ie2; ++it2)
|
|
it2->setOrdinal(FragmentIndex++);
|
|
}
|
|
|
|
// Layout until everything fits.
|
|
MCAsmLayout Layout(*this);
|
|
while (LayoutOnce(Layout))
|
|
continue;
|
|
|
|
DEBUG_WITH_TYPE("mc-dump", {
|
|
llvm::errs() << "assembler backend - post-relaxation\n--\n";
|
|
dump(); });
|
|
|
|
// Finalize the layout, including fragment lowering.
|
|
FinishLayout(Layout);
|
|
|
|
DEBUG_WITH_TYPE("mc-dump", {
|
|
llvm::errs() << "assembler backend - final-layout\n--\n";
|
|
dump(); });
|
|
|
|
uint64_t StartOffset = OS.tell();
|
|
llvm::OwningPtr<MCObjectWriter> Writer(getBackend().createObjectWriter(OS));
|
|
if (!Writer)
|
|
report_fatal_error("unable to create object writer!");
|
|
|
|
// Allow the object writer a chance to perform post-layout binding (for
|
|
// example, to set the index fields in the symbol data).
|
|
Writer->ExecutePostLayoutBinding(*this);
|
|
|
|
// Evaluate and apply the fixups, generating relocation entries as necessary.
|
|
for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
for (MCSectionData::iterator it2 = it->begin(),
|
|
ie2 = it->end(); it2 != ie2; ++it2) {
|
|
MCDataFragment *DF = dyn_cast<MCDataFragment>(it2);
|
|
if (!DF)
|
|
continue;
|
|
|
|
for (MCDataFragment::fixup_iterator it3 = DF->fixup_begin(),
|
|
ie3 = DF->fixup_end(); it3 != ie3; ++it3) {
|
|
MCAsmFixup &Fixup = *it3;
|
|
|
|
// Evaluate the fixup.
|
|
MCValue Target;
|
|
uint64_t FixedValue;
|
|
if (!EvaluateFixup(Layout, Fixup, DF, Target, FixedValue)) {
|
|
// The fixup was unresolved, we need a relocation. Inform the object
|
|
// writer of the relocation, and give it an opportunity to adjust the
|
|
// fixup value if need be.
|
|
Writer->RecordRelocation(*this, Layout, DF, Fixup, Target,FixedValue);
|
|
}
|
|
|
|
getBackend().ApplyFixup(Fixup, *DF, FixedValue);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Write the object file.
|
|
Writer->WriteObject(*this, Layout);
|
|
OS.flush();
|
|
|
|
stats::ObjectBytes += OS.tell() - StartOffset;
|
|
}
|
|
|
|
bool MCAssembler::FixupNeedsRelaxation(const MCAsmFixup &Fixup,
|
|
const MCFragment *DF,
|
|
const MCAsmLayout &Layout) const {
|
|
if (getRelaxAll())
|
|
return true;
|
|
|
|
// If we cannot resolve the fixup value, it requires relaxation.
|
|
MCValue Target;
|
|
uint64_t Value;
|
|
if (!EvaluateFixup(Layout, Fixup, DF, Target, Value))
|
|
return true;
|
|
|
|
// Otherwise, relax if the value is too big for a (signed) i8.
|
|
//
|
|
// FIXME: This is target dependent!
|
|
return int64_t(Value) != int64_t(int8_t(Value));
|
|
}
|
|
|
|
bool MCAssembler::FragmentNeedsRelaxation(const MCInstFragment *IF,
|
|
const MCAsmLayout &Layout) const {
|
|
// If this inst doesn't ever need relaxation, ignore it. This occurs when we
|
|
// are intentionally pushing out inst fragments, or because we relaxed a
|
|
// previous instruction to one that doesn't need relaxation.
|
|
if (!getBackend().MayNeedRelaxation(IF->getInst(), IF->getFixups()))
|
|
return false;
|
|
|
|
for (MCInstFragment::const_fixup_iterator it = IF->fixup_begin(),
|
|
ie = IF->fixup_end(); it != ie; ++it)
|
|
if (FixupNeedsRelaxation(*it, IF, Layout))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
bool MCAssembler::LayoutOnce(MCAsmLayout &Layout) {
|
|
++stats::RelaxationSteps;
|
|
|
|
// Layout the concrete sections and fragments.
|
|
uint64_t Address = 0;
|
|
for (iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
// Skip virtual sections.
|
|
if (getBackend().isVirtualSection(it->getSection()))
|
|
continue;
|
|
|
|
// Layout the section fragments and its size.
