[ubsan] Diagnose noreturn functions which return

Diagnose 'unreachable' UB when a noreturn function returns.

  1. Insert a check at the end of functions marked noreturn.

  2. A decl may be marked noreturn in the caller TU, but not marked in
     the TU where it's defined. To diagnose this scenario, strip away the
     noreturn attribute on the callee and insert check after calls to it.

Testing: check-clang, check-ubsan, check-ubsan-minimal, D40700

rdar://33660464

Differential Revision: https://reviews.llvm.org/D40698

llvm-svn: 321231

1 files changed, 81 insertions, 0 deletions

diff --git a/clang/test/CodeGenCXX/ubsan-unreachable.cpp b/clang/test/CodeGenCXX/ubsan-unreachable.cpp
new file mode 100644
index 00000000000..32a78048cfd
--- /dev/null
+++ b/clang/test/CodeGenCXX/ubsan-unreachable.cpp
@@ -0,0 +1,81 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -o - %s -fsanitize=unreachable | FileCheck %s
+
+extern void __attribute__((noreturn)) abort();
+
+// CHECK-LABEL: define void @_Z14calls_noreturnv
+void calls_noreturn() {
+  abort();
+
+  // Check that there are no attributes on the call site.
+  // CHECK-NOT: call void @_Z5abortv{{.*}}#
+
+  // CHECK: __ubsan_handle_builtin_unreachable
+  // CHECK: unreachable
+}
+
+struct A {
+  // CHECK: declare void @_Z5abortv{{.*}} [[ABORT_ATTR:#[0-9]+]]
+
+  // CHECK-LABEL: define linkonce_odr void @_ZN1A5call1Ev
+  void call1() {
+    // CHECK-NOT: call void @_ZN1A16does_not_return2Ev{{.*}}#
+    does_not_return2();
+
+    // CHECK: __ubsan_handle_builtin_unreachable
+    // CHECK: unreachable
+  }
+
+  // Test static members.
+  static void __attribute__((noreturn)) does_not_return1() {
+    // CHECK-NOT: call void @_Z5abortv{{.*}}#
+    abort();
+  }
+
+  // CHECK-LABEL: define linkonce_odr void @_ZN1A5call2Ev
+  void call2() {
+    // CHECK-NOT: call void @_ZN1A16does_not_return1Ev{{.*}}#
+    does_not_return1();
+
+    // CHECK: __ubsan_handle_builtin_unreachable
+    // CHECK: unreachable
+  }
+
+  // Test calls through pointers to non-static member functions.
+  typedef void __attribute__((noreturn)) (A::*MemFn)();
+
+  // CHECK-LABEL: define linkonce_odr void @_ZN1A5call3Ev
+  void call3() {
+    MemFn MF = &A::does_not_return2;
+    (this->*MF)();
+
+    // CHECK-NOT: call void %{{.*}}#
+    // CHECK: __ubsan_handle_builtin_unreachable
+    // CHECK: unreachable
+  }
+
+  // Test regular members.
+  // CHECK-LABEL: define linkonce_odr void @_ZN1A16does_not_return2Ev({{.*}})
+  // CHECK-SAME: [[DOES_NOT_RETURN_ATTR:#[0-9]+]]
+  void __attribute__((noreturn)) does_not_return2() {
+    // CHECK-NOT: call void @_Z5abortv(){{.*}}#
+    abort();
+
+    // CHECK: call void @__ubsan_handle_builtin_unreachable
+    // CHECK: unreachable
+
+    // CHECK: call void @__ubsan_handle_builtin_unreachable
+    // CHECK: unreachable
+  }
+};
+
+// CHECK: define linkonce_odr void @_ZN1A16does_not_return1Ev() [[DOES_NOT_RETURN_ATTR]]
+
+void force_irgen() {
+  A a;
+  a.call1();
+  a.call2();
+  a.call3();
+}
+
+// CHECK-NOT: [[ABORT_ATTR]] = {{[^}]+}}noreturn
+// CHECK-NOT: [[DOES_NOT_RETURN_ATTR]] = {{[^}]+}}noreturn