Allow aliases to be unnamed_addr.

Alias with unnamed_addr were in a strange state. It is stored in GlobalValue,
the language reference talks about "unnamed_addr aliases" but the verifier
was rejecting them.

It seems natural to allow unnamed_addr in aliases:

* It is a property of how it is accessed, not of the data itself.
* It is perfectly possible to write code that depends on the address
of an alias.

This patch then makes unname_addr legal for aliases. One side effect is that
the syntax changes for a corner case: In globals, unnamed_addr is now printed
before the address space.

llvm-svn: 210302

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Linker/LinkModules.cpp b/llvm/lib/Linker/LinkModules.cpp
index ad8e01dc1be..8e205bb621e 100644
--- a/llvm/lib/Linker/LinkModules.cpp
+++ b/llvm/lib/Linker/LinkModules.cpp
@@ -893,6 +893,7 @@ bool ModuleLinker::linkFunctionProto(Function *SF) {
 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
   GlobalValue *DGV = getLinkedToGlobal(SGA);
   llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
+  bool HasUnnamedAddr = SGA->hasUnnamedAddr();
 
   if (DGV) {
     GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
@@ -901,11 +902,13 @@ bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
     if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
       return true;
     NewVisibility = NV;
+    HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
 
     if (!LinkFromSrc) {
       // Set calculated linkage.
       DGV->setLinkage(NewLinkage);
       DGV->setVisibility(*NewVisibility);
+      DGV->setUnnamedAddr(HasUnnamedAddr);
 
       // Make sure to remember this mapping.
       ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
@@ -926,6 +929,7 @@ bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
   copyGVAttributes(NewDA, SGA);
   if (NewVisibility)
     NewDA->setVisibility(*NewVisibility);
+  NewDA->setUnnamedAddr(HasUnnamedAddr);
 
   if (DGV) {
     // Any uses of DGV need to change to NewDA, with cast.