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

[Daniel Schwierzeck]

Apply memoization to cc-option macro by caching the results of the
gcc calls. This macro is called very often so using cached results
leads to faster compilation times.

This feature can be enabled by setting CACHE_CC_OPTIONS=y in the
environment.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck at googlemail.com>
---

Some MAKEALL runs for ARM and MIPS (on Core 2 Duo E6600 at 2.4GHz):

time CROSS_COMPILE=/opt/codesourcery/arm-2011.03/bin/arm-none-linux-gnueabi-
MAKEALL_LOGDIR=../logs/ BUILD_DIR=../test/ ./MAKEALL -s omap3 -v ti

real	3m0.380s
user	9m30.570s
sys	1m34.550s


time CACHE_CC_OPTIONS=y CROSS_COMPILE=/opt/codesourcery/arm-2011.03/bin/arm-none-linux-gnueabi-
MAKEALL_LOGDIR=../logs/ BUILD_DIR=../test/ ./MAKEALL -s omap3 -v ti

real	1m15.661s
user	4m21.510s
sys	0m33.190s


time CROSS_COMPILE=/opt/codesourcery/mips-2011.03/bin/mips-linux-gnu-
MAKEALL_LOGDIR=../logs/ BUILD_DIR=../test/ ./MAKEALL mips4kc

real	2m49.883s
user	6m25.840s
sys	0m58.200s


time CACHE_CC_OPTIONS=y CROSS_COMPILE=/opt/codesourcery/mips-2011.03/bin/mips-linux-gnu-
MAKEALL_LOGDIR=../logs/ BUILD_DIR=../test/ ./MAKEALL mips4kc

real	2m18.205s
user	4m59.740s
sys	0m39.530s

 config.mk |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/config.mk b/config.mk
index 11b67e5..27c366f 100644
--- a/config.mk
+++ b/config.mk
@@ -107,8 +107,22 @@ HOSTCFLAGS	+= -pedantic
 # Option checker (courtesy linux kernel) to ensure
 # only supported compiler options are used
 #
+ifeq ($(CACHE_CC_OPTIONS),y)
+sinclude $(OBJTREE)/include/cc-options.mk
+
+cc-option-cached = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
+		> /dev/null 2>&1; then \
+		echo 'CC_OPTIONS += $(strip $1)' \
+			>> $(OBJTREE)/include/cc-options.mk; \
+		echo "$(1)"; else echo "$(2)"; fi ;)
+
+cc-option = $(if $(filter $1,$(CC_OPTIONS)),\
+		$(filter $1,$(CC_OPTIONS)),\
+		$(call cc-option-cached,$1,$2))
+else
 cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
 		> /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
+endif
 
 #
 # Include the make variables (CC, etc...)
-- 
1.7.7.1