| Message ID | 20090616201630.GA4971@oksana.dev.rtsoft.ru (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Wed, Jun 17, 2009 at 12:16:30AM +0400, Anton Vorontsov wrote: > According to Segher Boessenkool and GCC manual, -fomit-frame-pointer > is only the default when optimising on archs/ABIs where it doesn't > hinder debugging and -pg. So, we do not get it by default on x86, > not at any optimisation level. > > On the other hand, *using* -fno-omit-frame-pointer causes gcc to > produce buggy code on PowerPC targets. > > If Segher and GCC manual are right, this patch should be a no-op > for all arches except PowerPC, where the patch fixes gcc issues. > > Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> > --- > > See this thread for more discussion: > http://osdir.com/ml/linux-kernel/2009-05/msg01754.html > > p.s. > Obviously, I didn't test this patch on anything else but PPC32. ;-) > > Segher, do you know if all GCC versions that we support for > building Linux are behaving the way that GCC manual describe? No news is good news... Ingo, can we merge this into -tip for testing? Thanks, > Makefile | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/Makefile b/Makefile > index ea63667..70ad1ff 100644 > --- a/Makefile > +++ b/Makefile > @@ -535,7 +535,7 @@ KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) > endif > > ifdef CONFIG_FRAME_POINTER > -KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls > +KBUILD_CFLAGS += -fno-optimize-sibling-calls > else > KBUILD_CFLAGS += -fomit-frame-pointer > endif > -- > 1.6.3.1 > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev
[Sorry for not replying earlier, somehow I missed this mail] >> On the other hand, *using* -fno-omit-frame-pointer causes gcc to >> produce buggy code on PowerPC targets. It doesn't cause the problem, it only exposes it. And, of course, only on certain GCC versions. >> Segher, do you know if all GCC versions that we support for >> building Linux are behaving the way that GCC manual describe? I believe so, yes. Segher
* Anton Vorontsov <avorontsov@ru.mvista.com> wrote: > On Wed, Jun 17, 2009 at 12:16:30AM +0400, Anton Vorontsov wrote: > > According to Segher Boessenkool and GCC manual, -fomit-frame-pointer > > is only the default when optimising on archs/ABIs where it doesn't > > hinder debugging and -pg. So, we do not get it by default on x86, > > not at any optimisation level. > > > > On the other hand, *using* -fno-omit-frame-pointer causes gcc to > > produce buggy code on PowerPC targets. > > > > If Segher and GCC manual are right, this patch should be a no-op > > for all arches except PowerPC, where the patch fixes gcc issues. > > > > Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> > > --- > > > > See this thread for more discussion: > > http://osdir.com/ml/linux-kernel/2009-05/msg01754.html > > > > p.s. > > Obviously, I didn't test this patch on anything else but PPC32. ;-) > > > > Segher, do you know if all GCC versions that we support for > > building Linux are behaving the way that GCC manual describe? > > No news is good news... Ingo, can we merge this into -tip for > testing? Changes to the top level Makefile should really go via Sam's kbuild tree. Ingo
On Sat, Jul 18, 2009 at 02:01:45PM +0200, Ingo Molnar wrote: > > * Anton Vorontsov <avorontsov@ru.mvista.com> wrote: > > > On Wed, Jun 17, 2009 at 12:16:30AM +0400, Anton Vorontsov wrote: > > > According to Segher Boessenkool and GCC manual, -fomit-frame-pointer > > > is only the default when optimising on archs/ABIs where it doesn't > > > hinder debugging and -pg. So, we do not get it by default on x86, > > > not at any optimisation level. > > > > > > On the other hand, *using* -fno-omit-frame-pointer causes gcc to > > > produce buggy code on PowerPC targets. > > > > > > If Segher and GCC manual are right, this patch should be a no-op > > > for all arches except PowerPC, where the patch fixes gcc issues. > > > > > > Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> > > > --- > > > > > > See this thread for more discussion: > > > http://osdir.com/ml/linux-kernel/2009-05/msg01754.html > > > > > > p.s. > > > Obviously, I didn't test this patch on anything else but PPC32. ;-) > > > > > > Segher, do you know if all GCC versions that we support for > > > building Linux are behaving the way that GCC manual describe? > > > > No news is good news... Ingo, can we merge this into -tip for > > testing? > > Changes to the top level Makefile should really go via Sam's kbuild > tree. Sam, any thoughts about these patches? Thanks!
diff --git a/Makefile b/Makefile index ea63667..70ad1ff 100644 --- a/Makefile +++ b/Makefile @@ -535,7 +535,7 @@ KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) endif ifdef CONFIG_FRAME_POINTER -KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls +KBUILD_CFLAGS += -fno-optimize-sibling-calls else KBUILD_CFLAGS += -fomit-frame-pointer endif
According to Segher Boessenkool and GCC manual, -fomit-frame-pointer is only the default when optimising on archs/ABIs where it doesn't hinder debugging and -pg. So, we do not get it by default on x86, not at any optimisation level. On the other hand, *using* -fno-omit-frame-pointer causes gcc to produce buggy code on PowerPC targets. If Segher and GCC manual are right, this patch should be a no-op for all arches except PowerPC, where the patch fixes gcc issues. Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> --- See this thread for more discussion: http://osdir.com/ml/linux-kernel/2009-05/msg01754.html p.s. Obviously, I didn't test this patch on anything else but PPC32. ;-) Segher, do you know if all GCC versions that we support for building Linux are behaving the way that GCC manual describe? Thanks, Makefile | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)