mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-27 15:29:51 +00:00
Introduce a helper method to add a section to the end of a layout. This will be used by the ELF ObjectWriter code to add the metadata sections (symbol table, etc) to the end of an object file. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111171 91177308-0d34-0410-b5e6-96231b3b80d8
1071 lines
35 KiB
C++
1071 lines
35 KiB
C++
//===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "assembler"
|
|
#include "llvm/MC/MCAssembler.h"
|
|
#include "llvm/MC/MCAsmLayout.h"
|
|
#include "llvm/MC/MCCodeEmitter.h"
|
|
#include "llvm/MC/MCExpr.h"
|
|
#include "llvm/MC/MCObjectWriter.h"
|
|
#include "llvm/MC/MCSymbol.h"
|
|
#include "llvm/MC/MCValue.h"
|
|
#include "llvm/ADT/OwningPtr.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/ADT/StringExtras.h"
|
|
#include "llvm/ADT/Twine.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/ErrorHandling.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include "llvm/Target/TargetRegistry.h"
|
|
#include "llvm/Target/TargetAsmBackend.h"
|
|
|
|
#include <vector>
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
namespace stats {
|
|
STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
|
|
STATISTIC(EvaluateFixup, "Number of evaluated fixups");
|
|
STATISTIC(FragmentLayouts, "Number of fragment layouts");
|
|
STATISTIC(ObjectBytes, "Number of emitted object file bytes");
|
|
STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
|
|
STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
|
|
STATISTIC(SectionLayouts, "Number of section layouts");
|
|
}
|
|
}
|
|
|
|
// FIXME FIXME FIXME: There are number of places in this file where we convert
|
|
// what is a 64-bit assembler value used for computation into a value in the
|
|
// object file, which may truncate it. We should detect that truncation where
|
|
// invalid and report errors back.
|
|
|
|
/* *** */
|
|
|
|
MCAsmLayout::MCAsmLayout(MCAssembler &Asm)
|
|
: Assembler(Asm), LastValidFragment(0)
|
|
{
|
|
// Compute the section layout order. Virtual sections must go last.
|
|
for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
|
|
if (!Asm.getBackend().isVirtualSection(it->getSection()))
|
|
SectionOrder.push_back(&*it);
|
|
for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
|
|
if (Asm.getBackend().isVirtualSection(it->getSection()))
|
|
SectionOrder.push_back(&*it);
|
|
}
|
|
|
|
bool MCAsmLayout::isSectionUpToDate(const MCSectionData *SD) const {
|
|
// The first section is always up-to-date.
|
|
unsigned Index = SD->getLayoutOrder();
|
|
if (!Index)
|
|
return true;
|
|
|
|
// Otherwise, sections are always implicitly computed when the preceeding
|
|
// fragment is layed out.
|
|
const MCSectionData *Prev = getSectionOrder()[Index - 1];
|
|
return isFragmentUpToDate(&(Prev->getFragmentList().back()));
|
|
}
|
|
|
|
bool MCAsmLayout::isFragmentUpToDate(const MCFragment *F) const {
|
|
return (LastValidFragment &&
|
|
F->getLayoutOrder() <= LastValidFragment->getLayoutOrder());
|
|
}
|
|
|
|
void MCAsmLayout::UpdateForSlide(MCFragment *F, int SlideAmount) {
|
|
// If this fragment wasn't already up-to-date, we don't need to do anything.
|
|
if (!isFragmentUpToDate(F))
|
|
return;
|
|
|
|
// Otherwise, reset the last valid fragment to the predecessor of the
|
|
// invalidated fragment.
|
|
LastValidFragment = F->getPrevNode();
|
|
if (!LastValidFragment) {
|
|
unsigned Index = F->getParent()->getLayoutOrder();
|
|
if (Index != 0) {
|
|
MCSectionData *Prev = getSectionOrder()[Index - 1];
|
|
LastValidFragment = &(Prev->getFragmentList().back());
|
|
}
|
|
}
|
|
}
|
|
|
|
void MCAsmLayout::EnsureValid(const MCFragment *F) const {
|
|
// Advance the layout position until the fragment is up-to-date.
|
|
while (!isFragmentUpToDate(F)) {
|
|
// Advance to the next fragment.
