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-rw-r--r--lib/MC/ELFObjectWriter.cpp446
1 files changed, 264 insertions, 182 deletions
diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index e9b8fe2..0a54627 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -17,6 +17,7 @@
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
@@ -27,6 +28,8 @@
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCValue.h"
+#include "llvm/Object/StringTableBuilder.h"
+#include "llvm/Support/Compression.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ELF.h"
@@ -105,10 +108,9 @@ class ELFObjectWriter : public MCObjectWriter {
static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant);
static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout);
- static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
+ static bool isInSymtab(const MCAsmLayout &Layout, const MCSymbolData &Data,
bool Used, bool Renamed);
- static bool isLocal(const MCSymbolData &Data, bool isSignature,
- bool isUsedInReloc);
+ static bool isLocal(const MCSymbolData &Data, bool isUsedInReloc);
static bool IsELFMetaDataSection(const MCSectionData &SD);
static uint64_t DataSectionSize(const MCSectionData &SD);
static uint64_t GetSectionFileSize(const MCAsmLayout &Layout,
@@ -131,11 +133,11 @@ class ELFObjectWriter : public MCObjectWriter {
MCSymbolData *SymbolData;
uint64_t StringIndex;
uint32_t SectionIndex;
+ StringRef Name;
// Support lexicographic sorting.
bool operator<(const ELFSymbolData &RHS) const {
- return SymbolData->getSymbol().getName() <
- RHS.SymbolData->getSymbol().getName();
+ return Name < RHS.Name;
}
};
@@ -148,13 +150,13 @@ class ELFObjectWriter : public MCObjectWriter {
llvm::DenseMap<const MCSectionData *, std::vector<ELFRelocationEntry>>
Relocations;
- DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
+ StringTableBuilder ShStrTabBuilder;
/// @}
/// @name Symbol Table Data
/// @{
- SmallString<256> StringTable;
+ StringTableBuilder StrTabBuilder;
std::vector<uint64_t> FileSymbolData;
std::vector<ELFSymbolData> LocalSymbolData;
std::vector<ELFSymbolData> ExternalSymbolData;
@@ -214,7 +216,8 @@ class ELFObjectWriter : public MCObjectWriter {
const MCAsmLayout &Layout,
SectionIndexMapTy &SectionIndexMap);
- bool shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA,
+ bool shouldRelocateWithSymbol(const MCAssembler &Asm,
+ const MCSymbolRefExpr *RefA,
const MCSymbolData *SD, uint64_t C,
unsigned Type) const;
@@ -253,6 +256,8 @@ class ELFObjectWriter : public MCObjectWriter {
void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout,
RelMapTy &RelMap);
+ void CompressDebugSections(MCAssembler &Asm, MCAsmLayout &Layout);
+
void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
const RelMapTy &RelMap);
@@ -481,43 +486,18 @@ void ELFObjectWriter::WriteHeader(const MCAssembler &Asm,
Write16(ShstrtabIndex);
}
-uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &OrigData,
+uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data,
const MCAsmLayout &Layout) {
- MCSymbolData *Data = &OrigData;
- if (Data->isCommon() && Data->isExternal())
- return Data->getCommonAlignment();
-
- const MCSymbol *Symbol = &Data->getSymbol();
- bool IsThumbFunc = OrigData.getFlags() & ELF_Other_ThumbFunc;
-
- uint64_t Res = 0;
- if (Symbol->isVariable()) {
- const MCExpr *Expr = Symbol->getVariableValue();
- MCValue Value;
- if (!Expr->EvaluateAsRelocatable(Value, &Layout))
- llvm_unreachable("Invalid expression");
+ if (Data.isCommon() && Data.isExternal())
+ return Data.getCommonAlignment();
- assert(!Value.getSymB());
-
- Res = Value.getConstant();
-
- if (const MCSymbolRefExpr *A = Value.getSymA()) {
- Symbol = &A->getSymbol();
- Data = &Layout.getAssembler().getSymbolData(*Symbol);
- } else {
- Symbol = 0;
- Data = 0;
- }
- }
+ uint64_t Res;
+ if (!Layout.getSymbolOffset(&Data, Res))
+ return 0;
- if (IsThumbFunc)
+ if (Layout.getAssembler().isThumbFunc(&Data.getSymbol()))
Res |= 1;
- if (!Symbol || !Symbol->isInSection())
- return Res;
-
- Res += Layout.getSymbolOffset(Data);
-
return Res;
}
@@ -526,15 +506,17 @@ void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
// The presence of symbol versions causes undefined symbols and
// versions declared with @@@ to be renamed.
