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Instantiate Interp output section only when needed. 

This change simplifies interaction between Writer and the linker script
because we can make needsInterpSection() a file-scope function.

llvm-svn: 276261
This commit is contained in:
Rui Ueyama 2016-07-21 11:01:23 +00:00
parent 865bf8637b
commit fd03cfd27a
3 changed files with 13 additions and 17 deletions
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2
lld/ELF/LinkerScript.cpp
View File

@ -344,7 +344,7 @@ LinkerScript<ELFT>::createPhdrs(ArrayRef<OutputSectionBase<ELFT> *> Sections) {
switch (Cmd.Type) {
case PT_INTERP:
if (needsInterpSection<ELFT>())
if (Out<ELFT>::Interp)
Added.add(Out<ELFT>::Interp);
break;
case PT_DYNAMIC:

27
lld/ELF/Writer.cpp
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@ -112,6 +112,11 @@ void elf::reportDiscarded(InputSectionBase<ELFT> *IS,
<< "' in file '" << File->getName() << "'\n";
}
template <class ELFT> static bool needsInterpSection() {
return !Symtab<ELFT>::X->getSharedFiles().empty() &&
!Config->DynamicLinker.empty();
}
template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
typedef typename ELFT::uint uintX_t;
typedef typename ELFT::Ehdr Elf_Ehdr;
@ -121,7 +126,6 @@ template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
DynamicSection<ELFT> Dynamic;
EhOutputSection<ELFT> EhFrame;
GotSection<ELFT> Got;
InterpSection<ELFT> Interp;
PltSection<ELFT> Plt;
RelocationSection<ELFT> RelaDyn(Config->Rela ? ".rela.dyn" : ".rel.dyn",
Config->ZCombreloc);
@ -137,6 +141,7 @@ template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
ProgramHeaders.updateAlignment(sizeof(uintX_t));
// Instantiate optional output sections if they are needed.
std::unique_ptr<InterpSection<ELFT>> Interp;
std::unique_ptr<BuildIdSection<ELFT>> BuildId;
std::unique_ptr<EhFrameHeader<ELFT>> EhFrameHdr;
std::unique_ptr<GnuHashTableSection<ELFT>> GnuHashTab;
@ -148,6 +153,9 @@ template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
std::unique_ptr<OutputSection<ELFT>> MipsRldMap;
std::unique_ptr<VersionDefinitionSection<ELFT>> VerDef;
if (needsInterpSection<ELFT>())
Interp.reset(new InterpSection<ELFT>);
if (Config->BuildId == BuildIdKind::Fnv1)
BuildId.reset(new BuildIdFnv1<ELFT>);
else if (Config->BuildId == BuildIdKind::Md5)
@ -195,7 +203,7 @@ template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
Out<ELFT>::Got = &Got;
Out<ELFT>::GotPlt = GotPlt.get();
Out<ELFT>::HashTab = HashTab.get();
Out<ELFT>::Interp = &Interp;
Out<ELFT>::Interp = Interp.get();
Out<ELFT>::Plt = &Plt;
Out<ELFT>::RelaDyn = &RelaDyn;
Out<ELFT>::RelaPlt = RelaPlt.get();
@ -474,12 +482,6 @@ uint32_t elf::toPhdrFlags(uint64_t Flags) {
return Ret;
}
// Various helper functions
template <class ELFT> bool elf::needsInterpSection() {
return !Symtab<ELFT>::X->getSharedFiles().empty() &&
!Config->DynamicLinker.empty();
}
template <class ELFT> bool elf::isOutputDynamic() {
return !Symtab<ELFT>::X->getSharedFiles().empty() || Config->Pic;
}
@ -843,7 +845,7 @@ template <class ELFT> void Writer<ELFT>::addPredefinedSections() {
// Add .interp at first because some loaders want to see that section
// on the first page of the executable file when loaded into memory.
if (needsInterpSection<ELFT>())
if (Out<ELFT>::Interp)
OutputSections.insert(OutputSections.begin(), Out<ELFT>::Interp);
// This order is not the same as the final output order
@ -962,7 +964,7 @@ std::vector<PhdrEntry<ELFT>> Writer<ELFT>::createPhdrs() {
Hdr.add(Out<ELFT>::ProgramHeaders);
// PT_INTERP must be the second entry if exists.
if (needsInterpSection<ELFT>()) {
if (Out<ELFT>::Interp) {
Phdr &Hdr = *AddHdr(PT_INTERP, toPhdrFlags(Out<ELFT>::Interp->getFlags()));
Hdr.add(Out<ELFT>::Interp);
}
@ -1332,11 +1334,6 @@ template struct elf::PhdrEntry<ELF32BE>;
template struct elf::PhdrEntry<ELF64LE>;
template struct elf::PhdrEntry<ELF64BE>;
template bool elf::needsInterpSection<ELF32LE>();
template bool elf::needsInterpSection<ELF32BE>();
template bool elf::needsInterpSection<ELF64LE>();
template bool elf::needsInterpSection<ELF64BE>();
template bool elf::isOutputDynamic<ELF32LE>();
template bool elf::isOutputDynamic<ELF32BE>();
template bool elf::isOutputDynamic<ELF64LE>();

1
lld/ELF/Writer.h
View File

@ -25,7 +25,6 @@ template <class ELFT> class ObjectFile;
template <class ELFT> class SymbolTable;
template <class ELFT> void writeResult(SymbolTable<ELFT> *Symtab);
template <class ELFT> void markLive();
template <class ELFT> bool needsInterpSection();
template <class ELFT> bool isOutputDynamic();
template <class ELFT> bool isRelroSection(OutputSectionBase<ELFT> *Sec);
template <class ELFT> bool needsPtLoad(OutputSectionBase<ELFT> *Sec);