|
|
MCFragment *Cur = LastValidFragment;
|
|
if (Cur)
|
|
Cur = Cur->getNextNode();
|
|
if (!Cur) {
|
|
unsigned NextIndex = 0;
|
|
if (LastValidFragment)
|
|
NextIndex = LastValidFragment->getParent()->getLayoutOrder() + 1;
|
|
Cur = SectionOrder[NextIndex]->begin();
|
|
}
|
|
|
|
const_cast<MCAsmLayout*>(this)->LayoutFragment(Cur);
|
|
}
|
|
}
|
|
|
|
void MCAsmLayout::FragmentReplaced(MCFragment *Src, MCFragment *Dst) {
|
|
if (LastValidFragment == Src)
|
|
LastValidFragment = Dst;
|
|
|
|
Dst->Offset = Src->Offset;
|
|
Dst->EffectiveSize = Src->EffectiveSize;
|
|
}
|
|
|
|
uint64_t MCAsmLayout::getFragmentAddress(const MCFragment *F) const {
|
|
assert(F->getParent() && "Missing section()!");
|
|
return getSectionAddress(F->getParent()) + getFragmentOffset(F);
|
|
}
|
|
|
|
uint64_t MCAsmLayout::getFragmentEffectiveSize(const MCFragment *F) const {
|
|
EnsureValid(F);
|
|
assert(F->EffectiveSize != ~UINT64_C(0) && "Address not set!");
|
|
return F->EffectiveSize;
|
|
}
|
|
|
|
uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
|
|
EnsureValid(F);
|
|
assert(F->Offset != ~UINT64_C(0) && "Address not set!");
|
|
return F->Offset;
|
|
}
|
|
|
|
uint64_t MCAsmLayout::getSymbolAddress(const MCSymbolData *SD) const {
|
|
assert(SD->getFragment() && "Invalid getAddress() on undefined symbol!");
|
|
return getFragmentAddress(SD->getFragment()) + SD->getOffset();
|
|
}
|
|
|
|
uint64_t MCAsmLayout::getSectionAddress(const MCSectionData *SD) const {
|
|
EnsureValid(SD->begin());
|
|
assert(SD->Address != ~UINT64_C(0) && "Address not set!");
|
|
return SD->Address;
|
|
}
|
|
|
|
uint64_t MCAsmLayout::getSectionAddressSize(const MCSectionData *SD) const {
|
|
// The size is the last fragment's end offset.
|
|
const MCFragment &F = SD->getFragmentList().back();
|
|
return getFragmentOffset(&F) + getFragmentEffectiveSize(&F);
|
|
}
|
|
|
|
uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
|
|
// Virtual sections have no file size.
|
|
if (getAssembler().getBackend().isVirtualSection(SD->getSection()))
|
|
return 0;
|
|
|
|
// Otherwise, the file size is the same as the address space size.
|
|
return getSectionAddressSize(SD);
|
|
}
|
|
|
|
uint64_t MCAsmLayout::getSectionSize(const MCSectionData *SD) const {
|
|
// The logical size is the address space size minus any tail padding.
