[llvm-objcopy] [COFF] Implement --strip-all[-gnu] for symbols

Differential Revision: https://reviews.llvm.org/D56481

3 files changed, 68 insertions, 2 deletions

diff --git a/llvm/test/tools/llvm-objcopy/COFF/strip-all.yaml b/llvm/test/tools/llvm-objcopy/COFF/strip-all.yaml
new file mode 100644
index 00000000000..8a92ac61509
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/COFF/strip-all.yaml
@@ -0,0 +1,55 @@
+# RUN: yaml2obj %s > %t.in.o
+
+# RUN: llvm-objdump -t %t.in.o | FileCheck %s --check-prefixes=SYMBOLS,SYMBOLS-PRE
+
+# RUN: llvm-objcopy --strip-all %t.in.o %t.out.o
+# RUN: llvm-objdump -t %t.out.o | FileCheck %s --check-prefix=SYMBOLS
+# RUN: llvm-readobj -relocs %t.out.o | FileCheck %s --check-prefix=RELOCS
+
+# Test that -S, llvm-strip without arguments and --strip-all-gnu produces
+# output identical to --strip-all above.
+# RUN: llvm-objcopy -S %t.in.o %t.out-short.o
+# RUN: cmp %t.out.o %t.out-short.o
+
+# RUN: cp %t.in.o %t.out-strip.o
+# RUN: llvm-strip %t.out-strip.o
+# RUN: cmp %t.out.o %t.out-strip.o
+
+# RUN: llvm-objcopy --strip-all-gnu %t.in.o %t.out-gnu.o
+# RUN: cmp %t.out.o %t.out-gnu.o
+
+# SYMBOLS: SYMBOL TABLE:
+# SYMBOLS-PRE-NEXT: external
+# SYMBOLS-PRE-NEXT: external_undefined
+# SYMBOLS-EMPTY:
+
+# RELOCS:      Relocations [
+# RELOCS-NEXT: ]
+
+--- !COFF
+header:          
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:        
+  - Name:            .text
+    Characteristics: [  ]
+    Alignment:       4
+    SectionData:     488B0500000000C3
+    Relocations:     
+      - VirtualAddress:  3
+        SymbolName:      external_undefined
+        Type:            IMAGE_REL_AMD64_REL32
+symbols:         
+  - Name:            external
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            external_undefined
+    Value:           0
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp b/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
index ea46b841bcf..6b386d29979 100644
--- a/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
@@ -28,6 +28,11 @@ using namespace object;
 using namespace COFF;
 
 static Error handleArgs(const CopyConfig &Config, Object &Obj) {
+  // StripAll removes all symbols and thus also removes all relocations.
+  if (Config.StripAll || Config.StripAllGNU)
+    for (Section &Sec : Obj.Sections)
+      Sec.Relocs.clear();
+
   // If we need to do per-symbol removals, initialize the Referenced field.
   if (Config.StripUnneeded || Config.DiscardAll ||
       !Config.SymbolsToRemove.empty())
@@ -36,6 +41,11 @@ static Error handleArgs(const CopyConfig &Config, Object &Obj) {
 
   // Actually do removals of symbols.
   Obj.removeSymbols([&](const Symbol &Sym) {
+    // For StripAll, all relocations have been stripped and we remove all
+    // symbols.
+    if (Config.StripAll || Config.StripAllGNU)
+      return true;
+
     if (is_contained(Config.SymbolsToRemove, Sym.Name)) {
       // Explicitly removing a referenced symbol is an error.
       if (Sym.Referenced)
diff --git a/llvm/tools/llvm-objcopy/COFF/Writer.cpp b/llvm/tools/llvm-objcopy/COFF/Writer.cpp
index e32bf6832d9..385d43b1bae 100644
--- a/llvm/tools/llvm-objcopy/COFF/Writer.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/Writer.cpp
@@ -46,8 +46,9 @@ void COFFWriter::layoutSections() {
       S.Header.PointerToRawData = FileSize;
     FileSize += S.Header.SizeOfRawData; // For executables, this is already
                                         // aligned to FileAlignment.
-    if (S.Header.NumberOfRelocations > 0)
-      S.Header.PointerToRelocations = FileSize;
+    S.Header.NumberOfRelocations = S.Relocs.size();
+    S.Header.PointerToRelocations =
+        S.Header.NumberOfRelocations > 0 ? FileSize : 0;
     FileSize += S.Relocs.size() * sizeof(coff_relocation);
     FileSize = alignTo(FileSize, FileAlignment);