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Parse relocations only once. 

Relocations are the last thing that we wore storing a raw section
pointer to and parsing on demand.

With this patch we parse it only once and store a pointer to the
actual data.

The patch also changes where we store it. It is now in
InputSectionBase. Not all sections have relocations, but most do and
this simplifies the logic. It also means that we now only support one
relocation section per section. Given that that constraint is
maintained even with -r with gold bfd and lld, I think it is OK.

llvm-svn: 286459
This commit is contained in:
Rafael Espindola 2016-11-10 14:53:24 +00:00
parent e93e0adbb5
commit 9f0c4bb795
11 changed files with 100 additions and 126 deletions
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42
lld/ELF/ICF.cpp
View File

@ -120,10 +120,7 @@ private:
// relocation targets is not included in the hash value.
template <class ELFT> uint64_t ICF<ELFT>::getHash(InputSection<ELFT> *S) {
uint64_t Flags = S->Flags;
uint64_t H = hash_combine(Flags, S->getSize());
for (const Elf_Shdr *Rel : S->RelocSections)
H = hash_combine(H, (uint64_t)Rel->sh_size);
return H;
return hash_combine(Flags, S->getSize(), S->NumRelocations);
}
// Returns true if Sec is subject of ICF.
@ -212,21 +209,15 @@ bool ICF<ELFT>::relocationEq(ArrayRef<RelTy> RelsA, ArrayRef<RelTy> RelsB) {
template <class ELFT>
bool ICF<ELFT>::equalsConstant(const InputSection<ELFT> *A,
const InputSection<ELFT> *B) {
if (A->RelocSections.size() != B->RelocSections.size())
if (A->NumRelocations != B->NumRelocations)
return false;
for (size_t I = 0, E = A->RelocSections.size(); I != E; ++I) {
const Elf_Shdr *RA = A->RelocSections[I];
const Elf_Shdr *RB = B->RelocSections[I];
ELFFile<ELFT> FileA = A->getObj();
ELFFile<ELFT> FileB = B->getObj();
if (RA->sh_type == SHT_RELA) {
if (!relocationEq(check(FileA.relas(RA)), check(FileB.relas(RB))))
return false;
} else {
if (!relocationEq(check(FileA.rels(RA)), check(FileB.rels(RB))))
return false;
}
if (A->AreRelocsRela) {
if (!relocationEq(A->relas(), B->relas()))
return false;
} else {
if (!relocationEq(A->rels(), B->rels()))
return false;
}
return A->Flags == B->Flags && A->getSize() == B->getSize() &&
@ -268,20 +259,9 @@ bool ICF<ELFT>::variableEq(const InputSection<ELFT> *A,
template <class ELFT>
bool ICF<ELFT>::equalsVariable(const InputSection<ELFT> *A,
const InputSection<ELFT> *B) {
for (size_t I = 0, E = A->RelocSections.size(); I != E; ++I) {
const Elf_Shdr *RA = A->RelocSections[I];
const Elf_Shdr *RB = B->RelocSections[I];
ELFFile<ELFT> FileA = A->getObj();
ELFFile<ELFT> FileB = B->getObj();
if (RA->sh_type == SHT_RELA) {
if (!variableEq(A, B, check(FileA.relas(RA)), check(FileB.relas(RB))))
return false;
} else {
if (!variableEq(A, B, check(FileA.rels(RA)), check(FileB.rels(RB))))
return false;
}
}
return true;
if (A->AreRelocsRela)
return variableEq(A, B, A->relas(), B->relas());
return variableEq(A, B, A->rels(), B->rels());
}
// The main function of ICF.

33
lld/ELF/InputFiles.cpp
View File

@ -353,19 +353,28 @@ elf::ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec,
InputSectionBase<ELFT> *Target = getRelocTarget(Sec);
if (!Target)
return nullptr;
if (auto *S = dyn_cast<InputSection<ELFT>>(Target)) {
S->RelocSections.push_back(&Sec);
return nullptr;
if (Target->FirstRelocation)
fatal(getFilename(this) +
": multiple relocation sections to one section are not supported");
if (!isa<InputSection<ELFT>>(Target) && !isa<EhInputSection<ELFT>>(Target))
fatal(getFilename(this) +
": relocations pointing to SHF_MERGE are not supported");
size_t NumRelocations;
if (Sec.sh_type == SHT_RELA) {
ArrayRef<Elf_Rela> Rels = check(this->getObj().relas(&Sec));
Target->FirstRelocation = Rels.begin();
NumRelocations = Rels.size();
Target->AreRelocsRela = true;
} else {
ArrayRef<Elf_Rel> Rels = check(this->getObj().rels(&Sec));
Target->FirstRelocation = Rels.begin();
NumRelocations = Rels.size();
Target->AreRelocsRela = false;
}
if (auto *S = dyn_cast<EhInputSection<ELFT>>(Target)) {
if (S->RelocSection)
fatal(getFilename(this) +
": multiple relocation sections to .eh_frame are not supported");
S->RelocSection = &Sec;
return nullptr;
}
fatal(getFilename(this) +
": relocations pointing to SHF_MERGE are not supported");
assert(isUInt<31>(NumRelocations));
Target->NumRelocations = NumRelocations;
return nullptr;
}
}

