[LTO] Keep linkonce symbols when required.

Similarly to how we do with linkonce_odr symbols already, but
change their linkage to weak.

llvm-svn: 264181

3 files changed, 32 insertions, 1 deletions

diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
index ab97079bbd8..7197227a25a 100644
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -85,8 +85,16 @@ void BitcodeCompiler::add(BitcodeFile &F) {
     if (!BitcodeFile::shouldSkip(Sym)) {
       if (SymbolBody *B = Bodies[BodyIndex++])
         if (&B->repl() == B && isa<DefinedBitcode>(B)) {
-          if (GV->getLinkage() == llvm::GlobalValue::LinkOnceODRLinkage)
+          switch (GV->getLinkage()) {
+          default:
+            break;
+          case llvm::GlobalValue::LinkOnceAnyLinkage:
+            GV->setLinkage(GlobalValue::WeakAnyLinkage);
+            break;
+          case llvm::GlobalValue::LinkOnceODRLinkage:
             GV->setLinkage(GlobalValue::WeakODRLinkage);
+            break;
+          }
           Keep.push_back(GV);
         }
     }
diff --git a/lld/test/ELF/lto/Inputs/linkonce.ll b/lld/test/ELF/lto/Inputs/linkonce.ll
new file mode 100644
index 00000000000..a6738b3ad71
--- /dev/null
+++ b/lld/test/ELF/lto/Inputs/linkonce.ll
@@ -0,0 +1,6 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define linkonce void @f() {
+  ret void
+}
diff --git a/lld/test/ELF/lto/linkonce.ll b/lld/test/ELF/lto/linkonce.ll
new file mode 100644
index 00000000000..b32ffeb3372
--- /dev/null
+++ b/lld/test/ELF/lto/linkonce.ll
@@ -0,0 +1,17 @@
+; REQUIRES: x86
+; RUN: llvm-as %p/Inputs/linkonce.ll -o %t1.o
+; RUN: llc %s -o %t2.o -filetype=obj
+; RUN: ld.lld %t1.o %t2.o -o %t.so -shared -save-temps
+; RUN: llvm-dis %t.so.lto.opt.bc -o - | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+declare void @f()
+
+define void @g() {
+  call void @f()
+  ret void
+}
+
+; Be sure that 'f' is kept and has weak linkage.
+; CHECK: define weak void @f()