| //===- 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/MCContext.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/MC/MCObjectWriter.h" |
| #include "llvm/MC/MCSection.h" |
| #include "llvm/MC/MCSymbol.h" |
| #include "llvm/MC/MCValue.h" |
| #include "llvm/MC/MCDwarf.h" |
| #include "llvm/MC/MCAsmBackend.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/TargetRegistry.h" |
| |
| 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"); |
| } |
| } |
| |
| // 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() |
| { |
| // Compute the section layout order. Virtual sections must go last. |
| for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) |
| if (!it->getSection().isVirtualSection()) |
| SectionOrder.push_back(&*it); |
| for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) |
| if (it->getSection().isVirtualSection()) |
| SectionOrder.push_back(&*it); |
| } |
| |
| bool MCAsmLayout::isFragmentUpToDate(const MCFragment *F) const { |
| const MCSectionData &SD = *F->getParent(); |
| const MCFragment *LastValid = LastValidFragment.lookup(&SD); |
| if (!LastValid) |
| return false; |
| assert(LastValid->getParent() == F->getParent()); |
| return F->getLayoutOrder() <= LastValid->getLayoutOrder(); |
| } |
| |
| void MCAsmLayout::Invalidate(MCFragment *F) { |
| // 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 this fragment. |
| const MCSectionData &SD = *F->getParent(); |
| LastValidFragment[&SD] = F; |
| } |
| |
| void MCAsmLayout::EnsureValid(const MCFragment *F) const { |
| MCSectionData &SD = *F->getParent(); |
| |
| MCFragment *Cur = LastValidFragment[&SD]; |
| if (!Cur) |
| Cur = &*SD.begin(); |
| else |
| Cur = Cur->getNextNode(); |
| |
| // Advance the layout position until the fragment is up-to-date. |
| while (!isFragmentUpToDate(F)) { |
| const_cast<MCAsmLayout*>(this)->LayoutFragment(Cur); |
| Cur = Cur->getNextNode(); |
| } |
| } |
| |
| 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::getSymbolOffset(const MCSymbolData *SD) const { |
| const MCSymbol &S = SD->getSymbol(); |
| |
| // If this is a variable, then recursively evaluate now. |
| if (S.isVariable()) { |
| MCValue Target; |
| if (!S.getVariableValue()->EvaluateAsRelocatable(Target, *this)) |
| report_fatal_error("unable to evaluate offset for variable '" + |
| S.getName() + "'"); |
| |
| // Verify that any used symbols are defined. |
| if (Target.getSymA() && Target.getSymA()->getSymbol().isUndefined()) |
| report_fatal_error("unable to evaluate offset to undefined symbol '" + |
| Target.getSymA()->getSymbol().getName() + "'"); |
| if (Target.getSymB() && Target.getSymB()->getSymbol().isUndefined()) |
| report_fatal_error("unable to evaluate offset to undefined symbol '" + |
| Target.getSymB()->getSymbol().getName() + "'"); |
| |
| uint64_t Offset = Target.getConstant(); |
| if (Target.getSymA()) |
| Offset += getSymbolOffset(&Assembler.getSymbolData( |
| Target.getSymA()->getSymbol())); |
| if (Target.getSymB()) |
| Offset -= getSymbolOffset(&Assembler.getSymbolData( |
| Target.getSymB()->getSymbol())); |
| return Offset; |
| } |
| |
| assert(SD->getFragment() && "Invalid getOffset() on undefined symbol!"); |
| return getFragmentOffset(SD->getFragment()) + SD->getOffset(); |
| } |
| |
| 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) + getAssembler().ComputeFragmentSize(*this, F); |
| } |
| |
| uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const { |
| // Virtual sections have no file size. |
| if (SD->getSection().isVirtualSection()) |
| return 0; |
| |
| // Otherwise, the file size is the same as the address space size. |
| return getSectionAddressSize(SD); |
| } |
| |
| /* *** */ |
