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Commit 9a234a2e authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kbuild: create directory for make cache only when necessary 



Currently, the existence of $(dir $(make-cache)) is always checked,
and created if it is missing.

We can avoid unnecessary system calls by some tricks.

[1] If KBUILD_SRC is unset, we are building in the source tree.
    The output directory checks can be entirely skipped.
[2] If at least one cache data is found, it means the cache file
    was included.  Obviously its directory exists.  Skip "mkdir -p".
[3] If Makefile does not contain any call of __run-and-store, it will
    not create a cache file.  No need to create its directory.
[4] The "mkdir -p" should be only invoked by the first call of
    __run-and-store

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: default avatarDouglas Anderson <dianders@chromium.org>
parent 859fd586

scripts/Kbuild.include

+9 −4
Original line number Diff line number Diff line
@@ -99,18 +99,19 @@ cc-cross-prefix = \ 


# Include values from last time

make-cache := $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/,$(if $(obj),$(obj)/)).cache.mk

ifeq ($(wildcard $(dir $(make-cache))),)

$(shell mkdir -p '$(dir $(make-cache))')

endif

$(make-cache): ;

-include $(make-cache)



cached-data := $(filter __cached_%, $(.VARIABLES))



# If cache exceeds 1000 lines, shrink it down to 500.

ifneq ($(word 1000,$(filter __cached_%, $(.VARIABLES))),)

ifneq ($(word 1000,$(cached-data)),)

$(shell tail -n 500 $(make-cache) > $(make-cache).tmp; \

	mv $(make-cache).tmp $(make-cache))

endif



create-cache-dir := $(if $(KBUILD_SRC),$(if $(cache-data),,1))



# Usage: $(call __sanitize-opt,Hello=Hola$(comma)Goodbye Adios)

#

# Convert all '$', ')', '(', '\', '=', ' ', ',', ':' to '_'
@@ -136,6 +137,10 @@ __sanitize-opt = $(subst $$,_,$(subst $(right_paren),_,$(subst $(left_paren),_,$ 
define __run-and-store

ifeq ($(origin $(1)),undefined)

  $$(eval $(1) := $$(shell $$(2)))

ifeq ($(create-cache-dir),1)

  $$(shell mkdir -p $(dir $(make-cache)))

  $$(eval create-cache-dir :=)

endif

  $$(shell echo '$(1) := $$($(1))' >> $(make-cache))

endif

endef