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[ELF] - Implemented -z combrelocs/nocombreloc. 

This is the option which sorts relocs to optimize dynamic linker performance.
-z combelocs is the default in gold, also it ignores -z nocombreloc,
this patch do the same.

Patch sorts relocations by symbols only and do not create any
DT_REL[A]COUNT entries. That is different with what gold/bfd do.

More information about option is here:
http://www.airs.com/blog/archives/186
http://people.redhat.com/jakub/prelink.pdf, p.2

Differential revision: http://reviews.llvm.org/D19528

llvm-svn: 269066
This commit is contained in:
George Rimar 2016-05-10 15:47:57 +00:00
parent de1ec03779
commit c191acf097
15 changed files with 130 additions and 17 deletions
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1
lld/ELF/Config.h
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@ -88,6 +88,7 @@ struct Configuration {
bool Verbose;
bool VersionScript = false;
bool WarnCommon;
bool ZCombreloc;
bool ZExecStack;
bool ZNodelete;
bool ZNow;

1
lld/ELF/Driver.cpp
View File

@ -352,6 +352,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
if (Config->LtoJobs == 0)
error("number of threads must be > 0");
Config->ZCombreloc = !hasZOption(Args, "nocombreloc");
Config->ZExecStack = hasZOption(Args, "execstack");
Config->ZNodelete = hasZOption(Args, "nodelete");
Config->ZNow = hasZOption(Args, "now");

21
lld/ELF/OutputSections.cpp
View File

@ -301,9 +301,10 @@ template <class ELFT> void PltSection<ELFT>::finalize() {
}
template <class ELFT>
RelocationSection<ELFT>::RelocationSection(StringRef Name)
RelocationSection<ELFT>::RelocationSection(StringRef Name, bool Sort)
: OutputSectionBase<ELFT>(Name, Config->Rela ? SHT_RELA : SHT_REL,
SHF_ALLOC) {
SHF_ALLOC),
Sort(Sort) {
this->Header.sh_entsize = Config->Rela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
this->Header.sh_addralign = sizeof(uintX_t);
}
@ -313,7 +314,13 @@ void RelocationSection<ELFT>::addReloc(const DynamicReloc<ELFT> &Reloc) {
Relocs.push_back(Reloc);
}
template <class ELFT, class RelTy>
static bool compRelocations(const RelTy &A, const RelTy &B) {
return A.getSymbol(Config->Mips64EL) < B.getSymbol(Config->Mips64EL);
}
template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
uint8_t *BufBegin = Buf;
for (const DynamicReloc<ELFT> &Rel : Relocs) {
auto *P = reinterpret_cast<Elf_Rela *>(Buf);
Buf += Config->Rela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
@ -325,6 +332,16 @@ template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
uint32_t SymIdx = (!Rel.UseSymVA && Sym) ? Sym->DynsymIndex : 0;
P->setSymbolAndType(SymIdx, Rel.Type, Config->Mips64EL);
}
if (Sort) {
if (Config->Rela)
std::stable_sort((Elf_Rela *)BufBegin,
(Elf_Rela *)BufBegin + Relocs.size(),
compRelocations<ELFT, Elf_Rela>);
else
std::stable_sort((Elf_Rel *)BufBegin, (Elf_Rel *)BufBegin + Relocs.size(),
compRelocations<ELFT, Elf_Rel>);
}
}
template <class ELFT> unsigned RelocationSection<ELFT>::getRelocOffset() {

3
lld/ELF/OutputSections.h
View File

@ -274,7 +274,7 @@ class RelocationSection final : public OutputSectionBase<ELFT> {
typedef typename ELFT::uint uintX_t;
public:
RelocationSection(StringRef Name);
RelocationSection(StringRef Name, bool Sort);
void addReloc(const DynamicReloc<ELFT> &Reloc);
unsigned getRelocOffset();
void finalize() override;
@ -284,6 +284,7 @@ public:
bool Static = false;
private:
bool Sort;
std::vector<DynamicReloc<ELFT>> Relocs;
};

