#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/MC/MachObjectWriter.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/Support/Debug.h"
#include "llvm/Target/TargetRegistry.h"
#include "llvm/Target/TargetAsmBackend.h"
-// FIXME: Gross.
-#include "../Target/X86/X86FixupKinds.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.
-static bool isFixupKindPCRel(unsigned Kind) {
- switch (Kind) {
- default:
- return false;
- case X86::reloc_pcrel_1byte:
- case X86::reloc_pcrel_4byte:
- case X86::reloc_riprel_4byte:
- return true;
+/* *** */
+
+MCAsmLayout::MCAsmLayout(MCAssembler &Asm) : Assembler(Asm) {
+ // 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);
+}
+
+void MCAsmLayout::UpdateForSlide(MCFragment *F, int SlideAmount) {
+ // We shouldn't have to do anything special to support negative slides, and it
+ // is a perfectly valid thing to do as long as other parts of the system can
+ // guarantee convergence.
+ assert(SlideAmount >= 0 && "Negative slides not yet supported");
+
+ // Update the layout by simply recomputing the layout for the entire
+ // file. This is trivially correct, but very slow.
+ //
+ // FIXME-PERF: This is O(N^2), but will be eliminated once we get smarter.
+
+ // Layout the concrete sections and fragments.
+ uint64_t Address = 0;
+ for (iterator it = begin(), ie = end(); it != ie; ++it) {
+ // Layout the section fragments and its size.
+ Address = getAssembler().LayoutSection(**it, *this, Address);
}
}
+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 {
+ assert(F->EffectiveSize != ~UINT64_C(0) && "Address not set!");
+ return F->EffectiveSize;
+}
+
+void MCAsmLayout::setFragmentEffectiveSize(MCFragment *F, uint64_t Value) {
+ F->EffectiveSize = Value;
+}
+
+uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
+ assert(F->Offset != ~UINT64_C(0) && "Address not set!");
+ return F->Offset;
+}
+
+void MCAsmLayout::setFragmentOffset(MCFragment *F, uint64_t Value) {
+ F->Offset = Value;
+}
+
+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 {
+ assert(SD->Address != ~UINT64_C(0) && "Address not set!");
+ return SD->Address;
+}
+
+void MCAsmLayout::setSectionAddress(MCSectionData *SD, uint64_t Value) {
+ SD->Address = Value;
+}
+
+uint64_t MCAsmLayout::getSectionSize(const MCSectionData *SD) const {
+ assert(SD->Size != ~UINT64_C(0) && "File size not set!");
+ return SD->Size;
+}
+void MCAsmLayout::setSectionSize(MCSectionData *SD, uint64_t Value) {
+ SD->Size = Value;
+}
+
+uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
+ assert(SD->FileSize != ~UINT64_C(0) && "File size not set!");
+ return SD->FileSize;
+}
+void MCAsmLayout::setSectionFileSize(MCSectionData *SD, uint64_t Value) {
+ SD->FileSize = Value;
+}
+
/* *** */
MCFragment::MCFragment() : Kind(FragmentType(~0)) {
}
MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
- : Kind(_Kind),
- Parent(_Parent),
- FileSize(~UINT64_C(0))
+ : Kind(_Kind), Parent(_Parent), Atom(0), EffectiveSize(~UINT64_C(0))
{
if (Parent)
Parent->getFragmentList().push_back(this);
MCFragment::~MCFragment() {
}
-uint64_t MCFragment::getAddress() const {
- assert(getParent() && "Missing Section!");
- return getParent()->getAddress() + Offset;
-}
-
/* *** */
MCSectionData::MCSectionData() : Section(0) {}
/* *** */
MCAssembler::MCAssembler(MCContext &_Context, TargetAsmBackend &_Backend,
- raw_ostream &_OS)
- : Context(_Context), Backend(_Backend), OS(_OS), SubsectionsViaSymbols(false)
+ MCCodeEmitter &_Emitter, raw_ostream &_OS)
+ : Context(_Context), Backend(_Backend), Emitter(_Emitter),
+ OS(_OS), RelaxAll(false), SubsectionsViaSymbols(false)
{
}
static bool isScatteredFixupFullyResolvedSimple(const MCAssembler &Asm,
const MCAsmFixup &Fixup,
- const MCDataFragment *DF,
const MCValue Target,
const MCSection *BaseSection) {
// The effective fixup address is
// 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 consider symbol differences fully resolved.
