test/hotspot/jtreg/vmTestbase/nsk/jdwp/ThreadReference/ForceEarlyReturn/forceEarlyReturn002/libforceEarlyReturn002a.cpp

*** 1,7 ****
  /*
!  * Copyright (c) 2007, 2018, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 29,52 ****
  int always_true = 1;
  
  JNIEXPORT jint JNICALL
  Java_nsk_jdwp_ThreadReference_ForceEarlyReturn_forceEarlyReturn002_forceEarlyReturn002a_nativeMethod(JNIEnv *env, jobject classObject, jobject object)
  {
-     int dummy_counter = 0;
      // notify another thread that thread in native method
      jclass klass = env->GetObjectClass(object);
      jfieldID field = env->GetFieldID(klass, "threadInNative", "Z");
      env->SetBooleanField(object, field, 1);
  
!     // execute infinite loop to be sure that thread in native method
!     while (always_true)
!     {
!         // Need some dummy code so the optimizer does not remove this loop.
!         dummy_counter = dummy_counter < 1000 ? 0 : dummy_counter + 1;
!     }
!     // The optimizer can be surprisingly clever.
!     // Use dummy_counter so it can never be optimized out.
!     // This statement will always return 0.
!     return dummy_counter >= 0 ? 0 : 1;
  }
  
  }
--- 29,47 ----
  int always_true = 1;
  
  JNIEXPORT jint JNICALL
  Java_nsk_jdwp_ThreadReference_ForceEarlyReturn_forceEarlyReturn002_forceEarlyReturn002a_nativeMethod(JNIEnv *env, jobject classObject, jobject object)
  {
      // notify another thread that thread in native method
      jclass klass = env->GetObjectClass(object);
      jfieldID field = env->GetFieldID(klass, "threadInNative", "Z");
      env->SetBooleanField(object, field, 1);
  
!     // attempt to read char from stdin instead of infinite loop
!     // because infinite loop might be eliminated by compiler optimizer.
!     fgetc(stdin);
! 
!     // should not reach here
!     return -1;
  }
  
  }