MC/Mach-O: Fix some differences in symbol flag handling.

 - Don't clear weak reference flag, 'as' was only "trying" to do this, it wasn't
   actually succeeding.
 - Clear the "lazy bound" bit when we mark something external. This corresponds
   roughly to the lazy clearing of the bit that 'as' implements in
   symbol_table_lookup.
 - The exact meaning of these flags appears pretty loose, since 'as' isn't very
   consistent. For now we just try to match 'as', we will clean this up one day
   hopefully.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103964 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 2 deletions

diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index b27f151..b00e2bf 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -192,8 +192,14 @@ void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
   SD.setFragment(F);
   SD.setOffset(F->getContents().size());
 
-  // This causes the reference type and weak reference flags to be cleared.
-  SD.setFlags(SD.getFlags() & ~(SF_WeakReference | SF_ReferenceTypeMask));
+  // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
+  // to clear the weak reference and weak definition bits too, but the
+  // implementation was buggy. For now we just try to match 'as', for
+  // diffability.
+  //
+  // FIXME: Cleanup this code, these bits should be emitted based on semantic
+  // properties, not on the order of definition, etc.
+  SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
   
   Symbol->setSection(*CurSection);
 }
@@ -257,6 +263,13 @@ void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
 
   case MCSA_Global:
     SD.setExternal(true);
+    // This effectively clears the undefined lazy bit, in Darwin 'as', although
+    // it isn't very consistent because it implements this as part of symbol
+    // lookup.
+    //
+    // FIXME: Cleanup this code, these bits should be emitted based on semantic
+    // properties, not on the order of definition, etc.
+    SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
     break;
 
   case MCSA_LazyReference: