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

Fixes PR41692.

We currently sort dynamic relocations by (!is_relative,symbol_index).
Change it to (symbol_index,r_offset). We still place relative
relocations first because R_*_RELATIVE are the only dynamic relocations
with 0 symbol index (except on MIPS, which doesn't use DT_REL[A]COUNT
anyway).

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.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61477

llvm-svn: 361125
This commit is contained in:
Fangrui Song 2019-05-20 07:22:55 +00:00
parent 34e95ce259
commit 9f1a6de631
5 changed files with 58 additions and 107 deletions
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16
lld/ELF/SyntheticSections.cpp
View File

@ -1488,17 +1488,15 @@ 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 symbol index then by r_offset. Because we only emit R_*_RELATIVE as
// dynamic relocations with symbol index 0, this essentially places
// R_*_RELATIVE first (required by DT_REL[A]COUNT).
if (Sort) if (Sort)
llvm::stable_sort(Relocs, compRelocations); llvm::stable_sort(Relocs, [](const DynamicReloc &A, const DynamicReloc &B) {
return std::make_tuple(A.getSymIndex(), A.getOffset()) <
std::make_tuple(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
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@ -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 (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:

95
lld/test/ELF/combrelocs.s
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

2
lld/test/ELF/i386-got-and-copy.s
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@ -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: ]

4
lld/test/ELF/mips-mgot.s
View File

@ -34,14 +34,14 @@
# GOT-NEXT: 0x70024 R_MIPS_REL32 - 0x0 # GOT-NEXT: 0x70024 R_MIPS_REL32 - 0x0
# GOT-NEXT: 0x70028 R_MIPS_REL32 - 0x0 # GOT-NEXT: 0x70028 R_MIPS_REL32 - 0x0
# GOT-NEXT: 0x7002C R_MIPS_REL32 - 0x0 # GOT-NEXT: 0x7002C R_MIPS_REL32 - 0x0
# GOT-NEXT: 0x70030 R_MIPS_REL32 foo0 0x0
# GOT-NEXT: 0x70034 R_MIPS_REL32 foo2 0x0
# GOT-NEXT: 0x70044 R_MIPS_TLS_DTPMOD32 - 0x0 # GOT-NEXT: 0x70044 R_MIPS_TLS_DTPMOD32 - 0x0
# GOT-NEXT: 0x70010 R_MIPS_TLS_TPREL32 tls0 0x0 # GOT-NEXT: 0x70010 R_MIPS_TLS_TPREL32 tls0 0x0
# GOT-NEXT: 0x70038 R_MIPS_TLS_TPREL32 tls0 0x0 # GOT-NEXT: 0x70038 R_MIPS_TLS_TPREL32 tls0 0x0
# GOT-NEXT: 0x7003C R_MIPS_TLS_DTPMOD32 tls0 0x0 # GOT-NEXT: 0x7003C R_MIPS_TLS_DTPMOD32 tls0 0x0
# GOT-NEXT: 0x70040 R_MIPS_TLS_DTPREL32 tls0 0x0 # GOT-NEXT: 0x70040 R_MIPS_TLS_DTPREL32 tls0 0x0
# GOT-NEXT: 0x70014 R_MIPS_TLS_TPREL32 tls1 0x0 # GOT-NEXT: 0x70014 R_MIPS_TLS_TPREL32 tls1 0x0
# GOT-NEXT: 0x70030 R_MIPS_REL32 foo0 0x0
# GOT-NEXT: 0x70034 R_MIPS_REL32 foo2 0x0
# GOT-NEXT: } # GOT-NEXT: }
# GOT-NEXT: ] # GOT-NEXT: ]