[15] RFR(M): 8244207: Simplify usage of Compile::print_method() when debugging with gdb and enable its use with rr

[Tobias Hartmann]

+1

Best regards,
Tobias

On 08.05.20 20:33, Vladimir Kozlov wrote:
> Good.
> 
> Thanks,
> Vladimir
> 
> On 5/8/20 1:45 AM, Christian Hagedorn wrote:
>> Thank you Vladimir and Tobias for your reviews!
>>
>> On 08.05.20 08:24, Tobias Hartmann wrote:
>>> looks good to me too but please use (jio_)snprintf instead of unsafe sprintf.
>>
>> Thinking of which, we could probably directly use the phase_name parameter and call print_method()
>> without allocating a char array and using jio_snprintf. However, it might be a good idea to change
>> sprintf into jio_snprintf in Compile::print_method (where I got this code from). There it makes
>> sense to use an additional char array to concatenate two strings.
>>
>> I included those changes together with the typo fix in a new webrev:
>> http://cr.openjdk.java.net/~chagedorn/8244207/webrev.01/
>>
>> Best regards,
>> Christian
>>
>>> On 07.05.20 20:38, Vladimir Kozlov wrote:
>>>> Looks good.
>>>>
>>>> Thanks,
>>>> Vladimir
>>>>
>>>> On 5/7/20 5:09 AM, Christian Hagedorn wrote:
>>>>> Hi
>>>>>
>>>>> Please review the following debugging enhancement:
>>>>> https://bugs.openjdk.java.net/browse/JDK-8244207
>>>>> http://cr.openjdk.java.net/~chagedorn/8244207/webrev.00/
>>>>>
>>>>> This enhancement simplifies the usage for printing the ideal graph for visualization with the
>>>>> Ideal Graph Visualizer when debugging with gdb and enables graph printing with rr [1].
>>>>>
>>>>> Instead of calling Compile::current()->print_method(PHASE_X, y, z) from gdb, one can now just call
>>>>> igv_print() or igv_print(phase_name) with a custom phase name. There are multiple options
>>>>> depending on where the graph should be printed to (file or over network/locally to an opened Ideal
>>>>> Graph Visualizer). When choosing file, the output is always printed to a file named
>>>>> custom_debug.xml. I think the flexibility to choose another file name is not really required since
>>>>> it's only used while debugging. These new igv_print() methods can also be called from gdb without
>>>>> setting any flags required for the usual calls to Compile::current()->print_method(PHASE_X, y, z)
>>>>> to work.
>>>>>
>>>>> The standard Compile::current()->print_method(PHASE_X, y, z) call does not work while debugging a
>>>>> program trace with rr (and is probably also problematic with related replay tools). The call gets
>>>>> stuck somewhere. rr allows to alter some data at a breakpoint but as soon as execution continues
>>>>> on the replayed trace, the modifications are undone (except for file writes). This enhancement
>>>>> also addresses this such that the new igv_print() methods can be used with rr. However, when
>>>>> printing to a file is chosen, igv_print() will overwrite custom_debug.xml again at the next
>>>>> execution stop. To avoid that I added additional rr-specific igv_append() and
>>>>> igv_append(phase_name) methods that simply append a graph to the existing custom_debug.xml file
>>>>> without setting up a file header again. This allows all printed graphs to be kept in one file
>>>>> which makes it easier to navigate through them.
>>>>>
>>>>> Thank you!
>>>>>
>>>>> Best regards,
>>>>> Christian
>>>>>
>>>>>
>>>>> [1] https://rr-project.org/