5
lld/ELF/Writer.cpp
View File

@ -129,7 +129,8 @@ template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
GotSection<ELFT> Got;
InterpSection<ELFT> Interp;
PltSection<ELFT> Plt;
RelocationSection<ELFT> RelaDyn(Config->Rela ? ".rela.dyn" : ".rel.dyn");
RelocationSection<ELFT> RelaDyn(Config->Rela ? ".rela.dyn" : ".rel.dyn",
Config->ZCombreloc);
StringTableSection<ELFT> DynStrTab(".dynstr", true);
StringTableSection<ELFT> ShStrTab(".shstrtab", false);
SymbolTableSection<ELFT> DynSymTab(*Symtab, DynStrTab);
@ -165,7 +166,7 @@ template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
if (Target->UseLazyBinding) {
StringRef S = Config->Rela ? ".rela.plt" : ".rel.plt";
GotPlt.reset(new GotPltSection<ELFT>);
RelaPlt.reset(new RelocationSection<ELFT>(S));
RelaPlt.reset(new RelocationSection<ELFT>(S, false /*Sort*/));
}
if (!Config->StripAll) {
StrTab.reset(new StringTableSection<ELFT>(".strtab", false));

2
lld/test/ELF/aarch64-abs64-dyn.s
View File

@ -17,8 +17,8 @@ bar:
// RUN: llvm-readobj -symbols -dyn-relocations %t.so | FileCheck %s
// CHECK: Dynamic Relocations {
// CHECK-NEXT: {{.*}} R_AARCH64_ABS64 foo 0x0
// CHECK-NEXT: {{.*}} R_AARCH64_RELATIVE - [[BAR_ADDR:.*]]
// CHECK-NEXT: {{.*}} R_AARCH64_ABS64 foo 0x0
// CHECK-NEXT: }
// CHECK: Symbols [

2
lld/test/ELF/aarch64-tls-ie.s
View File

@ -24,8 +24,8 @@
#RELOC-NEXT: }
#RELOC: Relocations [
#RELOC-NEXT: Section ({{.*}}) .rela.dyn {
#RELOC-NEXT: 0x120B0 R_AARCH64_TLS_TPREL64 foo 0x0
#RELOC-NEXT: 0x120B8 R_AARCH64_TLS_TPREL64 bar 0x0
#RELOC-NEXT: 0x120B0 R_AARCH64_TLS_TPREL64 foo 0x0
#RELOC-NEXT: }
#RELOC-NEXT:]

