[LLD][MachO] Fix a FIXME: Subtract base address from atom address when building

export trie.

llvm-svn: 248217

lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp

@@ -195,6 +195,9 @@ void MachOLinkingContext::configure(HeaderFileType type, Arch arch, OS os,
       _pageZeroSize = 0x1000;
     }
 
+    // Initial base address is __PAGEZERO size.
+    _baseAddress = _pageZeroSize;
+
     // Make PIE by default when targetting newer OSs.
     switch (os) {
       case OS::macOSX:

lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp

@@ -1162,7 +1162,7 @@ void Util::addExportInfo(const lld::File &atomFile, NormalizedFile &nFile) {
       }
       Export exprt;
       exprt.name = atom->name();
-      exprt.offset = _atomToAddress[atom];   // FIXME: subtract base address
+      exprt.offset = _atomToAddress[atom] - _ctx.baseAddress();
       exprt.kind = EXPORT_SYMBOL_FLAGS_KIND_REGULAR;
       if (atom->merge() == DefinedAtom::mergeAsWeak)
         exprt.flags = EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION;

lld/test/mach-o/executable-exports.yaml

@@ -1,4 +1,4 @@
-# RUN: lld -flavor darwin -arch x86_64 -macosx_version_min 10.8 -dylib \
+# RUN: lld -flavor darwin -arch x86_64 -macosx_version_min 10.8 \
 # RUN:      %s %p/Inputs/libSystem.yaml -o %t  && \
 # RUN: llvm-objdump -exports-trie %t | FileCheck %s
 #
@@ -16,7 +16,7 @@ sections:
     type:            S_REGULAR
     attributes:      [ S_ATTR_PURE_INSTRUCTIONS, S_ATTR_SOME_INSTRUCTIONS ]
     address:         0x0000000000000000
-    content:         [ 0xC3, 0xC3, 0xC3 ]
+    content:         [ 0xC3, 0xC3, 0xC3, 0xC3 ]
 global-symbols:
   - name:            _myHidden
     type:            N_SECT
@@ -34,8 +34,13 @@ global-symbols:
     sect:            1
     desc:            [ N_WEAK_DEF ]
     value:           0x0000000000000002
+  - name:            _main
+    type:            N_SECT
+    scope:           [ N_EXT ]
+    sect:            1
+    value:           0x0000000000000003
 ...
 
 # CHECK-NOT:  _myHidden
-# CHECK:      _myRegular
-# CHECK:      _myWeak [weak_def]
+# CHECK:      0x00000FFD  _myRegular
+# CHECK:      0x00000FFE  _myWeak [weak_def]