From b75a50b1212a4d632d194457eb34dd74277f7535 Mon Sep 17 00:00:00 2001
From: "Ivan A. Kosarev" <ikosarev@accesssoftek.com>
Date: Tue, 26 Sep 2017 14:22:48 +0000
Subject: [PATCH] Fix TBAA information for reference accesses

This patch fixes clang to decorate reference accesses as pointers
and not as "omnipotent chars".

Differential Revision: https://reviews.llvm.org/D38074

llvm-svn: 314209
---
 clang/lib/CodeGen/CodeGenTBAA.cpp     |  4 ++--
 clang/test/CodeGen/tbaa-reference.cpp | 29 +++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/CodeGen/tbaa-reference.cpp

diff --git a/clang/lib/CodeGen/CodeGenTBAA.cpp b/clang/lib/CodeGen/CodeGenTBAA.cpp
index 8a75a55..3ae2956 100644
--- a/clang/lib/CodeGen/CodeGenTBAA.cpp
+++ b/clang/lib/CodeGen/CodeGenTBAA.cpp
@@ -145,10 +145,10 @@ CodeGenTBAA::getTBAAInfo(QualType QTy) {
   if (Ty->isStdByteType())
     return MetadataCache[Ty] = getChar();
 
-  // Handle pointers.
+  // Handle pointers and references.
   // TODO: Implement C++'s type "similarity" and consider dis-"similar"
   // pointers distinct.
-  if (Ty->isPointerType())
+  if (Ty->isPointerType() || Ty->isReferenceType())
     return MetadataCache[Ty] = createTBAAScalarType("any pointer",
                                                     getChar());
 
diff --git a/clang/test/CodeGen/tbaa-reference.cpp b/clang/test/CodeGen/tbaa-reference.cpp
new file mode 100644
index 0000000..aae6a82
--- /dev/null
+++ b/clang/test/CodeGen/tbaa-reference.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s -emit-llvm -o - | FileCheck %s
+//
+// Check that we generate correct TBAA information for reference accesses.
+
+struct S;
+
+struct B {
+  S &s;
+  B(S &s) : s(s) {}
+  void bar();
+};
+
+void foo(S &s) {
+  B b(s);
+  b.bar();
+}
+
+// CHECK-LABEL: _Z3fooR1S
+// Check initialization of the reference parameter in foo().
+// CHECK: store %struct.S* {{.*}}, %struct.S** {{.*}}, !tbaa [[TAG_pointer:!.*]]
+//
+// CHECK-LABEL: _ZN1BC2ER1S
+// TODO: Check loading of the reference parameter in B::B(S&).
+// Check initialization of B::s in B::B(S&).
+// CHECK: store %struct.S* {{.*}}, %struct.S** {{.*}}, !tbaa [[TAG_pointer]]
+//
+// CHECK-DAG: [[TAG_pointer]] = !{[[TYPE_pointer:!.*]], [[TYPE_pointer]], i64 0}
+// CHECK-DAG: [[TYPE_pointer]] = !{!"any pointer", [[TYPE_char:!.*]], i64 0}
+// CHECK-DAG: [[TYPE_char]] = !{!"omnipotent char", {{!.*}}, i64 0}
-- 
2.7.4