From 92a8d798b8d2b9333c6ad0cbfbd9d5d4b91aa9d2 Mon Sep 17 00:00:00 2001 From: Rui Ueyama Date: Mon, 1 May 2017 20:49:09 +0000 Subject: [PATCH] Add comments about how we handle mergeable sections with relocations. Also factored out code. llvm-svn: 301833 --- lld/ELF/InputFiles.cpp | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp index 2f4d8f1..9f14add 100644 --- a/lld/ELF/InputFiles.cpp +++ b/lld/ELF/InputFiles.cpp @@ -361,6 +361,15 @@ InputSectionBase *elf::ObjectFile::getRelocTarget(const Elf_Shdr &Sec) { return Target; } +// Create a regular InputSection class that has the same contents +// as a given section. +InputSectionBase *toRegularSection(MergeInputSection *Sec) { + auto *Ret = make(Sec->Flags, Sec->Type, Sec->Alignment, + Sec->Data, Sec->Name); + Ret->File = Sec->File; + return Ret; +} + template InputSectionBase * elf::ObjectFile::createInputSection(const Elf_Shdr &Sec, @@ -398,12 +407,15 @@ elf::ObjectFile::createInputSection(const Elf_Shdr &Sec, if (Target->FirstRelocation) fatal(toString(this) + ": multiple relocation sections to one section are not supported"); - if (isa(Target)) { - this->Sections[Sec.sh_info] = - make(Target->Flags, Target->Type, Target->Alignment, - Target->Data, Target->Name); - this->Sections[Sec.sh_info]->File = Target->File; - Target = this->Sections[Sec.sh_info]; + + // Mergeable sections with relocations are tricky because relocations + // need to be taken into account when comparing section contents for + // merging. The MergeInputSection class currently doesn't care about + // relocations, and it's unlikely to support it in future because such + // sections are rare. We simply handle such sections as non-mergeable. + if (auto *MS = dyn_cast(Target)) { + Target = toRegularSection(MS); + this->Sections[Sec.sh_info] = Target; } size_t NumRelocations; -- 2.7.4