On Wed, Aug 11, 2021 at 8:01 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > On Tue, Aug 10, 2021 at 01:42:37PM -0700, Nick Desaulniers wrote: > > cc-option, cc-option-yn, and cc-disable-warning all invoke the compiler > > during build time, and can slow down the build when these checks become > > stale for our supported compilers, whose minimally supported versions > > increases over time. See Documentation/process/changes.rst for the > > current supported minimal versions (GCC 4.9+, clang 10.0.1+). Compiler > > version support for these flags may be verified on godbolt.org. > > > > The following flags are GCC only and supported since at least GCC 4.9. > > Remove cc-option and cc-disable-warning tests. > > * -fno-tree-loop-im > > * -Wno-maybe-uninitialized > > * -fno-reorder-blocks > > * -fno-ipa-cp-clone > > * -fno-partial-inlining > > * -femit-struct-debug-baseonly > > * -fno-inline-functions-called-once > > * -fconserve-stack > > > > The following flags are supported by all supported versions of GCC and > > Clang. Remove their cc-option, cc-option-yn, and cc-disable-warning tests. > > * -fno-delete-null-pointer-checks > > * -fno-var-tracking > > * -mfentry > > * -Wno-array-bounds > > > > The following configs are made dependent on GCC, since they use GCC > > specific flags. > > * READABLE_ASM > > * DEBUG_SECTION_MISMATCH > > > > --param=allow-store-data-races=0 was renamed to --allow-store-data-races > > in the GCC 10 release. > > > > Also, base RETPOLINE_CFLAGS and RETPOLINE_VDSO_CFLAGS on CONFIC_CC_IS_* > > then remove cc-option tests for Clang. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1436 > > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > Fewer pointless calls to the compiler is always a good thing :) > > Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > Small comments inline. > > > --- > > Note: It may be preferred to move the test for > > -fno-inline-functions-called-once for DEBUG_SECTION_MISMATCH into > > Kconfig. That one does seem relatively more reasonable to implement in > > Clang. > > > > Makefile | 55 ++++++++++++++++++++++++++--------------------- > > lib/Kconfig.debug | 2 ++ > > 2 files changed, 33 insertions(+), 24 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index 027fdf2a14fe..3e3fb4affba1 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -730,9 +730,10 @@ endif # KBUILD_EXTMOD > > # Defaults to vmlinux, but the arch makefile usually adds further targets > > all: vmlinux > > > > -CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \ > > - $(call cc-option,-fno-tree-loop-im) \ > > - $(call cc-disable-warning,maybe-uninitialized,) > > +CFLAGS_GCOV := -fprofile-arcs -ftest-coverage > > +ifdef CONFIG_CC_IS_GCC > > +CFLAGS_GCOV += -fno-tree-loop-im > > +endif > > Eliminating -Wno-maybe-uninitialized might warrant a comment in the > commit message as I was initially confused then I realized that it is > unconditionally added later. Indeed. Commit 78a5255ffb6a1af189a83e493d916ba1c54d8c75 could have removed -Wno-maybe-initialized from CFLAGS_GCOV as well, but somehow it has been left over here... Comments in the commit log, or perhaps splitting this as 1/2 will be less confusing. -- Best Regards Masahiro Yamada
