Commit 8c4385d7 authored Jan 30, 2008 by Adrian Bunk Committed by Ingo Molnar Jan 30, 2008

x86: remove -maccumulate-outgoing-args on 32-bit



Contrary to the comment "newer gccs do it by default", newer gcc versions
default to -maccumulate-outgoing-args only with CONFIG_CC_OPTIMIZE_FOR_SIZE=n,
and then only with some CPU settings.

Measured with an i386 defconfig, gcc 4.2.1 and kernel 2.6.23-rc1 ("orig" is
the plain kernel, "changed is with -maccumulate-outgoing-args removed):

$ ls -la vmlinux*
-rwxrwxr-x 1 bunk bunk 6269713 2007-07-24 22:19 vmlinux.changed
-rwxrwxr-x 1 bunk bunk 6425361 2007-07-24 22:19 vmlinux.orig
$ size vmlinux.*
   text    data     bss     dec     hex filename
4493465  504108  614400 5611973  55a1c5 vmlinux.changed
4646160  504108  614400 5764668  57f63c vmlinux.orig
$

That's a 2.5% size increase that does for sure hurt small systems.

If the stack unwinder ever comes back and needs this as indicated in the
comment, adding it to the cflags when the user enabled the unwinder should be
a better option.

[ tglx: arch/x86 adaptation ]

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent 1c69524c

arch/x86/Makefile_32

+0 −4

Original line number	Diff line number	Diff line
		@@ -48,10 +48,6 @@ include $(srctree)/arch/x86/Makefile_32.cpu
		# temporary until string.h is fixed
		cflags-y += -ffreestanding

		# this works around some issues with generating unwind tables in older gccs
		# newer gccs do it by default
		cflags-y += -maccumulate-outgoing-args

		# Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use
		# a lot more stack due to the lack of sharing of stacklots:
		KBUILD_CFLAGS += $(shell if [ $(call cc-version) -lt 0400 ] ; then echo $(call cc-option,-fno-unit-at-a-time); fi ;)

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