+ // need to worry about considering symbol differences fully resolved.
// Non-relative fixups are only resolved if constant.
if (!BaseSection)
}
static bool isScatteredFixupFullyResolved(const MCAssembler &Asm,
+ const MCAsmLayout &Layout,
const MCAsmFixup &Fixup,
- const MCDataFragment *DF,
const MCValue Target,
const MCSymbolData *BaseSymbol) {
// The effective fixup address is
if (A->getKind() != MCSymbolRefExpr::VK_None)
return false;
- A_Base = Asm.getAtom(&Asm.getSymbolData(A->getSymbol()));
+ A_Base = Asm.getAtom(Layout, &Asm.getSymbolData(A->getSymbol()));
if (!A_Base)
return false;
}
if (B->getKind() != MCSymbolRefExpr::VK_None)
return false;
- B_Base = Asm.getAtom(&Asm.getSymbolData(B->getSymbol()));
+ B_Base = Asm.getAtom(Layout, &Asm.getSymbolData(B->getSymbol()));
if (!B_Base)
return false;
}
SD->getFragment()->getParent()->getSection());
}
-const MCSymbolData *MCAssembler::getAtomForAddress(const MCSectionData *Section,
- uint64_t Address) const {
- const MCSymbolData *Best = 0;
- for (MCAssembler::const_symbol_iterator it = symbol_begin(),
- ie = symbol_end(); it != ie; ++it) {
- // Ignore non-linker visible symbols.
- if (!isSymbolLinkerVisible(it))
- continue;
-
- // Ignore symbols not in the same section.
- if (!it->getFragment() || it->getFragment()->getParent() != Section)
- continue;
-
- // Otherwise, find the closest symbol preceding this address (ties are
- // resolved in favor of the last defined symbol).
- if (it->getAddress() <= Address &&
- (!Best || it->getAddress() >= Best->getAddress()))
- Best = it;
- }
-
- return Best;
-}
-
-const MCSymbolData *MCAssembler::getAtom(const MCSymbolData *SD) const {
+const MCSymbolData *MCAssembler::getAtom(const MCAsmLayout &Layout,
+ const MCSymbolData *SD) const {
// Linker visible symbols define atoms.
if (isSymbolLinkerVisible(SD))
return SD;
if (!SD->getFragment())
return 0;
- // Otherwise, search by address.
- return getAtomForAddress(SD->getFragment()->getParent(), SD->getAddress());
+ // 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, MCAsmFixup &Fixup,
- MCDataFragment *DF,
+bool MCAssembler::EvaluateFixup(const MCAsmLayout &Layout,
+ const MCAsmFixup &Fixup, const MCFragment *DF,
MCValue &Target, uint64_t &Value) const {
+ ++stats::EvaluateFixup;
+
if (!Fixup.Value->EvaluateAsRelocatable(Target, &Layout))
- llvm_report_error("expected relocatable expression");
+ 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
Value = Target.getConstant();
- bool IsResolved = true, IsPCRel = isFixupKindPCRel(Fixup.Kind);
+ bool IsPCRel =
+ Emitter.getFixupKindInfo(Fixup.Kind).Flags & MCFixupKindInfo::FKF_IsPCRel;
+ bool IsResolved = true;
if (const MCSymbolRefExpr *A = Target.getSymA()) {
if (A->getSymbol().isDefined())
- Value += getSymbolData(A->getSymbol()).getAddress();
+ Value += Layout.getSymbolAddress(&getSymbolData(A->getSymbol()));
else
IsResolved = false;
}
if (const MCSymbolRefExpr *B = Target.getSymB()) {
if (B->getSymbol().isDefined())
- Value -= getSymbolData(B->getSymbol()).getAddress();
+ Value -= Layout.getSymbolAddress(&getSymbolData(B->getSymbol()));
else
IsResolved = false;
}
// symbol) that the fixup value is relative to.
