Hello,
Please review this fix cleaning up the ccache setup in configure. This
patch addresses the concerns in the following bugs:
https://bugs.openjdk.java.net/browse/JDK-8065791
https://bugs.openjdk.java.net/browse/JDK-8014074
https://bugs.openjdk.java.net/browse/JDK-8062223
Webrev: http://cr.openjdk.java.net/~erikj/8062223/webrev.root.01/
I changed the test for ccache version to explicitly check for known
older versions that we don't want to use with precompiled headers. The
test is only done if precompiled headers are enabled, since without
precompiled headers, we don't know of any issues with ccache.
I fixed the ccache options needed to fully function with precompiled
headers in hotspot. These options will now be used if precompiled
headers are enabled. They currently aren't fully used.
I updated the documentation to reflect our current stance on ccache.
As noted in JDK-8014074, ccache works better without precompiled
headers, so I recommend turning it off when using ccache. (I actually
recommend turning it off on linux regardless.)
Some numbers building just hotspot ("make hotspot") from my machine
(E5-2665 @ 2.4GHz, 16 cores + HT) with JOBS=15 which is default:
Product/release with precompiled headers
no ccache: 03:13
empty cache: 03:37
perfect cache: 01:36
Product/release without precompiled headers
no ccache: 02:35
empty cache: 02:43
perfect cache: 01:04
/Erik