| |
| MCFragment::MCFragment() : Kind(FragmentType(~0)) { |
| } |
| |
| MCFragment::~MCFragment() { |
| } |
| |
| MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent) |
| : Kind(_Kind), Parent(_Parent), Atom(0), Offset(~UINT64_C(0)) |
| { |
| if (Parent) |
| Parent->getFragmentList().push_back(this); |
| } |
| |
| /* *** */ |
| |
| MCSectionData::MCSectionData() : Section(0) {} |
| |
| MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A) |
| : Section(&_Section), |
| Ordinal(~UINT32_C(0)), |
| Alignment(1), |
| 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_, MCAsmBackend &Backend_, |
| MCCodeEmitter &Emitter_, MCObjectWriter &Writer_, |
| raw_ostream &OS_) |
| : Context(Context_), Backend(Backend_), Emitter(Emitter_), Writer(Writer_), |
| OS(OS_), RelaxAll(false), NoExecStack(false), SubsectionsViaSymbols(false) |
| { |
| } |
| |
| MCAssembler::~MCAssembler() { |
| } |
| |
| 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 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"); |
| |
| bool IsPCRel = Backend.getFixupKindInfo( |
| Fixup.getKind()).Flags & MCFixupKindInfo::FKF_IsPCRel; |
| |
| bool IsResolved; |
| if (IsPCRel) { |
| if (Target.getSymB()) { |
| IsResolved = false; |
| } else if (!Target.getSymA()) { |
| IsResolved = false; |
| } else { |
| const MCSymbolRefExpr *A = Target.getSymA(); |
| const MCSymbol &SA = A->getSymbol(); |
| if (A->getKind() != MCSymbolRefExpr::VK_None || |
| SA.AliasedSymbol().isUndefined()) { |
| IsResolved = false; |
| } else { |
| const MCSymbolData &DataA = getSymbolData(SA); |
| IsResolved = |
| getWriter().IsSymbolRefDifferenceFullyResolvedImpl(*this, DataA, |
| *DF, false, true); |
| } |
| } |
| } else { |
| IsResolved = Target.isAbsolute(); |
| } |
| |
| Value = Target.getConstant(); |
| |
| bool IsThumb = false; |
| if (const MCSymbolRefExpr *A = Target.getSymA()) { |
| const MCSymbol &Sym = A->getSymbol().AliasedSymbol(); |
| if (Sym.isDefined()) |
| Value += Layout.getSymbolOffset(&getSymbolData(Sym)); |
| if (isThumbFunc(&Sym)) |
| IsThumb = true; |
| } |
| if (const MCSymbolRefExpr *B = Target.getSymB()) { |
| const MCSymbol &Sym = B->getSymbol().AliasedSymbol(); |
| if (Sym.isDefined()) |
| Value -= Layout.getSymbolOffset(&getSymbolData(Sym)); |
| } |
| |
| |
| bool ShouldAlignPC = Backend.getFixupKindInfo(Fixup.getKind()).Flags & |
| MCFixupKindInfo::FKF_IsAlignedDownTo32Bits; |
| assert((ShouldAlignPC ? IsPCRel : true) && |
| "FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!"); |
| |
| if (IsPCRel) { |
| uint32_t Offset = Layout.getFragmentOffset(DF) + Fixup.getOffset(); |
| |
| // A number of ARM fixups in Thumb mode require that the effective PC |
| // address be determined as the 32-bit aligned version of the actual offset. |
| if (ShouldAlignPC) Offset &= ~0x3; |
| Value -= Offset; |
| } |
| |
| // ARM fixups based from a thumb function address need to have the low |
| // bit set. The actual value is always at least 16-bit aligned, so the |
| // low bit is normally clear and available for use as an ISA flag for |
| // interworking. |
| if (IsThumb) |
| Value |= 1; |
| |
| return IsResolved; |
| } |
| |
| uint64_t MCAssembler::ComputeFragmentSize(const MCAsmLayout &Layout, |
| const MCFragment &F) 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_LEB: |
| return cast<MCLEBFragment>(F).getContents().size(); |
| |
| case MCFragment::FT_Align: { |
| const MCAlignFragment &AF = cast<MCAlignFragment>(F); |
| unsigned Offset = Layout.getFragmentOffset(&AF); |
| unsigned Size = OffsetToAlignment(Offset, AF.getAlignment()); |
| if (Size > AF.getMaxBytesToEmit()) |
| return 0; |
| return Size; |
| } |
| |
| case MCFragment::FT_Org: { |
