[clang] [compiler-rt] [compiler-rt][rtsan] Introduce rtsan_interface.h and ScopedDisabler (PR #106736)

[Chris Apple via cfe-commits]

================
@@ -0,0 +1,117 @@
+//===-- sanitizer/rtsan_interface.h -----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of RealtimeSanitizer.
+//
+// Public interface header.
+//===----------------------------------------------------------------------===//
+
+#ifndef SANITIZER_RTSAN_INTERFACE_H
+#define SANITIZER_RTSAN_INTERFACE_H
+
+#if __has_include(<sanitizer/common_interface_defs.h>)
+#include <sanitizer/common_interface_defs.h>
+#else
+#define SANITIZER_CDECL
+#endif // __has_include(<sanitizer/common_interface_defs.h>)
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+// Initializes rtsan if it has not been initialized yet.
+// Used by the RTSan runtime to ensure that rtsan is initialized before any
+// other rtsan functions are called.
+void SANITIZER_CDECL __rtsan_ensure_initialized();
+
+// Enter real-time context.
+// When in a real-time context, RTSan interceptors will error if realtime
+// violations are detected. Calls to this method are injected at the code
+// generation stage when RTSan is enabled.
+void SANITIZER_CDECL __rtsan_realtime_enter();
+
+// Exit the real-time context.
+// When not in a real-time context, RTSan interceptors will simply forward
+// intercepted method calls to the real methods.
+void SANITIZER_CDECL __rtsan_realtime_exit();
+
+// Disable all RTSan error reporting.
+void SANITIZER_CDECL __rtsan_disable(void);
+
+// Re-enable all RTSan error reporting.
+// The counterpart to `__rtsan_disable`.
+void SANITIZER_CDECL __rtsan_enable(void);
+
+// Expect that the next call to a function with the given name will not be
+// called from a realtime context.
+void SANITIZER_CDECL
+__rtsan_expect_not_realtime(const char *intercepted_function_name);
+
+#ifdef __cplusplus
+} // extern "C"
+
+namespace __rtsan {
+#if (defined(__has_feature) && __has_feature(realtime_sanitizer)) ||           \
+    SANITIZE_REALTIME
----------------
cjappl wrote:

Envisioned use case:

```cpp
#define SANITIZE_REALTIME (MY_CUSTOM_RTSAN_ENABLED)
#include <sanitizer/rtsan_interface.h>

void main() {
  __rtsan::Initialize();
  ...
}

void process() {
  __rtsan::ScopedEnabler rtsan{};

  auto x = std::make_unique<float>(3.0f);
}

```

https://github.com/llvm/llvm-project/pull/106736