Object: Don't mark alias unconditionally defined

[vitalybuka]

Summary

Can't remove EmitAssignment override as llvm/test/Object/X86/nm-bitcodeweak.test
expects this behavior.

Fixes PR37065

[pcc]

LGTM

llvm/lib/Object/RecordStreamer.cpp

for (auto AliasName : Symver.second) {
         const char *Separator = IsDefined ? "@@" : "@";
         AliasName =
             (Split.first + Separator + Split.second).toStringRef(NewName);
       }
       MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
       // TODO: Handle "@@@". Depending on SymbolAttribute value it needs to be
       // converted into @ or @@.
       const MCExpr *Value = MCSymbolRefExpr::create(Aliasee, getContext());
-      EmitAssignment(Alias, Value);
+      if (IsDefined)
+        markDefined(*Alias);
+      // Don't use EmitAssignment override as it always marks alias as defined.
+      MCStreamer::EmitAssignment(Alias, Value);
       if (Attr != MCSA_Invalid)
         EmitSymbolAttribute(Alias, Attr);
     }
   }
 }

llvm/test/LTO/X86/symver-asm3.ll

 ; Test special handling of @@@.
 
 ; RUN: llvm-as < %s >%t1
 ; RUN: llvm-nm %t1 | FileCheck %s
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 module asm "foo1:"
 ; CHECK-DAG: t foo1
 
 module asm ".symver foo1, foo@@@VER1"
 ; CHECK-DAG: t foo@@VER1
 
+module asm ".global foo2"
 module asm ".symver foo2, foo@@@VER2"
 ; CHECK-DAG: U foo2
-; CHECK-DAG: t foo@VER2
+; CHECK-DAG: U foo@VER2
+module asm "call foo2"
 
 module asm ".symver foo3, foo@@@VER3"
 ; CHECK-DAG: t foo@@VER3
 
 module asm ".symver foo4, foo@@@VER4"
 ; CHECK-DAG: T foo@@VER4
 
 module asm ".symver foo5, foo@@@VER5"
-; CHECK-DAG: T foo@VER5
+; CHECK-DAG: U foo@VER5
 
 module asm "foo3:"
 ; CHECK-DAG: t foo3
 
 module asm ".local foo1"
 module asm ".local foo3"
 
 define void @foo4() {
 ; CHECK-DAG: T foo4
   ret void
 }
 
 declare void @foo5()
 ; CHECK-DAG: U foo5