const MCSymbolData *BaseSymbol = 0;
if (IsPCRel) {
- BaseSymbol = getAtomForAddress(
- DF->getParent(), DF->getAddress() + Fixup.Offset);
+ BaseSymbol = DF->getAtom();
if (!BaseSymbol)
IsResolved = false;
}
if (IsResolved)
- IsResolved = isScatteredFixupFullyResolved(*this, Fixup, DF, Target,
+ IsResolved = isScatteredFixupFullyResolved(*this, Layout, Fixup, Target,
BaseSymbol);
} else {
const MCSection *BaseSection = 0;
if (IsPCRel)
BaseSection = &DF->getParent()->getSection();
- IsResolved = isScatteredFixupFullyResolvedSimple(*this, Fixup, DF, Target,
+ IsResolved = isScatteredFixupFullyResolvedSimple(*this, Fixup, Target,
BaseSection);
}
}
if (IsPCRel)
- Value -= DF->getAddress() + Fixup.Offset;
+ Value -= Layout.getFragmentAddress(DF) + Fixup.Offset;
return IsResolved;
}
-void MCAssembler::LayoutSection(MCSectionData &SD) {
- MCAsmLayout Layout(*this);
- uint64_t Address = SD.getAddress();
+uint64_t MCAssembler::LayoutSection(MCSectionData &SD,
+ MCAsmLayout &Layout,
+ uint64_t StartAddress) {
+ bool IsVirtual = getBackend().isVirtualSection(SD.getSection());
+
+ ++stats::SectionLayouts;
+
+ // Align this section if necessary by adding padding bytes to the previous
+ // section. It is safe to adjust this out-of-band, because no symbol or
+ // fragment is allowed to point past the end of the section at any time.
+ if (uint64_t Pad = OffsetToAlignment(StartAddress, SD.getAlignment())) {
+ // Unless this section is virtual (where we are allowed to adjust the offset
+ // freely), the padding goes in the previous section.
+ if (!IsVirtual) {
+ // Find the previous non-virtual section.
+ iterator it = &SD;
+ assert(it != begin() && "Invalid initial section address!");
+ for (--it; getBackend().isVirtualSection(it->getSection()); --it) ;
+ Layout.setSectionFileSize(&*it, Layout.getSectionFileSize(&*it) + Pad);
+ }
+ StartAddress += Pad;
+ }
+
+ // Set the aligned section address.
+ Layout.setSectionAddress(&SD, StartAddress);
+
+ uint64_t Address = StartAddress;
for (MCSectionData::iterator it = SD.begin(), ie = SD.end(); it != ie; ++it) {
MCFragment &F = *it;
- F.setOffset(Address - SD.getAddress());
+ ++stats::FragmentLayouts;
+
+ uint64_t FragmentOffset = Address - StartAddress;
+ Layout.setFragmentOffset(&F, FragmentOffset);
// Evaluate fragment size.
+ uint64_t EffectiveSize = 0;
switch (F.getKind()) {
case MCFragment::FT_Align: {
MCAlignFragment &AF = cast<MCAlignFragment>(F);
- uint64_t Size = OffsetToAlignment(Address, AF.getAlignment());
- if (Size > AF.getMaxBytesToEmit())
- AF.setFileSize(0);
- else
- AF.setFileSize(Size);
+ EffectiveSize = OffsetToAlignment(Address, AF.getAlignment());
+ if (EffectiveSize > AF.getMaxBytesToEmit())
+ EffectiveSize = 0;
break;
}
case MCFragment::FT_Data:
- case MCFragment::FT_Fill:
- F.setFileSize(F.getMaxFileSize());
+ EffectiveSize = cast<MCDataFragment>(F).getContents().size();
+ break;
+
+ case MCFragment::FT_Fill: {
+ MCFillFragment &FF = cast<MCFillFragment>(F);
+ EffectiveSize = FF.getValueSize() * FF.getCount();
+ break;
+ }
+
+ case MCFragment::FT_Inst:
+ EffectiveSize = cast<MCInstFragment>(F).getInstSize();
break;
case MCFragment::FT_Org: {
int64_t TargetLocation;
if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, &Layout))
- llvm_report_error("expected assembly-time absolute expression");
+ report_fatal_error("expected assembly-time absolute expression");
// FIXME: We need a way to communicate this error.
- int64_t Offset = TargetLocation - F.getOffset();
+ int64_t Offset = TargetLocation - FragmentOffset;
if (Offset < 0)
- llvm_report_error("invalid .org offset '" + Twine(TargetLocation) +
- "' (at offset '" + Twine(F.getOffset()) + "'");
+ report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
+ "' (at offset '" + Twine(FragmentOffset) + "'");
- F.setFileSize(Offset);
+ EffectiveSize = Offset;
break;
}
// Align the fragment offset; it is safe to adjust the offset freely since
// this is only in virtual sections.
