Fix a bug in __builtin_object_size cast removal

Apparently there are many cast kinds that may cause implicit pointer
arithmetic to happen. In light of this, the cast ignoring logic
introduced in r246877 has been changed to only ignore a small set of
cast kinds, and a test for this behavior has been added.

Thanks to Richard for catching this before it became a bug report. :)

llvm-svn: 246890

1 files changed, 30 insertions, 0 deletions

diff --git a/clang/test/CodeGen/object-size.cpp b/clang/test/CodeGen/object-size.cpp
new file mode 100644
index 00000000000..1c9d1ae945d
--- /dev/null
+++ b/clang/test/CodeGen/object-size.cpp
@@ -0,0 +1,30 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm -o - %s | FileCheck %s
+
+// C++-specific tests for __builtin_object_size
+
+int gi;
+
+// CHECK-LABEL: define void @_Z5test1v()
+void test1() {
+  // Guaranteeing that our cast removal logic doesn't break more interesting
+  // cases.
+  struct A { int a; };
+  struct B { int b; };
+  struct C: public A, public B {};
+
+  C c;
+
+  // CHECK: store i32 8
+  gi = __builtin_object_size(&c, 0);
+  // CHECK: store i32 8
+  gi = __builtin_object_size((A*)&c, 0);
+  // CHECK: store i32 4
+  gi = __builtin_object_size((B*)&c, 0);
+
+  // CHECK: store i32 8
+  gi = __builtin_object_size((char*)&c, 0);
+  // CHECK: store i32 8
+  gi = __builtin_object_size((char*)(A*)&c, 0);
+  // CHECK: store i32 4
+  gi = __builtin_object_size((char*)(B*)&c, 0);
+}