RFR(XXS): 8227338: templateInterpreter.cpp: copy_table() needs to be safer

[serguei.spitsyn at oracle.com]

Hi Dan,

This looks good too.

Thanks,
Serguei


n 7/9/19 07:09, Daniel D. Daugherty wrote:
> Greetings,
>
> I've made one minor tweak based on Kim's code review.
>
> Here's the full webrev:
>
> http://cr.openjdk.java.net/~dcubed/8227338-webrev/1_for_jdk14.full/
>
> Here's the incremental webrev:
>
> http://cr.openjdk.java.net/~dcubed/8227338-webrev/1_for_jdk14.inc/
>
> Here's the context diff:
>
> $ hg diff
> diff -r 32fe92d8b539 
> src/hotspot/share/interpreter/templateInterpreter.cpp
> --- a/src/hotspot/share/interpreter/templateInterpreter.cpp    Mon Jul 
> 08 16:58:27 2019 -0400
> +++ b/src/hotspot/share/interpreter/templateInterpreter.cpp    Tue Jul 
> 09 10:02:46 2019 -0400
> @@ -283,7 +283,7 @@
>    // Copy non-overlapping tables.
>    if (SafepointSynchronize::is_at_safepoint()) {
>      // Nothing is using the table at a safepoint so skip atomic word 
> copy.
> -    while (size-- > 0) *to++ = *from++;
> +    Copy::disjoint_words((HeapWord*)from, (HeapWord*)to, (size_t)size);
>    } else {
>      // Use atomic word copy when not at a safepoint for safety.
>      Copy::disjoint_words_atomic((HeapWord*)from, (HeapWord*)to, 
> (size_t)size);
>
> Thanks, in advance, for questions, comments or suggestions.
>
> Dan
>
>
> On 7/6/19 9:53 AM, Daniel D. Daugherty wrote:
>> Greetings,
>>
>> During the code review for the following fix:
>>
>>     JDK-8227117 normal interpreter table is not restored after single 
>> stepping with TLH
>>     https://bugs.openjdk.java.net/browse/JDK-8227117
>>
>> Erik O. noticed a potential race with templateInterpreter.cpp: 
>> copy_table()
>> depending on C++ compiler optimizations. The following bug is being used
>> to fix this issue:
>>
>>     JDK-8227338 templateInterpreter.cpp: copy_table() needs to be safer
>>     https://bugs.openjdk.java.net/browse/JDK-8227338
>>
>> Here's the webrev URL:
>>
>> http://cr.openjdk.java.net/~dcubed/8227338-webrev/0_for_jdk14/
>>
>> This fix has been tested via Mach5 Tier[1-3] on Oracle's usual 
>> platforms.
>> Mach5 tier[4-6] is running now. It has also been tested with the manual
>> jdb test from JDK-8227117 using 'release' and 'fastdebug' bits.
>>
>> Thanks, in advance, for questions, comments or suggestions.
>>
>> Dan
>>
>