#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"
namespace {
namespace stats {
-STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
-STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
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");
}
}
/* *** */
+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,
MCCodeEmitter &_Emitter, raw_ostream &_OS)
: Context(_Context), Backend(_Backend), Emitter(_Emitter),
- OS(_OS), SubsectionsViaSymbols(false)
+ OS(_OS), RelaxAll(false), SubsectionsViaSymbols(false)
{
}
// 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 MCValue Target,
const MCSymbolData *BaseSymbol) {
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,
++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
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, Target,
+ IsResolved = isScatteredFixupFullyResolved(*this, Layout, Fixup, Target,
BaseSymbol);
} else {
const MCSection *BaseSection = 0;
}
if (IsPCRel)
- Value -= DF->getAddress() + Fixup.Offset;
+ Value -= Layout.getFragmentAddress(DF) + Fixup.Offset;
return IsResolved;
}
-void MCAssembler::LayoutSection(MCSectionData &SD,
- MCAsmLayout &Layout) {
- 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:
- F.setFileSize(cast<MCDataFragment>(F).getContents().size());
+ EffectiveSize = cast<MCDataFragment>(F).getContents().size();
break;
case MCFragment::FT_Fill: {
MCFillFragment &FF = cast<MCFillFragment>(F);
- F.setFileSize(FF.getValueSize() * FF.getCount());
+ EffectiveSize = FF.getValueSize() * FF.getCount();
break;
}
case MCFragment::FT_Inst:
- F.setFileSize(cast<MCInstFragment>(F).getInstSize());
+ 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());
+ Layout.setSectionFileSize(&SD, Address - StartAddress);
+
+ return Address;
}
/// WriteFragmentData - Write the \arg F data to the output file.
-static void WriteFragmentData(const MCAssembler &Asm, 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;
++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
// If we are aligning with nops, ask that target to emit the right data.
if (AF.getEmitNops()) {
if (!Asm.getBackend().WriteNopData(Count, OW))
- llvm_report_error("unable to write nop sequence of " +
+ report_fatal_error("unable to write nop sequence of " +
Twine(Count) + " bytes");
break;
}
case MCFragment::FT_Data: {
MCDataFragment &DF = cast<MCDataFragment>(F);
- assert(DF.getFileSize() == DF.getContents().size() && "Invalid size!");
+ assert(FragmentSize == DF.getContents().size() && "Invalid size!");
OW->WriteBytes(DF.getContents().str());
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(*this, *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.
MCAsmLayout Layout(*this);
while (LayoutOnce(Layout))
uint64_t StartOffset = OS.tell();
llvm::OwningPtr<MCObjectWriter> Writer(getBackend().createObjectWriter(OS));
if (!Writer)
- llvm_report_error("unable to create object 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).
// 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, DF, Fixup, Target, FixedValue);
+ Writer->RecordRelocation(*this, Layout, DF, Fixup, Target,FixedValue);
}
getBackend().ApplyFixup(Fixup, *DF, FixedValue);
}
// Write the object file.
- Writer->WriteObject(*this);
+ 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;
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));
}
// 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;
-
- // Skip virtual sections.
- if (getBackend().isVirtualSection(SD.getSection()))
- continue;
-
- // 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;
- }
-
+ for (MCAsmLayout::iterator it = Layout.begin(),
+ ie = Layout.end(); it != ie; ++it) {
// Layout the section fragments and its size.
- SD.setAddress(Address);
- LayoutSection(SD, Layout);
- Address += SD.getFileSize();
-
- Prev = &SD;
- }
-
- // Layout the virtual sections.
- for (iterator it = begin(), ie = end(); it != ie; ++it) {
- MCSectionData &SD = *it;
-
- if (!getBackend().isVirtualSection(SD.getSection()))
- continue;
-
- // Align this section if necessary by adding padding bytes to the previous
- // section.
- if (uint64_t Pad = OffsetToAlignment(Address, it->getAlignment()))
- Address += Pad;
-
- SD.setAddress(Address);
- LayoutSection(SD, Layout);
- Address += SD.getSize();
+ 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;
VecOS.flush();
// Update the instruction fragment.
+ int SlideAmount = Code.size() - IF->getInstSize();
IF->setInst(Relaxed);
IF->getCode() = Code;
IF->getFixups().clear();
F.getKind()));
}
- // Restart layout.
- //
- // FIXME-PERF: This is O(N^2), but will be eliminated once we have a
- // smart MCAsmLayout object.
- return true;
+ // 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 false;
+ return WasRelaxed;
}
void MCAssembler::FinishLayout(MCAsmLayout &Layout) {
SD.getFragmentList().insert(it2, DF);
// Update the data fragments layout data.
+ //
+ // FIXME: Add MCAsmLayout utility for this.
DF->setParent(IF->getParent());
- DF->setOffset(IF->getOffset());
- DF->setFileSize(IF->getInstSize());
+ 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());
raw_ostream &OS = llvm::errs();
OS << "<MCFragment " << (void*) this << " Offset:" << Offset
- << " FileSize:" << FileSize;
+ << " EffectiveSize:" << EffectiveSize;
OS << ">";
}
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