From 61c4e41480ef81f4449acc8604efdcd1c26607b2 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 7 Oct 2014 04:06:13 +0000
Subject: [PATCH] gold plugin: Handle gold selecting a linkonce GV when a weak
 is present.

The plugin API doesn't have the notion of linkonce, only weak. It is up to the
plugin to figure out if a symbol used only for the symbol table can be dropped.
In particular, it has to avoid dropping a linkonce_odr selected by gold if there
is also a weak_odr.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219188 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/tools/gold/Inputs/linkonce-weak.ll |  3 +++
 test/tools/gold/linkonce-weak.ll        | 19 +++++++++++++++++++
 tools/gold/gold-plugin.cpp              |  8 +++++++-
 3 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 test/tools/gold/Inputs/linkonce-weak.ll
 create mode 100644 test/tools/gold/linkonce-weak.ll

diff --git a/test/tools/gold/Inputs/linkonce-weak.ll b/test/tools/gold/Inputs/linkonce-weak.ll
new file mode 100644
index 00000000000..f42af8faa84
--- /dev/null
+++ b/test/tools/gold/Inputs/linkonce-weak.ll
@@ -0,0 +1,3 @@
+define weak_odr void @f() {
+  ret void
+}
diff --git a/test/tools/gold/linkonce-weak.ll b/test/tools/gold/linkonce-weak.ll
new file mode 100644
index 00000000000..765275b09d5
--- /dev/null
+++ b/test/tools/gold/linkonce-weak.ll
@@ -0,0 +1,19 @@
+; RUN: llvm-as %s -o %t.o
+; RUN: llvm-as %p/Inputs/linkonce-weak.ll -o %t2.o
+
+; RUN: ld -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --plugin-opt=emit-llvm \
+; RUN:    -shared %t.o %t2.o -o %t3.o
+; RUN: llvm-dis %t3.o -o - | FileCheck %s
+
+; RUN: ld -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --plugin-opt=emit-llvm \
+; RUN:    -shared %t2.o %t.o -o %t3.o
+; RUN: llvm-dis %t3.o -o - | FileCheck %s
+
+define linkonce_odr void @f() {
+  ret void
+}
+
+; Test that we get a weak_odr regardless of the order of the files
+; CHECK: define weak_odr void @f() {
diff --git a/tools/gold/gold-plugin.cpp b/tools/gold/gold-plugin.cpp
index ffee1ff3258..d5d58d0e588 100644
--- a/tools/gold/gold-plugin.cpp
+++ b/tools/gold/gold-plugin.cpp
@@ -637,8 +637,14 @@ getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
       keepGlobalValue(*GV, KeptAliases);
       break;
 
-    case LDPR_PREEMPTED_REG:
     case LDPR_PREEMPTED_IR:
+      // Gold might have selected a linkonce_odr and preempted a weak_odr.
+      // In that case we have to make sure we don't end up internalizing it.
+      if (!GV->isDiscardableIfUnused())
+        Maybe.erase(Sym.name);
+
+      // fall-through
+    case LDPR_PREEMPTED_REG:
       Drop.insert(GV);
       break;
 
-- 
2.34.1