1 files changed, 17 insertions, 0 deletions
diff --git a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
index 2c2c9926447..0a5b5b0d066 100644
--- a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
+++ b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
@@ -168,6 +168,7 @@ struct CopyConfig {
   bool StripSections = false;
   bool StripNonAlloc = false;
   bool StripDWO = false;
+  bool StripUnneeded = false;
   bool ExtractDWO = false;
   bool LocalizeHidden = false;
   bool Weaken = false;
@@ -263,6 +264,14 @@ void HandleArgs(const CopyConfig &Config, Object &Obj, const Reader &Reader,
         Sym.Name = I->getValue();
     });
 
+    // The purpose of this loop is to mark symbols referenced by sections
+    // (like GroupSection or RelocationSection). This way, we know which
+    // symbols are still 'needed' and wich are not.
+    if (Config.StripUnneeded) {
+      for (auto &Section : Obj.sections())
+        Section.markSymbols();
+    }
+
     Obj.removeSymbols([&](const Symbol &Sym) {
       if (!Config.SymbolsToKeep.empty() &&
           is_contained(Config.SymbolsToKeep, Sym.Name))
@@ -281,6 +290,13 @@ void HandleArgs(const CopyConfig &Config, Object &Obj, const Reader &Reader,
         return true;
       }
 
+      // TODO: We might handle the 'null symbol' in a different way
+      // by probably handling it the same way as we handle 'null section' ?
+      if (Config.StripUnneeded && !Sym.Referenced && Sym.Index != 0 &&
+          (Sym.Binding == STB_LOCAL || Sym.getShndx() == SHN_UNDEF) &&
+          Sym.Type != STT_FILE && Sym.Type != STT_SECTION)
+        return true;
+
       return false;
     });
   }
@@ -509,6 +525,7 @@ CopyConfig ParseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
   Config.StripDWO = InputArgs.hasArg(OBJCOPY_strip_dwo);
   Config.StripSections = InputArgs.hasArg(OBJCOPY_strip_sections);
   Config.StripNonAlloc = InputArgs.hasArg(OBJCOPY_strip_non_alloc);
+  Config.StripUnneeded = InputArgs.hasArg(OBJCOPY_strip_unneeded);
   Config.ExtractDWO = InputArgs.hasArg(OBJCOPY_extract_dwo);
   Config.LocalizeHidden = InputArgs.hasArg(OBJCOPY_localize_hidden);
   Config.Weaken = InputArgs.hasArg(OBJCOPY_weaken);