|
|
Address = LayoutSection(*it, Layout, Address);
|
|
}
|
|
|
|
// Layout the virtual sections.
|
|
for (iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
if (!getBackend().isVirtualSection(it->getSection()))
|
|
continue;
|
|
|
|
// Layout the section fragments and its size.
|
|
Address = LayoutSection(*it, Layout, Address);
|
|
}
|
|
|
|
// Scan for fragments that need relaxation.
|
|
bool WasRelaxed = false;
|
|
for (iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
MCSectionData &SD = *it;
|
|
|
|
for (MCSectionData::iterator it2 = SD.begin(),
|
|
ie2 = SD.end(); it2 != ie2; ++it2) {
|
|
// Check if this is an instruction fragment that needs relaxation.
|
|
MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
|
|
if (!IF || !FragmentNeedsRelaxation(IF, Layout))
|
|
continue;
|
|
|
|
++stats::RelaxedInstructions;
|
|
|
|
// FIXME-PERF: We could immediately lower out instructions if we can tell
|
|
// they are fully resolved, to avoid retesting on later passes.
|
|
|
|
// Relax the fragment.
|
|
|
|
MCInst Relaxed;
|
|
getBackend().RelaxInstruction(IF, Relaxed);
|
|
|
|
// Encode the new instruction.
|
|
//
|
|
// FIXME-PERF: If it matters, we could let the target do this. It can
|
|
// probably do so more efficiently in many cases.
|
|
SmallVector<MCFixup, 4> Fixups;
|
|
SmallString<256> Code;
|
|
raw_svector_ostream VecOS(Code);
|
|
getEmitter().EncodeInstruction(Relaxed, VecOS, Fixups);
|
|
VecOS.flush();
|
|
|
|
// Update the instruction fragment.
|
|
int SlideAmount = Code.size() - IF->getInstSize();
|
|
IF->setInst(Relaxed);
|
|
IF->getCode() = Code;
|
|
IF->getFixups().clear();
|
|
for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
|
|
MCFixup &F = Fixups[i];
|
|
IF->getFixups().push_back(MCAsmFixup(F.getOffset(), *F.getValue(),
|
|
F.getKind()));
|
|
}
|
|
|
|
// Update the layout, and remember that we relaxed. If we are relaxing
|
|
// everything, we can skip this step since nothing will depend on updating
|
|
// the values.
|
|
if (!getRelaxAll())
|
|
Layout.UpdateForSlide(IF, SlideAmount);
|
|
WasRelaxed = true;
|
|
}
|
|
}
|
|
|
|
return WasRelaxed;
|
|
}
|
|
|
|
void MCAssembler::FinishLayout(MCAsmLayout &Layout) {
|
|
// Lower out any instruction fragments, to simplify the fixup application and
|
|
// output.
|
|
//
|
|
// FIXME-PERF: We don't have to do this, but the assumption is that it is
|
|
// cheap (we will mostly end up eliminating fragments and appending on to data
|
|
// fragments), so the extra complexity downstream isn't worth it. Evaluate
|
|
// this assumption.
|
|
for (iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
MCSectionData &SD = *it;
|
|
|
|
for (MCSectionData::iterator it2 = SD.begin(),
|
|
ie2 = SD.end(); it2 != ie2; ++it2) {
|
|
MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
|
|
if (!IF)
|
|
continue;
|
|
|
|
// Create a new data fragment for the instruction.
|
|
//
|
|
// FIXME-PERF: Reuse previous data fragment if possible.
|
|
MCDataFragment *DF = new MCDataFragment();
|
|
SD.getFragmentList().insert(it2, DF);
|
|
|
|
// Update the data fragments layout data.
|
|
//
|
|
// FIXME: Add MCAsmLayout utility for this.
|
|
DF->setParent(IF->getParent());
|
|
DF->setAtom(IF->getAtom());
|
|
DF->setOrdinal(IF->getOrdinal());
|
|
Layout.setFragmentOffset(DF, Layout.getFragmentOffset(IF));
|
|
Layout.setFragmentEffectiveSize(DF, Layout.getFragmentEffectiveSize(IF));
|
|
|
|
// Copy in the data and the fixups.
|
|
DF->getContents().append(IF->getCode().begin(), IF->getCode().end());
|
|
for (unsigned i = 0, e = IF->getFixups().size(); i != e; ++i)
|
|
DF->getFixups().push_back(IF->getFixups()[i]);
|
|
|
|
// Delete the instruction fragment and update the iterator.
