[GlobalsAA] Don't let dbg intrinsics affect analysis result

Summary:
This fixes PR35899.

Debug info intrinsics shouldn't affect code generation so ignore them
in GlobalsAA.

Reviewers: hfinkel, aprantl

Reviewed By: aprantl

Subscribers: aprantl, llvm-commits

Differential Revision: https://reviews.llvm.org/D41984

llvm-svn: 322470
diff --git a/llvm/lib/Analysis/GlobalsModRef.cpp b/llvm/lib/Analysis/GlobalsModRef.cpp
index daee932..9f33b94 100644
--- a/llvm/lib/Analysis/GlobalsModRef.cpp
+++ b/llvm/lib/Analysis/GlobalsModRef.cpp
@@ -582,6 +582,10 @@
           } else if (Function *Callee = CS.getCalledFunction()) {
             // The callgraph doesn't include intrinsic calls.
             if (Callee->isIntrinsic()) {
+              if (isa<DbgInfoIntrinsic>(I))
+                // Don't let dbg intrinsics affect alias info.
+                continue;
+
               FunctionModRefBehavior Behaviour =
                   AAResultBase::getModRefBehavior(Callee);
               FI.addModRefInfo(createModRefInfo(Behaviour));