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[ELF] Ensure output section is not discarded in addStartEndSymbols() 

Fixes https://bugs.llvm.org/show_bug.cgi?id=52534.

Differential Revision: https://reviews.llvm.org/D114179
This commit is contained in:
Andrew Ng 2021-11-17 17:15:20 +00:00
parent 812e64ef0c
commit 47eb3f155f
4 changed files with 48 additions and 2 deletions
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7
lld/ELF/LinkerScript.cpp
View File

@ -1034,7 +1034,7 @@ void LinkerScript::assignOffsets(OutputSection *sec) {
}
}
static bool isDiscardable(OutputSection &sec) {
static bool isDiscardable(const OutputSection &sec) {
if (sec.name == "/DISCARD/")
return true;
@ -1063,6 +1063,11 @@ static bool isDiscardable(OutputSection &sec) {
return true;
}
bool LinkerScript::isDiscarded(const OutputSection *sec) const {
return hasSectionsCommand && (getFirstInputSection(sec) == nullptr) &&
isDiscardable(*sec);
}
static void maybePropagatePhdrs(OutputSection &sec,
std::vector<StringRef> &phdrs) {
if (sec.phdrs.empty()) {

2
lld/ELF/LinkerScript.h
View File

@ -318,6 +318,8 @@ public:
void processSymbolAssignments();
void declareSymbols();
bool isDiscarded(const OutputSection *sec) const;
// Used to handle INSERT AFTER statements.
void processInsertCommands();

2
lld/ELF/Writer.cpp
View File

@ -2276,7 +2276,7 @@ template <class ELFT> void Writer<ELFT>::addStartEndSymbols() {
Default = Out::elfHeader;
auto define = [=](StringRef start, StringRef end, OutputSection *os) {
if (os) {
if (os && !script->isDiscarded(os)) {
addOptionalRegular(start, os, 0);
addOptionalRegular(end, os, -1);
} else {

39
lld/test/ELF/linkerscript/preinit-array-empty.test Normal file
View File

@ -0,0 +1,39 @@
# REQUIRES: x86
# RUN: split-file %s %t
# RUN: llvm-mc -filetype=obj -triple=x86_64 %t/t.s -o %t.o
## PR52534: https://bugs.llvm.org/show_bug.cgi?id=52534
## Check case where .preinit_array is discarded.
## Link should succeed without causing an out of range relocation error.
# RUN: ld.lld -T %t/discarded.script %t.o -o %t1 --image-base=0x80000000
# RUN: llvm-readelf -s %t1 | FileCheck --check-prefixes=CHECK,DISCARDED %s
## Check case where .preinit_array is emitted but empty.
# RUN: ld.lld -T %t/empty.script %t.o -o %t2
# RUN: llvm-readelf -s %t2 | FileCheck --check-prefixes=CHECK,EMPTY %s
# CHECK: [[#%x,ADDR:]] 0 NOTYPE LOCAL HIDDEN [[#]] __preinit_array_start
# CHECK-NEXT: [[#ADDR]] 0 NOTYPE LOCAL HIDDEN [[#]] __preinit_array_end
# DISCARDED-NEXT: [[#ADDR]] 0 NOTYPE GLOBAL DEFAULT [[#]] _start
# EMPTY-NOT: [[#ADDR]] 0 NOTYPE GLOBAL DEFAULT [[#]] _start
# EMPTY: [[#ADDR]] 0 NOTYPE GLOBAL DEFAULT [[#]] ADDR
#--- t.s
.global _start
_start:
movq __preinit_array_start@GOTPCREL(%rip),%rax
movq __preinit_array_end@GOTPCREL(%rip),%rax
#--- discarded.script
SECTIONS {
.text : { *(.text); }
.preinit_array : { *(.preinit_array); }
}
#--- empty.script
SECTIONS {
.text : { *(.text); }
.preinit_array : { ADDR = .; *(.preinit_array); }
}