[llvm-objcopy] [COFF] Implement --only-section

Differential Revision: https://reviews.llvm.org/D56873

llvm-svn: 351663

llvm/test/tools/llvm-objcopy/COFF/only-section.test

@@ -0,0 +1,21 @@
+RUN: yaml2obj %p/Inputs/only-keep-sections.yaml > %t.in.exe
+
+RUN: llvm-objcopy --only-section .debug_discardable %t.in.exe %t.out.exe
+RUN: llvm-objdump --section-headers -t %t.out.exe | FileCheck %s --check-prefixes=SECTIONS,SECTIONS-DEBUG,SYMBOLS,SYMBOLS-DEBUG
+
+Adding another section stripping option makes it return the intersection of
+kept sections - in this case keeping only .text.
+
+RUN: llvm-objcopy --only-section .debug_discardable --only-section .text --strip-debug %t.in.exe %t.combination.exe
+RUN: llvm-objdump --section-headers -t %t.combination.exe | FileCheck %s --check-prefixes=SECTIONS,SECTIONS-TEXT,SYMBOLS,SYMBOLS-TEXT
+
+SECTIONS:            Sections:
+SECTIONS-NEXT:       Idx Name
+SECTIONS-DEBUG-NEXT: .debug_discardable
+SECTIONS-TEXT-NEXT:  .text
+SECTIONS-EMPTY:
+
+SYMBOLS:            SYMBOL TABLE:
+SYMBOLS-DEBUG-NEXT: debug_discardable_sym
+SYMBOLS-TEXT-NEXT:  main
+SYMBOLS-EMPTY:

llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp

@@ -33,6 +33,12 @@ static bool isDebugSection(const Section &Sec) {
 static Error handleArgs(const CopyConfig &Config, Object &Obj) {
   // Perform the actual section removals.
   Obj.removeSections([&Config](const Section &Sec) {
+    // Contrary to --only-keep-debug, --only-section fully removes sections that
+    // aren't mentioned.
+    if (!Config.OnlySection.empty() &&
+        !is_contained(Config.OnlySection, Sec.Name))
+      return true;
+
     if (Config.StripDebug || Config.StripAll || Config.StripAllGNU ||
         Config.DiscardAll || Config.StripUnneeded) {
       if (isDebugSection(Sec) &&