Generated compiler command file overrides user specified compiler command file

[Aleksey Shipilev]

On 05/27/2014 11:07 PM, Nitsan Wakart wrote:
>>> 2. The merge expects 0 or one CompileCommandFile to be specified
>>> by the user. Only the first file is merged. Others are ignored.
>> 
>> Merging the first file is OK, since Hotspot will normally ignore 
>> multiple -XX:CCF.
>> 
> You are right, but it will take the last, not the first. I think we
> should do what the JVM should have done here and not allow
> it(preferred) OR merge them all.

All right, since multiple CCFs are the corner case nobody will use,
let's shoot for code clarity, and merge them all.

>> * What's the reason hintsFile and hintsFile(String) are almost 
>> identical? Can we merge them together? Also,
>> RunnerTest.tempFileWithLine is also similar. Should we introduce
>> the utility method? Get that into Utils.
> You are right on code smell. The difference here is that the hints
> file is cached when default but notionally needs rebuilding when
> merging is required(could introduce a map if cache is required).
> I'll come up with a better solution, but clarification on the need
> for caching is appreciated.

The caching there is the performance optimization, and it was proven
useful (think about the case when there are thousands of hints --
realistic for large benchmark suites). At the first slab, it might be
enough to just extract the file building part from both your methods
into a util method, and leave caching alone.

Thanks,
-Aleksey.