[PATCH] D19389: [LTO] Create Undefined Bitcode symbol when we drop a comdat member

[Davide Italiano via llvm-commits]

davide created this revision.
davide added a reviewer: rafael.
davide added a subscriber: llvm-commits.
Herald added a subscriber: joker.eph.

http://reviews.llvm.org/D19389

Files:
  ELF/InputFiles.cpp
  test/ELF/lto/Inputs/comdat.s
  test/ELF/lto/comdat2.ll

Index: test/ELF/lto/comdat2.ll
===================================================================
--- /dev/null
+++ test/ELF/lto/comdat2.ll
@@ -0,0 +1,25 @@
+; RUN: llvm-as %s -o %t.o
+; RUN: llvm-mc -triple=x86_64-pc-linux %p/Inputs/comdat.s -o %t2.o -filetype=obj
+; RUN: ld.lld -m elf_x86_64 %t.o %t2.o -o %t.so -shared
+; RUN: llvm-readobj -t %t.so | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+$c = comdat any
+
+define protected void @foo() comdat($c) {
+  ret void
+}
+
+; CHECK: Symbol {
+; CHECK:   Name: foo
+; CHECK-NEXT:   Value: 0x1000
+; CHECK-NEXT:   Size: 1
+; CHECK-NEXT:   Binding: Global
+; CHECK-NEXT:   Type: Function
+; CHECK-NEXT:   Other [
+; CHECK-NEXT:     STV_PROTECTED
+; CHECK-NEXT:   ]
+; CHECK-NEXT:   Section: .text
+; CHECK-NEXT: }
Index: test/ELF/lto/Inputs/comdat.s
===================================================================
--- /dev/null
+++ test/ELF/lto/Inputs/comdat.s
@@ -0,0 +1,5 @@
+    .section .text.f,"axG", at progbits,c,comdat
+    .globl foo
+
+foo:
+    retq
Index: ELF/InputFiles.cpp
===================================================================
--- ELF/InputFiles.cpp
+++ ELF/InputFiles.cpp
@@ -461,28 +461,32 @@
                               const IRObjectFile &Obj,
                               const BasicSymbolRef &Sym) {
   const GlobalValue *GV = Obj.getSymbolGV(Sym.getRawDataRefImpl());
-  if (GV)
-    if (const Comdat *C = GV->getComdat())
-      if (!KeptComdats.count(C))
-        return nullptr;
+  SmallString<64> Name;
+  raw_svector_ostream OS(Name);
+  Sym.printName(OS);
+  StringRef NameRef = Saver.save(StringRef(Name));
+  SymbolBody *Body;
 
   uint32_t Flags = Sym.getFlags();
+  bool IsWeak = Flags & BasicSymbolRef::SF_Weak;
+
   uint8_t Visibility;
   if (GV)
     Visibility = getGvVisibility(GV);
   else
     // FIXME: Set SF_Hidden flag correctly for module asm symbols, and expose
     // protected visibility.
     Visibility = STV_DEFAULT;
 
-  SmallString<64> Name;
-  raw_svector_ostream OS(Name);
-  Sym.printName(OS);
-  StringRef NameRef = Saver.save(StringRef(Name));
+  if (GV)
+    if (const Comdat *C = GV->getComdat())
+      if (!KeptComdats.count(C)) {
+        Body = new (Alloc)
+          UndefinedBitcode(NameRef, IsWeak, Visibility);
+        return Body;
+      }
 
   const Module &M = Obj.getModule();
-  SymbolBody *Body;
-  bool IsWeak = Flags & BasicSymbolRef::SF_Weak;
   if (Flags & BasicSymbolRef::SF_Undefined) {
     Body = new (Alloc) UndefinedBitcode(NameRef, IsWeak, Visibility);
   } else if (Flags & BasicSymbolRef::SF_Common) {


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