[llvm-objcopy] Add support of symbol modification flags for MachO (#120895)

RIscRIpt · web-flow · commit 334a5766d759 · 2024-12-24T16:05:10.000+02:00
This patch adds support of the following llvm-objcopy flags for MachO:

- `--globalize-symbol`, `--globalize-symbols`,
- `--keep-global-symbol`, `-G`, `--keep-global-symbols`,
- `--localize-symbol`, `-L`, `--localize-symbols`,
- `--skip-symbol`, `--skip-symbols`.

Code in `updateAndRemoveSymbols` for MachO
is kept similar to its version for ELF.

Fixes #120894
diff --git a/llvm/docs/CommandGuide/llvm-objcopy.rst b/llvm/docs/CommandGuide/llvm-objcopy.rst
@@ -78,10 +78,47 @@ multiple file formats.
  Enable deterministic mode when copying archives, i.e. use 0 for archive member
  header UIDs, GIDs and timestamp fields. On by default.
 
+.. option:: --globalize-symbol <symbol>
+
+ Mark any defined symbols named ``<symbol>`` as global symbols in the output.
+ Can be specified multiple times to mark multiple symbols.
+
+.. option:: --globalize-symbols <filename>
+
+ Read a list of names from the file ``<filename>`` and mark defined symbols with
+ those names as global in the output. In the file, each line represents a single
+ symbol, with leading and trailing whitespace ignored, as is anything following
+ a '#'. Can be specified multiple times to read names from multiple files.
+
 .. option:: --help, -h
 
  Print a summary of command line options.
 
+.. option:: --keep-global-symbol <symbol>, -G
+
+ Mark all symbols local in the output, except for symbols with the name
+ ``<symbol>``. Can be specified multiple times to ignore multiple symbols.
+
+.. option:: --keep-global-symbols <filename>
+
+ Mark all symbols local in the output, except for symbols named in the file
+ ``<filename>``. In the file, each line represents a single symbol, with leading
+ and trailing whitespace ignored, as is anything following a '#'. Can be
+ specified multiple times to read names from multiple files.
+
+.. option:: --localize-symbol <symbol>, -L
+
+ Mark any defined non-common symbol named ``<symbol>`` as a local symbol in the
+ output. Can be specified multiple times to mark multiple symbols as local.
+
+.. option:: --localize-symbols <filename>
+
+ Read a list of names from the file ``<filename>`` and mark defined non-common
+ symbols with those names as local in the output. In the file, each line
+ represents a single symbol, with leading and trailing whitespace ignored, as is
+ anything following a '#'. Can be specified multiple times to read names from
+ multiple files.
+
 .. option:: --only-keep-debug
 
  Produce a debug file as the output that only preserves contents of sections
@@ -177,6 +214,19 @@ multiple file formats.
    flags.
  - `share` = add the `IMAGE_SCN_MEM_SHARED` and `IMAGE_SCN_MEM_READ` flags.
 
+.. option:: --skip-symbol <symbol>
+
+ Do not change the parameters of symbol ``<symbol>`` when executing other
+ options that can change the symbol's name, binding or visibility.
+
+.. option:: --skip-symbols <filename>
+
+ Do not change the parameters of symbols named in the file ``<filename>`` when
+ executing other options that can change the symbol's name, binding or
+ visibility. In the file, each line represents a single symbol, with leading
+ and trailing whitespace ignored, as is anything following a '#'.
+ Can be specified multiple times to read names from multiple files.
+
 .. option:: --strip-all-gnu
 
  Remove all symbols, debug sections and relocations from the output. This option
@@ -355,18 +405,6 @@ them.
  For binary outputs, fill the gaps between sections with ``<value>`` instead
  of zero. The value must be an unsigned 8-bit integer.
 
-.. option:: --globalize-symbol <symbol>
-
- Mark any defined symbols named ``<symbol>`` as global symbols in the output.
- Can be specified multiple times to mark multiple symbols.
-
-.. option:: --globalize-symbols <filename>
-
- Read a list of names from the file ``<filename>`` and mark defined symbols with
- those names as global in the output. In the file, each line represents a single
- symbol, with leading and trailing whitespace ignored, as is anything following
- a '#'. Can be specified multiple times to read names from multiple files.
-
 .. option:: --input-target <format>, -I
 
  Read the input as the specified format. See `SUPPORTED FORMATS`_ for a list of
@@ -377,18 +415,6 @@ them.
 
  Keep symbols of type `STT_FILE`, even if they would otherwise be stripped.
 
-.. option:: --keep-global-symbol <symbol>, -G
-
- Mark all symbols local in the output, except for symbols with the name
- ``<symbol>``. Can be specified multiple times to ignore multiple symbols.
-
-.. option:: --keep-global-symbols <filename>
-
- Mark all symbols local in the output, except for symbols named in the file
- ``<filename>``. In the file, each line represents a single symbol, with leading
- and trailing whitespace ignored, as is anything following a '#'. Can be
- specified multiple times to read names from multiple files.
-
 .. option:: --keep-section <section>
 
  When removing sections from the output, do not remove sections named
@@ -410,19 +436,6 @@ them.
 
  Mark all symbols with hidden or internal visibility local in the output.
 
-.. option:: --localize-symbol <symbol>, -L
-
- Mark any defined non-common symbol named ``<symbol>`` as a local symbol in the
- output. Can be specified multiple times to mark multiple symbols as local.
-
-.. option:: --localize-symbols <filename>
-
- Read a list of names from the file ``<filename>`` and mark defined non-common
- symbols with those names as local in the output. In the file, each line
- represents a single symbol, with leading and trailing whitespace ignored, as is
- anything following a '#'. Can be specified multiple times to read names from
- multiple files.
-
 .. option:: --new-symbol-visibility <visibility>
 
  Specify the visibility of the symbols automatically created when using binary
@@ -489,19 +502,6 @@ them.
  Read a list of symbols from <filename> and change their visibility to the
  specified value. Visibility values: default, internal, hidden, protected.
 
-.. option:: --skip-symbol <symbol>
-
- Do not change the parameters of symbol ``<symbol>`` when executing other
- options that can change the symbol's name, binding or visibility.
-
-.. option:: --skip-symbols <filename>
-
- Do not change the parameters of symbols named in the file ``<filename>`` when
- executing other options that can change the symbol's name, binding or
- visibility. In the file, each line represents a single symbol, with leading
- and trailing whitespace ignored, as is anything following a '#'.
- Can be specified multiple times to read names from multiple files.
-
 .. option:: --split-dwo <dwo-file>
 
  Equivalent to running :program:`llvm-objcopy` with :option:`--extract-dwo` and
diff --git a/llvm/docs/ReleaseNotes.md b/llvm/docs/ReleaseNotes.md
@@ -350,6 +350,12 @@ Changes to the Debug Info
 Changes to the LLVM tools
 ---------------------------------
 
+* llvm-objcopy now supports the following options for Mach-O:
+  `--globalize-symbol`, `--globalize-symbols`,
+  `--keep-global-symbol`, `--keep-global-symbols`,
+  `--localize-symbol`, `--localize-symbols`,
+  `--skip-symbol`, `--skip-symbols`.
+
 Changes to LLDB
 ---------------------------------
 
diff --git a/llvm/lib/ObjCopy/ConfigManager.cpp b/llvm/lib/ObjCopy/ConfigManager.cpp
@@ -36,11 +36,9 @@ Expected<const COFFConfig &> ConfigManager::getCOFFConfig() const {
 
