[llvm-objcopy] Add --strip-debug

Many projects use this option. There are two ways to use it. You can
either a) Just use --strip-debug and keep the old file with debug
content or b) you can use --strip-debug, --only-keep-debug, and
--add-gnu-debuglink all in conjunction to create two separate files, the
stripped file and the debug file. --only-keep-debug is more complicated
than --strip-debug because it keeps the section headers without keeping
section contents. That's not really supported by llvm-objcopy at the
moment but I plan on adding it. So this change just supports a) and
options to support b) will come soon.

Differential Revision: https://reviews.llvm.org/D39919

llvm-svn: 318094

llvm/test/tools/llvm-objcopy/strip-debug.test

@@ -0,0 +1,54 @@
+# RUN: yaml2obj %s > %t
+# RUN: llvm-objcopy -strip-debug %t %t2
+# RUN: llvm-readobj -file-headers -sections -symbols %t2 | FileCheck %s
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .debugfoo
+    Type:            SHT_PROGBITS
+    Content:         "00000000"
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000010
+    Content:         "00000000"
+Symbols:
+  Global:
+    - Name: foo
+      Section: .text
+    - Name: debugfoo
+      Section: .debugfoo
+
+# CHECK: SectionHeaderCount: 5
+
+# CHECK: Name: .text
+# CHECK: Name: .symtab
+# CHECK: Name: .strtab
+# CHECK: Name: .shstrtab
+
+# Check that *only* foo is copied and not debugfoo
+# CHECK:      Symbols [
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name:
+# CHECK-NEXT:     Value:
+# CHECK-NEXT:     Size:
+# CHECK-NEXT:     Binding:
+# CHECK-NEXT:     Type:
+# CHECK-NEXT:     Other:
+# CHECK-NEXT:     Section: Undefined
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: foo
+# CHECK-NEXT:     Value:
+# CHECK-NEXT:     Size:
+# CHECK-NEXT:     Binding: Global
+# CHECK-NEXT:     Type:
+# CHECK-NEXT:     Other:
+# CHECK-NEXT:     Section: .text
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]

llvm/tools/llvm-objcopy/llvm-objcopy.cpp

@@ -83,6 +83,8 @@ static cl::alias ToRemoveA("R", cl::desc("Alias for remove-section"),
                            cl::aliasopt(ToRemove));
 static cl::opt<bool> StripAll("strip-all",
                               cl::desc("Removes symbol, relocation, and debug information"));
+static cl::opt<bool> StripDebug("strip-debug",
+                                cl::desc("Removes all debug information"));
 static cl::opt<bool> StripSections("strip-sections",
                                    cl::desc("Remove all section headers"));
 static cl::opt<bool>
@@ -197,6 +199,12 @@ void CopyBinary(const ELFObjectFile<ELF64LE> &ObjFile) {
     Obj->WriteSectionHeaders = false;
   }
 
+  if (StripDebug) {
+    RemovePred = [RemovePred](const SectionBase &Sec) {
+      return RemovePred(Sec) || Sec.Name.startswith(".debug");
+    };
+  }
+
   Obj->removeSections(RemovePred);
   Obj->finalize();
   WriteObjectFile(*Obj, OutputFilename.getValue());