On Tue, Jul 10, 2012 at 10:00:17AM -0700, Allen Martin wrote: > Disable sibling call optimization based on binutils version. This is > to work around a bug in the assember in binutils versions < 2.22. > Branches to weak symbols can be incorrectly optimized in thumb mode to > a short branch (b.n instruction) that won't reach when the symbol gets > preempted. > > http://sourceware.org/bugzilla/show_bug.cgi?id=12532 > > Signed-off-by: Allen Martin <amar...@nvidia.com> > --- > changes for v2: > -changed GAS_BUG_12532 from yes/no to y/n to be consistent > -added additional warning about code size increase > --- > arch/arm/config.mk | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/arch/arm/config.mk b/arch/arm/config.mk > index 3f4453a..bcabf17 100644 > --- a/arch/arm/config.mk > +++ b/arch/arm/config.mk > @@ -87,3 +87,24 @@ endif > ifndef CONFIG_NAND_SPL > LDFLAGS_u-boot += -pie > endif > + > +# > +# binutils versions < 2.22 have a bug in the assembler where branches > +# to weak symbols can be incorrectly optimized in thumb mode to a > +# short branch (b.n instruction) that won't reach when the symbol > +# gets preempted > +# > +# http://sourceware.org/bugzilla/show_bug.cgi?id=12532 > +# > +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) > +ifeq ($(GAS_BUG_12532),) > +export GAS_BUG_12532:=$(shell if [ $(call binutils-version) -lt 0222 ] ; > then echo y; else echo n; fi)
Please don't squash out whitespace, just break this out into a multi-line test ala the others in the toplevel config.mk. > +ifeq ($(GAS_BUG_12532),y) > +$(warning *** disabling sibling call optimzation because binutils version < > 2.22) > +$(warning *** code size may be slightly larger) > +endif > +endif > +ifeq ($(GAS_BUG_12532),y) > +PLATFORM_RELFLAGS += -fno-optimize-sibling-calls > +endif > +endif This seems a bit longer than needed. Just check that it's y once and do both things. Also, I _think_ we should be able to squish this down to: ifeq ($(CONFIG_SYS_THUMB_BUILD),y) GAS_BUG_12532 := $(shell if [ $(call binutils-version) -lt 0222 ] ; \ then echo y; else echo n; fi) ifeq ($(GAS_BUG_125320),y) $(warning ...) $(warning ...) PLATFORM_RELFLAGS += ... endif endif But I haven't tested it. -- Tom
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