RFR: JDK-8027584 disable ccache by default

[David Holmes]

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.

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