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[ELF] - Do not create reserved symbols in case of relocatable output. 

This patch stops creating symbols like __ehdr_start, 
_end/_etext_edata,__tls_get_addr when using -r.

This fixes PR30984.

Differential revision: https://reviews.llvm.org/D26600

llvm-svn: 286941
This commit is contained in:
George Rimar 2016-11-15 08:19:02 +00:00
parent 463984d4bf
commit 7beff42f8f
6 changed files with 36 additions and 4 deletions
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9
lld/ELF/Writer.cpp
View File

@ -134,7 +134,9 @@ template <class ELFT> void elf::writeResult() { Writer<ELFT>().run(); }
// The main function of the writer.
template <class ELFT> void Writer<ELFT>::run() {
createSyntheticSections();
addReservedSymbols();
if (!Config->Relocatable)
addReservedSymbols();
if (Target->NeedsThunks)
forEachRelSec(createThunks<ELFT>);
@ -604,7 +606,7 @@ template <class ELFT> void Writer<ELFT>::addRelIpltSymbols() {
// The linker is expected to define some symbols depending on
// the linking result. This function defines such symbols.
template <class ELFT> void Writer<ELFT>::addReservedSymbols() {
if (Config->EMachine == EM_MIPS && !Config->Relocatable) {
if (Config->EMachine == EM_MIPS) {
// Define _gp for MIPS. st_value of _gp symbol will be updated by Writer
// so that it points to an absolute address which is relative to GOT.
// See "Global Data Symbols" in Chapter 6 in the following document:
@ -636,8 +638,7 @@ template <class ELFT> void Writer<ELFT>::addReservedSymbols() {
// an undefined symbol in the .o files.
// Given that the symbol is effectively unused, we just create a dummy
// hidden one to avoid the undefined symbol error.
if (!Config->Relocatable)
Symtab<ELFT>::X->addIgnored("_GLOBAL_OFFSET_TABLE_");
Symtab<ELFT>::X->addIgnored("_GLOBAL_OFFSET_TABLE_");
// __tls_get_addr is defined by the dynamic linker for dynamic ELFs. For
// static linking the linker is required to optimize away any references to

1
lld/test/ELF/Inputs/relocatable-tls.s Normal file
View File

@ -0,0 +1 @@
callq __tls_get_addr@PLT

6
lld/test/ELF/edata-etext.s
View File

@ -23,6 +23,12 @@
# CHECK-NEXT: 0000000000011001 *ABS* 00000000 _etext
# CHECK-NEXT: 0000000000011000 .text 00000000 _start
# RUN: ld.lld -r %t.o -o %t2
# RUN: llvm-objdump -t %t2 | FileCheck %s --check-prefix=RELOCATABLE
# RELOCATABLE: 0000000000000000 *UND* 00000000 _edata
# RELOCATABLE-NEXT: 0000000000000000 *UND* 00000000 _end
# RELOCATABLE-NEXT: 0000000000000000 *UND* 00000000 _etext
.global _start,_end,_etext,_edata
.text
_start:

5
lld/test/ELF/ehdr_start.s
View File

@ -9,3 +9,8 @@
.global _start, __ehdr_start
_start:
.quad __ehdr_start
# RUN: ld.lld -r %t.o -o %t.r
# RUN: llvm-objdump -t %t.r | FileCheck %s --check-prefix=RELOCATABLE
# RELOCATABLE: 0000000000000000 *UND* 00000000 __ehdr_start

4
lld/test/ELF/end.s
View File

@ -23,6 +23,10 @@
// DEFAULT-NEXT: Value: 0x12008
// DEFAULT: ]
// RUN: ld.lld -r %t.o -o %t2
// RUN: llvm-objdump -t %t2 | FileCheck %s --check-prefix=RELOCATABLE
// RELOCATABLE: 0000000000000000 *UND* 00000000 _end
.global _start,_end
.text
_start:

15
lld/test/ELF/relocatable-tls.s Normal file
View File

@ -0,0 +1,15 @@
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
# RUN: %S/Inputs/relocatable-tls.s -o %t2.o
# RUN: ld.lld -r %t2.o -o %t3.r
# RUN: llvm-objdump -t %t3.r | FileCheck --check-prefix=RELOCATABLE %s
# RELOCATABLE: SYMBOL TABLE:
# RELOCATABLE: 0000000000000000 *UND* 00000000 __tls_get_addr
# RUN: ld.lld -shared %t2.o %t3.r -o %t4.out
# RUN: llvm-objdump -t %t4.out | FileCheck --check-prefix=DSO %s
# DSO: SYMBOL TABLE:
# DSO: 0000000000000000 *UND* 00000000 __tls_get_addr
callq __tls_get_addr@PLT