Running make results in over 40 invocations of the compiler just during processing of the Makefile, before any actual rules are run. To reduce this overhead, cache the results of $(shell) calls to the compiler. On my machine, this reduces make's processing time by over 96%: $ make kernelversion && perf stat -r5 make kernelversion Before: 0,252219929 seconds time elapsed ( +- 0,39% ) After: 0,008607464 seconds time elapsed ( +- 0,50% ) Signed-off-by: Rabin Vincent <rabin@xxxxxx> --- Makefile | 15 ++++++++------- scripts/Kbuild.include | 42 +++++++++++++++++++++++++++++++++++------- 2 files changed, 43 insertions(+), 14 deletions(-) diff --git a/Makefile b/Makefile index 91baa282f3fa..90237e706bf8 100644 --- a/Makefile +++ b/Makefile @@ -304,11 +304,6 @@ HOSTCXX = g++ HOSTCFLAGS = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89 HOSTCXXFLAGS = -O2 -ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1) -HOSTCFLAGS += -Wno-unused-value -Wno-unused-parameter \ - -Wno-missing-field-initializers -fno-delete-null-pointer-checks -endif - # Decide whether to build built-in, modular, or both. # Normally, just do built-in. @@ -343,6 +338,11 @@ export KBUILD_CHECKSRC KBUILD_SRC KBUILD_EXTMOD scripts/Kbuild.include: ; include scripts/Kbuild.include +ifeq ($(call cached-shell,$(HOSTCC) -v 2>&1 | grep -c "clang version"), 1) +HOSTCFLAGS += -Wno-unused-value -Wno-unused-parameter \ + -Wno-missing-field-initializers -fno-delete-null-pointer-checks +endif + # Make variables (CC, etc...) AS = $(CROSS_COMPILE)as LD = $(CROSS_COMPILE)ld @@ -767,7 +767,7 @@ KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once) endif # arch Makefile may override CC so keep this after arch Makefile is included -NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) +NOSTDINC_FLAGS += -nostdinc -isystem $(call cached-shell,$(CC) -print-file-name=include) CHECKFLAGS += $(NOSTDINC_FLAGS) # warn about C99 declaration after statement @@ -798,7 +798,7 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types) KBUILD_ARFLAGS := $(call ar-option,D) # check for 'asm goto' -ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC)), y) +ifeq ($(call cached-shell,$(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC)), y) KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO endif @@ -1237,6 +1237,7 @@ endif # CONFIG_MODULES # Directories & files removed with 'make clean' CLEAN_DIRS += $(MODVERDIR) +CLEAN_FILES += $(KBUILD_SHELLCACHE) # Directories & files removed with 'make mrproper' MRPROPER_DIRS += include/config usr/include include/generated \ diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 0f82314621f2..e90e43fa3c81 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -7,6 +7,7 @@ quote := " squote := ' empty := space := $(empty) $(empty) +tab := $(empty) $(empty) space_escape := _-_SPACE_-_ ### @@ -83,11 +84,35 @@ cc-cross-prefix = \ # output directory for tests below TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/) +KBUILD_SHELLCACHE := .shellcache + +ifeq ($(KBUILD_SHELLCACHE),) +cached-shell = $(shell $(1)) +else +-include $(KBUILD_SHELLCACHE) + +sanitize = $(subst $(space),_, \ + $(subst $(tab),_, \ + $(subst \n,_, \ + $(subst :,_, \ + $(subst \#,_, \ + $(subst =,_, \ + $(subst $$,_, \ + $(subst ',_, \ + $(subst ",_, \ + $(1)))))))))) + +cached-shell = $(if $(cmd$(call sanitize,$(1))),$(subst CACHED,,$(cmd$(call sanitize,$(1)))),$(shell \ + res='$(shell $(1))'; \ + echo "$$res"; \ + echo 'cmd$(call sanitize,$(1)) = CACHED'"$$res" >> $(KBUILD_SHELLCACHE))) +endif + # try-run # Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise) # Exit code chooses option. "$$TMP" is can be used as temporary file and # is automatically cleaned up. -try-run = $(shell set -e; \ +try-run = $(call cached-shell,set -e; \ TMP="$(TMPOUT).$$$$.tmp"; \ TMPO="$(TMPOUT).$$$$.o"; \ if ($(1)) >/dev/null 2>&1; \ @@ -131,18 +156,19 @@ cc-disable-warning = $(call try-run,\ # cc-name # Expands to either gcc or clang -cc-name = $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc) +cc-name = $(call cached-shell,$(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc) # cc-version -cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC)) +cc-version = $(call cached-shell,$(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC)) # cc-fullversion -cc-fullversion = $(shell $(CONFIG_SHELL) \ +cc-fullversion = $(call cached-shell $(CONFIG_SHELL) \ $(srctree)/scripts/gcc-version.sh -p $(CC)) # cc-ifversion # Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1) -cc-ifversion = $(shell [ $(cc-version) $(1) $(2) ] && echo $(3) || echo $(4)) +cc-ifversion = $(call cached-shell, \ + [ $(cc-version) $(1) $(2) ] && echo $(3) || echo $(4)) # cc-ldoption # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both) @@ -161,11 +187,13 @@ ar-option = $(call try-run, $(AR) rc$(1) "$$TMP",$(1),$(2)) # ld-version # Note this is mainly for HJ Lu's 3 number binutil versions -ld-version = $(shell $(LD) --version | $(srctree)/scripts/ld-version.sh) +ld-version = $(call cached-shell, \ + $(LD) --version | $(srctree)/scripts/ld-version.sh) # ld-ifversion # Usage: $(call ld-ifversion, -ge, 22252, y) -ld-ifversion = $(shell [ $(ld-version) $(1) $(2) ] && echo $(3) || echo $(4)) +ld-ifversion = $(call cached-shell, \ + [ $(ld-version) $(1) $(2) ] && echo $(3) || echo $(4)) ###### -- 2.8.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
