IRGen: When performing CFI checks, load vtable pointer from vbase when necessary.

Under the Microsoft ABI, it is possible for an object not to have
a virtual table pointer of its own if all of its virtual functions
were introduced by virtual bases. In that case, we need to load the
vtable pointer from one of the virtual bases and perform the type
check using its type.

Differential Revision: https://reviews.llvm.org/D41036

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@320638 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 56 insertions, 0 deletions

diff --git a/test/CodeGenCXX/cfi-ms-vbase-derived-cast.cpp b/test/CodeGenCXX/cfi-ms-vbase-derived-cast.cpp
new file mode 100644
index 0000000000..3276d8f33e
--- /dev/null
+++ b/test/CodeGenCXX/cfi-ms-vbase-derived-cast.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -flto -flto-unit -emit-llvm -o - -triple=x86_64-pc-win32 %s -fsanitize=cfi-derived-cast -fsanitize-trap=cfi-derived-cast | FileCheck %s
+
+struct foo {
+  virtual ~foo() {}
+  virtual void f() = 0;
+};
+
+template <typename T>
+struct bar : virtual public foo {
+  void f() {
+    // CHECK: define{{.*}}@"\01?f@?$bar@Ubaz@@@@UEAAXXZ"
+    // Load "this", vbtable, vbase offset and vtable.
+    // CHECK: load
+    // CHECK: load
+    // CHECK: load
+    // CHECK: load
+    // CHECK: @llvm.type.test{{.*}}!"?AUfoo@@"
+    static_cast<T&>(*this);
+  }
+};
+
+struct baz : public bar<baz> {
+  virtual ~baz() {}
+};
+
+int main() {
+  baz *z = new baz;
+  z->f();
+}
diff --git a/test/CodeGenCXX/cfi-ms-vbase-nvcall.cpp b/test/CodeGenCXX/cfi-ms-vbase-nvcall.cpp
new file mode 100644
index 0000000000..ab61062823
--- /dev/null
+++ b/test/CodeGenCXX/cfi-ms-vbase-nvcall.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -flto -flto-unit -emit-llvm -o - -triple=x86_64-pc-win32 %s -fsanitize=cfi-nvcall -fsanitize-trap=cfi-nvcall | FileCheck %s
+
+struct foo {
+  virtual ~foo() {}
+  virtual void f() = 0;
+};
+
+template <typename T>
+struct bar : virtual public foo {
+  void f() {}
+};
+
+struct baz : public bar<baz> {
+  virtual ~baz() {}
+  void g() {}
+};
+
+void f(baz *z) {
+  // CHECK: define{{.*}}@"\01?f@@YAXPEAUbaz@@@Z"
+  // Load z, vbtable, vbase offset and vtable.
+  // CHECK: load
+  // CHECK: load
+  // CHECK: load
+  // CHECK: load
+  // CHECK: @llvm.type.test{{.*}}!"?AUfoo@@"
+  z->g();
+}