Review request (s): 7116081: USE_PRECOMPILED_HEADER=0 triggers a single threaded build of the JVM

[David Holmes]

Hi Stefan,

On 29/11/2011 12:34 AM, Stefan Karlsson wrote:
> http://cr.openjdk.java.net/~stefank/7116081/webrev/
>
> Turning off the precompiled headers is somewhat broken. It triggers a
> single threaded build even when HOTSPOT_BUILD_JOBS has been set. With
> this fix the compile times went from around 14 minutes to 2.5 minutes,
> on an 8 core machine.

Took me a while to figure out why this was the case :)

> This affects both Linux and BSD builds, but has only been tested on
> Linux. It would be great if someone with access to a BSD machine could
> verify this fix.

The problem here was using

ifdef USE_PRECOMPILED_HEADER

when defining it to 0 is used to turn it off - so it seems to me the 
better fix here was to simply change to:

ifeq ($(USE_PRECOMPILED_HEADER),1)


The removal of:

PrecompiledOption = -DUSE_PRECOMPILED_HEADER

seems okay.

Cheers,
David