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.

llvm-svn: 103964

llvm/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:

llvm/test/MC/MachO/symbol-flags.s

@@ -5,6 +5,10 @@
 sym_ref_def_A:
 sym_ref_def_C:  
         .reference sym_ref_def_C
+        .reference sym_ref_def_D
+        .globl sym_ref_def_D
+        .globl sym_ref_def_E
+        .reference sym_ref_def_E
         
         .weak_reference sym_weak_ref_A
         .weak_reference sym_weak_ref_def_A
@@ -16,12 +20,22 @@ sym_weak_ref_def_B:
         .globl sym_weak_def_A
         .weak_definition sym_weak_def_A        
 sym_weak_def_A:
+sym_weak_def_B:
+        .weak_definition sym_weak_def_B
+        .globl sym_weak_def_B
+        .weak_definition sym_weak_def_C
+sym_weak_def_C:
+        .globl sym_weak_def_C
 
         .lazy_reference sym_lazy_ref_A
         .lazy_reference sym_lazy_ref_B
 sym_lazy_ref_B:
 sym_lazy_ref_C:
         .lazy_reference sym_lazy_ref_C
+        .lazy_reference sym_lazy_ref_D
+        .globl sym_lazy_ref_D
+        .globl sym_lazy_ref_E
+        .lazy_reference sym_lazy_ref_E
 
         .private_extern sym_private_ext_A
         .private_extern sym_private_ext_B
@@ -30,6 +44,8 @@ sym_private_ext_C:
         .private_extern sym_private_ext_C
         .private_extern sym_private_ext_D
         .globl sym_private_ext_D
+        .globl sym_private_ext_E
+        .private_extern sym_private_ext_E
 