 Expected<const MachOConfig &> ConfigManager::getMachOConfig() const {
   if (!Common.SplitDWO.empty() || !Common.SymbolsPrefix.empty() ||
-      !Common.SymbolsPrefixRemove.empty() || !Common.SymbolsToSkip.empty() ||
+      !Common.SymbolsPrefixRemove.empty() ||
       !Common.AllocSectionsPrefix.empty() || !Common.KeepSection.empty() ||
-      !Common.SymbolsToGlobalize.empty() || !Common.SymbolsToKeep.empty() ||
-      !Common.SymbolsToLocalize.empty() ||
-      !Common.SymbolsToKeepGlobal.empty() || !Common.SectionsToRename.empty() ||
+      !Common.SymbolsToKeep.empty() || !Common.SectionsToRename.empty() ||
       !Common.UnneededSymbolsToRemove.empty() ||
       !Common.SetSectionAlignment.empty() || !Common.SetSectionFlags.empty() ||
       !Common.SetSectionType.empty() || Common.ExtractDWO ||
diff --git a/llvm/lib/ObjCopy/MachO/MachOObjcopy.cpp b/llvm/lib/ObjCopy/MachO/MachOObjcopy.cpp
@@ -93,19 +93,38 @@ static void markSymbols(const CommonConfig &, Object &Obj) {
 static void updateAndRemoveSymbols(const CommonConfig &Config,
                                    const MachOConfig &MachOConfig,
                                    Object &Obj) {
-  for (SymbolEntry &Sym : Obj.SymTable) {
-    // Weaken symbols first to match ELFObjcopy behavior.
-    bool IsExportedAndDefined =
-        (Sym.n_type & llvm::MachO::N_EXT) &&
-        (Sym.n_type & llvm::MachO::N_TYPE) != llvm::MachO::N_UNDF;
-    if (IsExportedAndDefined &&
+  Obj.SymTable.updateSymbols([&](SymbolEntry &Sym) {
+    if (Config.SymbolsToSkip.matches(Sym.Name))
+      return;
+
+    if (!Sym.isUndefinedSymbol() && Config.SymbolsToLocalize.matches(Sym.Name))
+      Sym.n_type &= ~MachO::N_EXT;
+
+    // Note: these two globalize flags have very similar names but different
+    // meanings:
+    //
+    // --globalize-symbol: promote a symbol to global
+    // --keep-global-symbol: all symbols except for these should be made local
+    //
+    // If --globalize-symbol is specified for a given symbol, it will be
+    // global in the output file even if it is not included via
+    // --keep-global-symbol. Because of that, make sure to check
+    // --globalize-symbol second.
+    if (!Sym.isUndefinedSymbol() && !Config.SymbolsToKeepGlobal.empty() &&
+        !Config.SymbolsToKeepGlobal.matches(Sym.Name))
+      Sym.n_type &= ~MachO::N_EXT;
+
+    if (!Sym.isUndefinedSymbol() && Config.SymbolsToGlobalize.matches(Sym.Name))
+      Sym.n_type |= MachO::N_EXT;
+
+    if (Sym.isExternalSymbol() && !Sym.isUndefinedSymbol() &&
         (Config.Weaken || Config.SymbolsToWeaken.matches(Sym.Name)))
-      Sym.n_desc |= llvm::MachO::N_WEAK_DEF;
+      Sym.n_desc |= MachO::N_WEAK_DEF;
 
     auto I = Config.SymbolsToRename.find(Sym.Name);
     if (I != Config.SymbolsToRename.end())
       Sym.Name = std::string(I->getValue());
-  }
+  });
 
   auto RemovePred = [&Config, &MachOConfig,
                      &Obj](const std::unique_ptr<SymbolEntry> &N) {
diff --git a/llvm/lib/ObjCopy/MachO/MachOObject.cpp b/llvm/lib/ObjCopy/MachO/MachOObject.cpp
@@ -33,6 +33,19 @@ SymbolEntry *SymbolTable::getSymbolByIndex(uint32_t Index) {
       static_cast<const SymbolTable *>(this)->getSymbolByIndex(Index));
 }
 
+void SymbolTable::updateSymbols(function_ref<void(SymbolEntry &)> Callable) {
+  for (auto &Sym : Symbols)
+    Callable(*Sym);
+
+  // Partition symbols: local < defined external < undefined external.
+  auto ExternalBegin = std::stable_partition(
+      std::begin(Symbols), std::end(Symbols),
+      [](const auto &Sym) { return Sym->isLocalSymbol(); });
+  std::stable_partition(ExternalBegin, std::end(Symbols), [](const auto &Sym) {
+    return !Sym->isUndefinedSymbol();
+  });
+}
+
 void SymbolTable::removeSymbols(
     function_ref<bool(const std::unique_ptr<SymbolEntry> &)> ToRemove) {
   llvm::erase_if(Symbols, ToRemove);
diff --git a/llvm/lib/ObjCopy/MachO/MachOObject.h b/llvm/lib/ObjCopy/MachO/MachOObject.h
@@ -142,6 +142,7 @@ struct SymbolTable {
 
