Handle .weak in IRObjectFile RecordStreamer

[• rafael]

LGTM with a nit:

+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-freebsd11.0"
+
+module asm ".weak libc_blah"
+module asm ".equ libc_blah, blah"

The test body can be just

module asm ".weak libc_blah"
module asm "libc_blah:"

no need to include an IR function.

Cheers,
Rafael

llvm/trunk/lib/Object/RecordStreamer.cpp

 
 void RecordStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
   markDefined(*Symbol);
   MCStreamer::EmitAssignment(Symbol, Value);
 }
 
 bool RecordStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
                                          MCSymbolAttr Attribute) {
-  if (Attribute == MCSA_Global)
+  if (Attribute == MCSA_Global || Attribute == MCSA_Weak)
     markGlobal(*Symbol);
   return true;
 }
 
 void RecordStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
                                   uint64_t Size, unsigned ByteAlignment) {
   markDefined(*Symbol);
 }
 
 void RecordStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                       unsigned ByteAlignment) {
   markDefined(*Symbol);
 }

llvm/trunk/test/Object/X86/nm-bitcodeweak.test

+; RUN: llvm-as %s -o=%t1
+; RUN: llvm-nm %t1 | FileCheck %s
+
+; CHECK: T __libc_blah
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-freebsd11.0"
+
+module asm ".weak __libc_blah"
+module asm ".equ __libc_blah, blah"