         .no_dead_strip sym_no_dead_strip_A
 
@@ -73,6 +89,8 @@ sym_desc_flags:
 // CHECK:     ('reserved1', 0)
 // CHECK:     ('reserved2', 0)
 // CHECK:    ),
+// CHECK:   ('_relocations', [
+// CHECK:   ])
 // CHECK:     # Section 1
 // CHECK:    (('section_name', '__data\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
 // CHECK:     ('segment_name', '__DATA\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
@@ -86,19 +104,21 @@ sym_desc_flags:
 // CHECK:     ('reserved1', 0)
 // CHECK:     ('reserved2', 0)
 // CHECK:    ),
+// CHECK:   ('_relocations', [
+// CHECK:   ])
 // CHECK:   ])
 // CHECK:  ),
 // CHECK:   # Load Command 1
 // CHECK:  (('command', 2)
 // CHECK:   ('size', 24)
 // CHECK:   ('symoff', 324)
-// CHECK:   ('nsyms', 16)
-// CHECK:   ('stroff', 516)
-// CHECK:   ('strsize', 260)
-// CHECK:   ('_string_data', '\x00sym_ref_A\x00sym_weak_ref_A\x00sym_weak_def_A\x00sym_lazy_ref_A\x00sym_private_ext_A\x00sym_private_ext_B\x00sym_private_ext_C\x00sym_private_ext_D\x00sym_no_dead_strip_A\x00sym_ref_def_A\x00sym_ref_def_C\x00sym_weak_ref_def_A\x00sym_weak_ref_def_B\x00sym_lazy_ref_B\x00sym_lazy_ref_C\x00sym_desc_flags\x00\x00')
+// CHECK:   ('nsyms', 23)
+// CHECK:   ('stroff', 600)
+// CHECK:   ('strsize', 368)
+// CHECK:   ('_string_data', '\x00sym_ref_A\x00sym_ref_def_D\x00sym_ref_def_E\x00sym_weak_ref_A\x00sym_weak_def_A\x00sym_weak_def_B\x00sym_weak_def_C\x00sym_lazy_ref_A\x00sym_lazy_ref_D\x00sym_lazy_ref_E\x00sym_private_ext_A\x00sym_private_ext_B\x00sym_private_ext_C\x00sym_private_ext_D\x00sym_private_ext_E\x00sym_no_dead_strip_A\x00sym_ref_def_A\x00sym_ref_def_C\x00sym_weak_ref_def_A\x00sym_weak_ref_def_B\x00sym_lazy_ref_B\x00sym_lazy_ref_C\x00sym_desc_flags\x00\x00\x00\x00')
 // CHECK:   ('_symbols', [
 // CHECK:     # Symbol 0
-// CHECK:    (('n_strx', 148)
+// CHECK:    (('n_strx', 254)
 // CHECK:     ('n_type', 0xe)
 // CHECK:     ('n_sect', 1)
 // CHECK:     ('n_desc', 32)
@@ -106,7 +126,7 @@ sym_desc_flags:
 // CHECK:     ('_string', 'sym_ref_def_A')
 // CHECK:    ),
 // CHECK:     # Symbol 1
-// CHECK:    (('n_strx', 162)
+// CHECK:    (('n_strx', 268)
 // CHECK:     ('n_type', 0xe)
 // CHECK:     ('n_sect', 1)
 // CHECK:     ('n_desc', 32)
@@ -114,15 +134,15 @@ sym_desc_flags:
 // CHECK:     ('_string', 'sym_ref_def_C')
 // CHECK:    ),
 // CHECK:     # Symbol 2
-// CHECK:    (('n_strx', 176)
+// CHECK:    (('n_strx', 282)
 // CHECK:     ('n_type', 0xe)
 // CHECK:     ('n_sect', 1)
-// CHECK:     ('n_desc', 0)
+// CHECK:     ('n_desc', 64)
 // CHECK:     ('n_value', 0)
 // CHECK:     ('_string', 'sym_weak_ref_def_A')
 // CHECK:    ),
 // CHECK:     # Symbol 3
-// CHECK:    (('n_strx', 195)
+// CHECK:    (('n_strx', 301)
 // CHECK:     ('n_type', 0xe)
 // CHECK:     ('n_sect', 1)
 // CHECK:     ('n_desc', 0)
@@ -130,7 +150,7 @@ sym_desc_flags:
 // CHECK:     ('_string', 'sym_weak_ref_def_B')
 // CHECK:    ),
 // CHECK:     # Symbol 4
-// CHECK:    (('n_strx', 214)
+// CHECK:    (('n_strx', 320)
 // CHECK:     ('n_type', 0xe)
 // CHECK:     ('n_sect', 2)
 // CHECK:     ('n_desc', 32)
@@ -138,7 +158,7 @@ sym_desc_flags:
 // CHECK:     ('_string', 'sym_lazy_ref_B')
 // CHECK:    ),
 // CHECK:     # Symbol 5
-// CHECK:    (('n_strx', 229)
+// CHECK:    (('n_strx', 335)
 // CHECK:     ('n_type', 0xe)
 // CHECK:     ('n_sect', 2)
 // CHECK:     ('n_desc', 32)
@@ -146,15 +166,15 @@ sym_desc_flags:
 // CHECK:     ('_string', 'sym_lazy_ref_C')
 // CHECK:    ),
 // CHECK:     # Symbol 6
-// CHECK:    (('n_strx', 244)
+// CHECK:    (('n_strx', 350)
 // CHECK:     ('n_type', 0xe)
 // CHECK:     ('n_sect', 2)
-// CHECK:     ('n_desc', 0)
+// CHECK:     ('n_desc', 64)
 // CHECK:     ('n_value', 0)
 // CHECK:     ('_string', 'sym_desc_flags')
 // CHECK:    ),
 // CHECK:     # Symbol 7
-// CHECK:    (('n_strx', 74)
+// CHECK:    (('n_strx', 162)
 // CHECK:     ('n_type', 0x1f)
 // CHECK:     ('n_sect', 2)
 // CHECK:     ('n_desc', 0)
@@ -162,7 +182,7 @@ sym_desc_flags:
 // CHECK:     ('_string', 'sym_private_ext_B')
 // CHECK:    ),
 // CHECK:     # Symbol 8
-// CHECK:    (('n_strx', 92)
+// CHECK:    (('n_strx', 180)
 // CHECK:     ('n_type', 0x1f)
 // CHECK:     ('n_sect', 2)
