[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

diff --git a/llvm/test/tools/llvm-objcopy/keep-symbol-remove-section.test b/llvm/test/tools/llvm-objcopy/keep-symbol-remove-section.test
new file mode 100644 (file)
index 0000000..6b02caa
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/keep-symbol-remove-section.test
@@ -0,0 +1,36 @@
+# RUN: yaml2obj %s > %t
+# RUN: llvm-objcopy --remove-section .text --keep-symbol foo %t %t2
+# RUN: llvm-readobj -symbols %t2 | FileCheck %s
+
+!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_FUNC
+      Section:  .text
+      Value:    0x1000
+      Size:     8
+
+#CHECK: Symbols [
+#CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name:
+#CHECK-NEXT:    Value: 0x0
+#CHECK-NEXT:    Size: 0
+#CHECK-NEXT:    Binding: Local
+#CHECK-NEXT:    Type: None
+#CHECK-NEXT:    Other: 0
+#CHECK-NEXT:    Section: Undefined
+#CHECK-NEXT:  }
+#CHECK-NEXT:]

diff --git a/llvm/test/tools/llvm-objcopy/keep-symbol.test b/llvm/test/tools/llvm-objcopy/keep-symbol.test
new file mode 100644 (file)
index 0000000..8c6415f
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/keep-symbol.test
@@ -0,0 +1,66 @@
+# RUN: yaml2obj %s > %t
+# RUN: llvm-objcopy --discard-all -K foo --keep-symbol bar %t %t2
+# RUN: llvm-objcopy -K foo -N foo -N bar --keep-symbol bar -N baz %t %t3
+# RUN: llvm-readobj -symbols %t2 | FileCheck %s
+# RUN: llvm-readobj -symbols %t3 | FileCheck %s
+
+!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_FUNC
+      Section:  .text
+      Value:    0x1000
+      Size:     8
+    - Name:     bar
+      Type:     STT_FUNC
+      Section:  .text
+      Value:    0x1008
+      Size:     8
+    - Name:     baz
+      Type:     STT_FUNC
+      Section:  .text
+      Value:    0x1010
+      Size:     8
+
+#CHECK: Symbols [
+#CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name:
+#CHECK-NEXT:    Value: 0x0
+#CHECK-NEXT:    Size: 0
+#CHECK-NEXT:    Binding: Local
+#CHECK-NEXT:    Type: None
+#CHECK-NEXT:    Other: 0
+#CHECK-NEXT:    Section: Undefined
+#CHECK-NEXT:  }
+#CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name: foo
+#CHECK-NEXT:    Value: 0x1000
+#CHECK-NEXT:    Size: 8
+#CHECK-NEXT:    Binding: Local
+#CHECK-NEXT:    Type: Function
+#CHECK-NEXT:    Other: 0
+#CHECK-NEXT:    Section: .text
+#CHECK-NEXT:  }
+#CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name: bar
+#CHECK-NEXT:    Value: 0x1008
+#CHECK-NEXT:    Size: 8
+#CHECK-NEXT:    Binding: Local
+#CHECK-NEXT:    Type: Function
+#CHECK-NEXT:    Other: 0
+#CHECK-NEXT:    Section: .text
+#CHECK-NEXT:  }
+#CHECK-NEXT:]

diff --git a/llvm/tools/llvm-objcopy/ObjcopyOpts.td b/llvm/tools/llvm-objcopy/ObjcopyOpts.td
index 0ab658b..92f2c74 100644 (file)
--- a/llvm/tools/llvm-objcopy/ObjcopyOpts.td
+++ b/llvm/tools/llvm-objcopy/ObjcopyOpts.td
@@ -83,3 +83,8 @@ defm strip_symbol : Eq<"strip-symbol">,
                        HelpText<"Remove symbol <symbol>">;
 def N : JoinedOrSeparate<["-"], "N">,
         Alias<strip_symbol>;
+defm keep_symbol : Eq<"keep-symbol">,
+                       MetaVarName<"symbol">,
+                       HelpText<"Do not remove symbol <symbol>">;
+def K : JoinedOrSeparate<["-"], "K">,
+        Alias<keep_symbol>;

diff --git a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
index c71e2b9..24ec188 100644 (file)
--- 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;
 }