[llvm-objcopy] Make --strip-debug strip .gdb_index

[MaskRay]

Summary

See binutils-gdb/bfd/elf.c, GNU objcopy also strips .stab* (STABS)
.line* (DWARF 1) .gnu.linkonce.wi.* (linkonce section for .debug_info) but
I'm not sure we need to be compatible with it.

[jakehehrlich]

Can we add test? Otherwise this LGTM.

[MaskRay]

Add test

[alexander-shaposhnikov]

LG

[jakehehrlich]

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

94

This wasn't a typeo, it was put there on purpose to test that anything start with ".debug" would trigger

[MaskRay]

Use .debugfoo and .zdebugfoo

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

 
 # RUN: rm -f %t.thin.a
 # Copy %t to %t.thin.archive.member to avoid changing %t directly.
 # RUN: cp %t %t.thin.archive.member
 # RUN: llvm-ar crsT %t.thin.a %t.thin.archive.member
 # RUN: llvm-objcopy --strip-debug %t.thin.a %t2.thin.a
 # RUN: cat %t.thin.a | FileCheck %s --check-prefix=VERIFY-THIN-ARCHIVE
 # RUN: cat %t2.thin.a | FileCheck %s --check-prefix=VERIFY-THIN-ARCHIVE
- 
 # VERIFY-THIN-ARCHIVE: !<thin>
 
 # Verify that the member of a thin archive was properly modified.
 # RUN: cmp %t2 %t.thin.archive.member
 
 # RUN: rm -f %t.non-object.thin.a
 # RUN: llvm-ar crsT %t.non-object.thin.a %t1.o %t2.txt %t3.o
 # RUN: cp %t.non-object.thin.a %t.non-object.thin.copy.a
 # RUN: not llvm-objcopy --strip-debug %t.non-object.thin.a %t.non-object.thin.a 2>&1 | FileCheck %s --check-prefix=BAD-FORMAT
 
 # Verify that in the case of error thin archive and its memebers are not getting modified.
 # RUN: cmp %t.non-object.thin.a %t.non-object.thin.copy.a
 # RUN: cmp %t %t1.o
 # RUN: cmp %s %t2.txt
 # RUN: cmp %t %t3.o
 
 !ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
   Type:            ET_REL
   Machine:         EM_X86_64
 Sections:
-  - Name:            .debugfoo
+  - Name:            .debug_info
+    Type:            SHT_PROGBITS
+    Content:         "00000000"
+  - Name:            .zdebug_info
+    Type:            SHT_PROGBITS
+    Content:         "00000000"
+  - Name:            .gdb_index
     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
+    - Name: debug_info
+      Section: .debug_info
 
 # CHECK: SectionHeaderCount: 5
 
 # CHECK: Name: .text
 # CHECK: Name: .symtab
 # CHECK: Name: .strtab
 # CHECK: Name: .shstrtab
 

tools/llvm-objcopy/llvm-objcopy.cpp

LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, Error E) {
   errs() << ToolName << ": '" << File << "': " << Buf;
   exit(1);
 }
 
 } // end namespace objcopy
 } // end namespace llvm
 
 static bool IsDebugSection(const SectionBase &Sec) {
-  return Sec.Name.startswith(".debug") || Sec.Name.startswith(".zdebug");
+  return Sec.Name.startswith(".debug") || Sec.Name.startswith(".zdebug") ||
+         Sec.Name == ".gdb_index";
 }
 
 static bool IsDWOSection(const SectionBase &Sec) {
   return Sec.Name.endswith(".dwo");
 }
 
 static bool OnlyKeepDWOPred(const Object &Obj, const SectionBase &Sec) {
   // We can't remove the section header string table.