From: Peter Collingbourne <peter@pcc.me.uk>
Date: Thu, 10 Aug 2017 01:07:44 +0000 (+0000)
Subject: Linker: Create a function declaration when moving a non-prevailing alias of function... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9e6aa3e0fefb3f5df241ba5175c5e0907199bb01;p=llvm

Linker: Create a function declaration when moving a non-prevailing alias of function type.

We were previously creating a global variable of function type,
which is invalid IR. This issue was exposed by r304690, in which we
started asserting that global variables were of a valid type.

Fixes PR33462.

Differential Revision: https://reviews.llvm.org/D36438

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310543 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Linker/IRMover.cpp b/lib/Linker/IRMover.cpp
index f486e525b5e..ee067a912e3 100644
--- a/lib/Linker/IRMover.cpp
+++ b/lib/Linker/IRMover.cpp
@@ -640,6 +640,10 @@ GlobalValue *IRLinker::copyGlobalValueProto(const GlobalValue *SGV,
   } else {
     if (ForDefinition)
       NewGV = copyGlobalAliasProto(cast<GlobalAlias>(SGV));
+    else if (SGV->getValueType()->isFunctionTy())
+      NewGV =
+          Function::Create(cast<FunctionType>(TypeMap.get(SGV->getValueType())),
+                           GlobalValue::ExternalLinkage, SGV->getName(), &DstM);
     else
       NewGV = new GlobalVariable(
           DstM, TypeMap.get(SGV->getValueType()),
diff --git a/test/LTO/Resolution/X86/function-alias-non-prevailing.ll b/test/LTO/Resolution/X86/function-alias-non-prevailing.ll
new file mode 100644
index 00000000000..ab2cefebb42
--- /dev/null
+++ b/test/LTO/Resolution/X86/function-alias-non-prevailing.ll
@@ -0,0 +1,17 @@
+; RUN: llvm-as -o %t %s
+; RUN: llvm-lto2 run %t -r %t,foo, -r %t,baz,p -o %t2 -save-temps
+; RUN: llvm-dis -o - %t2.0.0.preopt.bc | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--fuchsia"
+
+; CHECK: declare void @foo()
+@foo = weak alias void(), void()* @bar
+
+define internal void @bar() {
+  ret void
+}
+
+define void()* @baz() {
+  ret void()* @foo
+}