[lld] r220598 - [mach-o] Support old style objc class names in export lists

[Nick Kledzik]

Author: kledzik
Date: Fri Oct 24 17:28:54 2014
New Revision: 220598

URL: http://llvm.org/viewvc/llvm-project?rev=220598&view=rev
Log:
[mach-o] Support old style objc class names in export lists

Objective-C switched to a new ABI which uses a different mangling for class
names.  But to keep projects building that use export lists that use the old
class name mangling, the linker recognizes the old names and transforms them
to the new mangling.

Added:
    lld/trunk/test/mach-o/objc_export_list.yaml
Modified:
    lld/trunk/lib/ReaderWriter/MachO/MachOLinkingContext.cpp

Modified: lld/trunk/lib/ReaderWriter/MachO/MachOLinkingContext.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/MachOLinkingContext.cpp?rev=220598&r1=220597&r2=220598&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/MachOLinkingContext.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/MachOLinkingContext.cpp Fri Oct 24 17:28:54 2014
@@ -715,6 +715,26 @@ bool MachOLinkingContext::sectionAligned
 
 
 void MachOLinkingContext::addExportSymbol(StringRef sym) {
+  // Support old crufty export lists with bogus entries.
+  if (sym.endswith(".eh") || sym.startswith(".objc_category_name_")) {
+    llvm::errs() << "warning: ignoring " << sym << " in export list\n";
+    return;
+  }
+  // Only i386 MacOSX uses old ABI, so don't change those.
+  if ((_os != OS::macOSX) || (_arch != arch_x86)) {
+    // ObjC has two differnent ABIs.  Be nice and allow one export list work for
+    // both ABIs by renaming symbols.
+    if (sym.startswith(".objc_class_name_")) {
+      std::string abi2className("_OBJC_CLASS_$_");
+      abi2className += sym.substr(17);
+      _exportedSymbols.insert(copy(abi2className));
+      std::string abi2metaclassName("_OBJC_METACLASS_$_");
+      abi2metaclassName += sym.substr(17);
+      _exportedSymbols.insert(copy(abi2metaclassName));
+      return;
+    }
+  }
+
   // FIXME: Support wildcards.
   _exportedSymbols.insert(sym);
 }

Added: lld/trunk/test/mach-o/objc_export_list.yaml
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/mach-o/objc_export_list.yaml?rev=220598&view=auto
==============================================================================
--- lld/trunk/test/mach-o/objc_export_list.yaml (added)
+++ lld/trunk/test/mach-o/objc_export_list.yaml Fri Oct 24 17:28:54 2014
@@ -0,0 +1,63 @@
+# RUN: lld -flavor darwin -arch x86_64 -dylib %s -o %t \
+# RUN:     -exported_symbol .objc_class_name_Foo %p/Inputs/libSystem.yaml
+# RUN: llvm-nm -m %t | FileCheck %s
+#
+# Test that exported objc classes can be specificed using old naming
+# (.e.g .objc_class_name_Foo instead of _OBJC_CLASS_$_Foo)
+#
+
+--- !mach-o
+arch:            x86_64
+file-type:       MH_OBJECT
+flags:           [ MH_SUBSECTIONS_VIA_SYMBOLS ]
+sections:
+  - segment:         __DATA
+    section:         __objc_data
+    type:            S_REGULAR
+    attributes:      [  ]
+    alignment:       3
+    address:         0x0000000000000000
+    content:         [ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ]
+    relocations:
+      - offset:          0x00000030
+        type:            X86_64_RELOC_UNSIGNED
+        length:          3
+        pc-rel:          false
+        extern:          true
+        symbol:          0
+      - offset:          0x00000028
+        type:            X86_64_RELOC_UNSIGNED
+        length:          3
+        pc-rel:          false
+        extern:          true
+        symbol:          1
+      - offset:          0x00000000
+        type:            X86_64_RELOC_UNSIGNED
+        length:          3
+        pc-rel:          false
+        extern:          true
+        symbol:          1
+global-symbols:
+  - name:            '_OBJC_CLASS_$_Foo'
+    type:            N_SECT
+    scope:           [ N_EXT ]
+    sect:            1
+    value:           0x0000000000000000
+  - name:            '_OBJC_METACLASS_$_Foo'
+    type:            N_SECT
+    scope:           [ N_EXT ]
+    sect:            1
+    value:           0x0000000000000028
+...
+
+# CHECK:  (__DATA,__objc_data) external _OBJC_CLASS_$_Foo
+# CHECK:  (__DATA,__objc_data) external _OBJC_METACLASS_$_Foo