92
lld/test/ELF/combrelocs.s Normal file
View File

@ -0,0 +1,92 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
# RUN: ld.lld -shared %t.o -o %t.out
# RUN: llvm-readobj -r --expand-relocs --dynamic-table %t.out | FileCheck %s
# CHECK: Relocations [
# CHECK-NEXT: Section ({{.*}}) .rela.dyn {
# CHECK-NEXT: Relocation {
# CHECK-NEXT: Offset: 0x2000
# CHECK-NEXT: Type: R_X86_64_64
# CHECK-NEXT: Symbol: aaa (1)
# CHECK-NEXT: Addend: 0x0
# CHECK-NEXT: }
# CHECK-NEXT: Relocation {
# CHECK-NEXT: Offset: 0x2018
# CHECK-NEXT: Type: R_X86_64_64
# CHECK-NEXT: Symbol: aaa (1)
# CHECK-NEXT: Addend: 0x0
# CHECK-NEXT: }
# CHECK-NEXT: Relocation {
# CHECK-NEXT: Offset: 0x2010
# CHECK-NEXT: Type: R_X86_64_64
# CHECK-NEXT: Symbol: bbb (2)
# CHECK-NEXT: Addend: 0x0
# CHECK-NEXT: }
# CHECK-NEXT: Relocation {
# CHECK-NEXT: Offset: 0x2008
# CHECK-NEXT: Type: R_X86_64_64
# CHECK-NEXT: Symbol: ccc (3)
# CHECK-NEXT: Addend: 0x0
# CHECK-NEXT: }
# CHECK-NEXT: Relocation {
# CHECK-NEXT: Offset: 0x2020
# CHECK-NEXT: Type: R_X86_64_64
# CHECK-NEXT: Symbol: ddd (4)
# CHECK-NEXT: Addend: 0x0
# CHECK-NEXT: }
# CHECK-NEXT: }
# CHECK-NEXT: ]
# CHECK: DynamicSection [
# CHECK-NEXT: Tag
# CHECK-NOT: RELACOUNT
# RUN: ld.lld -z nocombreloc -shared %t.o -o %t.out
# RUN: llvm-readobj -r --expand-relocs --dynamic-table %t.out | \
# RUN: FileCheck --check-prefix=NOCOMB %s
# NOCOMB: Relocations [
# NOCOMB-NEXT: Section ({{.*}}) .rela.dyn {
# NOCOMB-NEXT: Relocation {
# NOCOMB-NEXT: Offset: 0x2000
# NOCOMB-NEXT: Type: R_X86_64_64
# NOCOMB-NEXT: Symbol: aaa (1)
# NOCOMB-NEXT: Addend: 0x0
# NOCOMB-NEXT: }
# NOCOMB-NEXT: Relocation {
# NOCOMB-NEXT: Offset: 0x2008
# NOCOMB-NEXT: Type: R_X86_64_64
# NOCOMB-NEXT: Symbol: ccc (3)
# NOCOMB-NEXT: Addend: 0x0
# NOCOMB-NEXT: }
# NOCOMB-NEXT: Relocation {
# NOCOMB-NEXT: Offset: 0x2010
# NOCOMB-NEXT: Type: R_X86_64_64
# NOCOMB-NEXT: Symbol: bbb (2)
# NOCOMB-NEXT: Addend: 0x0
# NOCOMB-NEXT: }
# NOCOMB-NEXT: Relocation {
# NOCOMB-NEXT: Offset: 0x2018
# NOCOMB-NEXT: Type: R_X86_64_64
# NOCOMB-NEXT: Symbol: aaa (1)
# NOCOMB-NEXT: Addend: 0x0
# NOCOMB-NEXT: }
# NOCOMB-NEXT: Relocation {
# NOCOMB-NEXT: Offset: 0x2020
# NOCOMB-NEXT: Type: R_X86_64_64
# NOCOMB-NEXT: Symbol: ddd (4)
# NOCOMB-NEXT: Addend: 0x0
# NOCOMB-NEXT: }
# NOCOMB-NEXT: }
# NOCOMB-NEXT: ]
# NOCOMB: DynamicSection [
# NOCOMB-NEXT: Tag
# NOCOMB-NOT: RELACOUNT
.data
.quad aaa
.quad ccc
.quad bbb
.quad aaa
.quad ddd

2
lld/test/ELF/gotpcrelx.s
View File

@ -24,7 +24,7 @@ movl bar@GOTPCREL(%rip), %eax
// CHECK: Relocations [
// CHECK-NEXT: Section ({{.*}}) .rela.dyn {
// CHECK-NEXT: 0x2090 R_X86_64_GLOB_DAT foo 0x0
// CHECK-NEXT: 0x2098 R_X86_64_GLOB_DAT bar 0x0
// CHECK-NEXT: 0x2090 R_X86_64_GLOB_DAT foo 0x0
// CHECK-NEXT: }
// CHECK-NEXT: ]

6
lld/test/ELF/i386-tls-ie-shared.s
View File

@ -24,16 +24,16 @@
// GOTRELSHARED: Relocations [
// GOTRELSHARED-NEXT: Section ({{.*}}) .rel.dyn {
// GOTRELSHARED-NEXT: 0x2002 R_386_RELATIVE - 0x0
// GOTRELSHARED-NEXT: 0x1050 R_386_TLS_TPOFF tlslocal0 0x0
// GOTRELSHARED-NEXT: 0x200A R_386_RELATIVE - 0x0
// GOTRELSHARED-NEXT: 0x2013 R_386_RELATIVE - 0x0
// GOTRELSHARED-NEXT: 0x201C R_386_RELATIVE - 0x0
// GOTRELSHARED-NEXT: 0x1054 R_386_TLS_TPOFF tlslocal1 0x0
// GOTRELSHARED-NEXT: 0x2024 R_386_RELATIVE - 0x0
// GOTRELSHARED-NEXT: 0x202D R_386_RELATIVE - 0x0
// GOTRELSHARED-NEXT: 0x2036 R_386_RELATIVE - 0x0
// GOTRELSHARED-NEXT: 0x1058 R_386_TLS_TPOFF tlsshared0 0x0
// GOTRELSHARED-NEXT: 0x203F R_386_RELATIVE - 0x0
// GOTRELSHARED-NEXT: 0x1050 R_386_TLS_TPOFF tlslocal0 0x0
// GOTRELSHARED-NEXT: 0x1054 R_386_TLS_TPOFF tlslocal1 0x0
// GOTRELSHARED-NEXT: 0x1058 R_386_TLS_TPOFF tlsshared0 0x0
// GOTRELSHARED-NEXT: 0x105C R_386_TLS_TPOFF tlsshared1 0x0
// GOTRELSHARED-NEXT: }
// GOTRELSHARED-NEXT: ]