2
lld/ELF/InputFiles.h
View File

@ -121,6 +121,8 @@ protected:
// .o file.
template <class ELFT> class ObjectFile : public ELFFileBase<ELFT> {
typedef ELFFileBase<ELFT> Base;
typedef typename ELFT::Rel Elf_Rel;
typedef typename ELFT::Rela Elf_Rela;
typedef typename ELFT::Sym Elf_Sym;
typedef typename ELFT::Shdr Elf_Shdr;
typedef typename ELFT::SymRange Elf_Sym_Range;

22
lld/ELF/InputSection.cpp
View File

@ -56,6 +56,9 @@ InputSectionBase<ELFT>::InputSectionBase(elf::ObjectFile<ELFT> *File,
!Config->GcSections || !(Flags & SHF_ALLOC)),
File(File), Flags(Flags), Entsize(Entsize), Type(Type), Link(Link),
Info(Info), Repl(this) {
NumRelocations = 0;
AreRelocsRela = false;
// The ELF spec states that a value of 0 means the section has
// no alignment constraits.
uint64_t V = std::max<uint64_t>(Addralign, 1);
@ -466,12 +469,10 @@ void InputSectionBase<ELFT>::relocate(uint8_t *Buf, uint8_t *BufEnd) {
// we handle relocations directly here.
auto *IS = dyn_cast<InputSection<ELFT>>(this);
if (IS && !(IS->Flags & SHF_ALLOC)) {
for (const Elf_Shdr *RelSec : IS->RelocSections) {
if (RelSec->sh_type == SHT_RELA)
IS->relocateNonAlloc(Buf, check(IS->getObj().relas(RelSec)));
else
IS->relocateNonAlloc(Buf, check(IS->getObj().rels(RelSec)));
}
if (IS->AreRelocsRela)
IS->relocateNonAlloc(Buf, IS->relas());
else
IS->relocateNonAlloc(Buf, IS->rels());
return;
}
@ -609,12 +610,11 @@ template <class ELFT> void EhInputSection<ELFT>::split() {
if (!this->Pieces.empty())
return;
if (RelocSection) {
ELFFile<ELFT> Obj = this->getObj();
if (RelocSection->sh_type == SHT_RELA)
split(check(Obj.relas(RelocSection)));
if (this->NumRelocations) {
if (this->AreRelocsRela)
split(this->relas());
else
split(check(Obj.rels(RelocSection)));
split(this->rels());
return;
}
split(makeArrayRef<typename ELFT::Rela>(nullptr, nullptr));

24
lld/ELF/InputSection.h
View File

@ -96,7 +96,10 @@ public:
InputSectionBase()
: InputSectionData(Regular, "", ArrayRef<uint8_t>(), false, false),
Repl(this) {}
Repl(this) {
NumRelocations = 0;
AreRelocsRela = false;
}
InputSectionBase(ObjectFile<ELFT> *File, const Elf_Shdr *Header,
StringRef Name, Kind SectionKind);
@ -106,6 +109,20 @@ public:
Kind SectionKind);
OutputSectionBase *OutSec = nullptr;
// Relocations that refer to this section.
const Elf_Rel *FirstRelocation = nullptr;
unsigned NumRelocations : 31;
unsigned AreRelocsRela : 1;
ArrayRef<Elf_Rel> rels() const {
assert(!AreRelocsRela);
return llvm::makeArrayRef(FirstRelocation, NumRelocations);
}
ArrayRef<Elf_Rela> relas() const {
assert(AreRelocsRela);
return llvm::makeArrayRef(static_cast<const Elf_Rela *>(FirstRelocation),
NumRelocations);
}
// This pointer points to the "real" instance of this instance.
// Usually Repl == this. However, if ICF merges two sections,
// Repl pointer of one section points to another section. So,
@ -219,8 +236,6 @@ public:
// rather than a single large blob of data.
std::vector<EhSectionPiece> Pieces;
// Relocation section that refer to this one.
const Elf_Shdr *RelocSection = nullptr;
};
// This corresponds to a non SHF_MERGE section of an input file.
@ -247,9 +262,6 @@ public:
// beginning of the output section.
void writeTo(uint8_t *Buf);
// Relocation sections that refer to this one.
llvm::TinyPtrVector<const Elf_Shdr *> RelocSections;
// The offset from beginning of the output sections this section was assigned
// to. The writer sets a value.
uint64_t OutSecOff = 0;