|
|
uint64_t Size = getSectionAddressSize(SD);
|
|
const MCAlignFragment *AF =
|
|
dyn_cast<MCAlignFragment>(&(SD->getFragmentList().back()));
|
|
if (AF && AF->hasOnlyAlignAddress())
|
|
Size -= getFragmentEffectiveSize(AF);
|
|
|
|
return Size;
|
|
}
|
|
|
|
/* *** */
|
|
|
|
MCFragment::MCFragment() : Kind(FragmentType(~0)) {
|
|
}
|
|
|
|
MCFragment::~MCFragment() {
|
|
}
|
|
|
|
MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
|
|
: Kind(_Kind), Parent(_Parent), Atom(0), Offset(~UINT64_C(0)),
|
|
EffectiveSize(~UINT64_C(0))
|
|
{
|
|
if (Parent)
|
|
Parent->getFragmentList().push_back(this);
|
|
}
|
|
|
|
/* *** */
|
|
|
|
MCSectionData::MCSectionData() : Section(0) {}
|
|
|
|
MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
|
|
: Section(&_Section),
|
|
Alignment(1),
|
|
Address(~UINT64_C(0)),
|
|
HasInstructions(false)
|
|
{
|
|
if (A)
|
|
A->getSectionList().push_back(this);
|
|
}
|
|
|
|
/* *** */
|
|
|
|
MCSymbolData::MCSymbolData() : Symbol(0) {}
|
|
|
|
MCSymbolData::MCSymbolData(const MCSymbol &_Symbol, MCFragment *_Fragment,
|
|
uint64_t _Offset, MCAssembler *A)
|
|
: Symbol(&_Symbol), Fragment(_Fragment), Offset(_Offset),
|
|
IsExternal(false), IsPrivateExtern(false),
|
|
CommonSize(0), SymbolSize(0), CommonAlign(0),
|
|
Flags(0), Index(0)
|
|
{
|
|
if (A)
|
|
A->getSymbolList().push_back(this);
|
|
}
|
|
|
|
/* *** */
|
|
|
|
MCAssembler::MCAssembler(MCContext &_Context, TargetAsmBackend &_Backend,
|
|
MCCodeEmitter &_Emitter, raw_ostream &_OS)
|
|
: Context(_Context), Backend(_Backend), Emitter(_Emitter),
|
|
OS(_OS), RelaxAll(false), SubsectionsViaSymbols(false)
|
|
{
|
|
}
|
|
|
|
MCAssembler::~MCAssembler() {
|
|
}
|
|
|
|
static bool isScatteredFixupFullyResolvedSimple(const MCAssembler &Asm,
|
|
const MCFixup &Fixup,
|
|
const MCValue Target,
|
|
const MCSection *BaseSection) {
|
|
// The effective fixup address is
|
|
// addr(atom(A)) + offset(A)
|
|
// - addr(atom(B)) - offset(B)
|
|
// - addr(<base symbol>) + <fixup offset from base symbol>
|
|
// and the offsets are not relocatable, so the fixup is fully resolved when
|
|
// addr(atom(A)) - addr(atom(B)) - addr(<base symbol>)) == 0.
|
|
//
|
|
// 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.
|
|
|
|
// Non-relative fixups are only resolved if constant.
|
|
if (!BaseSection)
|
|
return Target.isAbsolute();
|
|
|
|
// Otherwise, relative fixups are only resolved if not a difference and the
|
|
// target is a temporary in the same section.
|
|
if (Target.isAbsolute() || Target.getSymB())
|
|
return false;
|
|
|
|
const MCSymbol *A = &Target.getSymA()->getSymbol();
|
|
if (!A->isTemporary() || !A->isInSection() ||
|
|
&A->getSection() != BaseSection)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool isScatteredFixupFullyResolved(const MCAssembler &Asm,
|
|
const MCAsmLayout &Layout,
|
|
const MCFixup &Fixup,
|
|
const MCValue Target,
|
|
const MCSymbolData *BaseSymbol) {
|
|
// The effective fixup address is
|
|
// addr(atom(A)) + offset(A)
|
|
// - addr(atom(B)) - offset(B)
|
|
// - addr(BaseSymbol) + <fixup offset from base symbol>
|
|
// and the offsets are not relocatable, so the fixup is fully resolved when
|
|
// addr(atom(A)) - addr(atom(B)) - addr(BaseSymbol) == 0.
|
|
//
|
|
// Note that "false" is almost always conservatively correct (it means we emit
|
|
// a relocation which is unnecessary), except when it would force us to emit a
|
|
// relocation which the target cannot encode.
|
|
|
|
const MCSymbolData *A_Base = 0, *B_Base = 0;
|
|
if (const MCSymbolRefExpr *A = Target.getSymA()) {
|
|
// Modified symbol references cannot be resolved.
|
|
if (A->getKind() != MCSymbolRefExpr::VK_None)
|
|
return false;
|
|
|
|
A_Base = Asm.getAtom(Layout, &Asm.getSymbolData(A->getSymbol()));
|
|
if (!A_Base)
|
|
return false;
|
|
}
|
|
|
|
if (const MCSymbolRefExpr *B = Target.getSymB()) {
|
|
// Modified symbol references cannot be resolved.
