kbuild: optimize object directory creation for incremental build (c4da7ed0) · Commits · 戴 / test

The previous commit largely optimized the object directory creation. We can optimize it more for incremental build. There are already *.cmd files in the output directory. The existing *.cmd files have been picked up by $(wildcard ...). Obviously, directories containing them exist too, so we can skip "mkdir -p". With this, Kbuild runs almost zero "mkdir -p" in incremental building. Signed-off-by:

Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/Makefile.build

+5 −0

Original line number	Diff line number	Diff line
		@@ -583,8 +583,13 @@ endif
		ifneq ($(KBUILD_SRC),)
		# Create directories for object files if they do not exist
		obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
		# If cmd_files exist, their directories apparently exist. Skip mkdir.
		exist-dirs := $(sort $(patsubst %/,%, $(dir $(cmd_files))))
		obj-dirs := $(strip $(filter-out $(exist-dirs), $(obj-dirs)))
		ifneq ($(obj-dirs),)
		$(shell mkdir -p $(obj-dirs))
		endif
		endif

		# Declare the contents of the .PHONY variable as phony. We keep that
		# information in a variable se we can use it in if_changed and friends.

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