commit b47475c058b1da5b8ff8aba4e1fd9bb9a9871882
author Jordan Rupprecht <rupprecht@google.com> Thu Nov 01 17:26:36 2018 +0000
committer Jordan Rupprecht <rupprecht@google.com> Thu Nov 01 17:26:36 2018 +0000
tree 46890b206f9704b3b5b8ec53680272418f454ac6
parent ab205a31d40eafa0103bddc0abac9e3cfd0041ed

[llvm-objcopy] Don't apply --localize flags to common symbols

Summary:
--localize-symbol and --localize-hidden will currently localize common symbols. GNU objcopy will not localize these symbols even when explicitly requested, which seems reasonable; common symbols should always be global so they can be merged during linking.

See PR39461

Reviewers: jakehehrlich, jhenderson, alexshap, MaskRay, espindola

Reviewed By: jakehehrlich, jhenderson, alexshap, MaskRay

Subscribers: emaste, arichardson, alexshap, MaskRay, llvm-commits

Differential Revision: https://reviews.llvm.org/D53782

llvm-svn: 345856

llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp

diff --git a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
index 2bad270..a367a30 100644
--- a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
@@ -213,10 +213,11 @@
   // them.
   if (Obj.SymbolTable) {
     Obj.SymbolTable->updateSymbols([&](Symbol &Sym) {
-      if ((Config.LocalizeHidden &&
-           (Sym.Visibility == STV_HIDDEN || Sym.Visibility == STV_INTERNAL)) ||
-          (!Config.SymbolsToLocalize.empty() &&
-           is_contained(Config.SymbolsToLocalize, Sym.Name)))
+      if (!Sym.isCommon() &&
+          ((Config.LocalizeHidden &&
+            (Sym.Visibility == STV_HIDDEN || Sym.Visibility == STV_INTERNAL)) ||
+           (!Config.SymbolsToLocalize.empty() &&
+            is_contained(Config.SymbolsToLocalize, Sym.Name))))
         Sym.Binding = STB_LOCAL;
 
       // Note: these two globalize flags have very similar names but different

llvm/tools/llvm-objcopy/ELF/Object.cpp

diff --git a/llvm/tools/llvm-objcopy/ELF/Object.cpp b/llvm/tools/llvm-objcopy/ELF/Object.cpp
index ef3029b..c2af99f 100644
--- a/llvm/tools/llvm-objcopy/ELF/Object.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/Object.cpp
@@ -332,6 +332,8 @@
   llvm_unreachable("Symbol with invalid ShndxType encountered");
 }
 
+bool Symbol::isCommon() const { return getShndx() == SHN_COMMON; }
+
 void SymbolTableSection::assignIndices() {
   uint32_t Index = 0;
   for (auto &Sym : Symbols)

llvm/tools/llvm-objcopy/ELF/Object.h

diff --git a/llvm/tools/llvm-objcopy/ELF/Object.h b/llvm/tools/llvm-objcopy/ELF/Object.h
index 4aa3125..91ff1cd 100644
--- a/llvm/tools/llvm-objcopy/ELF/Object.h
+++ b/llvm/tools/llvm-objcopy/ELF/Object.h
@@ -415,6 +415,7 @@
   bool Referenced = false;
 
   uint16_t getShndx() const;
+  bool isCommon() const;
 };
 
 class SectionIndexSection : public SectionBase {