[llvm-objcopy] Add --keep-symbol (-K) option

This option permits to explicitly keep the specified
symbol so that it doesn't get removed.

Differential Revision: https://reviews.llvm.org/D46819

llvm-svn: 332356

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
index c71e2b94728..24ec18817c9 100644
--- a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
+++ b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
@@ -148,6 +148,7 @@ struct CopyConfig {
   std::vector<StringRef> SymbolsToGlobalize;
   std::vector<StringRef> SymbolsToWeaken;
   std::vector<StringRef> SymbolsToRemove;
+  std::vector<StringRef> SymbolsToKeep;
   StringMap<StringRef> SymbolsToRename;
   bool StripAll = false;
   bool StripAllGNU = false;
@@ -373,6 +374,10 @@ void HandleArgs(const CopyConfig &Config, Object &Obj, const Reader &Reader,
     });
 
     Obj.removeSymbols([&](const Symbol &Sym) {
+      if (!Config.SymbolsToKeep.empty() &&
+          is_contained(Config.SymbolsToKeep, Sym.Name))
+        return false;
+
       if (Config.DiscardAll && Sym.Binding == STB_LOCAL &&
           Sym.getShndx() != SHN_UNDEF && Sym.Type != STT_FILE &&
           Sym.Type != STT_SECTION)
@@ -485,6 +490,8 @@ CopyConfig ParseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
     Config.SymbolsToWeaken.push_back(Arg->getValue());
   for (auto Arg : InputArgs.filtered(OBJCOPY_strip_symbol))
     Config.SymbolsToRemove.push_back(Arg->getValue());
+  for (auto Arg : InputArgs.filtered(OBJCOPY_keep_symbol))
+    Config.SymbolsToKeep.push_back(Arg->getValue());
 
   return Config;
 }