From d2e0ff3b7ff356f47973647da7cd90f8a4962bb9 Mon Sep 17 00:00:00 2001
From: Teresa Johnson <tejohnson@google.com>
Date: Wed, 4 Nov 2015 16:01:16 +0000
Subject: [PATCH] [ThinLTO] Always set linkage type to external when converting
 alias

When converting an alias to a non-alias when the aliasee is not
imported, ensure that the linkage type is set to external so that it is
a valid linkage type. Added a test case that exposed this issue.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252054 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Linker/LinkModules.cpp |  6 ++++--
 test/Linker/funcimport.ll  | 11 +++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index b7aab9e9644..a855ec06d17 100644
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -841,10 +841,12 @@ GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
       assert(F);
       NewGV = copyFunctionProto(TypeMap, F);
     }
-    // Set the linkage to ExternalWeak, see also comments in
-    // ModuleLinker::getLinkage.
+    // Set the linkage to External or ExternalWeak (see comments in
+    // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
     if (SGA->hasWeakAnyLinkage())
       NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
+    else
+      NewGV->setLinkage(GlobalValue::ExternalLinkage);
     // Don't attempt to link body, needs to be a declaration.
     DoNotLinkFromSource.insert(SGA);
     return NewGV;
diff --git a/test/Linker/funcimport.ll b/test/Linker/funcimport.ll
index 1b9a08694d8..97a34ffd233 100644
--- a/test/Linker/funcimport.ll
+++ b/test/Linker/funcimport.ll
@@ -14,11 +14,16 @@
 
 ; Ensure that both weak alias to an imported function and strong alias to a
 ; non-imported function are correctly turned into declarations.
+; Also ensures that alias to a linkonce function is turned into a declaration
+; and that the associated linkonce function is not in the output, as it is
+; lazily linked and never referenced/materialized.
 ; RUN: llvm-link %t2.bc -functionindex=%t3.thinlto.bc -import=globalfunc1:%t.bc -S | FileCheck %s --check-prefix=IMPORTGLOB1
 ; IMPORTGLOB1: define available_externally void @globalfunc1
 ; IMPORTGLOB1: declare void @globalfunc2
 ; IMPORTGLOB1: declare extern_weak void @weakalias
 ; IMPORTGLOB1: declare void @analias
+; IMPORTGLOB1: declare void @linkoncealias
+; IMPORTGLOB1-NOT: @linkoncefunc
 
 ; Ensure that weak alias to a non-imported function is correctly
 ; turned into a declaration, but that strong alias to an imported function
@@ -91,6 +96,7 @@
 
 @weakalias = weak alias void (...), bitcast (void ()* @globalfunc1 to void (...)*)
 @analias = alias void (...), bitcast (void ()* @globalfunc2 to void (...)*)
+@linkoncealias = alias void (...), bitcast (void ()* @linkoncefunc to void (...)*)
 
 define void @globalfunc1() #0 {
 entry:
@@ -102,6 +108,11 @@ entry:
   ret void
 }
 
+define linkonce_odr void @linkoncefunc() #0 {
+entry:
+  ret void
+}
+
 define i32 @referencestatics(i32 %i) #0 {
 entry:
   %i.addr = alloca i32, align 4
-- 
2.34.1