| MCOrgFragment &OF = cast<MCOrgFragment>(F); |
| 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. |
| uint64_t FragmentOffset = Layout.getFragmentOffset(&OF); |
| int64_t Size = TargetLocation - FragmentOffset; |
| if (Size < 0 || Size >= 0x40000000) |
| report_fatal_error("invalid .org offset '" + Twine(TargetLocation) + |
| "' (at offset '" + Twine(FragmentOffset) + "')"); |
| return Size; |
| } |
| |
| case MCFragment::FT_Dwarf: |
| return cast<MCDwarfLineAddrFragment>(F).getContents().size(); |
| case MCFragment::FT_DwarfFrame: |
| return cast<MCDwarfCallFrameFragment>(F).getContents().size(); |
| } |
| |
| assert(0 && "invalid fragment kind"); |
| return 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 it's predecessor |
| // isn't up-to-date. |
| assert((!Prev || isFragmentUpToDate(Prev)) && |
| "Attempt to compute fragment before it's predecessor!"); |
| |
| ++stats::FragmentLayouts; |
| |
| // Compute fragment offset and size. |
| uint64_t Offset = 0; |
| if (Prev) |
| Offset += Prev->Offset + getAssembler().ComputeFragmentSize(*this, *Prev); |
| |
| F->Offset = Offset; |
| LastValidFragment[F->getParent()] = F; |
| } |
| |
| /// WriteFragmentData - Write the \arg F data to the output file. |
| static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout, |
| const MCFragment &F) { |
| MCObjectWriter *OW = &Asm.getWriter(); |
| uint64_t Start = OW->getStream().tell(); |
| (void) Start; |
| |
| ++stats::EmittedFragments; |
| |
| // FIXME: Embed in fragments instead? |
| uint64_t FragmentSize = Asm.ComputeFragmentSize(Layout, 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: { |
| MCInstFragment &IF = cast<MCInstFragment>(F); |
| OW->WriteBytes(StringRef(IF.getCode().begin(), IF.getCode().size())); |
| break; |
| } |
| |
| case MCFragment::FT_LEB: { |
| MCLEBFragment &LF = cast<MCLEBFragment>(F); |
| OW->WriteBytes(LF.getContents().str()); |
| 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_Dwarf: { |
| const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F); |
| OW->WriteBytes(OF.getContents().str()); |
| break; |
| } |
| case MCFragment::FT_DwarfFrame: { |
| const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F); |
| OW->WriteBytes(CF.getContents().str()); |
| break; |
| } |
| } |
| |
| assert(OW->getStream().tell() - Start == FragmentSize); |
| } |
| |
| void MCAssembler::WriteSectionData(const MCSectionData *SD, |
| const MCAsmLayout &Layout) const { |
| // Ignore virtual sections. |
| if (SD->getSection().isVirtualSection()) { |
| 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_Data: { |
| // Check that we aren't trying to write a non-zero contents (or fixups) |
| // into a virtual section. This is to support clients which use standard |
| // directives to fill the contents of virtual sections. |
| MCDataFragment &DF = cast<MCDataFragment>(*it); |
| assert(DF.fixup_begin() == DF.fixup_end() && |
| "Cannot have fixups in virtual section!"); |
| for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i) |
| assert(DF.getContents()[i] == 0 && |
| "Invalid data value for virtual section!"); |
| break; |
| } |
| case MCFragment::FT_Align: |
| // Check that we aren't trying to write a non-zero value into a virtual |
| // section. |
| assert((!cast<MCAlignFragment>(it)->getValueSize() || |
| !cast<MCAlignFragment>(it)->getValue()) && |
| "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 = getWriter().getStream().tell(); |
| (void) Start; |
| |
| for (MCSectionData::const_iterator it = SD->begin(), |
| ie = SD->end(); it != ie; ++it) |
| WriteFragmentData(*this, Layout, *it); |
| |
| assert(getWriter().getStream().tell() - Start == |