+ //
+ // FIXME: We shouldn't be doing this here.
Address = RoundUpToAlignment(Address, ZFF.getAlignment());
- F.setOffset(Address - SD.getAddress());
+ Layout.setFragmentOffset(&F, Address - StartAddress);
- // FIXME: This is misnamed.
- F.setFileSize(ZFF.getSize());
+ EffectiveSize = ZFF.getSize();
break;
}
}
- Address += F.getFileSize();
+ Layout.setFragmentEffectiveSize(&F, EffectiveSize);
+ Address += EffectiveSize;
}
// Set the section sizes.
- SD.setSize(Address - SD.getAddress());
- if (getBackend().isVirtualSection(SD.getSection()))
- SD.setFileSize(0);
+ Layout.setSectionSize(&SD, Address - StartAddress);
+ if (IsVirtual)
+ Layout.setSectionFileSize(&SD, 0);
else
- SD.setFileSize(Address - SD.getAddress());
-}
-
-/// WriteNopData - Write optimal nops to the output file for the \arg Count
-/// bytes. This returns the number of bytes written. It may return 0 if
-/// the \arg Count is more than the maximum optimal nops.
-///
-/// FIXME this is X86 32-bit specific and should move to a better place.
-static uint64_t WriteNopData(uint64_t Count, MCObjectWriter *OW) {
- static const uint8_t Nops[16][16] = {
- // nop
- {0x90},
- // xchg %ax,%ax
- {0x66, 0x90},
- // nopl (%[re]ax)
- {0x0f, 0x1f, 0x00},
- // nopl 0(%[re]ax)
- {0x0f, 0x1f, 0x40, 0x00},
- // nopl 0(%[re]ax,%[re]ax,1)
- {0x0f, 0x1f, 0x44, 0x00, 0x00},
- // nopw 0(%[re]ax,%[re]ax,1)
- {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
- // nopl 0L(%[re]ax)
- {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
- // nopl 0L(%[re]ax,%[re]ax,1)
- {0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
- // nopw 0L(%[re]ax,%[re]ax,1)
- {0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
- // nopw %cs:0L(%[re]ax,%[re]ax,1)
- {0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
- // nopl 0(%[re]ax,%[re]ax,1)
- // nopw 0(%[re]ax,%[re]ax,1)
- {0x0f, 0x1f, 0x44, 0x00, 0x00,
- 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
- // nopw 0(%[re]ax,%[re]ax,1)
- // nopw 0(%[re]ax,%[re]ax,1)
- {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00,
- 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
- // nopw 0(%[re]ax,%[re]ax,1)
- // nopl 0L(%[re]ax) */
- {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00,
- 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
- // nopl 0L(%[re]ax)
- // nopl 0L(%[re]ax)
- {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00,
- 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
- // nopl 0L(%[re]ax)
- // nopl 0L(%[re]ax,%[re]ax,1)
- {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00,
- 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}
- };
-
- if (Count > 15)
- return 0;
-
- for (uint64_t i = 0; i < Count; i++)
- OW->Write8(uint8_t(Nops[Count - 1][i]));
+ Layout.setSectionFileSize(&SD, Address - StartAddress);
- return Count;
+ return Address;
}
/// WriteFragmentData - Write the \arg F data to the output file.
-static void WriteFragmentData(const MCFragment &F, MCObjectWriter *OW) {
+static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout,
+ const MCFragment &F, MCObjectWriter *OW) {
uint64_t Start = OW->getStream().tell();
(void) Start;
- ++EmittedFragments;
+ ++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 = AF.getFileSize() / AF.getValueSize();
+ 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() != AF.getFileSize())
- llvm_report_error("undefined .align directive, value size '" +
+ if (Count * AF.getValueSize() != FragmentSize)
+ report_fatal_error("undefined .align directive, value size '" +
Twine(AF.getValueSize()) +
"' is not a divisor of padding size '" +
- Twine(AF.getFileSize()) + "'");
+ 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()) {
- uint64_t NopByteCount = WriteNopData(Count, OW);
- Count -= NopByteCount;
+ 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:
}
case MCFragment::FT_Data: {
- OW->WriteBytes(cast<MCDataFragment>(F).getContents().str());
+ MCDataFragment &DF = cast<MCDataFragment>(F);
+ assert(FragmentSize == DF.getContents().size() && "Invalid size!");
+ OW->WriteBytes(DF.getContents().str());
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 = OF.getFileSize(); i != e; ++i)
+ for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
OW->Write8(uint8_t(OF.getValue()));
break;
}
}
- assert(OW->getStream().tell() - Start == F.getFileSize());
+ 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(SD->getFileSize() == 0);
+ assert(SectionFileSize == 0 && "Invalid size for section!");
return;
}
for (MCSectionData::const_iterator it = SD->begin(),
ie = SD->end(); it != ie; ++it)
- WriteFragmentData(*it, OW);
+ WriteFragmentData(*this, Layout, *it, OW);
// Add section padding.
