ARM: 7777/1: Avoid extra calls to the C compiler

Starting up the C compiler can be a slow operation on some systems.
Though these calls don't individually take a lot of time, they add up.
Rearrange the ARM Makefile a bit to avoid extra calls to the compiler
when they can be easily avoided.

When running with the Chrome OS ARM cross compiler
"armv7a-cros-linux-gnueabi-", this shaved .55 seconds (from 5.31
seconds to 4.76 seconds) off an incremental build of the kernel:
  time make -j32 ARCH=arm CROSS_COMPILE=armv7a-cros-linux-gnueabi-

Thanks to Mike Frysinger for the clean trick to make this work.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 10c08092378f3a21097c50c7618b2865f444c140..20559a089442b05d1efb8406e3fcfefa59ba671a 100644 (file)
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -59,37 +59,43 @@ comma = ,
 # Note that GCC does not numerically define an architecture version
 # macro, but instead defines a whole series of macros which makes
 # testing for a specific architecture or later rather impossible.
-arch-$(CONFIG_CPU_32v7)                :=-D__LINUX_ARM_ARCH__=7 $(call cc-option,-march=armv7-a,-march=armv5t -Wa$(comma)-march=armv7-a)
-arch-$(CONFIG_CPU_32v6)                :=-D__LINUX_ARM_ARCH__=6 $(call cc-option,-march=armv6,-march=armv5t -Wa$(comma)-march=armv6)
+arch-$(CONFIG_CPU_32v7)                =-D__LINUX_ARM_ARCH__=7 $(call cc-option,-march=armv7-a,-march=armv5t -Wa$(comma)-march=armv7-a)
+arch-$(CONFIG_CPU_32v6)                =-D__LINUX_ARM_ARCH__=6 $(call cc-option,-march=armv6,-march=armv5t -Wa$(comma)-march=armv6)
 # Only override the compiler option if ARMv6. The ARMv6K extensions are
 # always available in ARMv7
 ifeq ($(CONFIG_CPU_32v6),y)
-arch-$(CONFIG_CPU_32v6K)       :=-D__LINUX_ARM_ARCH__=6 $(call cc-option,-march=armv6k,-march=armv5t -Wa$(comma)-march=armv6k)
+arch-$(CONFIG_CPU_32v6K)       =-D__LINUX_ARM_ARCH__=6 $(call cc-option,-march=armv6k,-march=armv5t -Wa$(comma)-march=armv6k)
 endif
-arch-$(CONFIG_CPU_32v5)                :=-D__LINUX_ARM_ARCH__=5 $(call cc-option,-march=armv5te,-march=armv4t)
-arch-$(CONFIG_CPU_32v4T)       :=-D__LINUX_ARM_ARCH__=4 -march=armv4t
-arch-$(CONFIG_CPU_32v4)                :=-D__LINUX_ARM_ARCH__=4 -march=armv4
-arch-$(CONFIG_CPU_32v3)                :=-D__LINUX_ARM_ARCH__=3 -march=armv3
+arch-$(CONFIG_CPU_32v5)                =-D__LINUX_ARM_ARCH__=5 $(call cc-option,-march=armv5te,-march=armv4t)
+arch-$(CONFIG_CPU_32v4T)       =-D__LINUX_ARM_ARCH__=4 -march=armv4t
+arch-$(CONFIG_CPU_32v4)                =-D__LINUX_ARM_ARCH__=4 -march=armv4
+arch-$(CONFIG_CPU_32v3)                =-D__LINUX_ARM_ARCH__=3 -march=armv3
+
+# Evaluate arch cc-option calls now
+arch-y := $(arch-y)
 
 # This selects how we optimise for the processor.
-tune-$(CONFIG_CPU_ARM7TDMI)    :=-mtune=arm7tdmi
-tune-$(CONFIG_CPU_ARM720T)     :=-mtune=arm7tdmi
-tune-$(CONFIG_CPU_ARM740T)     :=-mtune=arm7tdmi
-tune-$(CONFIG_CPU_ARM9TDMI)    :=-mtune=arm9tdmi
-tune-$(CONFIG_CPU_ARM940T)     :=-mtune=arm9tdmi
-tune-$(CONFIG_CPU_ARM946E)     :=$(call cc-option,-mtune=arm9e,-mtune=arm9tdmi)
-tune-$(CONFIG_CPU_ARM920T)     :=-mtune=arm9tdmi
-tune-$(CONFIG_CPU_ARM922T)     :=-mtune=arm9tdmi
-tune-$(CONFIG_CPU_ARM925T)     :=-mtune=arm9tdmi
-tune-$(CONFIG_CPU_ARM926T)     :=-mtune=arm9tdmi
-tune-$(CONFIG_CPU_FA526)       :=-mtune=arm9tdmi
-tune-$(CONFIG_CPU_SA110)       :=-mtune=strongarm110
-tune-$(CONFIG_CPU_SA1100)      :=-mtune=strongarm1100
-tune-$(CONFIG_CPU_XSCALE)      :=$(call cc-option,-mtune=xscale,-mtune=strongarm110) -Wa,-mcpu=xscale
-tune-$(CONFIG_CPU_XSC3)                :=$(call cc-option,-mtune=xscale,-mtune=strongarm110) -Wa,-mcpu=xscale
-tune-$(CONFIG_CPU_FEROCEON)    :=$(call cc-option,-mtune=marvell-f,-mtune=xscale)
-tune-$(CONFIG_CPU_V6)          :=$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm)
-tune-$(CONFIG_CPU_V6K)         :=$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm)
+tune-$(CONFIG_CPU_ARM7TDMI)    =-mtune=arm7tdmi
+tune-$(CONFIG_CPU_ARM720T)     =-mtune=arm7tdmi
+tune-$(CONFIG_CPU_ARM740T)     =-mtune=arm7tdmi
+tune-$(CONFIG_CPU_ARM9TDMI)    =-mtune=arm9tdmi
+tune-$(CONFIG_CPU_ARM940T)     =-mtune=arm9tdmi
+tune-$(CONFIG_CPU_ARM946E)     =$(call cc-option,-mtune=arm9e,-mtune=arm9tdmi)
+tune-$(CONFIG_CPU_ARM920T)     =-mtune=arm9tdmi
+tune-$(CONFIG_CPU_ARM922T)     =-mtune=arm9tdmi
+tune-$(CONFIG_CPU_ARM925T)     =-mtune=arm9tdmi
+tune-$(CONFIG_CPU_ARM926T)     =-mtune=arm9tdmi
+tune-$(CONFIG_CPU_FA526)       =-mtune=arm9tdmi
+tune-$(CONFIG_CPU_SA110)       =-mtune=strongarm110
+tune-$(CONFIG_CPU_SA1100)      =-mtune=strongarm1100
+tune-$(CONFIG_CPU_XSCALE)      =$(call cc-option,-mtune=xscale,-mtune=strongarm110) -Wa,-mcpu=xscale
+tune-$(CONFIG_CPU_XSC3)                =$(call cc-option,-mtune=xscale,-mtune=strongarm110) -Wa,-mcpu=xscale
+tune-$(CONFIG_CPU_FEROCEON)    =$(call cc-option,-mtune=marvell-f,-mtune=xscale)
+tune-$(CONFIG_CPU_V6)          =$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm)
+tune-$(CONFIG_CPU_V6K)         =$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm)
+
+# Evaluate tune cc-option calls now
+tune-y := $(tune-y)
 
 ifeq ($(CONFIG_AEABI),y)
 CFLAGS_ABI     :=-mabi=aapcs-linux -mno-thumb-interwork