24
lld/ELF/MarkLive.cpp
View File

@ -80,15 +80,12 @@ static ResolvedReloc<ELFT> resolveReloc(InputSectionBase<ELFT> &Sec,
template <class ELFT>
static void forEachSuccessor(InputSection<ELFT> &Sec,
std::function<void(ResolvedReloc<ELFT>)> Fn) {
ELFFile<ELFT> Obj = Sec.getFile()->getObj();
for (const typename ELFT::Shdr *RelSec : Sec.RelocSections) {
if (RelSec->sh_type == SHT_RELA) {
for (const typename ELFT::Rela &Rel : check(Obj.relas(RelSec)))
Fn(resolveReloc(Sec, Rel));
} else {
for (const typename ELFT::Rel &Rel : check(Obj.rels(RelSec)))
Fn(resolveReloc(Sec, Rel));
}
if (Sec.AreRelocsRela) {
for (const typename ELFT::Rela &Rel : Sec.relas())
Fn(resolveReloc(Sec, Rel));
} else {
for (const typename ELFT::Rel &Rel : Sec.rels())
Fn(resolveReloc(Sec, Rel));
}
if (Sec.DependentSection)
Fn({Sec.DependentSection, 0});
@ -146,18 +143,17 @@ template <class ELFT>
static void
scanEhFrameSection(EhInputSection<ELFT> &EH,
std::function<void(ResolvedReloc<ELFT>)> Enqueue) {
if (!EH.RelocSection)
if (!EH.NumRelocations)
return;
// Unfortunately we need to split .eh_frame early since some relocations in
// .eh_frame keep other section alive and some don't.
EH.split();
ELFFile<ELFT> EObj = EH.getFile()->getObj();
if (EH.RelocSection->sh_type == SHT_RELA)
scanEhFrameSection(EH, check(EObj.relas(EH.RelocSection)), Enqueue);
if (EH.AreRelocsRela)
scanEhFrameSection(EH, EH.relas(), Enqueue);
else
scanEhFrameSection(EH, check(EObj.rels(EH.RelocSection)), Enqueue);
scanEhFrameSection(EH, EH.rels(), Enqueue);
}
// We do not garbage-collect two types of sections:

9
lld/ELF/OutputSections.cpp
View File

@ -1162,12 +1162,11 @@ void EhOutputSection<ELFT>::addSection(InputSectionData *C) {
if (Sec->Pieces.empty())
return;
if (const Elf_Shdr *RelSec = Sec->RelocSection) {
ELFFile<ELFT> Obj = Sec->getFile()->getObj();
if (RelSec->sh_type == SHT_RELA)
addSectionAux(Sec, check(Obj.relas(RelSec)));
if (Sec->NumRelocations) {
if (Sec->AreRelocsRela)
addSectionAux(Sec, Sec->relas());
else
addSectionAux(Sec, check(Obj.rels(RelSec)));
addSectionAux(Sec, Sec->rels());
return;
}
addSectionAux(Sec, makeArrayRef<Elf_Rela>(nullptr, nullptr));

