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[LLD] [COFF] Fix including the personality function for DWARF EH when linking with --gc-sections

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Since c579a5b1d92a9bc2046d00ee2d427832e0f5ddec we don't traverse
.eh_frame when doing GC. But the exception handling personality
function needs to be included, and is only referenced from within
.eh_frame.

Differential Revision: https://reviews.llvm.org/D102138
This commit is contained in:
Martin Storsjö 2021-05-09 23:27:35 +03:00
parent 6bd3d8a17c
commit 7e0768329c
2 changed files with 54 additions and 1 deletions
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19
lld/COFF/Driver.cpp
View File

@ -2226,8 +2226,25 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
config->printSymbolOrder = arg->getValue();
// Identify unreferenced COMDAT sections.
if (config->doGC)
if (config->doGC) {
if (config->mingw) {
// markLive doesn't traverse .eh_frame, but the personality function is
// only reached that way. The proper solution would be to parse and
// traverse the .eh_frame section, like the ELF linker does.
// For now, just manually try to retain the known possible personality
// functions. This doesn't bring in more object files, but only marks
// functions that already have been included to be retained.
for (const char *n : {"__gxx_personality_v0", "__gcc_personality_v0"}) {
Defined *d = dyn_cast_or_null<Defined>(symtab->findUnderscore(n));
if (d && !d->isGCRoot) {
d->isGCRoot = true;
config->gcroot.push_back(d);
}
}
}
markLive(symtab->getChunks());
}
// Needs to happen after the last call to addFile().
convertResources();

36
lld/test/COFF/gc-dwarf-eh.s Normal file
View File

@ -0,0 +1,36 @@
# REQUIRES: x86
# RUN: llvm-mc -triple=i686-windows-gnu %s -filetype=obj -o %t.obj
# RUN: lld-link -lldmingw -lldmap:%t.map -out:%t.exe -opt:ref -entry:main %t.obj -verbose 2>&1 | FileCheck %s
# RUN: FileCheck %s --check-prefix=MAP --input-file=%t.map
# CHECK: Discarded _unused
# MAP: In Symbol
# MAP: gc-dwarf-eh.s.tmp.obj:(.text)
# MAP: {{ ___gxx_personality_v0$}}
.def _main; .scl 2; .type 32; .endef
.section .text,"xr",one_only,_main
.globl _main
.cfi_startproc
.cfi_personality 0, ___gxx_personality_v0
_main:
xorl %eax, %eax
ret
.cfi_endproc
.def ___gxx_personality_v0; .scl 2; .type 32; .endef
.section .text,"xr",one_only,___gxx_personality_v0
.globl ___gxx_personality_v0
___gxx_personality_v0:
ret
.def _unused; .scl 2; .type 32; .endef
.section .text,"xr",one_only,_unused
.globl _unused
.cfi_startproc
.cfi_personality 0, ___gxx_personality_v0
_unused:
ret
.cfi_endproc