| Layout.getSectionAddressSize(SD)); |
| } |
| |
| |
| uint64_t MCAssembler::HandleFixup(const MCAsmLayout &Layout, |
| MCFragment &F, |
| const MCFixup &Fixup) { |
| // Evaluate the fixup. |
| MCValue Target; |
| uint64_t FixedValue; |
| if (!EvaluateFixup(Layout, Fixup, &F, 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. |
| getWriter().RecordRelocation(*this, Layout, &F, Fixup, Target, FixedValue); |
| } |
| return FixedValue; |
| } |
| |
| void MCAssembler::Finish() { |
| DEBUG_WITH_TYPE("mc-dump", { |
| llvm::errs() << "assembler backend - pre-layout\n--\n"; |
| dump(); }); |
| |
| // Create the layout object. |
| MCAsmLayout Layout(*this); |
| |
| // 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 MCDataFragment(it); |
| |
| it->setOrdinal(SectionIndex++); |
| } |
| |
| // Assign layout order indices to sections and fragments. |
| for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) { |
| MCSectionData *SD = Layout.getSectionOrder()[i]; |
| SD->setLayoutOrder(i); |
| |
| unsigned FragmentIndex = 0; |
| 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(); |
| |
| // Allow the object writer a chance to perform post-layout binding (for |
| // example, to set the index fields in the symbol data). |
| getWriter().ExecutePostLayoutBinding(*this, Layout); |
| |
| // 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) { |
| for (MCDataFragment::fixup_iterator it3 = DF->fixup_begin(), |
| ie3 = DF->fixup_end(); it3 != ie3; ++it3) { |
| MCFixup &Fixup = *it3; |
| uint64_t FixedValue = HandleFixup(Layout, *DF, Fixup); |
| getBackend().ApplyFixup(Fixup, DF->getContents().data(), |
| DF->getContents().size(), FixedValue); |
| } |
| } |
| MCInstFragment *IF = dyn_cast<MCInstFragment>(it2); |
| if (IF) { |
| for (MCInstFragment::fixup_iterator it3 = IF->fixup_begin(), |
| ie3 = IF->fixup_end(); it3 != ie3; ++it3) { |
| MCFixup &Fixup = *it3; |
| uint64_t FixedValue = HandleFixup(Layout, *IF, Fixup); |
| getBackend().ApplyFixup(Fixup, IF->getCode().data(), |
| IF->getCode().size(), FixedValue); |
| } |
| } |
| } |
| } |
| |
| // Write the object file. |
| getWriter().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::RelaxInstruction(MCAsmLayout &Layout, |
| MCInstFragment &IF) { |
| if (!FragmentNeedsRelaxation(&IF, Layout)) |
| return false; |
| |
| ++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. |
| 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]); |
| |
| return true; |
| } |
| |
| bool MCAssembler::RelaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) { |
| int64_t Value = 0; |
| uint64_t OldSize = LF.getContents().size(); |
| bool IsAbs = LF.getValue().EvaluateAsAbsolute(Value, Layout); |
| (void)IsAbs; |
| assert(IsAbs); |
| SmallString<8> &Data = LF.getContents(); |
| Data.clear(); |
| raw_svector_ostream OSE(Data); |
| if (LF.isSigned()) |
| MCObjectWriter::EncodeSLEB128(Value, OSE); |
| else |
| MCObjectWriter::EncodeULEB128(Value, OSE); |
| OSE.flush(); |
| return OldSize != LF.getContents().size(); |
| } |
| |
| bool MCAssembler::RelaxDwarfLineAddr(MCAsmLayout &Layout, |
| MCDwarfLineAddrFragment &DF) { |
| int64_t AddrDelta = 0; |
| uint64_t OldSize = DF.getContents().size(); |
| bool IsAbs = DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout); |
| (void)IsAbs; |
| assert(IsAbs); |
| int64_t LineDelta; |
| LineDelta = DF.getLineDelta(); |
| SmallString<8> &Data = DF.getContents(); |
| Data.clear(); |
| raw_svector_ostream OSE(Data); |
| MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OSE); |
| OSE.flush(); |
| return OldSize != Data.size(); |
| } |
| |
| bool MCAssembler::RelaxDwarfCallFrameFragment(MCAsmLayout &Layout, |
| MCDwarfCallFrameFragment &DF) { |
