Fix PR26152

[eugenis]

Summary

Fix the condition for when the new global takes over the name of
the existing one to be the negation of the condition for the new
global to get internal linkage.

[• rafael]

LGTM.

Thanks!

[eugenis]

Thanks, committed as
http://reviews.llvm.org/rL258355

lib/Linker/IRMover.cpp

Constant *IRLinker::linkGlobalValueProto(GlobalValue *SGV, bool ForAlias) {
   } else {
     // If we are done linking global value bodies (i.e. we are performing
     // metadata linking), don't link in the global value due to this
     // reference, simply map it to null.
     if (DoneLinkingBodies)
       return nullptr;
 
     NewGV = copyGlobalValueProto(SGV, ShouldLink);
-    if (!ForAlias)
+    if (ShouldLink || !ForAlias)
       forceRenaming(NewGV, SGV->getName());
   }
   if (ShouldLink || ForAlias) {
     if (const Comdat *SC = SGV->getComdat()) {
       if (auto *GO = dyn_cast<GlobalObject>(NewGV)) {
         Comdat *DC = DstM.getOrInsertComdat(SC->getName());
         DC->setSelectionKind(SC->getSelectionKind());
         GO->setComdat(DC);

test/Linker/Inputs/alias-2.ll

+define void @B() {
+  call void @A()
+  ret void
+}
+
+declare void @A()
+

test/Linker/alias-2.ll

+; RUN: llvm-link %s %S/Inputs/alias-2.ll -S -o - | FileCheck %s
+; RUN: llvm-link %S/Inputs/alias-2.ll %s -S -o - | FileCheck %s
+
+; Test the fix for PR26152, where A from the second module is
+; erroneously renamed to A.1 and not linked to the declaration from
+; the first module
+
+@C = alias void (), void ()* @A
+
+define void @D() {
+  call void @C()
+  ret void
+}
+
+define void @A() {
+  ret void
+}
+
+; CHECK-DAG: @C = alias void (), void ()* @A
+; CHECK-DAG: define void @B()
+; CHECK-DAG:   call void @A()
+; CHECK-DAG: define void @D()
+; CHECK-DAG:   call void @C()
+; CHECK-DAG: define void @A()