[WebAssembly] Support VPtr sanitizer for Emscripten

Summary:
After https://github.com/emscripten-core/emscripten/pull/8651, Emscripten
supports the full UBSan runtime. This includes the VPtr sanitizer.

This diff allows clang to generate code that uses the VPtr sanitizer for
Emscripten.

Patch by Guanzhong Chen

Reviewers: tlively, aheejin

Reviewed By: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, sunfish, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62559

llvm-svn: 362004

1 files changed, 20 insertions, 0 deletions

diff --git a/clang/test/CodeGenCXX/wasm-sanitize-vptr.cpp b/clang/test/CodeGenCXX/wasm-sanitize-vptr.cpp
new file mode 100644
index 00000000000..2a9055aea1e
--- /dev/null
+++ b/clang/test/CodeGenCXX/wasm-sanitize-vptr.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -std=c++11 -fsanitize=vptr -emit-llvm %s -o - -triple wasm32-unknown-emscripten | FileCheck %s
+
+struct S {
+  virtual ~S() {}
+  int a;
+};
+
+struct T : S {
+  int b;
+};
+
+// CHECK-LABEL: @_Z15bad_static_castv
+void bad_static_cast() {
+  S s;
+  // CHECK: br i1 %[[NONNULL:.*]], label %[[CONT:.*]], label %[[MISS:.*]], !prof
+  // CHECK: [[MISS]]:
+  // CHECK: call void @__ubsan_handle_dynamic_type_cache_miss_abort
+  // CHECK: [[CONT]]:
+  T &r = static_cast<T &>(s);
+}