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

[Daniel Schwierzeck]

Hi SImon,

On Fri, Nov 4, 2011 at 5:32 PM, Simon Glass <sjg at chromium.org> wrote:
> 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?

Probably not but it is safer and does not really harm ;)

>
>> +                       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?

You are right, the if is redundant. I will optimize this.

>
>> +_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
>

Thanks,
Daniel