[PATCH] x86: Use -maccumulate-outgoing-args (cdfce1f5) · Commits · 戴 / test

This avoids some problems with gcc 4.x and earlier generating invalid unwind information. In 4.1 the option is default when unwind information is enabled. And it seems to generate smaller code too, so it's probably a good thing on its own. With gcc 4.0: i386: 4683198 902112 480868 6066178 5c9002 vmlinux (before) 4449895 902112 480868 5832875 5900ab vmlinux (after) x86-64: 4939761 1449584 648216 7037561 6b6279 vmlinux (before) 4854193 1449584 648216 6951993 6a1439 vmlinux (after) On 4.1 it shouldn't make much difference because it is default when unwind is enabled anyways. Suggested by Michael Matz and Jan Beulich Cc: jbeulich@novell.com Signed-off-by:

Andi Kleen <ak@suse.de>

arch/i386/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -42,6 +42,10 @@ cflags-$(CONFIG_REGPARM) += -mregparm=3
		# 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:
		CFLAGS += $(shell if [ $(call cc-version) -lt 0400 ] ; then echo $(call cc-option,-fno-unit-at-a-time); fi ;)

arch/x86_64/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -54,6 +54,10 @@ endif
		cflags-y += $(call cc-option,-funit-at-a-time)
		# prevent gcc from generating any FP code by mistake
		cflags-y += $(call cc-option,-mno-sse -mno-mmx -mno-sse2 -mno-3dnow,)
		# this works around some issues with generating unwind tables in older gccs
		# newer gccs do it by default
		cflags-y += -maccumulate-outgoing-args

		# do binutils support CFI?
		cflags-y += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,)
		AFLAGS += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,)

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