[ELF] -z combreloc: sort dynamic relocations by (!is_relative,symbol_index,r_offset)

We currently sort dynamic relocations by (!is_relative,symbol_index).
Add r_offset as the third key. This makes `readelf -r` debugging easier
(relocations to the same symbol are ordered by r_offset).

Refactor the test combreloc.s (renamed from combrelocs.s) to check
R_X86_64_RELATIVE, and delete --expand-relocs.

The difference from the reverted D61477 is that we keep !is_relative as
the first key. In local dynamic TLS model, DTPMOD (e.g.
R_ARM_TLS_DTPMOD32 R_X86_64_DTPMOD and R_PPC{,64}_DTPMOD) may use 0 as
the symbol index.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D62141

llvm-svn: 361164
This commit is contained in:
Fangrui Song 2019-05-20 15:25:01 +00:00
parent 1e593f342f
commit 055906e1e5
4 changed files with 58 additions and 105 deletions

View File

@ -1488,17 +1488,17 @@ RelocationSection<ELFT>::RelocationSection(StringRef Name, bool Sort)
this->Entsize = Config->IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel); this->Entsize = Config->IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
} }
static bool compRelocations(const DynamicReloc &A, const DynamicReloc &B) {
bool AIsRel = A.Type == Target->RelativeRel;
bool BIsRel = B.Type == Target->RelativeRel;
if (AIsRel != BIsRel)
return AIsRel;
return A.getSymIndex() < B.getSymIndex();
}
template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) { template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
// Sort by (!IsRelative,SymIndex,r_offset). DT_REL[A]COUNT requires us to
// place R_*_RELATIVE first. SymIndex is to improve locality, while r_offset
// is to make results easier to read.
if (Sort) if (Sort)
llvm::stable_sort(Relocs, compRelocations); llvm::stable_sort(Relocs, [](const DynamicReloc &A, const DynamicReloc &B) {
return std::make_tuple(A.Type != Target->RelativeRel, A.getSymIndex(),
A.getOffset()) <
std::make_tuple(B.Type != Target->RelativeRel, B.getSymIndex(),
B.getOffset());
});
for (const DynamicReloc &Rel : Relocs) { for (const DynamicReloc &Rel : Relocs) {
encodeDynamicReloc<ELFT>(reinterpret_cast<Elf_Rela *>(Buf), Rel); encodeDynamicReloc<ELFT>(reinterpret_cast<Elf_Rela *>(Buf), Rel);

48
lld/test/ELF/combreloc.s Normal file
View File

@ -0,0 +1,48 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
# RUN: echo 'mov aaa@gotpcrel(%rip), %rax' | llvm-mc -filetype=obj -triple=x86_64 - -o %t1.o
# RUN: ld.lld -shared %t.o %t1.o -o %t.so
# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck %s
# RUN: ld.lld -shared %t.o %t1.o -o %t.so -z combreloc
# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck %s
# -z combreloc is the default: sort relocations by (!IsRelative,SymIndex,r_offset),
# and emit DT_RELACOUNT (except on MIPS) to indicate the number of relative
# relocations.
# CHECK: Relocations [
# CHECK-NEXT: Section ({{.*}}) .rela.dyn {
# CHECK-NEXT: 0x3020 R_X86_64_RELATIVE - 0x3028
# CHECK-NEXT: 0x20B0 R_X86_64_GLOB_DAT aaa 0x0
# CHECK-NEXT: 0x3000 R_X86_64_64 aaa 0x0
# CHECK-NEXT: 0x3018 R_X86_64_64 aaa 0x0
# CHECK-NEXT: 0x3010 R_X86_64_64 bbb 0x0
# CHECK-NEXT: 0x3008 R_X86_64_64 ccc 0x0
# CHECK-NEXT: }
# CHECK: DynamicSection [
# CHECK: RELACOUNT 1
# RUN: ld.lld -z nocombreloc -shared %t.o %t1.o -o %t.so
# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck --check-prefix=NOCOMB %s
# NOCOMB: Relocations [
# NOCOMB-NEXT: Section ({{.*}}) .rela.dyn {
# NOCOMB-NEXT: 0x3000 R_X86_64_64 aaa 0x0
# NOCOMB-NEXT: 0x3008 R_X86_64_64 ccc 0x0
# NOCOMB-NEXT: 0x3010 R_X86_64_64 bbb 0x0
# NOCOMB-NEXT: 0x3018 R_X86_64_64 aaa 0x0
# NOCOMB-NEXT: 0x3020 R_X86_64_RELATIVE - 0x3028
# NOCOMB-NEXT: 0x20A0 R_X86_64_GLOB_DAT aaa 0x0
# NOCOMB-NEXT: }
# NOCOMB: DynamicSection [
# NOCOMB-NOT: RELACOUNT
.data
.quad aaa
.quad ccc
.quad bbb
.quad aaa
.quad relative
relative:

View File

@ -1,95 +0,0 @@
# 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
# RUN: ld.lld -shared %t.o -o %t.out -z combreloc
# 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

View File

@ -14,8 +14,8 @@
# CHECK: Relocations [ # CHECK: Relocations [
# CHECK-NEXT: Section (4) .rel.dyn { # CHECK-NEXT: Section (4) .rel.dyn {
# CHECK-NEXT: 0x{{[0-9A-F]+}} R_386_COPY foo
# CHECK-NEXT: 0x{{[0-9A-F]+}} R_386_GLOB_DAT foo # CHECK-NEXT: 0x{{[0-9A-F]+}} R_386_GLOB_DAT foo
# CHECK-NEXT: 0x{{[0-9A-F]+}} R_386_COPY foo
# CHECK-NEXT: } # CHECK-NEXT: }
# CHECK-NEXT: ] # CHECK-NEXT: ]