Link the type of aliases.

They are not more or less "well typed" than GlobalVariables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222725 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Linker/LinkModules.cpp

@@ -786,6 +786,11 @@ void ModuleLinker::computeTypeMapping() {
       TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
   }
 
+  for (GlobalValue &SGV : SrcM->aliases()) {
+    if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
+      TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
+  }
+
   // Incorporate types by name, scanning all the types in the source module.
   // At this point, the destination module may have a type "%foo = { i32 }" for
   // example.  When the source module got loaded into the same LLVMContext, if
@@ -829,8 +834,6 @@ void ModuleLinker::computeTypeMapping() {
         TypeMap.addTypeMapping(DST, ST);
   }
 
-  // Don't bother incorporating aliases, they aren't generally typed well.
-
   // Now that we have discovered all of the type equivalences, get a body for
   // any 'opaque' types in the dest module that are now resolved.
   TypeMap.linkDefinedTypeBodies();

test/Linker/Inputs/type-unique-alias.ll

@@ -0,0 +1,4 @@
+%u = type { i8 }
+
+@g2 = global %u zeroinitializer
+@a = weak alias %u* @g2

test/Linker/type-unique-alias.ll

@@ -0,0 +1,10 @@
+; RUN: llvm-link -S %s %p/Inputs/type-unique-alias.ll | FileCheck %s
+
+%t = type { i8 }
+
+@g = global %t zeroinitializer
+@a = weak alias %t* @g
+
+; CHECK: @g = global %t zeroinitializer
+; CHECK: @g2 = global %t zeroinitializer
+; CHECK: @a = weak alias %t* @g