|
|
if (B->getKind() != MCSymbolRefExpr::VK_None)
|
|
return false;
|
|
|
|
B_Base = Asm.getAtom(Layout, &Asm.getSymbolData(B->getSymbol()));
|
|
if (!B_Base)
|
|
return false;
|
|
}
|
|
|
|
// If there is no base, A and B have to be the same atom for this fixup to be
|
|
// fully resolved.
|
|
if (!BaseSymbol)
|
|
return A_Base == B_Base;
|
|
|
|
// Otherwise, B must be missing and A must be the base.
|
|
return !B_Base && BaseSymbol == A_Base;
|
|
}
|
|
|
|
bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
|
|
// Non-temporary labels should always be visible to the linker.
|
|
if (!Symbol.isTemporary())
|
|
return true;
|
|
|
|
// Absolute temporary labels are never visible.
|
|
if (!Symbol.isInSection())
|
|
return false;
|
|
|
|
// Otherwise, check if the section requires symbols even for temporary labels.
|
|
return getBackend().doesSectionRequireSymbols(Symbol.getSection());
|
|
}
|
|
|
|
const MCSymbolData *MCAssembler::getAtom(const MCAsmLayout &Layout,
|
|
const MCSymbolData *SD) const {
|
|
// Linker visible symbols define atoms.
|
|
if (isSymbolLinkerVisible(SD->getSymbol()))
|
|
return SD;
|
|
|
|
// Absolute and undefined symbols have no defining atom.
|
|
if (!SD->getFragment())
|
|
return 0;
|
|
|
|
// Non-linker visible symbols in sections which can't be atomized have no
|
|
// defining atom.
|
|
if (!getBackend().isSectionAtomizable(
|
|
SD->getFragment()->getParent()->getSection()))
|
|
return 0;
|
|
|
|
// Otherwise, return the atom for the containing fragment.
|
|
return SD->getFragment()->getAtom();
|
|
}
|
|
|
|
bool MCAssembler::EvaluateFixup(const MCAsmLayout &Layout,
|
|
const MCFixup &Fixup, const MCFragment *DF,
|
|
MCValue &Target, uint64_t &Value) const {
|
|
++stats::EvaluateFixup;
|
|
|
|
if (!Fixup.getValue()->EvaluateAsRelocatable(Target, &Layout))
|
|
report_fatal_error("expected relocatable expression");
|
|
|
|
// FIXME: How do non-scattered symbols work in ELF? I presume the linker
|
|
// doesn't support small relocations, but then under what criteria does the
|
|
// assembler allow symbol differences?
|
|
|
|
Value = Target.getConstant();
|
|
|
|
bool IsPCRel = Emitter.getFixupKindInfo(
|
|
Fixup.getKind()).Flags & MCFixupKindInfo::FKF_IsPCRel;
|
|
bool IsResolved = true;
|
|
if (const MCSymbolRefExpr *A = Target.getSymA()) {
|
|
if (A->getSymbol().isDefined())
|
|
Value += Layout.getSymbolAddress(&getSymbolData(A->getSymbol()));
|
|
else
|
|
IsResolved = false;
|
|
}
|
|
if (const MCSymbolRefExpr *B = Target.getSymB()) {
|
|
if (B->getSymbol().isDefined())
|
|
Value -= Layout.getSymbolAddress(&getSymbolData(B->getSymbol()));
|
|
else
|
|
IsResolved = false;
|
|
}
|
|
|
|
// If we are using scattered symbols, determine whether this value is actually
|
|
// resolved; scattering may cause atoms to move.
|
|
if (IsResolved && getBackend().hasScatteredSymbols()) {
|
|
if (getBackend().hasReliableSymbolDifference()) {
|
|
// If this is a PCrel relocation, find the base atom (identified by its
|
|
// symbol) that the fixup value is relative to.
