RFR [16] 8248170 Excessive include of compiledMethod, codeCache, javaClasses and systemDictionary

[Ioi Lam]

On 6/23/20 9:08 PM, David Holmes wrote:
> Hi Ioi,
>
> On 24/06/2020 6:10 am, Ioi Lam wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8248170
>> http://cr.openjdk.java.net/~iklam/jdk16/8248170-fix-includes-compiledMethod-etc.v01/ 
>>
>>
>> {compiledMethod, codeCache, javaClasses, systemDictionary}.hpp are 
>> unnecessarily included in some popular headers. This introduces 
>> unnecessary dependencies and slows down compile time.
>
> Based on your non-PCH local builds?
>
> I have no issue with removing unnecessary includes but I see far more 
> added includes in your changes than I see removals, so I'm a little 
> confused by that. I also have to wonder how on earth you concluded 
> that these particular includes were the cause of your problem ??
>
I ran a script on my local non-PCH build and got the following output. I 
scan the file from the bottom to look for things to fix.

http://cr.openjdk.java.net/~iklam/jdk16/misc/8248170-headers.txt

The reasons for adding new includes: the fix has 2 parts

(a) Remove unnecessary headers included by popular files such as thread.hpp
(b) The above causes some sources files to break, because they were 
missing includes. These files could compile before my patch because the 
missing dependency was transitively included by thread.hpp, etc. Now I 
need to add the missing includes.

E.g., os_windows.cpp has this

2342     CodeBlob* cb = CodeCache::find_blob(pc);

... so it needs to include codeCache.hpp, but that was transitively 
included by vmOperations.hpp.

=============

I updated the patch based on Coleen's off-line feedback:

http://cr.openjdk.java.net/~iklam/jdk16/8248170-fix-includes-compiledMethod-etc.v02/
http://cr.openjdk.java.net/~iklam/jdk16/8248170-fix-includes-compiledMethod-etc.v02.delta/


Thanks
- Ioi

> The change seems harmless so I don't object.
>
> Thanks,
> David
>
>> slowdebug:
>> total number of files compiled: 264606 -> 260588 = -1.5%
>> total number of lines compiled: 76073364 -> 74477347 = -2.1%
>> size of libjvm.so (internal symbols): 234180296 bytes -> 233129904 
>> bytes = -0.5%
>>
>> (I got the statistics by parsing the *.d files in the build directory).
>>
>> Thanks
>> - Ioi