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From "Chunrong Lai (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-5714) [drlvm] Remove extra synchronization runtime helpers.
Date Wed, 12 Nov 2008 07:17:44 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-5714?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12646819#action_12646819
] 

Chunrong Lai commented on HARMONY-5714:
---------------------------------------


 The confused issues in this patch are listed in below:

- * Throw <code>java/lang/NullPointerException</code>, if the argument is null.
+ * Doesn't throw <code>java/lang/NullPointerException</code>, if the argument
+ * is null, it assumes that the argument is non-null. Passing a null argument
+ * will result in undefined behavior..

- * Throw <code>java/lang/NullPointerException</code>, if the argument is null.
+ * Doesn't throw <code>java/lang/NullPointerException</code>, if the argument
+ * is null, it assumes that the argument is non-null. Passing a null argument
+ * will result in undefined behavior.

+#ifdef _DEBUG_CHECK_NULL_ //_DEBUG    
+    //npe check
     ss = test(ss,  ecx_opnd,   ecx_opnd);
     ss = branch8(ss, Condition_Z,  Imm_Opnd(size_8, 0));
     char *backpatch_address__null_pointer = ((char *)ss) - 1;
+#endif

+#ifdef _DEBUG_CHECK_NULL_//_DEBUG    
     // Handle NPE here
     signed npe_offset = (signed)ss - (signed)backpatch_address__null_pointer - 1;
     *backpatch_address__null_pointer = (char)npe_offset;
@@ -118,53 +101,10 @@
     }
     // Object is null so throw a null pointer exception
     ss = jump(ss, (char*)exn_get_rth_throw_null_pointer());
-
+#endif

   Say, the patch removed the null_check in the stub of vm_moniter_enter but
   requires JIT's support to never pass a NullObject to it.
   I am not sure if we have previous discussion about such convention to allow that.
   Anyway a safe way to me is re-enable the CHECK_NULL in the stub.

   Can some JIT experts also give your opinion in this issue?


> [drlvm] Remove extra synchronization runtime helpers.
> -----------------------------------------------------
>
>                 Key: HARMONY-5714
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5714
>             Project: Harmony
>          Issue Type: Improvement
>          Components: DRLVM
>            Reporter: Pavel Afremov
>            Assignee: Chunrong Lai
>         Attachments: extra_strong_assert_fix.patch, extra_strong_assert_fix.patch, remove_extra_monitors_helper_1.patch,
remove_extra_monitors_helper_2.patch, remove_extra_monitors_helper_3.patch
>
>
> Remove extra synchronization runtime helpers.
> All list of synchronization runtime helpers:
> •	VM_RT_MONITOR_ENTER_NON_NULL
> •	VM_RT_MONITOR_EXIT_NON_NULL
> •	VM_RT_MONITOR_ENTER_STATIC
> •	VM_RT_MONITOR_EXIT_STATIC
> •	VM_RT_MONITOR_ENTER
> •	VM_RT_MONITOR_EXIT
>  can be replace by two helpers only:
> •	VM_RT_MONITOR_ENTER
> •	VM_RT_MONITOR_EXIT
> It reduces quantity of synchronization helpers in 3 times.

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