   const SymbolEntry *getSymbolByIndex(uint32_t Index) const;
   SymbolEntry *getSymbolByIndex(uint32_t Index);
+  void updateSymbols(function_ref<void(SymbolEntry &)> Callable);
   void removeSymbols(
       function_ref<bool(const std::unique_ptr<SymbolEntry> &)> ToRemove);
 };
diff --git a/llvm/test/tools/llvm-objcopy/MachO/globalize-symbol.test b/llvm/test/tools/llvm-objcopy/MachO/globalize-symbol.test
@@ -0,0 +1,134 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy --wildcard --globalize-symbol="*" %t %t.copy
+# RUN: llvm-readobj --symbols %t.copy | FileCheck %s
+
+# RUN: echo "*" > %t-star.txt
+# RUN: llvm-objcopy --wildcard --globalize-symbols="%t-star.txt" %t %t.copy
+# RUN: llvm-readobj --symbols %t.copy | FileCheck %s
+
+# CHECK:      Symbols [
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: _PrivateSymbol
+# CHECK-NEXT:     Extern
+# CHECK-NEXT:     Type: Section (0xE)
+# CHECK-NEXT:     Section: __text (0x1)
+# CHECK-NEXT:     RefType: UndefinedNonLazy (0x0)
+# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Value: 0x1
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: _PrivateExternalSymbol
+# CHECK-NEXT:     PrivateExtern
+# CHECK-NEXT:     Extern
+# CHECK-NEXT:     Type: Section (0xE)
+# CHECK-NEXT:     Section: __text (0x1)
+# CHECK-NEXT:     RefType: UndefinedNonLazy (0x0)
+# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Value: 0x2
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: _CommonSymbol
+# CHECK-NEXT:     Extern
+# CHECK-NEXT:     Type: Section (0xE)
+# CHECK-NEXT:     Section: __text (0x1)
+# CHECK-NEXT:     RefType: UndefinedNonLazy (0x0)
+# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Value: 0x3
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: _UndefinedExternalSymbol
+# CHECK-NEXT:     Extern
+# CHECK-NEXT:     Type: Undef (0x0)
+# CHECK-NEXT:     Section:  (0x0)
+# CHECK-NEXT:     RefType: UndefinedNonLazy (0x0)
+# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Value: 0x0
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACF
+  cputype:         0x100000C
+  cpusubtype:      0x0
+  filetype:        0x2
+  ncmds:           3
+  sizeofcmds:      328
+  flags:           0x200085
+  reserved:        0x0
+LoadCommands:
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         152
+    segname:         __TEXT
+    vmaddr:          4294967296
+    vmsize:          4096
+    fileoff:         0
+    filesize:        4096
+    maxprot:         5
+    initprot:        5
+    nsects:          1
+    flags:           0
+    Sections:
+      - sectname:        __text
+        segname:         __TEXT
+        addr:            0x100000FF8
+        size:            8
+        offset:          0xFF8
+        align:           2
+        reloff:          0x0
+        nreloc:          0
+        flags:           0x80000400
+        reserved1:       0x0
+        reserved2:       0x0
+        reserved3:       0x0
+        content:         00008052C0035FD6
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         72
+    segname:         __LINKEDIT
+    vmaddr:          4294971392
+    vmsize:          4096
+    fileoff:         4096
+    filesize:        67
+    maxprot:         1
+    initprot:        1
+    nsects:          0
+    flags:           0
+  - cmd:             LC_SYMTAB
+    cmdsize:         24
+    symoff:          4096
+    nsyms:           4
+    stroff:          4164
+    strsize:         79
+LinkEditData:
+  NameList:
+    - n_strx:          2
+      n_type:          0x0E
+      n_sect:          1
+      n_desc:          0
+      n_value:         1
+    - n_strx:          17
+      n_type:          0x1E
+      n_sect:          1
+      n_desc:          0
+      n_value:         2
+    - n_strx:          40
+      n_type:          0x0F
+      n_sect:          1
+      n_desc:          0
+      n_value:         3
+    - n_strx:          54
+      n_type:          0x01
+      n_sect:          0
+      n_desc:          0
+      n_value:         0
+  StringTable:
+    - ' '
+    - _PrivateSymbol
+    - _PrivateExternalSymbol
+    - _CommonSymbol
+    - _UndefinedExternalSymbol
+...
diff --git a/llvm/test/tools/llvm-objcopy/MachO/keep-global-symbol.test b/llvm/test/tools/llvm-objcopy/MachO/keep-global-symbol.test
diff --git a/llvm/test/tools/llvm-objcopy/MachO/localize-symbol.test b/llvm/test/tools/llvm-objcopy/MachO/localize-symbol.test
diff --git a/llvm/test/tools/llvm-objcopy/MachO/skip-symbol.test b/llvm/test/tools/llvm-objcopy/MachO/skip-symbol.test
