android: Realign stack pointer on JNI entry.

base/android/jni_generator/jni_generator_helper.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-
 #ifndef BASE_ANDROID_JNI_GENERATOR_JNI_GENERATOR_HELPER_H_
 #define BASE_ANDROID_JNI_GENERATOR_JNI_GENERATOR_HELPER_H_
 
 #include <jni.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/logging.h"
+#include "build/build_config.h"
 
 // Project-specific macros used by the header files generated by
 // jni_generator.py. Different projects can then specify their own
 // implementation for this file.
 #define CHECK_NATIVE_PTR(env, jcaller, native_ptr, method_name, ...) \
-    DCHECK(native_ptr) << method_name;
+  DCHECK(native_ptr) << method_name;
 
-#define CHECK_CLAZZ(env, jcaller, clazz, ...) \
-    DCHECK(clazz);
+#define CHECK_CLAZZ(env, jcaller, clazz, ...) DCHECK(clazz);
+
+#if defined(ARCH_CPU_X86)
+// Dalvik JIT generated code doesn't guarantee 16-byte stack alignment on
+// x86 - use force_align_arg_pointer to realign the stack at the JNI
+// boundary. crbug.com/655248
+#define JNI_GENERATOR_EXPORT \
+  extern "C" __attribute__((visibility("default"), force_align_arg_pointer))
+#else
+#define JNI_GENERATOR_EXPORT extern "C" __attribute__((visibility("default")))
+#endif
 
 namespace jni_generator {
 
-  inline void HandleRegistrationError(JNIEnv* env, jclass clazz,
-                                      const char* filename) {
-    LOG(ERROR) << "RegisterNatives failed in " << filename;
-  }
+inline void HandleRegistrationError(JNIEnv* env,
+                                    jclass clazz,
+                                    const char* filename) {
+  LOG(ERROR) << "RegisterNatives failed in " << filename;
+}
 
-  inline void CheckException(JNIEnv* env) {
-    base::android::CheckException(env);
-  }
+inline void CheckException(JNIEnv* env) {
+  base::android::CheckException(env);
+}
 
 }  // namespace jni_generator
 
 #endif  // BASE_ANDROID_JNI_GENERATOR_JNI_GENERATOR_HELPER_H_