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

[Daniel Schwierzeck]

Hi Albert, Wolfgang,

following code from arch/arm/config does not work correctly with my optimization

PF_CPPFLAGS_ABI := $(call cc-option,\
			-mabi=aapcs-linux -mno-thumb-interwork,\
			$(call cc-option,\
				-mapcs-32,\
				$(call cc-option,\
					-mabi=apcs-gnu,\
				)\
			) $(call cc-option,-mno-thumb-interwork,)\
		)
PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARM) $(PF_CPPFLAGS_ABI)

Compiling with seabord_config and latest CodeSourcery toolchain the
generated cache file
has following content:

CC_OPTIONS += -marm
CC_OPTIONS += -mabi=apcs-gnu
CC_OPTIONS_NOP += -mabi=apcs-gnu
CC_OPTIONS += -mno-thumb-interwork
CC_OPTIONS += -mabi=aapcs-linux -mno-thumb-interwork
CC_OPTIONS += -fno-stack-protector
CC_OPTIONS += -Wno-format-nonliteral
CC_OPTIONS += -Wno-format-security
CC_OPTIONS += -fno-toplevel-reorder

If I rewrite that code to

PF_CPPFLAGS_ABI := $(call cc-option,-mabi=aapcs-linux,)
ifeq ($(PF_CPPFLAGS_ABI),)
PF_CPPFLAGS_ABI := $(call cc-option,-mapcs-32,-mabi=apcs-gnu)
endif
PF_CPPFLAGS_THUMB := $(call cc-option,-mno-thumb-interwork,)
PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARM) $(PF_CPPFLAGS_ABI) $(PF_CPPFLAGS_THUMB)

the cache file looks better:

CC_OPTIONS += -marm
CC_OPTIONS += -mabi=aapcs-linux
CC_OPTIONS += -mno-thumb-interwork
CC_OPTIONS += -fno-stack-protector
CC_OPTIONS += -Wno-format-nonliteral
CC_OPTIONS += -Wno-format-security
CC_OPTIONS += -fno-toplevel-reorder

Should we change it? is the semantic still the same?

Best regards,
Daniel