|
|
const MCSymbolData *BaseSymbol = 0;
|
|
if (IsPCRel) {
|
|
BaseSymbol = DF->getAtom();
|
|
if (!BaseSymbol)
|
|
IsResolved = false;
|
|
}
|
|
|
|
if (IsResolved)
|
|
IsResolved = isScatteredFixupFullyResolved(*this, Layout, Fixup, Target,
|
|
BaseSymbol);
|
|
} else {
|
|
const MCSection *BaseSection = 0;
|
|
if (IsPCRel)
|
|
BaseSection = &DF->getParent()->getSection();
|
|
|
|
IsResolved = isScatteredFixupFullyResolvedSimple(*this, Fixup, Target,
|
|
BaseSection);
|
|
}
|
|
}
|
|
|
|
if (IsPCRel)
|
|
Value -= Layout.getFragmentAddress(DF) + Fixup.getOffset();
|
|
|
|
return IsResolved;
|
|
}
|
|
|
|
uint64_t MCAssembler::ComputeFragmentSize(MCAsmLayout &Layout,
|
|
const MCFragment &F,
|
|
uint64_t SectionAddress,
|
|
uint64_t FragmentOffset) const {
|
|
switch (F.getKind()) {
|
|
case MCFragment::FT_Data:
|
|
return cast<MCDataFragment>(F).getContents().size();
|
|
case MCFragment::FT_Fill:
|
|
return cast<MCFillFragment>(F).getSize();
|
|
case MCFragment::FT_Inst:
|
|
return cast<MCInstFragment>(F).getInstSize();
|
|
|
|
case MCFragment::FT_Align: {
|
|
const MCAlignFragment &AF = cast<MCAlignFragment>(F);
|
|
|
|
assert((!AF.hasOnlyAlignAddress() || !AF.getNextNode()) &&
|
|
"Invalid OnlyAlignAddress bit, not the last fragment!");
|
|
|
|
uint64_t Size = OffsetToAlignment(SectionAddress + FragmentOffset,
|
|
AF.getAlignment());
|
|
|
|
// Honor MaxBytesToEmit.
|
|
if (Size > AF.getMaxBytesToEmit())
|
|
return 0;
|
|
|
|
return Size;
|
|
}
|
|
|
|
case MCFragment::FT_Org: {
|
|
const MCOrgFragment &OF = cast<MCOrgFragment>(F);
|
|
|
|
// FIXME: We should compute this sooner, we don't want to recurse here, and
|
|
// we would like to be more functional.
|
|
int64_t TargetLocation;
|
|
if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, &Layout))
|
|
report_fatal_error("expected assembly-time absolute expression");
|
|
|
|
// FIXME: We need a way to communicate this error.
|
|
int64_t Offset = TargetLocation - FragmentOffset;
|
|
if (Offset < 0)
|
|
report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
|
|
"' (at offset '" + Twine(FragmentOffset) + "'");
|
|
|
|
return Offset;
|
|
}
|
|
}
|
|
|
|
assert(0 && "invalid fragment kind");
|
|
return 0;
|
|
}
|
|
|
|
void MCAsmLayout::LayoutFile() {
|
|
// Initialize the first section and set the valid fragment layout point. All
|
|
// actual layout computations are done lazily.
|
|
LastValidFragment = 0;
|
|
if (!getSectionOrder().empty())
|
|
getSectionOrder().front()->Address = 0;
|
|
}
|
|
|
|
void MCAsmLayout::LayoutFragment(MCFragment *F) {
|
|
MCFragment *Prev = F->getPrevNode();
|
|
|
|
// We should never try to recompute something which is up-to-date.
|
|
assert(!isFragmentUpToDate(F) && "Attempt to recompute up-to-date fragment!");
|
|
// We should never try to compute the fragment layout if the section isn't
|
|
// up-to-date.
|
|
assert(isSectionUpToDate(F->getParent()) &&
|
|
"Attempt to compute fragment before it's section!");
|
|
// We should never try to compute the fragment layout if it's predecessor
|
|
// isn't up-to-date.
|
|
assert((!Prev || isFragmentUpToDate(Prev)) &&
|
|
"Attempt to compute fragment before it's predecessor!");
|
|
|
|
++stats::FragmentLayouts;
|
|
|
|
// Compute the fragment start address.
|
|
uint64_t StartAddress = F->getParent()->Address;
|
|
uint64_t Address = StartAddress;
|
|
if (Prev)
|
|
Address += Prev->Offset + Prev->EffectiveSize;
|
|
|
|
// Compute fragment offset and size.
