| Message ID | CAG5bF+RvumzKK0E-GAT223jnBvkRe1RN_0J9cGpfPOqCBvfWyw@mail.gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Revert "kbuild: use -Oz instead of -Os when using clang" | expand |
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
On Mon, Mar 18, 2019 at 02:47:13PM -0700, 'Nick Desaulniers' via Clang Built Linux wrote: > 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)? Nope, for reverts checkpatch is happy with it, I suppose because by default the subject of the reverted patch is part of the revert's subject. > 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. I can send a v2 if 'needed'. > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Thanks! Matthias > > > > 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 > > >
On March 18, 2019 2:56:05 PM PDT, Matthias Kaehlcke <mka@chromium.org> wrote: >On Mon, Mar 18, 2019 at 02:47:13PM -0700, 'Nick Desaulniers' via Clang >Built Linux wrote: >> 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)? > >Nope, for reverts checkpatch is happy with it, I suppose because by >default the subject of the reverted patch is part of the revert's >subject. > >> 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. > >I can send a v2 if 'needed'. > >> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > >Thanks! > >Matthias > >> > >> > 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 >> >> >> Would be nice, still, to have -Ok.
On Mon, Mar 18, 2019 at 3:07 PM <hpa@zytor.com> wrote: > > On March 18, 2019 2:56:05 PM PDT, Matthias Kaehlcke <mka@chromium.org> wrote: > >> > 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 > > Would be nice, still, to have -Ok. April fools *is* coming up. 0:-)
On Tue, Mar 19, 2019 at 6:10 AM 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. > > Suggested-by: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Applied to linux-kbuild/fixes. Thanks. > --- > 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
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
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. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)