- for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
- ie = Asm.symbol_end(); it != ie; ++it) {
- const MCSymbol &Alias = it->getSymbol();
- const MCSymbol &Symbol = Alias.AliasedSymbol();
- MCSymbolData &SD = Asm.getSymbolData(Symbol);
+ for (MCSymbolData &OriginalData : Asm.symbols()) {
+ const MCSymbol &Alias = OriginalData.getSymbol();
// Not an alias.
- if (&Symbol == &Alias)
+ if (!Alias.isVariable())
+ continue;
+ auto *Ref = dyn_cast<MCSymbolRefExpr>(Alias.getVariableValue());
+ if (!Ref)
continue;
+ const MCSymbol &Symbol = Ref->getSymbol();
+ MCSymbolData &SD = Asm.getSymbolData(Symbol);
StringRef AliasName = Alias.getName();
size_t Pos = AliasName.find('@');
@@ -543,8 +525,8 @@ void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
// Aliases defined with .symvar copy the binding from the symbol they alias.
// This is the first place we are able to copy this information.
- it->setExternal(SD.isExternal());
- MCELF::SetBinding(*it, MCELF::GetBinding(SD));
+ OriginalData.setExternal(SD.isExternal());
+ MCELF::SetBinding(OriginalData, MCELF::GetBinding(SD));
StringRef Rest = AliasName.substr(Pos);
if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
@@ -594,26 +576,14 @@ static uint8_t mergeTypeForSet(uint8_t origType, uint8_t newType) {
return Type;
}
-static const MCSymbol *getBaseSymbol(const MCAsmLayout &Layout,
- const MCSymbol &Symbol) {
- if (!Symbol.isVariable())
- return &Symbol;
-
- const MCExpr *Expr = Symbol.getVariableValue();
- MCValue Value;
- if (!Expr->EvaluateAsRelocatable(Value, &Layout))
- llvm_unreachable("Invalid Expression");
- assert(!Value.getSymB());
- const MCSymbolRefExpr *A = Value.getSymA();
- if (!A)
- return nullptr;
- return getBaseSymbol(Layout, A->getSymbol());
-}
-
void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD,
const MCAsmLayout &Layout) {
MCSymbolData &OrigData = *MSD.SymbolData;
- const MCSymbol *Base = getBaseSymbol(Layout, OrigData.getSymbol());
+ assert((!OrigData.getFragment() ||
+ (&OrigData.getFragment()->getParent()->getSection() ==
+ &OrigData.getSymbol().getSection())) &&
+ "The symbol's section doesn't match the fragment's symbol");
+ const MCSymbol *Base = Layout.getBaseSymbol(OrigData.getSymbol());
// This has to be in sync with when computeSymbolTable uses SHN_ABS or
// SHN_COMMON.