|
|
F->Offset = Address - StartAddress;
|
|
F->EffectiveSize = getAssembler().ComputeFragmentSize(*this, *F, StartAddress,
|
|
F->Offset);
|
|
LastValidFragment = F;
|
|
|
|
// If this is the last fragment in a section, update the next section address.
|
|
if (!F->getNextNode()) {
|
|
unsigned NextIndex = F->getParent()->getLayoutOrder() + 1;
|
|
if (NextIndex != getSectionOrder().size())
|
|
LayoutSection(getSectionOrder()[NextIndex]);
|
|
}
|
|
}
|
|
|
|
void MCAsmLayout::LayoutSection(MCSectionData *SD) {
|
|
unsigned SectionOrderIndex = SD->getLayoutOrder();
|
|
|
|
++stats::SectionLayouts;
|
|
|
|
// Compute the section start address.
|
|
uint64_t StartAddress = 0;
|
|
if (SectionOrderIndex) {
|
|
MCSectionData *Prev = getSectionOrder()[SectionOrderIndex - 1];
|
|
StartAddress = getSectionAddress(Prev) + getSectionAddressSize(Prev);
|
|
}
|
|
|
|
// Honor the section alignment requirements.
|
|
StartAddress = RoundUpToAlignment(StartAddress, SD->getAlignment());
|
|
|
|
// Set the section address.
|
|
SD->Address = StartAddress;
|
|
}
|
|
|
|
/// WriteFragmentData - Write the \arg F data to the output file.
|
|
static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout,
|
|
const MCFragment &F, MCObjectWriter *OW) {
|
|
uint64_t Start = OW->getStream().tell();
|
|
(void) Start;
|
|
|
|
++stats::EmittedFragments;
|
|
|
|
// FIXME: Embed in fragments instead?
|
|
uint64_t FragmentSize = Layout.getFragmentEffectiveSize(&F);
|
|
switch (F.getKind()) {
|
|
case MCFragment::FT_Align: {
|
|
MCAlignFragment &AF = cast<MCAlignFragment>(F);
|
|
uint64_t Count = FragmentSize / AF.getValueSize();
|
|
|
|
assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
|
|
|
|
// 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.hasEmitNops()) {
|
|
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);
|
|
|
|
assert(FF.getValueSize() && "Invalid virtual align in concrete fragment!");
|
|
|
|
for (uint64_t i = 0, e = FF.getSize() / FF.getValueSize(); 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;
|
|
}
|
|
}
|
|
|
|
assert(OW->getStream().tell() - Start == FragmentSize);
|
|
}
|
|
|
|
void MCAssembler::WriteSectionData(const MCSectionData *SD,
|
|
const MCAsmLayout &Layout,
|
|
MCObjectWriter *OW) const {
|
|
// Ignore virtual sections.
|
|
if (getBackend().isVirtualSection(SD->getSection())) {
|
|
assert(Layout.getSectionFileSize(SD) == 0 && "Invalid size for section!");
|
|
|
|
// Check that contents are only things legal inside a virtual section.
|
|
for (MCSectionData::const_iterator it = SD->begin(),
|
|
ie = SD->end(); it != ie; ++it) {
|
|
switch (it->getKind()) {
|
|
default:
|
|
assert(0 && "Invalid fragment in virtual section!");
|
|
case MCFragment::FT_Align:
|
|
assert(!cast<MCAlignFragment>(it)->getValueSize() &&
|
|
"Invalid align in virtual section!");
|
|
break;
|
|
case MCFragment::FT_Fill:
|
|
assert(!cast<MCFillFragment>(it)->getValueSize() &&
|
|
"Invalid fill in virtual section!");
|
|
break;
|
|
}
|
|
}
|
|
|
|
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);
|
|
|
|
assert(OW->getStream().tell() - Start == Layout.getSectionFileSize(SD));
|
|
}
|
|
|
|
void MCAssembler::AddSectionToTheEnd(MCSectionData &SD, MCAsmLayout &Layout) {
|
|
// Create dummy fragments and assign section ordinals.
|
|
unsigned SectionIndex = 0;
|
|
for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it)
|
|
SectionIndex++;
|
|
|
|
SD.setOrdinal(SectionIndex);
|
|
|
|
// Assign layout order indices to sections and fragments.
