RFR: JDK-8027584 disable ccache by default

[Erik Joelsson]

On 2014-01-29 10:03, David Holmes wrote:
> Hi Magnus,
>
> I don't object to ccache being off by default but I would like the 
> --disable-ccache flag to remain otherwise I will have to edit a bunch 
> of build scripts and will need different versions for 9 vs 8. So 
> please maintain backward compatibility here.
>
> Aside: it would make most sense to me for there to be both --enable-x 
> and --disable-x flags regardless of what the default might be.
>
That is actually the case already. AC_ARG_ENABLE adds both the 
--enable-x and --disable-x as valid configure arguments so 
--disable-ccache will still be accepted (and have no effect).

/Erik
> Thanks,
> David
>
> On 29/01/2014 9:31 AM, Magnus Ihse Bursie wrote:
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8027584
>>
>> While ccache can be used to speed up recompilations, there are also
>> several issues with ccache. Old versions does not work correctly for the
>> jdk (we try to detect that). It does not work well on other platforms
>> than Linux; on Windows it does not work at all. Nevertheless is ccache
>> enabled on Windows if it is installed, which it apparently tends to be
>> with Cygwin nowadays, requiring the use of --disable-ccache to avoid
>> compilation failure.
>>
>> In many circumstances ccache also does not provide any performance
>> benefit. For instance, new compilations gets a performance hit. Only
>> recompilations benefits.
>>
>> It is better to turn this upside down. This patch makes ccache disabled
>> by default, on all platforms. If you want ccache and are sure you are in
>> a situation that benefits from it, then you can enable it. It also
>> removes the output in configure hinting that ccache should be used.
>>
>> WebRev:
>> http://cr.openjdk.java.net/~ihse/JDK-8027584-disable-ccache-by-default/webrev.01 
>>
>>
>>
>> /Magnus