@@ -627,8 +597,6 @@ void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD,
BaseSD = &Layout.getAssembler().getSymbolData(*Base);
Type = mergeTypeForSet(Type, MCELF::GetType(*BaseSD));
}
- if (OrigData.getFlags() & ELF_Other_ThumbFunc)
- Type = ELF::STT_FUNC;
uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
// Other and Visibility share the same byte with Visibility using the lower
@@ -638,8 +606,6 @@ void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD,
Other |= Visibility;
uint64_t Value = SymbolValue(OrigData, Layout);
- if (OrigData.getFlags() & ELF_Other_ThumbFunc)
- Value |= 1;
uint64_t Size = 0;
const MCExpr *ESize = OrigData.getSize();
@@ -664,7 +630,6 @@ void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
SectionIndexMapTy &SectionIndexMap) {
// The string table must be emitted first because we need the index
// into the string table for all the symbol names.
- assert(StringTable.size() && "Missing string table");
// FIXME: Make sure the start of the symbol table is aligned.
@@ -725,7 +690,8 @@ void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
// It is always valid to create a relocation with a symbol. It is preferable
// to use a relocation with a section if that is possible. Using the section
// allows us to omit some local symbols from the symbol table.
-bool ELFObjectWriter::shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA,
+bool ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm,
+ const MCSymbolRefExpr *RefA,
const MCSymbolData *SD,
uint64_t C,
unsigned Type) const {
@@ -809,11 +775,37 @@ bool ELFObjectWriter::shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA,
if (Flags & ELF::SHF_TLS)
return true;
+ // If the symbol is a thumb function the final relocation must set the lowest
+ // bit. With a symbol that is done by just having the symbol have that bit
+ // set, so we would lose the bit if we relocated with the section.
+ // FIXME: We could use the section but add the bit to the relocation value.
+ if (Asm.isThumbFunc(&Sym))
+ return true;
+
if (TargetObjectWriter->needsRelocateWithSymbol(Type))
return true;
return false;
}
+static const MCSymbol *getWeakRef(const MCSymbolRefExpr &Ref) {
+ const MCSymbol &Sym = Ref.getSymbol();
+
+ if (Ref.getKind() == MCSymbolRefExpr::VK_WEAKREF)
+ return &Sym;
+
+ if (!Sym.isVariable())
+ return nullptr;
+
+ const MCExpr *Expr = Sym.getVariableValue();
+ const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
+ if (!Inner)
+ return nullptr;
+
+ if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
+ return &Inner->getSymbol();
+ return nullptr;
+}
+
void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
@@ -868,7 +860,7 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCSymbolData *SymAD = SymA ? &Asm.getSymbolData(*SymA) : nullptr;
unsigned Type = GetRelocType(Target, Fixup, IsPCRel);
- bool RelocateWithSymbol = shouldRelocateWithSymbol(RefA, SymAD, C, Type);
+ bool RelocateWithSymbol = shouldRelocateWithSymbol(Asm, RefA, SymAD, C, Type);
if (!RelocateWithSymbol && SymA && !SymA->isUndefined())
C += Layout.getSymbolOffset(SymAD);
@@ -899,8 +891,8 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
if (const MCSymbol *R = Renames.lookup(SymA))
SymA = R;
- if (RefA->getKind() == MCSymbolRefExpr::VK_WEAKREF)
- WeakrefUsedInReloc.insert(SymA);
+ if (const MCSymbol *WeakRef = getWeakRef(*RefA))
+ WeakrefUsedInReloc.insert(WeakRef);
else
UsedInReloc.insert(SymA);
}
@@ -913,13 +905,13 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
uint64_t
ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
const MCSymbol *S) {
- MCSymbolData &SD = Asm.getSymbolData(*S);
+ const MCSymbolData &SD = Asm.getSymbolData(*S);
return SD.getIndex();
}
-bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm,
- const MCSymbolData &Data,
- bool Used, bool Renamed) {
+bool ELFObjectWriter::isInSymtab(const MCAsmLayout &Layout,