|
|
unsigned FragmentIndex = 0;
|
|
unsigned i = 0;
|
|
for (unsigned e = Layout.getSectionOrder().size(); i != e; ++i) {
|
|
MCSectionData *SD = Layout.getSectionOrder()[i];
|
|
|
|
for (MCSectionData::iterator it2 = SD->begin(),
|
|
ie2 = SD->end(); it2 != ie2; ++it2)
|
|
FragmentIndex++;
|
|
}
|
|
|
|
SD.setLayoutOrder(i);
|
|
for (MCSectionData::iterator it2 = SD.begin(),
|
|
ie2 = SD.end(); it2 != ie2; ++it2) {
|
|
it2->setLayoutOrder(FragmentIndex++);
|
|
}
|
|
Layout.getSectionOrder().push_back(&SD);
|
|
|
|
Layout.LayoutSection(&SD);
|
|
|
|
// Layout until everything fits.
|
|
while (LayoutOnce(Layout))
|
|
continue;
|
|
|
|
}
|
|
|
|
void MCAssembler::Finish(MCObjectWriter *Writer) {
|
|
DEBUG_WITH_TYPE("mc-dump", {
|
|
llvm::errs() << "assembler backend - pre-layout\n--\n";
|
|
dump(); });
|
|
|
|
// Create the layout object.
|
|
MCAsmLayout Layout(*this);
|
|
|
|
// Insert additional align fragments for concrete sections to explicitly pad
|
|
// the previous section to match their alignment requirements. This is for
|
|
// 'gas' compatibility, it shouldn't strictly be necessary.
|
|
//
|
|
// FIXME: This may be Mach-O specific.
|
|
for (unsigned i = 1, e = Layout.getSectionOrder().size(); i < e; ++i) {
|
|
MCSectionData *SD = Layout.getSectionOrder()[i];
|
|
|
|
// Ignore sections without alignment requirements.
|
|
unsigned Align = SD->getAlignment();
|
|
if (Align <= 1)
|
|
continue;
|
|
|
|
// Ignore virtual sections, they don't cause file size modifications.
|
|
if (getBackend().isVirtualSection(SD->getSection()))
|
|
continue;
|
|
|
|
// Otherwise, create a new align fragment at the end of the previous
|
|
// section.
|
|
MCAlignFragment *AF = new MCAlignFragment(Align, 0, 1, Align,
|
|
Layout.getSectionOrder()[i - 1]);
|
|
AF->setOnlyAlignAddress(true);
|
|
}
|
|
|
|
// Create dummy fragments and assign section ordinals.
|
|
unsigned SectionIndex = 0;
|
|
for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
|
|
// Create dummy fragments to eliminate any empty sections, this simplifies
|
|
// layout.
|
|
if (it->getFragmentList().empty())
|
|
new MCFillFragment(0, 1, 0, it);
|
|
|
|
it->setOrdinal(SectionIndex++);
|
|
}
|
|
|
|
// Assign layout order indices to sections and fragments.
|
|
unsigned FragmentIndex = 0;
|
|
for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {
|
|
MCSectionData *SD = Layout.getSectionOrder()[i];
|
|
SD->setLayoutOrder(i);
|
|
|
|
for (MCSectionData::iterator it2 = SD->begin(),
|
|
ie2 = SD->end(); it2 != ie2; ++it2)
|
|
it2->setLayoutOrder(FragmentIndex++);
|
|
}
|
|
|
|
// Layout until everything fits.
|
|
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> OwnWriter(0);
|
|
if (Writer == 0) {
|
|
//no custom Writer_ : create the default one life-managed by OwningPtr
|
|
OwnWriter.reset(getBackend().createObjectWriter(OS));
|
|
Writer = OwnWriter.get();
|
|
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) {
|
|
MCFixup &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);
|
|
|
|
stats::ObjectBytes += OS.tell() - StartOffset;
|
|
}
|
|
|
|
bool MCAssembler::FixupNeedsRelaxation(const MCFixup &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()))
|
|
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 sections in order.
|
|
Layout.LayoutFile();
|
|
|
|
// 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->getInst(), 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();
|
|
// FIXME: Eliminate copy.
