[llvm-objcopy] Add --keep-file-symbols option

This option prevent from removing file symbols while removing symbols.

Differential Revision: https://reviews.llvm.org/D46830

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333339 91177308-0d34-0410-b5e6-96231b3b80d8

test/tools/llvm-objcopy/keep-file-symbols.test

@@ -0,0 +1,70 @@
+# RUN: yaml2obj %s > %t
+# RUN: llvm-objcopy --strip-all --keep-file-symbols %t %t2
+# RUN: llvm-readobj -symbols %t2 | FileCheck %s --check-prefix=STRIPALL
+# RUN: llvm-objcopy --keep-file-symbols --strip-symbol foo %t %t2
+# RUN: llvm-readobj -symbols %t2 | FileCheck %s --check-prefix=STRIP
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Size:            64
+Symbols:
+  Local:
+    - Name:     foo
+      Type:     STT_FILE
+      Section:  .text
+  Global:
+    - Name:     bar
+      Type:     STT_FUNC
+      Section:  .text
+
+#STRIPALL: Symbols [
+#STRIPALL-NEXT:  Symbol {
+#STRIPALL-NEXT:    Name: foo
+#STRIPALL-NEXT:    Value: 0x0
+#STRIPALL-NEXT:    Size: 0
+#STRIPALL-NEXT:    Binding: Local
+#STRIPALL-NEXT:    Type: File
+#STRIPALL-NEXT:    Other: 0
+#STRIPALL-NEXT:    Section: .text
+#STRIPALL-NEXT:  }
+#STRIPALL-NEXT:]
+
+#STRIP: Symbols [
+#STRIP-NEXT:  Symbol {
+#STRIP-NEXT:    Name:
+#STRIP-NEXT:    Value: 0x0
+#STRIP-NEXT:    Size: 0
+#STRIP-NEXT:    Binding: Local
+#STRIP-NEXT:    Type: None
+#STRIP-NEXT:    Other: 0
+#STRIP-NEXT:    Section: Undefined
+#STRIP-NEXT:  }
+#STRIP-NEXT:  Symbol {
+#STRIP-NEXT:    Name: foo
+#STRIP-NEXT:    Value: 0x0
+#STRIP-NEXT:    Size: 0
+#STRIP-NEXT:    Binding: Local
+#STRIP-NEXT:    Type: File
+#STRIP-NEXT:    Other: 0
+#STRIP-NEXT:    Section: .text
+#STRIP-NEXT:  }
+#STRIP-NEXT:  Symbol {
+#STRIP-NEXT:    Name: bar
+#STRIP-NEXT:    Value: 0x0
+#STRIP-NEXT:    Size: 0
+#STRIP-NEXT:    Binding: Global
+#STRIP-NEXT:    Type: Function
+#STRIP-NEXT:    Other: 0
+#STRIP-NEXT:    Section: .text
+#STRIP-NEXT:  }
+#STRIP-NEXT:]

tools/llvm-objcopy/ObjcopyOpts.td

@@ -92,3 +92,5 @@ def only_keep_debug : Flag<["-", "--"], "only-keep-debug">,
                           HelpText<"Currently ignored. Only for compaitability with GNU objcopy.">;
 def strip_unneeded : Flag<["-", "--"], "strip-unneeded">,
                       HelpText<"Remove all symbols not needed by relocations">;
+def keep_file_symbols : Flag<["-", "--"], "keep-file-symbols">,
+                      HelpText<"Do not remove file symbols">;

tools/llvm-objcopy/llvm-objcopy.cpp

@@ -174,6 +174,7 @@ struct CopyConfig {
   bool Weaken = false;
   bool DiscardAll = false;
   bool OnlyKeepDebug = false;
+  bool KeepFileSymbols = false;
 };
 
 using SectionPred = std::function<bool(const SectionBase &Sec)>;
@@ -273,8 +274,9 @@ 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))
+      if ((!Config.SymbolsToKeep.empty() &&
+           is_contained(Config.SymbolsToKeep, Sym.Name)) ||
+          (Config.KeepFileSymbols && Sym.Type == STT_FILE))
         return false;
 
       if (Config.DiscardAll && Sym.Binding == STB_LOCAL &&
@@ -410,7 +412,8 @@ void HandleArgs(const CopyConfig &Config, Object &Obj, const Reader &Reader,
   // and at least one of those symbols is present
   // (equivalently, the updated symbol table is not empty)
   // the symbol table and the string table should not be removed.
-  if (!Config.SymbolsToKeep.empty() && !Obj.SymbolTable->empty()) {
+  if ((!Config.SymbolsToKeep.empty() || Config.KeepFileSymbols) &&
+      !Obj.SymbolTable->empty()) {
     RemovePred = [&Obj, RemovePred](const SectionBase &Sec) {
       if (&Sec == Obj.SymbolTable || &Sec == Obj.SymbolTable->getStrTab())
         return false;
@@ -531,6 +534,7 @@ CopyConfig ParseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
   Config.Weaken = InputArgs.hasArg(OBJCOPY_weaken);
   Config.DiscardAll = InputArgs.hasArg(OBJCOPY_discard_all);
   Config.OnlyKeepDebug = InputArgs.hasArg(OBJCOPY_only_keep_debug);
+  Config.KeepFileSymbols = InputArgs.hasArg(OBJCOPY_keep_file_symbols);
   for (auto Arg : InputArgs.filtered(OBJCOPY_localize_symbol))
     Config.SymbolsToLocalize.push_back(Arg->getValue());
   for (auto Arg : InputArgs.filtered(OBJCOPY_globalize_symbol))