+ const MCSymbolData &Data, bool Used,
+ bool Renamed) {
const MCSymbol &Symbol = Data.getSymbol();
if (Symbol.isVariable()) {
const MCExpr *Expr = Symbol.getVariableValue();
@@ -938,9 +930,11 @@ bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm,
if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
return true;
- const MCSymbol &A = Symbol.AliasedSymbol();
- if (Symbol.isVariable() && !A.isVariable() && A.isUndefined())
- return false;
+ if (Symbol.isVariable()) {
+ const MCSymbol *Base = Layout.getBaseSymbol(Symbol);
+ if (Base && Base->isUndefined())
+ return false;
+ }
bool IsGlobal = MCELF::GetBinding(Data) == ELF::STB_GLOBAL;
if (!Symbol.isVariable() && Symbol.isUndefined() && !IsGlobal)
@@ -952,20 +946,16 @@ bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm,
return true;
}
-bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isSignature,
- bool isUsedInReloc) {
+bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isUsedInReloc) {
if (Data.isExternal())
return false;
const MCSymbol &Symbol = Data.getSymbol();
- const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
-
- if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
- if (isSignature && !isUsedInReloc)
- return true;
+ if (Symbol.isDefined())
+ return true;
+ if (isUsedInReloc)
return false;
- }
return true;
}
@@ -1013,58 +1003,36 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
MCELF::SetBinding(Data, ELF::STB_GLOBAL);
}
- // Index 0 is always the empty string.
- StringMap<uint64_t> StringIndexMap;
- StringTable += '\x00';
-
- // FIXME: We could optimize suffixes in strtab in the same way we
- // optimize them in shstrtab.
-
- for (MCAssembler::const_file_name_iterator it = Asm.file_names_begin(),
- ie = Asm.file_names_end();
- it != ie;
- ++it) {
- StringRef Name = *it;
- uint64_t &Entry = StringIndexMap[Name];
- if (!Entry) {
- Entry = StringTable.size();
- StringTable += Name;
- StringTable += '\x00';
- }
- FileSymbolData.push_back(Entry);
- }
-
// Add the data for the symbols.
- for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
- ie = Asm.symbol_end(); it != ie; ++it) {
- const MCSymbol &Symbol = it->getSymbol();
+ for (MCSymbolData &SD : Asm.symbols()) {
+ const MCSymbol &Symbol = SD.getSymbol();
bool Used = UsedInReloc.count(&Symbol);
bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
bool isSignature = RevGroupMap.count(&Symbol);
- if (!isInSymtab(Asm, *it,
+ if (!isInSymtab(Layout, SD,
Used || WeakrefUsed || isSignature,
Renames.count(&Symbol)))
continue;
ELFSymbolData MSD;
- MSD.SymbolData = it;
- const MCSymbol *BaseSymbol = getBaseSymbol(Layout, Symbol);
+ MSD.SymbolData = &SD;
+ const MCSymbol *BaseSymbol = Layout.getBaseSymbol(Symbol);
// Undefined symbols are global, but this is the first place we
// are able to set it.
- bool Local = isLocal(*it, isSignature, Used);
- if (!Local && MCELF::GetBinding(*it) == ELF::STB_LOCAL) {
+ bool Local = isLocal(SD, Used);
+ if (!Local && MCELF::GetBinding(SD) == ELF::STB_LOCAL) {
assert(BaseSymbol);
- MCSymbolData &SD = Asm.getSymbolData(*BaseSymbol);
- MCELF::SetBinding(*it, ELF::STB_GLOBAL);
+ MCSymbolData &BaseData = Asm.getSymbolData(*BaseSymbol);
MCELF::SetBinding(SD, ELF::STB_GLOBAL);
+ MCELF::SetBinding(BaseData, ELF::STB_GLOBAL);
}
if (!BaseSymbol) {
MSD.SectionIndex = ELF::SHN_ABS;
- } else if (it->isCommon()) {
+ } else if (SD.isCommon()) {
assert(!Local);
MSD.SectionIndex = ELF::SHN_COMMON;
} else if (BaseSymbol->isUndefined()) {
@@ -1073,7 +1041,7 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
else
MSD.SectionIndex = ELF::SHN_UNDEF;
if (!Used && WeakrefUsed)
- MCELF::SetBinding(*it, ELF::STB_WEAK);
+ MCELF::SetBinding(SD, ELF::STB_WEAK);
} else {
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(BaseSymbol->getSection());
@@ -1085,7 +1053,6 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
// @@ in defined ones.