|
|
for (unsigned i = 0, e = Fixups.size(); i != e; ++i)
|
|
IF->getFixups().push_back(Fixups[i]);
|
|
|
|
// Update the layout, and remember that we relaxed.
|
|
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.
|
|
DF->setParent(IF->getParent());
|
|
DF->setAtom(IF->getAtom());
|
|
DF->setLayoutOrder(IF->getLayoutOrder());
|
|
Layout.FragmentReplaced(IF, DF);
|
|
|
|
// 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 MCFixup &AF) {
|
|
OS << "<MCFixup" << " Offset:" << AF.getOffset()
|
|
<< " Value:" << *AF.getValue()
|
|
<< " Kind:" << AF.getKind() << ">";
|
|
return OS;
|
|
}
|
|
|
|
}
|
|
|
|
void MCFragment::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<";
|
|
switch (getKind()) {
|
|
case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
|
|
case MCFragment::FT_Data: OS << "MCDataFragment"; break;
|
|
case MCFragment::FT_Fill: OS << "MCFillFragment"; break;
|
|
case MCFragment::FT_Inst: OS << "MCInstFragment"; break;
|
|
case MCFragment::FT_Org: OS << "MCOrgFragment"; break;
|
|
}
|
|
|
|
OS << "<MCFragment " << (void*) this << " LayoutOrder:" << LayoutOrder
|
|
<< " Offset:" << Offset << " EffectiveSize:" << EffectiveSize << ">";
|
|
|
|
switch (getKind()) {
|
|
case MCFragment::FT_Align: {
|
|
const MCAlignFragment *AF = cast<MCAlignFragment>(this);
|
|
if (AF->hasEmitNops())
|
|
OS << " (emit nops)";
|
|
if (AF->hasOnlyAlignAddress())
|
|
OS << " (only align section)";
|
|
OS << "\n ";
|
|
OS << " Alignment:" << AF->getAlignment()
|
|
<< " Value:" << AF->getValue() << " ValueSize:" << AF->getValueSize()
|
|
<< " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
|
|
break;
|
|
}
|
|
case MCFragment::FT_Data: {
|
|
const MCDataFragment *DF = cast<MCDataFragment>(this);
|
|
OS << "\n ";
|
|
OS << " Contents:[";
|
|
const SmallVectorImpl<char> &Contents = DF->getContents();
|
|
for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
|
|
if (i) OS << ",";
|
|
OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
|
|
}
|
|
OS << "] (" << Contents.size() << " bytes)";
|
|
|
|
if (!DF->getFixups().empty()) {
|
|
OS << ",\n ";
|
|
OS << " Fixups:[";
|
|
for (MCDataFragment::const_fixup_iterator it = DF->fixup_begin(),
|
|
ie = DF->fixup_end(); it != ie; ++it) {
|
|
if (it != DF->fixup_begin()) OS << ",\n ";
|
|
OS << *it;
|
|
}
|
|
OS << "]";
|
|
}
|
|
break;
|
|
}
|
|
case MCFragment::FT_Fill: {
|
|
const MCFillFragment *FF = cast<MCFillFragment>(this);
|
|
OS << " Value:" << FF->getValue() << " ValueSize:" << FF->getValueSize()
|
|
<< " Size:" << FF->getSize();
|
|
break;
|
|
}
|
|
case MCFragment::FT_Inst: {
|
|
const MCInstFragment *IF = cast<MCInstFragment>(this);
|
|
OS << "\n ";
|
|
OS << " Inst:";
|
|
IF->getInst().dump_pretty(OS);
|
|
break;
|
|
}
|
|
case MCFragment::FT_Org: {
|
|
const MCOrgFragment *OF = cast<MCOrgFragment>(this);
|
|
OS << "\n ";
|
|
OS << " Offset:" << OF->getOffset() << " Value:" << OF->getValue();
|
|
break;
|
|
}
|
|
}
|
|
OS << ">";
|
|
}
|
|
|
|
void MCSectionData::dump() {
|
|
raw_ostream &OS = llvm::errs();
|
|
|
|
OS << "<MCSectionData";
|
|
OS << " Alignment:" << getAlignment() << " Address:" << Address
|
|
<< " 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";
|
|
}
|