- assert(SD->getFileSize() >= SD->getSize() && "Invalid section sizes!");
- OW->WriteZeros(SD->getFileSize() - SD->getSize());
+ assert(SectionFileSize >= SectionSize && "Invalid section sizes!");
+ OW->WriteZeros(SectionFileSize - SectionSize);
- assert(OW->getStream().tell() - Start == SD->getFileSize());
+ assert(OW->getStream().tell() - Start == SectionFileSize);
}
void MCAssembler::Finish() {
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.
- while (LayoutOnce())
+ MCAsmLayout Layout(*this);
+ while (LayoutOnce(Layout))
continue;
DEBUG_WITH_TYPE("mc-dump", {
- llvm::errs() << "assembler backend - post-layout\n--\n";
+ 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(); });
- // FIXME: Factor out MCObjectWriter.
- bool Is64Bit = StringRef(getBackend().getTarget().getName()) == "x86-64";
- MachObjectWriter MOW(OS, Is64Bit);
+ 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).
- MOW.ExecutePostLayoutBinding(*this);
+ Writer->ExecutePostLayoutBinding(*this);
// Evaluate and apply the fixups, generating relocation entries as necessary.
- //
- // FIXME: Share layout object.
- MCAsmLayout Layout(*this);
for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
for (MCSectionData::iterator it2 = it->begin(),
ie2 = it->end(); it2 != ie2; ++it2) {
// 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.
- MOW.RecordRelocation(*this, *DF, Fixup, Target, FixedValue);
+ Writer->RecordRelocation(*this, Layout, DF, Fixup, Target,FixedValue);
}
getBackend().ApplyFixup(Fixup, *DF, FixedValue);
}
// Write the object file.
- MOW.WriteObject(*this);
-
+ Writer->WriteObject(*this, Layout);
OS.flush();
-}
-bool MCAssembler::FixupNeedsRelaxation(MCAsmFixup &Fixup, MCDataFragment *DF) {
- // FIXME: Share layout object.
- MCAsmLayout Layout(*this);
+ stats::ObjectBytes += OS.tell() - StartOffset;
+}
- // Currently we only need to relax X86::reloc_pcrel_1byte.
- if (unsigned(Fixup.Kind) != X86::reloc_pcrel_1byte)
- return false;
+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;
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::LayoutOnce() {
- // Layout the concrete sections and fragments.
- uint64_t Address = 0;
- MCSectionData *Prev = 0;
- for (iterator it = begin(), ie = end(); it != ie; ++it) {
- MCSectionData &SD = *it;
+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;
- // Skip virtual sections.
- if (getBackend().isVirtualSection(SD.getSection()))
- continue;
+ for (MCInstFragment::const_fixup_iterator it = IF->fixup_begin(),
+ ie = IF->fixup_end(); it != ie; ++it)
+ if (FixupNeedsRelaxation(*it, IF, Layout))
+ return true;
- // Align this section if necessary by adding padding bytes to the previous
- // section.
- if (uint64_t Pad = OffsetToAlignment(Address, it->getAlignment())) {
- assert(Prev && "Missing prev section!");
- Prev->setFileSize(Prev->getFileSize() + Pad);
- Address += Pad;
- }
+ return false;
+}
- // Layout the section fragments and its size.
- SD.setAddress(Address);
- LayoutSection(SD);
- Address += SD.getFileSize();
+bool MCAssembler::LayoutOnce(MCAsmLayout &Layout) {
+ ++stats::RelaxationSteps;
- Prev = &SD;
+ // Layout the concrete sections and fragments.
