[llvm][Object] set SF_Hidden flag for MachO files

[pete]

LGTM

[ributzka]

Test case?

[cishida]

Update lld tests to include .hidden attribute.

[ributzka]

LGTM

lld/test/MachO/alias-symbols.s

 
 ## local aliases should be dropped entirely. --implicit-check-not doesn't seem
 ## to work well with -DAG matches, so we check for _local_alias' absence in a
 ## separate step.
 # RUN: llvm-objdump --macho --syms %t/out | FileCheck /dev/null --implicit-check-not _local_alias
 
 # CHECK-DAG: [[#%.16x,STRONG:]] g     F __TEXT,__text _strong
 # CHECK-DAG: [[#%.16x,WEAK_1:]]  w    F __TEXT,__text _weak_1
-# CHECK-DAG: [[#%.16x,PEXT:]]   l     F __TEXT,__text _pext
+# CHECK-DAG: [[#%.16x,PEXT:]]   l     F __TEXT,__text .hidden _pext
 # CHECK-DAG: [[#%.16x,DEAD:]]   g     F __TEXT,__text _dead
-# CHECK-DAG: [[#STRONG]]        l     F __TEXT,__text _pext_alias
-# CHECK-DAG: [[#PEXT]]          l     F __TEXT,__text _alias_to_pext
+# CHECK-DAG: [[#STRONG]]        l     F __TEXT,__text .hidden _pext_alias
+# CHECK-DAG: [[#PEXT]]          l     F __TEXT,__text .hidden _alias_to_pext
 # CHECK-DAG: [[#STRONG]]        g     F __TEXT,__text _extern_alias_to_strong
 # CHECK-DAG: [[#WEAK_1]]         w    F __TEXT,__text _weak_extern_alias_to_weak
 # CHECK-DAG: [[#DEAD]]          g     F __TEXT,__text _no_dead_strip_alias
 # CHECK-DAG: [[#STRONG]]        g     F __TEXT,__text _weak_extern_alias_to_strong
 
 # RUN: %lld -lSystem -dead_strip %t/aliases.o %t/definitions.o -o %t/dead-stripped
 # RUN: llvm-objdump --macho --syms %t/dead-stripped | FileCheck %s --check-prefix=STRIPPED
 

lld/test/MachO/lto-explicit-exports.ll

 ; RUN: llvm-dis %t/refs-foo.thinlto.o.2.internalize.bc -o - | FileCheck %s --check-prefix=THINLTO-REFS-FOO
 ; RUN: llvm-objdump --macho --syms %t/test-thinlto | FileCheck %s --check-prefix=THINLTO-SYMS
 
 ; THINLTO-FOO: define dso_local void @foo()
 ; THINLTO-FOO: define internal void @same_module_callee()
 ; THINLTO-REFS-FOO: declare dso_local void @foo()
 ; THINLTO-REFS-FOO: define dso_local void @refs_foo()
 
-; THINLTO-SYMS: l     F __TEXT,__text _foo
+; THINLTO-SYMS: l     F __TEXT,__text .hidden _foo
 ; THINLTO-SYMS: g     F __TEXT,__text _same_module_caller
 ; THINLTO-SYMS: g     F __TEXT,__text _refs_foo
 
 ;--- foo.ll
 
 target triple = "x86_64-apple-macosx10.15.0"
 target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 

lld/test/MachO/weak-definition-gc.s

 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/weak-aligned-1.s -o %t/weak-aligned-1.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/weak-aligned-2.s -o %t/weak-aligned-2.o
 # RUN: %lld -o %t/out -lSystem %t/weak-aligned-1.o %t/weak-aligned-2.o
 # RUN: llvm-objdump --syms --section=__const --full-contents %t/out | FileCheck --check-prefixes=ALIGN,ALIGN2 %s
 # RUN: %lld -o %t/out -lSystem %t/weak-aligned-1.o %t/weak-aligned-2.o -dead_strip
 # RUN: llvm-objdump --syms --section=__const --full-contents %t/out | FileCheck --check-prefixes=ALIGN,ALIGN3 %s
 # ALIGN:       SYMBOL TABLE:
-# ALIGN-DAG:   [[#%x, ADDR:]]       l     O __DATA_CONST,__const _weak1
-# ALIGN2-DAG:  {{0*}}[[#ADDR+ 0x4]] l     O __DATA_CONST,__const _weak3
-# ALIGN3-DAG:  {{0*}}[[#ADDR+ 0x4]] l     O __DATA_CONST,__const _weak2
-# ALIGN2-DAG:  {{0*}}[[#ADDR+ 0x8]] l     O __DATA_CONST,__const _weak2
+# ALIGN-DAG:   [[#%x, ADDR:]]       l     O __DATA_CONST,__const .hidden _weak1
+# ALIGN2-DAG:  {{0*}}[[#ADDR+ 0x4]] l     O __DATA_CONST,__const .hidden _weak3
+# ALIGN3-DAG:  {{0*}}[[#ADDR+ 0x4]] l     O __DATA_CONST,__const .hidden _weak2
+# ALIGN2-DAG:  {{0*}}[[#ADDR+ 0x8]] l     O __DATA_CONST,__const .hidden _weak2
 # ALIGN-DAG:   {{0*}}[[#ADDR+0x10]] g     O __DATA_CONST,__const _aligned
 # ALIGN:       Contents of section __DATA_CONST,__const:
 # ALIGN2-NEXT: {{0*}}[[#ADDR]]      11111111 33333333 22222222 00000000
 # ALIGN3-NEXT: {{0*}}[[#ADDR]]      11111111 22222222 00000000 00000000
 # ALIGN-NEXT:  {{0*}}[[#ADDR+0x10]] 81818181 81818181 82828282 82828282
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/weak-def.s -o %t/weak-def.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/strong-def.s -o %t/strong-def.o

llvm/lib/Object/MachOObjectFile.cpp

if (MachOType & MachO::N_EXT) {
     Result |= SymbolRef::SF_Global;
     if ((MachOType & MachO::N_TYPE) == MachO::N_UNDF) {
       if (getNValue(DRI))
         Result |= SymbolRef::SF_Common;
       else
         Result |= SymbolRef::SF_Undefined;
     }
 
-    if (!(MachOType & MachO::N_PEXT))
+    if (MachOType & MachO::N_PEXT)
+      Result |= SymbolRef::SF_Hidden;
+    else
       Result |= SymbolRef::SF_Exported;
-  }
+
+  } else if (MachOType & MachO::N_PEXT)
+    Result |= SymbolRef::SF_Hidden;
 
   if (MachOFlags & (MachO::N_WEAK_REF | MachO::N_WEAK_DEF))
     Result |= SymbolRef::SF_Weak;
 
   if (MachOFlags & (MachO::N_ARM_THUMB_DEF))
     Result |= SymbolRef::SF_Thumb;
 
   if ((MachOType & MachO::N_TYPE) == MachO::N_ABS)