46
lld/ELF/Relocations.cpp
View File

@ -787,14 +787,11 @@ static void scanRelocs(InputSectionBase<ELFT> &C, ArrayRef<RelTy> Rels) {
}
}
template <class ELFT>
void scanRelocations(InputSectionBase<ELFT> &S,
const typename ELFT::Shdr &RelSec) {
ELFFile<ELFT> EObj = S.getFile()->getObj();
if (RelSec.sh_type == SHT_RELA)
scanRelocs(S, check(EObj.relas(&RelSec)));
template <class ELFT> void scanRelocations(InputSectionBase<ELFT> &S) {
if (S.AreRelocsRela)
scanRelocs(S, S.relas());
else
scanRelocs(S, check(EObj.rels(&RelSec)));
scanRelocs(S, S.rels());
}
template <class ELFT, class RelTy>
@ -817,33 +814,22 @@ static void createThunks(InputSectionBase<ELFT> &C, ArrayRef<RelTy> Rels) {
}
}
template <class ELFT>
void createThunks(InputSectionBase<ELFT> &S,
const typename ELFT::Shdr &RelSec) {
ELFFile<ELFT> EObj = S.getFile()->getObj();
if (RelSec.sh_type == SHT_RELA)
createThunks(S, check(EObj.relas(&RelSec)));
template <class ELFT> void createThunks(InputSectionBase<ELFT> &S) {
if (S.AreRelocsRela)
createThunks(S, S.relas());
else
createThunks(S, check(EObj.rels(&RelSec)));
createThunks(S, S.rels());
}
template void scanRelocations<ELF32LE>(InputSectionBase<ELF32LE> &,
const ELF32LE::Shdr &);
template void scanRelocations<ELF32BE>(InputSectionBase<ELF32BE> &,
const ELF32BE::Shdr &);
template void scanRelocations<ELF64LE>(InputSectionBase<ELF64LE> &,
const ELF64LE::Shdr &);
template void scanRelocations<ELF64BE>(InputSectionBase<ELF64BE> &,
const ELF64BE::Shdr &);
template void scanRelocations<ELF32LE>(InputSectionBase<ELF32LE> &);
template void scanRelocations<ELF32BE>(InputSectionBase<ELF32BE> &);
template void scanRelocations<ELF64LE>(InputSectionBase<ELF64LE> &);
template void scanRelocations<ELF64BE>(InputSectionBase<ELF64BE> &);
template void createThunks<ELF32LE>(InputSectionBase<ELF32LE> &,
const ELF32LE::Shdr &);
template void createThunks<ELF32BE>(InputSectionBase<ELF32BE> &,
const ELF32BE::Shdr &);
template void createThunks<ELF64LE>(InputSectionBase<ELF64LE> &,
const ELF64LE::Shdr &);
template void createThunks<ELF64BE>(InputSectionBase<ELF64BE> &,
const ELF64BE::Shdr &);
template void createThunks<ELF32LE>(InputSectionBase<ELF32LE> &);
template void createThunks<ELF32BE>(InputSectionBase<ELF32BE> &);
template void createThunks<ELF64LE>(InputSectionBase<ELF64LE> &);
template void createThunks<ELF64BE>(InputSectionBase<ELF64BE> &);
template std::string getLocation<ELF32LE>(InputSectionBase<ELF32LE> &S,
uint32_t Offset);

6
lld/ELF/Relocations.h
View File

@ -81,11 +81,9 @@ struct Relocation {
SymbolBody *Sym;
};
template <class ELFT>
void scanRelocations(InputSectionBase<ELFT> &, const typename ELFT::Shdr &);
template <class ELFT> void scanRelocations(InputSectionBase<ELFT> &);
template <class ELFT>
void createThunks(InputSectionBase<ELFT> &, const typename ELFT::Shdr &);
template <class ELFT> void createThunks(InputSectionBase<ELFT> &);
template <class ELFT>
std::string getLocation(InputSectionBase<ELFT> &S, typename ELFT::uint Offset);

16
lld/ELF/Writer.cpp
View File

@ -54,8 +54,7 @@ private:
void addReservedSymbols();
void addInputSec(InputSectionBase<ELFT> *S);
void createSections();
void forEachRelSec(std::function<void(InputSectionBase<ELFT> &,
const typename ELFT::Shdr &)> Fn);
void forEachRelSec(std::function<void(InputSectionBase<ELFT> &)> Fn);
void sortSections();
void finalizeSections();
void addPredefinedSections();
@ -694,8 +693,7 @@ static void sortBySymbolsOrder(ArrayRef<OutputSectionBase *> V) {
template <class ELFT>
void Writer<ELFT>::forEachRelSec(
std::function<void(InputSectionBase<ELFT> &, const typename ELFT::Shdr &)>
Fn) {
std::function<void(InputSectionBase<ELFT> &)> Fn) {
for (InputSectionBase<ELFT> *IS : Symtab<ELFT>::X->Sections) {
if (!IS->Live)
continue;
@ -706,14 +704,8 @@ void Writer<ELFT>::forEachRelSec(
// processed by InputSection::relocateNonAlloc.
if (!(IS->Flags & SHF_ALLOC))
continue;
if (auto *S = dyn_cast<InputSection<ELFT>>(IS)) {
for (const Elf_Shdr *RelSec : S->RelocSections)
Fn(*S, *RelSec);
continue;
}
if (auto *S = dyn_cast<EhInputSection<ELFT>>(IS))
if (S->RelocSection)
Fn(*S, *S->RelocSection);
if (isa<InputSection<ELFT>>(IS) || isa<EhInputSection<ELFT>>(IS))
Fn(*IS);
}
}

2
lld/test/ELF/invalid/invalid-elf.test
View File

@ -26,6 +26,6 @@
# RUN: not ld.lld %p/Inputs/multiple-eh-relocs.elf -o %t2 2>&1 | \
# RUN: FileCheck --check-prefix=INVALID-EH-RELOCS %s
# INVALID-EH-RELOCS: multiple relocation sections to .eh_frame are not supported
# INVALID-EH-RELOCS: multiple relocation sections to one section are not supported
.long foo