|
|
SD.getFragmentList().erase(IF);
|
|
it2 = DF;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Debugging methods
|
|
|
|
namespace llvm {
|
|
|
|
raw_ostream &operator<<(raw_ostream &OS, const MCAsmFixup &AF) {
|
|
OS << "<MCAsmFixup" << " Offset:" << AF.Offset << " Value:" << *AF.Value
|
|
<< " Kind:" << AF.Kind << ">";
|
|
return OS;
|
|
}
|
|
|
|
}
|
|
|
|
void MCFragment::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCFragment " << (void*) this << " Offset:" << Offset
|
|
<< " EffectiveSize:" << EffectiveSize;
|
|
|
|
OS << ">";
|
|
}
|
|
|
|
void MCAlignFragment::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCAlignFragment ";
|
|
this->MCFragment::dump();
|
|
OS << "\n ";
|
|
OS << " Alignment:" << getAlignment()
|
|
<< " Value:" << getValue() << " ValueSize:" << getValueSize()
|
|
<< " MaxBytesToEmit:" << getMaxBytesToEmit() << ">";
|
|
}
|
|
|
|
void MCDataFragment::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCDataFragment ";
|
|
this->MCFragment::dump();
|
|
OS << "\n ";
|
|
OS << " Contents:[";
|
|
for (unsigned i = 0, e = getContents().size(); i != e; ++i) {
|
|
if (i) OS << ",";
|
|
OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
|
|
}
|
|
OS << "] (" << getContents().size() << " bytes)";
|
|
|
|
if (!getFixups().empty()) {
|
|
OS << ",\n ";
|
|
OS << " Fixups:[";
|
|
for (fixup_iterator it = fixup_begin(), ie = fixup_end(); it != ie; ++it) {
|
|
if (it != fixup_begin()) OS << ",\n ";
|
|
OS << *it;
|
|
}
|
|
OS << "]";
|
|
}
|
|
|
|
OS << ">";
|
|
}
|
|
|
|
void MCFillFragment::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCFillFragment ";
|
|
this->MCFragment::dump();
|
|
OS << "\n ";
|
|
OS << " Value:" << getValue() << " ValueSize:" << getValueSize()
|
|
<< " Count:" << getCount() << ">";
|
|
}
|
|
|
|
void MCInstFragment::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCInstFragment ";
|
|
this->MCFragment::dump();
|
|
OS << "\n ";
|
|
OS << " Inst:";
|
|
getInst().dump_pretty(OS);
|
|
OS << ">";
|
|
}
|
|
|
|
void MCOrgFragment::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCOrgFragment ";
|
|
this->MCFragment::dump();
|
|
OS << "\n ";
|
|
OS << " Offset:" << getOffset() << " Value:" << getValue() << ">";
|
|
}
|
|
|
|
void MCZeroFillFragment::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCZeroFillFragment ";
|
|
this->MCFragment::dump();
|
|
OS << "\n ";
|
|
OS << " Size:" << getSize() << " Alignment:" << getAlignment() << ">";
|
|
}
|
|
|
|
void MCSectionData::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCSectionData";
|
|
OS << " Alignment:" << getAlignment() << " Address:" << Address
|
|
<< " Size:" << Size << " FileSize:" << FileSize
|
|
<< " Fragments:[\n ";
|
|
for (iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
if (it != begin()) OS << ",\n ";
|
|
it->dump();
|
|
}
|
|
OS << "]>";
|
|
}
|
|
|
|
void MCSymbolData::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCSymbolData Symbol:" << getSymbol()
|
|
<< " Fragment:" << getFragment() << " Offset:" << getOffset()
|
|
<< " Flags:" << getFlags() << " Index:" << getIndex();
|
|
if (isCommon())
|
|
OS << " (common, size:" << getCommonSize()
|
|
<< " align: " << getCommonAlignment() << ")";
|
|
if (isExternal())
|
|
OS << " (external)";
|
|
if (isPrivateExtern())
|
|
OS << " (private extern)";
|
|
OS << ">";
|
|
}
|
|
|
|
void MCAssembler::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCAssembler\n";
|
|
OS << " Sections:[\n ";
|
|
for (iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
if (it != begin()) OS << ",\n ";
|
|
it->dump();
|
|
}
|
|
OS << "],\n";
|
|
OS << " Symbols:[";
|
|
|
|
for (symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
|
|
if (it != symbol_begin()) OS << ",\n ";
|
|
it->dump();
|
|
}
|
|
OS << "]>\n";
|
|
}
|