[U-Boot] [PATCH v2] config.mk: use memoization in cc-option macro to speed up compilation

[Simon Glass]

On Fri, Nov 4, 2011 at 5:53 AM, Daniel Schwierzeck
<daniel.schwierzeck at googlemail.com> wrote:
> Apply memoization to cc-option macro by caching the results of the
> gcc calls. This macro is called very often so using cached results
> leads to faster compilation times.
>
> Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck at googlemail.com>

Tested-by: Simon Glass <sjg at chromium.org>

I see a big speed-up with this:

full build 7.05s -> 4.1s
incremental 2.25s -> 1.05s

> ---
> Changes for v2:
>  - move cache file to $(obj)/include/generated
>  - reworked completely
>  - cache also non-working gcc options
>  - remove CACHE_CC_OPTIONS config switch and enable this optimization
>   by default
>
>  config.mk |   23 +++++++++++++++++++++--
>  1 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/config.mk b/config.mk
> index 918cffe..0da961a 100644
> --- a/config.mk
> +++ b/config.mk
> @@ -107,8 +107,27 @@ HOSTCFLAGS += -pedantic
>  # Option checker (courtesy linux kernel) to ensure
>  # only supported compiler options are used
>  #
> -cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
> -               > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
> +CC_OPTIONS_CACHE_FILE := $(OBJTREE)/include/generated/cc_options.mk
> +
> +$(if $(wildcard $(CC_OPTIONS_CACHE_FILE)),,\
> +       $(shell mkdir -p $(dir $(CC_OPTIONS_CACHE_FILE))))
> +
> +sinclude $(CC_OPTIONS_CACHE_FILE)
> +
> +_ccopt_sys = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
> +               > /dev/null 2>&1; then \
> +               echo 'CC_OPTIONS += $(strip $1)' >> $(CC_OPTIONS_CACHE_FILE); \
> +               echo "$(1)"; else \
> +               [ "x$(strip $2)" != "x" ] && \

Do shell still need that x bit?

> +                       echo 'CC_OPTIONS_NOP += $(strip $2)' >> $(CC_OPTIONS_CACHE_FILE); \
> +               echo "$(2)"; fi)
> +
> +_ccopt_cached = $(if $(filter $1,$(CC_OPTIONS)),$1,)

Do you need the $(if - doesn't filter give you what you want by itself?

> +_ccopt_nop_cached = $(if $(filter $1,$(CC_OPTIONS_NOP)),$1,)
> +
> +cc-option = $(if $(call _ccopt_cached,$1),$1,\
> +               $(if $(call _ccopt_nop_cached,$2),$2,\
> +               $(call _ccopt_sys,$1,$2)))
>
>  #
>  # Include the make variables (CC, etc...)
> --
> 1.7.7.1
>
>

Thanks for doing this!

Regards,
Simon