Please use GitHub pull requests for new patches. Phabricator shutdown timeline

Differential D26346 Diff 77014 ELF/Writer.cpp

Changeset View

Standalone View

ELF/Writer.cpp

Show First 20 Lines • Show All 580 Lines • ▼ Show 20 Lines	if (Config->EMachine == EM_MIPS && !Config->Relocatable) {

// The __gnu_local_gp is a magic symbol equal to the current value of 'gp'		// The __gnu_local_gp is a magic symbol equal to the current value of 'gp'
// pointer. This symbol is used in the code generated by .cpload pseudo-op		// pointer. This symbol is used in the code generated by .cpload pseudo-op
// in case of using -mno-shared option.		// in case of using -mno-shared option.
// https://sourceware.org/ml/binutils/2004-12/msg00094.html		// https://sourceware.org/ml/binutils/2004-12/msg00094.html
addOptionalSynthetic("__gnu_local_gp", Out<ELFT>::Got, MipsGPOffset);		addOptionalSynthetic("__gnu_local_gp", Out<ELFT>::Got, MipsGPOffset);
}		}

		if (Config->EMachine == EM_PPC && !Config->Relocatable) {
		// In the event a non-relocatable PPC32 target is being built, reserve
		// Small Data base registers. These will be relocated midway through
		// the .sdata and .sdata2 sections (if used). This symbol is meant to
		// be applied in EABI systems, where r13 and r2 are initialized to these
		// linker-generated symbols by the C runtime initialization.
		Symbol *Sym;
		constexpr OutputSectionBase<ELFT> *NullSec = nullptr;
		Sym = addOptionalSynthetic("_SDA_BASE_", NullSec, 0);
		if (Sym)
		ElfSym<ELFT>::SdaBase = cast<DefinedSynthetic<ELFT>>(Sym->body());
		Sym = addOptionalSynthetic("_SDA2_BASE_", NullSec, 0);
		if (Sym)
		ElfSym<ELFT>::Sda2Base = cast<DefinedSynthetic<ELFT>>(Sym->body());
		}

// In the assembly for 32 bit x86 the _GLOBAL_OFFSET_TABLE_ symbol		// In the assembly for 32 bit x86 the _GLOBAL_OFFSET_TABLE_ symbol
// is magical and is used to produce a R_386_GOTPC relocation.		// is magical and is used to produce a R_386_GOTPC relocation.
// The R_386_GOTPC relocation value doesn't actually depend on the		// The R_386_GOTPC relocation value doesn't actually depend on the
// symbol value, so it could use an index of STN_UNDEF which, according		// symbol value, so it could use an index of STN_UNDEF which, according
// to the spec, means the symbol value is 0.		// to the spec, means the symbol value is 0.
// Unfortunately both gas and MC keep the _GLOBAL_OFFSET_TABLE_ symbol in		// Unfortunately both gas and MC keep the _GLOBAL_OFFSET_TABLE_ symbol in
// the object file.		// the object file.
// The situation is even stranger on x86_64 where the assembly doesn't		// The situation is even stranger on x86_64 where the assembly doesn't
▲ Show 20 Lines • Show All 666 Lines • ▼ Show 20 Lines
// This function is called after we have assigned address and size		// This function is called after we have assigned address and size
// to each section. This function fixes some predefined absolute		// to each section. This function fixes some predefined absolute
// symbol values that depend on section address and size.		// symbol values that depend on section address and size.
template <class ELFT> void Writer<ELFT>::fixAbsoluteSymbols() {		template <class ELFT> void Writer<ELFT>::fixAbsoluteSymbols() {
// __ehdr_start is the location of program headers.		// __ehdr_start is the location of program headers.
if (ElfSym<ELFT>::EhdrStart)		if (ElfSym<ELFT>::EhdrStart)
ElfSym<ELFT>::EhdrStart->Value = Out<ELFT>::ProgramHeaders->getVA();		ElfSym<ELFT>::EhdrStart->Value = Out<ELFT>::ProgramHeaders->getVA();

		auto SectionMidpoint = [](OutputSectionBase<ELFT> *Sec) ->
		typename ELFT::uint {
		return ((Sec->getSize() / 2) & ~0x3) + Sec->getVA();
		};

		// PPC-EABI systems will need the _SDA_BASE_ and _SDA2_BASE_ symbols
		// synthesized for use by C runtime init. The section midpoints are used
		// to maximize addressing range.
		if (ElfSym<ELFT>::SdaBase) {
		OutputSectionBase<ELFT> *Sec = findSection(".sdata");
		if (!Sec) Sec = findSection(".sbss");
		if (Sec)
		ElfSym<ELFT>::SdaBase->Value = SectionMidpoint(Sec);
		}
		if (ElfSym<ELFT>::Sda2Base) {
		OutputSectionBase<ELFT> *Sec = findSection(".sdata2");
		if (Sec)
		ElfSym<ELFT>::Sda2Base->Value = SectionMidpoint(Sec);
		}

auto Set = [](DefinedRegular<ELFT> S1, DefinedRegular<ELFT> S2, uintX_t V) {		auto Set = [](DefinedRegular<ELFT> S1, DefinedRegular<ELFT> S2, uintX_t V) {
if (S1)		if (S1)
S1->Value = V;		S1->Value = V;
if (S2)		if (S2)
S2->Value = V;		S2->Value = V;
};		};

// _etext is the first location after the last read-only loadable segment.		// _etext is the first location after the last read-only loadable segment.
▲ Show 20 Lines • Show All 189 Lines • Show Last 20 Lines