[Buildroot] [PATCH] qt5: use ccache for building host code

[Peter Seiderer <ps.report@gmx.net>]

Hello Thomas,

On Sat, 20 Oct 2018 15:25:35 +0200, Thomas Petazzoni <thomas.petazzoni@bootlin.com> wrote:

> qt5 currently doesn't use HOSTCC/HOSTCXX, so it doesn't use ccache
> when building all its host code (especially qmake). This means that
> even with ccache enabled and a hot cache, it still takes a long time
> to build qt5base.
> 
> Before this patch, building qt5base takes:
> 
>  - 446 seconds with a cold ccache
>  - 185 seconds with a hot ccache
> 
> This is because the ccache is not used for host code.
> 
> After this patch, building qt5base takes:
> 
>  - 450 seconds with a cold ccache
>  - 15 seconds with a hot ccache
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> ---
>  package/qt5/qt5base/qt5base.mk | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/package/qt5/qt5base/qt5base.mk b/package/qt5/qt5base/qt5base.mk
> index ab2b883fc4..d9f7af7196 100644
> --- a/package/qt5/qt5base/qt5base.mk
> +++ b/package/qt5/qt5base/qt5base.mk
> @@ -264,6 +264,13 @@ define QT5BASE_CONFIGURE_ARCH_CONFIG
>  endef
>  endif
>  
> +# This allows to use ccache when available
> +define QT5BASE_CONFIGURE_HOSTCC
> +	$(SED) 's,^QMAKE_COMPILER\s*=.*,QMAKE_COMPILER=$(HOSTCC),' $(@D)/mkspecs/common/g++-base.conf
> +	$(SED) 's,^QMAKE_CC\s*=.*,QMAKE_CC=$(HOSTCC),' $(@D)/mkspecs/common/g++-base.conf
> +	$(SED) 's,^QMAKE_CXX\s*=.*,QMAKE_CXX=$(HOSTCXX),' $(@D)/mkspecs/common/g++-base.conf
> +endef
> +

With this sed commands applied, a qmake host compile is always using ccache (same
behavior already for the cross/target compile?)?

Regards,
Peter

>  define QT5BASE_CONFIGURE_CMDS
>  	mkdir -p $(@D)/mkspecs/devices/linux-buildroot-g++/
>  	sed 's/@EGLFS_DEVICE@/$(QT5BASE_EGLFS_DEVICE)/g' \
> @@ -274,6 +281,7 @@ define QT5BASE_CONFIGURE_CMDS
>  	$(QT5BASE_CONFIGURE_CONFIG_FILE)
>  	touch $(QT5BASE_ARCH_CONFIG_FILE)
>  	$(QT5BASE_CONFIGURE_ARCH_CONFIG)
> +	$(QT5BASE_CONFIGURE_HOSTCC)
>  	(cd $(@D); \
>  		$(TARGET_MAKE_ENV) \
>  		PKG_CONFIG="$(PKG_CONFIG_HOST_BINARY)" \