diff options
| -rw-r--r-- | lld/ELF/MarkLive.cpp | 14 | ||||
| -rw-r--r-- | lld/test/ELF/non-alloc-link-order-gc.s | 34 |
2 files changed, 44 insertions, 4 deletions
diff --git a/lld/ELF/MarkLive.cpp b/lld/ELF/MarkLive.cpp index afdb69ea456..bacbf0eee06 100644 --- a/lld/ELF/MarkLive.cpp +++ b/lld/ELF/MarkLive.cpp @@ -275,13 +275,18 @@ template <class ELFT> void elf::markLive() { // The -gc-sections option works only for SHF_ALLOC sections // (sections that are memory-mapped at runtime). So we can - // unconditionally make non-SHF_ALLOC sections alive. + // unconditionally make non-SHF_ALLOC sections alive except + // SHF_LINK_ORDER and SHT_REL/SHT_RELA sections. // - // Non SHF_ALLOC sections are not removed even if they are + // Usually, SHF_ALLOC sections are not removed even if they are // unreachable through relocations because reachability is not // a good signal whether they are garbage or not (e.g. there is // usually no section referring to a .comment section, but we - // want to keep it.) + // want to keep it.). + // + // Note on SHF_LINK_ORDER: Such sections contain metadata and they + // have a reverse dependency on the InputSection they are linked with. + // We are able to garbage collect them. // // Note on SHF_REL{,A}: Such sections reach here only when -r // or -emit-reloc were given. And they are subject of garbage @@ -289,8 +294,9 @@ template <class ELFT> void elf::markLive() { // remove its relocation section. for (InputSectionBase *Sec : InputSections) { bool IsAlloc = (Sec->Flags & SHF_ALLOC); + bool IsLinkOrder = (Sec->Flags & SHF_LINK_ORDER); bool IsRel = (Sec->Type == SHT_REL || Sec->Type == SHT_RELA); - if (!IsAlloc && !IsRel) + if (!IsAlloc && !IsLinkOrder && !IsRel) Sec->Live = true; } diff --git a/lld/test/ELF/non-alloc-link-order-gc.s b/lld/test/ELF/non-alloc-link-order-gc.s new file mode 100644 index 00000000000..8147c45090d --- /dev/null +++ b/lld/test/ELF/non-alloc-link-order-gc.s @@ -0,0 +1,34 @@ +# REQUIRES: x86 +# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o +# RUN: ld.lld %t.o -o %t1 --gc-sections +# RUN: llvm-objdump -section-headers -D %t1 | FileCheck %s + +## Check that we are able to GC non-allocatable metadata sections without crash. + +# CHECK: Disassembly of section .stack_sizes: +# CHECK-NEXT: .stack_sizes: +# CHECK-NEXT: 01 + +# CHECK: Name Size +# CHECK: .stack_sizes 00000001 + +.section .text.live,"ax",@progbits +.globl live +live: + nop + +.section .stack_sizes,"o",@progbits,.text.live,unique,0 +.byte 1 + +.section .text.dead,"ax",@progbits +.globl dead +dead: + nop + +.section .stack_sizes,"o",@progbits,.text.dead,unique,1 +.byte 2 + +.section .text.main,"ax",@progbits +.globl _start +_start: + callq live@PLT |