2
lld/test/ELF/mips-32.s
View File

@ -47,8 +47,8 @@ v2:
# REL: Relocations [
# REL-NEXT: Section (7) .rel.dyn {
# REL-NEXT: 0x30004 R_MIPS_REL32 v2 0x0
# REL-NEXT: 0x30008 R_MIPS_REL32 - 0x0
# REL-NEXT: 0x30004 R_MIPS_REL32 v2 0x0
# REL-NEXT: }
# REL-NEXT: ]

2
lld/test/ELF/mips-64.s
View File

@ -36,8 +36,8 @@ v2:
# CHECK: Relocations [
# CHECK-NEXT: Section (7) .rela.dyn {
# CHECK-NEXT: 0x30008 R_MIPS_REL32/R_MIPS_64/R_MIPS_NONE v2 0x8
# CHECK-NEXT: 0x30010 R_MIPS_REL32/R_MIPS_64/R_MIPS_NONE - 0x30000
# CHECK-NEXT: 0x30008 R_MIPS_REL32/R_MIPS_64/R_MIPS_NONE v2 0x8
# CHECK-NEXT: }
# CHECK-NEXT: ]

4
lld/test/ELF/tls-dynamic-i686.s
View File

@ -67,12 +67,12 @@ addl tls1@gotntpoff(%ebx),%eax
// CHECK: Relocations [
// CHECK: Section ({{.+}}) .rel.dyn {
// CHECK-NEXT: 0x2078 R_386_TLS_DTPMOD32 - 0x0
// CHECK-NEXT: 0x2068 R_386_TLS_DTPMOD32 tls0 0x0
// CHECK-NEXT: 0x206C R_386_TLS_DTPOFF32 tls0 0x0
// CHECK-NEXT: 0x2080 R_386_TLS_TPOFF tls0 0x0
// CHECK-NEXT: 0x2070 R_386_TLS_DTPMOD32 tls1 0x0
// CHECK-NEXT: 0x2074 R_386_TLS_DTPOFF32 tls1 0x0
// CHECK-NEXT: 0x2078 R_386_TLS_DTPMOD32 - 0x0
// CHECK-NEXT: 0x2080 R_386_TLS_TPOFF tls0 0x0
// CHECK-NEXT: 0x2084 R_386_TLS_TPOFF tls1 0x0
// CHECK-NEXT: }

2
lld/test/ELF/tls-got.s
View File

@ -24,8 +24,8 @@
// CHECK: Relocations [
// CHECK-NEXT: Section (4) .rela.dyn {
// CHECK-NEXT: [[ADDR]] R_X86_64_TPOFF64 tls1 0x0
// CHECK-NEXT: 0x120B8 R_X86_64_TPOFF64 tls0 0x0
// CHECK-NEXT: [[ADDR]] R_X86_64_TPOFF64 tls1 0x0
// CHECK-NEXT: }
// CHECK-NEXT: ]

2
lld/test/ELF/tls-i686.s
View File

@ -62,8 +62,8 @@ _start:
// RELOCSHARED: Relocations [
// RELOCSHARED-NEXT: Section (4) .rel.dyn {
// RELOCSHARED-NEXT: 0x2001 R_386_TLS_TPOFF32 var 0x0
// RELOCSHARED-NEXT: 0x200F R_386_TLS_TPOFF32 var1 0x0
// RELOCSHARED-NEXT: 0x2025 R_386_TLS_TPOFF var 0x0
// RELOCSHARED-NEXT: 0x200F R_386_TLS_TPOFF32 var1 0x0
// RELOCSHARED-NEXT: 0x2032 R_386_TLS_TPOFF var1 0x0
// RELOCSHARED-NEXT: }
// RELOCSHARED-NEXT: ]