| int64_t AddrDelta = 0; |
| uint64_t OldSize = DF.getContents().size(); |
| bool IsAbs = DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout); |
| (void)IsAbs; |
| assert(IsAbs); |
| SmallString<8> &Data = DF.getContents(); |
| Data.clear(); |
| raw_svector_ostream OSE(Data); |
| MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OSE); |
| OSE.flush(); |
| return OldSize != Data.size(); |
| } |
| |
| bool MCAssembler::LayoutSectionOnce(MCAsmLayout &Layout, |
| MCSectionData &SD) { |
| MCFragment *FirstInvalidFragment = NULL; |
| // Scan for fragments that need relaxation. |
| for (MCSectionData::iterator it2 = SD.begin(), |
| ie2 = SD.end(); it2 != ie2; ++it2) { |
| // Check if this is an fragment that needs relaxation. |
| bool relaxedFrag = false; |
| switch(it2->getKind()) { |
| default: |
| break; |
| case MCFragment::FT_Inst: |
| relaxedFrag = RelaxInstruction(Layout, *cast<MCInstFragment>(it2)); |
| break; |
| case MCFragment::FT_Dwarf: |
| relaxedFrag = RelaxDwarfLineAddr(Layout, |
| *cast<MCDwarfLineAddrFragment>(it2)); |
| break; |
| case MCFragment::FT_DwarfFrame: |
| relaxedFrag = |
| RelaxDwarfCallFrameFragment(Layout, |
| *cast<MCDwarfCallFrameFragment>(it2)); |
| break; |
| case MCFragment::FT_LEB: |
| relaxedFrag = RelaxLEB(Layout, *cast<MCLEBFragment>(it2)); |
| break; |
| } |
| // Update the layout, and remember that we relaxed. |
| if (relaxedFrag && !FirstInvalidFragment) |
| FirstInvalidFragment = it2; |
| } |
| if (FirstInvalidFragment) { |
| Layout.Invalidate(FirstInvalidFragment); |
| return true; |
| } |
| return false; |
| } |
| |
| bool MCAssembler::LayoutOnce(MCAsmLayout &Layout) { |
| ++stats::RelaxationSteps; |
| |
| bool WasRelaxed = false; |
| for (iterator it = begin(), ie = end(); it != ie; ++it) { |
| MCSectionData &SD = *it; |
| while(LayoutSectionOnce(Layout, SD)) |
| WasRelaxed = true; |
| } |
| |
| return WasRelaxed; |
| } |
| |
| void MCAssembler::FinishLayout(MCAsmLayout &Layout) { |
| // The layout is done. Mark every fragment as valid. |
| for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) { |
| Layout.getFragmentOffset(&*Layout.getSectionOrder()[i]->rbegin()); |
| } |
| } |
| |
| // 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; |
| case MCFragment::FT_Dwarf: OS << "MCDwarfFragment"; break; |
| case MCFragment::FT_DwarfFrame: OS << "MCDwarfCallFrameFragment"; break; |
| case MCFragment::FT_LEB: OS << "MCLEBFragment"; break; |
| } |
| |
| OS << "<MCFragment " << (void*) this << " LayoutOrder:" << LayoutOrder |
| << " Offset:" << Offset << ">"; |
| |
| switch (getKind()) { |
| case MCFragment::FT_Align: { |
| const MCAlignFragment *AF = cast<MCAlignFragment>(this); |
| if (AF->hasEmitNops()) |
| OS << " (emit nops)"; |
| 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; |
| } |
| case MCFragment::FT_Dwarf: { |
| const MCDwarfLineAddrFragment *OF = cast<MCDwarfLineAddrFragment>(this); |
| OS << "\n "; |
| OS << " AddrDelta:" << OF->getAddrDelta() |
| << " LineDelta:" << OF->getLineDelta(); |
| break; |
| } |
| case MCFragment::FT_DwarfFrame: { |
| const MCDwarfCallFrameFragment *CF = cast<MCDwarfCallFrameFragment>(this); |
| OS << "\n "; |
| OS << " AddrDelta:" << CF->getAddrDelta(); |
| break; |
| } |
| case MCFragment::FT_LEB: { |
| const MCLEBFragment *LF = cast<MCLEBFragment>(this); |
| OS << "\n "; |
| OS << " Value:" << LF->getValue() << " Signed:" << LF->isSigned(); |
| break; |
| } |
| } |
| OS << ">"; |
| } |
| |
| void MCSectionData::dump() { |
| raw_ostream &OS = llvm::errs(); |
| |
| OS << "<MCSectionData"; |
| OS << " Alignment:" << getAlignment() << " 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"; |
| } |