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. Obiously 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: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---
scripts/Kbuild.include | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index be1c9d6..4fb1be1 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -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
+cache-dir := $(if $(KBUILD_SRC),$(if $(cache-data),,$(dir $(make-cache))))
+
# 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)))
+ifneq ($(cache-dir),)
+ $$(shell mkdir -p $(cache-dir))
+ $$(eval cache-dir :=)
+endif
$$(shell echo '$(1) := $$($(1))' >> $(make-cache))
endif
endef
--
2.7.4
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