Messages in this thread | | | From | Nick Desaulniers <> | Date | Mon, 18 Mar 2019 14:47:13 -0700 | Subject | Re: [PATCH] Revert "kbuild: use -Oz instead of -Os when using clang" |
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On Mon, Mar 18, 2019 at 2:10 PM Matthias Kaehlcke <mka@chromium.org> wrote: > > The clang option -Oz enables *aggressive* optimization for size, > which doesn't necessarily result in smaller images, but can have > negative impact on performance. Switch back to the less aggressive > -Os. > > This reverts commit 6748cb3c299de1ffbe56733647b01dbcc398c419.
Does scripts/checkpatch.pl complain about this format (full sha, no title)? Not sure that necessitates a v2, but if so would be good to mention that Clang generates excessive calls into libgcc/compiler-rt at -Oz. Thanks for the patch and the discussion/sanity check. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> > Suggested-by: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Matthias Kaehlcke <mka@chromium.org> > --- > Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/Makefile b/Makefile > index 9ef547fc7ffe..191f3ce3cb5e 100644 > --- a/Makefile > +++ b/Makefile > @@ -667,7 +667,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow) > KBUILD_CFLAGS += $(call cc-disable-warning, int-in-bool-context) > > ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE > -KBUILD_CFLAGS += $(call cc-option,-Oz,-Os) > +KBUILD_CFLAGS += -Os > else > KBUILD_CFLAGS += -O2 > endif > -- > 2.21.0.225.g810b269d1ac-goog
-- Thanks, ~Nick Desaulniers
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