StringRef Name = Symbol.getName();
SmallString<32> Buf;
-
size_t Pos = Name.find("@@@");
if (Pos != StringRef::npos) {
Buf += Name.substr(0, Pos);
@@ -1093,14 +1060,8 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
Buf += Name.substr(Pos + Skip);
Name = Buf;
}
+ MSD.Name = StrTabBuilder.add(Name);
- uint64_t &Entry = StringIndexMap[Name];
- if (!Entry) {
- Entry = StringTable.size();
- StringTable += Name;
- StringTable += '\x00';
- }
- MSD.StringIndex = Entry;
if (MSD.SectionIndex == ELF::SHN_UNDEF)
UndefinedSymbolData.push_back(MSD);
else if (Local)
@@ -1109,6 +1070,21 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
ExternalSymbolData.push_back(MSD);
}
+ for (auto i = Asm.file_names_begin(), e = Asm.file_names_end(); i != e; ++i)
+ StrTabBuilder.add(*i);
+
+ StrTabBuilder.finalize();
+
+ for (auto i = Asm.file_names_begin(), e = Asm.file_names_end(); i != e; ++i)
+ FileSymbolData.push_back(StrTabBuilder.getOffset(*i));
+
+ for (ELFSymbolData& MSD : LocalSymbolData)
+ MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
+ for (ELFSymbolData& MSD : ExternalSymbolData)
+ MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
+ for (ELFSymbolData& MSD : UndefinedSymbolData)
+ MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
+
// Symbols are required to be in lexicographic order.
array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
@@ -1168,6 +1144,151 @@ void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm,
}
}
+static SmallVector<char, 128>
+getUncompressedData(MCAsmLayout &Layout,
+ MCSectionData::FragmentListType &Fragments) {
+ SmallVector<char, 128> UncompressedData;
+ for (const MCFragment &F : Fragments) {
+ const SmallVectorImpl<char> *Contents;
+ switch (F.getKind()) {
+ case MCFragment::FT_Data:
+ Contents = &cast<MCDataFragment>(F).getContents();
+ break;
+ case MCFragment::FT_Dwarf:
+ Contents = &cast<MCDwarfLineAddrFragment>(F).getContents();
+ break;
+ case MCFragment::FT_DwarfFrame:
+ Contents = &cast<MCDwarfCallFrameFragment>(F).getContents();
+ break;
+ default:
+ llvm_unreachable(
+ "Not expecting any other fragment types in a debug_* section");
+ }
+ UncompressedData.append(Contents->begin(), Contents->end());
+ }
+ return UncompressedData;
+}
+
+// Include the debug info compression header:
+// "ZLIB" followed by 8 bytes representing the uncompressed size of the section,
+// useful for consumers to preallocate a buffer to decompress into.
+static bool
+prependCompressionHeader(uint64_t Size,
+ SmallVectorImpl<char> &CompressedContents) {
+ static const StringRef Magic = "ZLIB";
+ if (Size <= Magic.size() + sizeof(Size) + CompressedContents.size())
+ return false;
+ if (sys::IsLittleEndianHost)
+ Size = sys::SwapByteOrder(Size);
+ CompressedContents.insert(CompressedContents.begin(),
+ Magic.size() + sizeof(Size), 0);
+ std::copy(Magic.begin(), Magic.end(), CompressedContents.begin());
+ std::copy(reinterpret_cast<char *>(&Size),
+ reinterpret_cast<char *>(&Size + 1),
+ CompressedContents.begin() + Magic.size());
+ return true;
+}
+
+// Return a single fragment containing the compressed contents of the whole
+// section. Null if the section was not compressed for any reason.