+ uint64_t Address = 0;
+ for (MCAsmLayout::iterator it = Layout.begin(),
+ ie = Layout.end(); it != ie; ++it) {
+ // Layout the section fragments and its size.
+ Address = LayoutSection(**it, Layout, Address);
}
- // Layout the virtual sections.
+ // Scan for fragments that need relaxation.
+ bool WasRelaxed = false;
for (iterator it = begin(), ie = end(); it != ie; ++it) {
MCSectionData &SD = *it;
- if (!getBackend().isVirtualSection(SD.getSection()))
- continue;
+ 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;
- // Align this section if necessary by adding padding bytes to the previous
- // section.
- if (uint64_t Pad = OffsetToAlignment(Address, it->getAlignment()))
- Address += Pad;
+ ++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()));
+ }
- SD.setAddress(Address);
- LayoutSection(SD);
- Address += SD.getSize();
+ // 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;
+ }
}
- // Scan the fixups in order and relax any that don't fit.
+ 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) {
- MCDataFragment *DF = dyn_cast<MCDataFragment>(it2);
- if (!DF)
+ MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
+ if (!IF)
continue;
- for (MCDataFragment::fixup_iterator it3 = DF->fixup_begin(),
- ie3 = DF->fixup_end(); it3 != ie3; ++it3) {
- MCAsmFixup &Fixup = *it3;
-
- // Check whether we need to relax this fixup.
- if (!FixupNeedsRelaxation(Fixup, DF))
- continue;
-
- // Relax the instruction.
- //
- // FIXME: This is a huge temporary hack which just looks for x86
- // branches; the only thing we need to relax on x86 is
- // 'X86::reloc_pcrel_1byte'. Once we have MCInst fragments, this will be
- // replaced by a TargetAsmBackend hook (most likely tblgen'd) to relax
- // an individual MCInst.
- SmallVectorImpl<char> &C = DF->getContents();
- uint64_t PrevOffset = Fixup.Offset;
- unsigned Amt = 0;
-
- // jcc instructions
- if (unsigned(C[Fixup.Offset-1]) >= 0x70 &&
- unsigned(C[Fixup.Offset-1]) <= 0x7f) {
- C[Fixup.Offset] = C[Fixup.Offset-1] + 0x10;
- C[Fixup.Offset-1] = char(0x0f);
- ++Fixup.Offset;
- Amt = 4;
-
- // jmp rel8
- } else if (C[Fixup.Offset-1] == char(0xeb)) {
- C[Fixup.Offset-1] = char(0xe9);
- Amt = 3;
-
- } else
- llvm_unreachable("unknown 1 byte pcrel instruction!");
-
- Fixup.Value = MCBinaryExpr::Create(
- MCBinaryExpr::Sub, Fixup.Value,
- MCConstantExpr::Create(3, getContext()),
- getContext());
- C.insert(C.begin() + Fixup.Offset, Amt, char(0));
- Fixup.Kind = MCFixupKind(X86::reloc_pcrel_4byte);
-
- // Update the remaining fixups, which have slid.
- //
- // FIXME: This is bad for performance, but will be eliminated by the
- // move to MCInst specific fragments.
- ++it3;
- for (; it3 != ie3; ++it3)
- it3->Offset += Amt;
-
- // Update all the symbols for this fragment, which may have slid.
- //
- // FIXME: This is really really bad for performance, but will be
- // eliminated by the move to MCInst specific fragments.
- for (MCAssembler::symbol_iterator it = symbol_begin(),
- ie = symbol_end(); it != ie; ++it) {
- MCSymbolData &SD = *it;
-
- if (it->getFragment() != DF)
- continue;
-
- if (SD.getOffset() > PrevOffset)
- SD.setOffset(SD.getOffset() + Amt);
- }
-
- // Restart layout.
- //
- // FIXME: This is O(N^2), but will be eliminated once we have a smart
- // MCAsmLayout object.
- return true;
- }
+ // 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;
}
}
-
- return false;
}
// Debugging methods
raw_ostream &OS = llvm::errs();
OS << "<MCFragment " << (void*) this << " Offset:" << Offset
- << " FileSize:" << FileSize;
+ << " EffectiveSize:" << EffectiveSize;
OS << ">";
}
<< " 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();
projects / oota-llvm.git / blobdiff