 // CHECK:     ('n_desc', 0)
@@ -170,7 +190,7 @@ sym_desc_flags:
 // CHECK:     ('_string', 'sym_private_ext_C')
 // CHECK:    ),
 // CHECK:     # Symbol 9
-// CHECK:    (('n_strx', 26)
+// CHECK:    (('n_strx', 54)
 // CHECK:     ('n_type', 0xf)
 // CHECK:     ('n_sect', 2)
 // CHECK:     ('n_desc', 128)
@@ -178,38 +198,78 @@ sym_desc_flags:
 // CHECK:     ('_string', 'sym_weak_def_A')
 // CHECK:    ),
 // CHECK:     # Symbol 10
-// CHECK:    (('n_strx', 41)
+// CHECK:    (('n_strx', 69)
+// CHECK:     ('n_type', 0xf)
+// CHECK:     ('n_sect', 2)
+// CHECK:     ('n_desc', 128)
+// CHECK:     ('n_value', 0)
+// CHECK:     ('_string', 'sym_weak_def_B')
+// CHECK:    ),
+// CHECK:     # Symbol 11
+// CHECK:    (('n_strx', 84)
+// CHECK:     ('n_type', 0xf)
+// CHECK:     ('n_sect', 2)
+// CHECK:     ('n_desc', 128)
+// CHECK:     ('n_value', 0)
+// CHECK:     ('_string', 'sym_weak_def_C')
+// CHECK:    ),
+// CHECK:     # Symbol 12
+// CHECK:    (('n_strx', 99)
 // CHECK:     ('n_type', 0x1)
 // CHECK:     ('n_sect', 0)
 // CHECK:     ('n_desc', 33)
 // CHECK:     ('n_value', 0)
 // CHECK:     ('_string', 'sym_lazy_ref_A')
 // CHECK:    ),
-// CHECK:     # Symbol 11
-// CHECK:    (('n_strx', 128)
+// CHECK:     # Symbol 13
+// CHECK:    (('n_strx', 114)
+// CHECK:     ('n_type', 0x1)
+// CHECK:     ('n_sect', 0)
+// CHECK:     ('n_desc', 32)
+// CHECK:     ('n_value', 0)
+// CHECK:     ('_string', 'sym_lazy_ref_D')
+// CHECK:    ),
+// CHECK:     # Symbol 14
+// CHECK:    (('n_strx', 129)
+// CHECK:     ('n_type', 0x1)
+// CHECK:     ('n_sect', 0)
+// CHECK:     ('n_desc', 33)
+// CHECK:     ('n_value', 0)
+// CHECK:     ('_string', 'sym_lazy_ref_E')
+// CHECK:    ),
+// CHECK:     # Symbol 15
+// CHECK:    (('n_strx', 234)
 // CHECK:     ('n_type', 0x1)
 // CHECK:     ('n_sect', 0)
 // CHECK:     ('n_desc', 32)
 // CHECK:     ('n_value', 0)
 // CHECK:     ('_string', 'sym_no_dead_strip_A')
 // CHECK:    ),
-// CHECK:     # Symbol 12
-// CHECK:    (('n_strx', 56)
+// CHECK:     # Symbol 16
+// CHECK:    (('n_strx', 144)
 // CHECK:     ('n_type', 0x11)
 // CHECK:     ('n_sect', 0)
 // CHECK:     ('n_desc', 0)
 // CHECK:     ('n_value', 0)
 // CHECK:     ('_string', 'sym_private_ext_A')
 // CHECK:    ),
-// CHECK:     # Symbol 13
-// CHECK:    (('n_strx', 110)
+// CHECK:     # Symbol 17
+// CHECK:    (('n_strx', 198)
 // CHECK:     ('n_type', 0x11)
 // CHECK:     ('n_sect', 0)
 // CHECK:     ('n_desc', 0)
 // CHECK:     ('n_value', 0)
 // CHECK:     ('_string', 'sym_private_ext_D')
 // CHECK:    ),
-// CHECK:     # Symbol 14
+// CHECK:     # Symbol 18
+// CHECK:    (('n_strx', 216)
+// CHECK:     ('n_type', 0x11)
+// CHECK:     ('n_sect', 0)
+// CHECK:     ('n_desc', 0)
+// CHECK:     ('n_value', 0)
+// CHECK:     ('_string', 'sym_private_ext_E')
+// CHECK:    ),
+// CHECK:     # Symbol 19
 // CHECK:    (('n_strx', 1)
 // CHECK:     ('n_type', 0x1)
 // CHECK:     ('n_sect', 0)
@@ -217,10 +277,26 @@ sym_desc_flags:
 // CHECK:     ('n_value', 0)
 // CHECK:     ('_string', 'sym_ref_A')
 // CHECK:    ),
-// CHECK:     # Symbol 15
+// CHECK:     # Symbol 20
 // CHECK:    (('n_strx', 11)
 // CHECK:     ('n_type', 0x1)
 // CHECK:     ('n_sect', 0)
+// CHECK:     ('n_desc', 32)
+// CHECK:     ('n_value', 0)
+// CHECK:     ('_string', 'sym_ref_def_D')
+// CHECK:    ),
+// CHECK:     # Symbol 21
+// CHECK:    (('n_strx', 25)
+// CHECK:     ('n_type', 0x1)
+// CHECK:     ('n_sect', 0)
+// CHECK:     ('n_desc', 32)
+// CHECK:     ('n_value', 0)
+// CHECK:     ('_string', 'sym_ref_def_E')
+// CHECK:    ),
+// CHECK:     # Symbol 22
+// CHECK:    (('n_strx', 39)
+// CHECK:     ('n_type', 0x1)
+// CHECK:     ('n_sect', 0)
 // CHECK:     ('n_desc', 64)
 // CHECK:     ('n_value', 0)
 // CHECK:     ('_string', 'sym_weak_ref_A')
@@ -233,9 +309,9 @@ sym_desc_flags:
 // CHECK:   ('ilocalsym', 0)
 // CHECK:   ('nlocalsym', 7)
 // CHECK:   ('iextdefsym', 7)
-// CHECK:   ('nextdefsym', 3)
-// CHECK:   ('iundefsym', 10)
-// CHECK:   ('nundefsym', 6)
+// CHECK:   ('nextdefsym', 5)
+// CHECK:   ('iundefsym', 12)
+// CHECK:   ('nundefsym', 11)
 // CHECK:   ('tocoff', 0)
 // CHECK:   ('ntoc', 0)
 // CHECK:   ('modtaboff', 0)