+static std::unique_ptr<MCDataFragment>
+getCompressedFragment(MCAsmLayout &Layout,
+ MCSectionData::FragmentListType &Fragments) {
+ std::unique_ptr<MCDataFragment> CompressedFragment(new MCDataFragment());
+
+ // Gather the uncompressed data from all the fragments, recording the
+ // alignment fragment, if seen, and any fixups.
+ SmallVector<char, 128> UncompressedData =
+ getUncompressedData(Layout, Fragments);
+
+ SmallVectorImpl<char> &CompressedContents = CompressedFragment->getContents();
+
+ zlib::Status Success = zlib::compress(
+ StringRef(UncompressedData.data(), UncompressedData.size()),
+ CompressedContents);
+ if (Success != zlib::StatusOK)
+ return nullptr;
+
+ if (!prependCompressionHeader(UncompressedData.size(), CompressedContents))
+ return nullptr;
+
+ return CompressedFragment;
+}
+
+typedef DenseMap<const MCSectionData *, std::vector<MCSymbolData *>>
+DefiningSymbolMap;
+
+static void UpdateSymbols(const MCAsmLayout &Layout,
+ const std::vector<MCSymbolData *> &Symbols,
+ MCFragment &NewFragment) {
+ for (MCSymbolData *Sym : Symbols) {
+ Sym->setOffset(Sym->getOffset() +
+ Layout.getFragmentOffset(Sym->getFragment()));
+ Sym->setFragment(&NewFragment);
+ }
+}
+
+static void CompressDebugSection(MCAssembler &Asm, MCAsmLayout &Layout,
+ const DefiningSymbolMap &DefiningSymbols,
+ const MCSectionELF &Section,
+ MCSectionData &SD) {
+ StringRef SectionName = Section.getSectionName();
+ MCSectionData::FragmentListType &Fragments = SD.getFragmentList();
+
+ std::unique_ptr<MCDataFragment> CompressedFragment =
+ getCompressedFragment(Layout, Fragments);
+
+ // Leave the section as-is if the fragments could not be compressed.
+ if (!CompressedFragment)
+ return;
+
+ // Update the fragment+offsets of any symbols referring to fragments in this
+ // section to refer to the new fragment.
+ auto I = DefiningSymbols.find(&SD);
+ if (I != DefiningSymbols.end())
+ UpdateSymbols(Layout, I->second, *CompressedFragment);
+
+ // Invalidate the layout for the whole section since it will have new and
+ // different fragments now.
+ Layout.invalidateFragmentsFrom(&Fragments.front());
+ Fragments.clear();
+
+ // Complete the initialization of the new fragment
+ CompressedFragment->setParent(&SD);
+ CompressedFragment->setLayoutOrder(0);
+ Fragments.push_back(CompressedFragment.release());
+
+ // Rename from .debug_* to .zdebug_*
+ Asm.getContext().renameELFSection(&Section,
+ (".z" + SectionName.drop_front(1)).str());
+}
+
+void ELFObjectWriter::CompressDebugSections(MCAssembler &Asm,
+ MCAsmLayout &Layout) {
+ if (!Asm.getContext().getAsmInfo()->compressDebugSections())
+ return;
+
+ DefiningSymbolMap DefiningSymbols;
+
+ for (MCSymbolData &SD : Asm.symbols())
+ if (MCFragment *F = SD.getFragment())
+ DefiningSymbols[F->getParent()].push_back(&SD);
+
+ for (MCSectionData &SD : Asm) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(SD.getSection());
+ StringRef SectionName = Section.getSectionName();
+
+ // Compressing debug_frame requires handling alignment fragments which is
+ // more work (possibly generalizing MCAssembler.cpp:writeFragment to allow
+ // for writing to arbitrary buffers) for little benefit.
+ if (!SectionName.startswith(".debug_") || SectionName == ".debug_frame")
+ continue;
+
+ CompressDebugSection(Asm, Layout, DefiningSymbols, Section, SD);
+ }
+}
+
void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
const RelMapTy &RelMap) {
for (MCAssembler::const_iterator it = Asm.begin(),
@@ -1274,23 +1395,6 @@ void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
}
}
-static int compareBySuffix(const MCSectionELF *const *a,
- const MCSectionELF *const *b) {
- const StringRef &NameA = (*a)->getSectionName();
- const StringRef &NameB = (*b)->getSectionName();
- const unsigned sizeA = NameA.size();
- const unsigned sizeB = NameB.size();
- const unsigned len = std::min(sizeA, sizeB);
- for (unsigned int i = 0; i < len; ++i) {
- char ca = NameA[sizeA - i - 1];
- char cb = NameB[sizeB - i - 1];
- if (ca != cb)
- return cb - ca;
- }
-
- return sizeB - sizeA;
-}
-
void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
MCAsmLayout &Layout,
SectionIndexMapTy &SectionIndexMap,
@@ -1331,45 +1435,20 @@ void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
WriteSymbolTable(F, Asm, Layout, SectionIndexMap);
F = new MCDataFragment(&StrtabSD);
- F->getContents().append(StringTable.begin(), StringTable.end());
+ F->getContents().append(StrTabBuilder.data().begin(),
+ StrTabBuilder.data().end());
F = new MCDataFragment(&ShstrtabSD);
- std::vector<const MCSectionELF*> Sections;
- for (MCAssembler::const_iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it) {
+ // Section header string table.
+ for (auto it = Asm.begin(), ie = Asm.end(); it != ie; ++it) {
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(it->getSection());
- Sections.push_back(&Section);
- }
- array_pod_sort(Sections.begin(), Sections.end(), compareBySuffix);
-
- // Section header string table.
- //
- // The first entry of a string table holds a null character so skip
- // section 0.
- uint64_t Index = 1;
- F->getContents().push_back('\x00');
-
- for (unsigned int I = 0, E = Sections.size(); I != E; ++I) {
- const MCSectionELF &Section = *Sections[I];
-
- StringRef Name = Section.getSectionName();
- if (I != 0) {
- StringRef PreviousName = Sections[I - 1]->getSectionName();
- if (PreviousName.endswith(Name)) {
- SectionStringTableIndex[&Section] = Index - Name.size() - 1;
- continue;
- }
- }
- // Remember the index into the string table so we can write it
- // into the sh_name field of the section header table.
- SectionStringTableIndex[&Section] = Index;
-
- Index += Name.size() + 1;
- F->getContents().append(Name.begin(), Name.end());
- F->getContents().push_back('\x00');
+ ShStrTabBuilder.add(Section.getSectionName());
}
+ ShStrTabBuilder.finalize();
+ F->getContents().append(ShStrTabBuilder.data().begin(),
+ ShStrTabBuilder.data().end());
}
void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
@@ -1437,7 +1516,7 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm,
switch(Section.getType()) {
case ELF::SHT_DYNAMIC:
- sh_link = SectionStringTableIndex[&Section];
+ sh_link = ShStrTabBuilder.getOffset(Section.getSectionName());
sh_info = 0;
break;
@@ -1518,7 +1597,8 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm,
}
}
- WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
+ WriteSecHdrEntry(ShStrTabBuilder.getOffset(Section.getSectionName()),
+ Section.getType(),
Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
Alignment, Section.getEntrySize());
}
@@ -1652,6 +1732,8 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
unsigned NumUserSections = Asm.size();
+ CompressDebugSections(Asm, const_cast<MCAsmLayout &>(Layout));
+
DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap;
CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
generated by cgit v1.1 at 2024-05-18 02:33:48 +0000