[GWP-ASan] Use weak abort message definition.

[hctim]

Summary

New shard out of the Check() function for GWP-ASan uses
android_set_abort_message. This is happily present on bionic Android,
but not Android for glibc host x86. Fix up to use the weak definition
always, so we don't have to worry.

[eugenis]

compiler-rt/lib/gwp_asan/platform_specific/utilities_posix.cpp

12–13

Is this include needed?

23

don't just return if the function is not available.
abort()

[hctim]

compiler-rt/lib/gwp_asan/platform_specific/utilities_posix.cpp

12–13

Removed.

[hctim]

• Addressed eugenis@ comments.

[eugenis]

LGTM

[pcc]

compiler-rt/lib/gwp_asan/platform_specific/utilities_posix.cpp

12

Who is defining ANDROID? Shouldn't the code be checking __BIONIC__ instead?

compiler-rt/lib/gwp_asan/definitions.h

 #define GWP_ASAN_DEFINITIONS_H_
 
 #define GWP_ASAN_TLS_INITIAL_EXEC                                              \
   __thread __attribute__((tls_model("initial-exec")))
 
 #define GWP_ASAN_UNLIKELY(X) __builtin_expect(!!(X), 0)
 #define GWP_ASAN_ALWAYS_INLINE inline __attribute__((always_inline))
 
+#define GWP_ASAN_WEAK __attribute__((weak))
+
 #endif // GWP_ASAN_DEFINITIONS_H_

compiler-rt/lib/gwp_asan/platform_specific/utilities_posix.cpp

 //===-- utilities_posix.cpp -------------------------------------*- 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
 //
 //===----------------------------------------------------------------------===//
 
+#include "gwp_asan/definitions.h"
 #include "gwp_asan/utilities.h"
 
 #ifdef ANDROID
-#include <android/set_abort_message.h>
 #include <stdlib.h>
+extern "C" GWP_ASAN_WEAK void android_set_abort_message(const char *);
 #else // ANDROID
 #include <stdio.h>
 #endif
 
 namespace gwp_asan {
 
 #ifdef ANDROID
 void Check(bool Condition, const char *Message) {
   if (Condition)
     return;
+  if (&android_set_abort_message != nullptr)
     android_set_abort_message(Message);
   abort();
 }
 #else  // ANDROID
 void Check(bool Condition, const char *Message) {
   if (Condition)
     return;
   fprintf(stderr, "%s", Message);
   __builtin_trap();
 }
 #endif // ANDROID
 
 } // namespace gwp_asan