Fwd: We REALLY nead a NON-PCH build in JPRT NOW!

[Jon Masamitsu]

-------- Forwarded Message --------
Subject: 	We REALLY nead a NON-PCH build in JPRT NOW!
Date: 	Thu, 2 Apr 2015 18:06:01 +0200
From: 	Volker Simonis <volker.simonis at gmail.com>
To: 	HotSpot Open Source Developers <hotspot-dev at openjdk.java.net>



Hi,

while precompiled headers (PCH) are a nice and effective way of
improving hotspot build times this feature also drastically increases
the risk of introducing missing dependencies into the source base.
This is especially annoying on platforms where precompield headers
aren't available at all.

In the last two weeks we had two cases [1,2] of such missing
dependencies which haven't been caught by JPRT because JPRT uses the
default platform settings and thus always uses PCHs on all platforms
where they are supported.

I want to strongly advocate for a change in the JPRT configurations
such that at least on one Windows and one Linux platform the automatic
pre-integration builds are done with
"--with-debug-level=[slow/fast]debug --disable-precompiled-headers".
This simple change which comes at the minor cost of a few CPU-cycles
will save a big amount of (hopfully) much more precious developer
cycles and at the same time considerably improve the code quality.
Notice that I intentionally ask for a *debug build without PCHs
because debug builds exercise much more source code and are
specifically prone to missing include dependency errors.

As this change can only be decided upon and implemented inside Oracle
I hereby kindly ask for an appropriate sponsor.

Thank you and best regards,
Volker

[1]
Introduced by: https://bugs.openjdk.java.net/browse/JDK-8075416
Fixed by: https://bugs.openjdk.java.net/browse/JDK-8075735

[2]
Introduced by: https://bugs.openjdk.java.net/browse/JDK-8076314
Fix proposed: http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2015-April/012659.html