[Openmp-commits] [libc] [lld] [clang] [libunwind] [compiler-rt] [flang] [lldb] [openmp] [libcxx] [mlir] [llvm] [pstl] [clang-tools-extra] [ELF] Don't resolve relocations referencing SHN_ABS to tombstone in non-SHF_ALLOC sections (PR #79238)
Fangrui Song via Openmp-commits
openmp-commits at lists.llvm.org
Wed Jan 24 08:52:09 PST 2024
https://github.com/MaskRay updated https://github.com/llvm/llvm-project/pull/79238
>From 97b500a7061041b5478b6b1b1094e76140e3d9c3 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Tue, 23 Jan 2024 17:53:31 -0800
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.4
---
lld/ELF/InputSection.cpp | 13 ++++++-------
lld/test/ELF/dead-reloc-in-nonalloc.s | 2 +-
2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index c728dd6c6306aa0..0e0b9783bd88a0f 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -961,12 +961,11 @@ void InputSection::relocateNonAlloc(uint8_t *buf, ArrayRef<RelTy> rels) {
// vector. The computed value is st_value plus a non-negative offset.
// Negative values are invalid, so -1 can be used as the tombstone value.
//
- // If the referenced symbol is discarded (made Undefined), or the
- // section defining the referenced symbol is garbage collected,
- // sym.getOutputSection() is nullptr. `ds->folded` catches the ICF folded
- // case. However, resolving a relocation in .debug_line to -1 would stop
- // debugger users from setting breakpoints on the folded-in function, so
- // exclude .debug_line.
+ // If the referenced symbol is relative to a discarded section (due to
+ // --gc-sections, COMDAT, etc), it has been converted to a Undefined.
+ // `ds->folded` catches the ICF folded case. However, resolving a
+ // relocation in .debug_line to -1 would stop debugger users from setting
+ // breakpoints on the folded-in function, so exclude .debug_line.
//
// For pre-DWARF-v5 .debug_loc and .debug_ranges, -1 is a reserved value
// (base address selection entry), use 1 (which is used by GNU ld for
@@ -974,7 +973,7 @@ void InputSection::relocateNonAlloc(uint8_t *buf, ArrayRef<RelTy> rels) {
//
// TODO To reduce disruption, we use 0 instead of -1 as the tombstone
// value. Enable -1 in a future release.
- if (!sym.getOutputSection() || (ds && ds->folded && !isDebugLine)) {
+ if (!ds || (ds->folded && !isDebugLine)) {
// If -z dead-reloc-in-nonalloc= is specified, respect it.
uint64_t value = SignExtend64<bits>(*tombstone);
// For a 32-bit local TU reference in .debug_names, X86_64::relocate
diff --git a/lld/test/ELF/dead-reloc-in-nonalloc.s b/lld/test/ELF/dead-reloc-in-nonalloc.s
index 145604eb883a9af..b675fc50fc2ea2f 100644
--- a/lld/test/ELF/dead-reloc-in-nonalloc.s
+++ b/lld/test/ELF/dead-reloc-in-nonalloc.s
@@ -17,7 +17,7 @@
# AA: Contents of section .debug_info:
# AA-NEXT: 0000 [[ADDR]] 00000000 aaaaaaaa 00000000
# AA: Contents of section .not_debug:
-# AA-NEXT: 0000 bbbbbbbb bbbbbbbb 00000000 .
+# AA-NEXT: 0000 bbbbbbbb 2a000000 00000000 .
## Specifying zero can get a behavior similar to GNU ld.
# RUN: ld.lld --icf=all -z dead-reloc-in-nonalloc=.debug_info=0 %t.o %tabs.o -o %tzero
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