On Fri, Aug 13, 2021 at 6:43 PM Masahiro Yamada [off-list ref] wrote:

On Wed, Aug 11, 2021 at 5:42 AM Nick Desaulniers
[off-list ref] wrote:

quoted

diff --git a/Makefile b/Makefile
index 027fdf2a14fe..3e3fb4affba1 100644
--- a/Makefile
+++ b/Makefile

@@ -798,7 +801,7 @@ include/config/auto.conf:
 endif # may-sync-config
 endif # need-config

-KBUILD_CFLAGS  += $(call cc-option,-fno-delete-null-pointer-checks,)
+KBUILD_CFLAGS  += -fno-delete-null-pointer-checks
 KBUILD_CFLAGS  += $(call cc-disable-warning,frame-address,)
 KBUILD_CFLAGS  += $(call cc-disable-warning, format-truncation)
 KBUILD_CFLAGS  += $(call cc-disable-warning, format-overflow)

@@ -844,17 +847,17 @@ KBUILD_RUSTFLAGS += -Copt-level=z
 endif

 # Tell gcc to never replace conditional load with a non-conditional one
-KBUILD_CFLAGS  += $(call cc-option,--param=allow-store-data-races=0)
+ifdef CONFIG_CC_IS_GCC

Can you insert a comment here?

# GCC 10 renamed --param=allow-store-data-races=0 to --allow-store-data-races


It will remind us of dropping this conditional
in the (long long distant) future.

quoted

+KBUILD_CFLAGS  += $(call cc-option,--allow-store-data-races,--param=allow-store-data-races=0)
 KBUILD_CFLAGS  += $(call cc-option,-fno-allow-store-data-races)
+endif

So it looks like `-fallow-store-data-races` was also supported. Reading through
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97309
https://gcc.gnu.org/wiki/Atomic/GCCMM/ExecutiveSummary
it seems that the default is not to allow "store data races." So I
should not be adding `--allow-store-data-races` or
`-fallow-store-data-races`; so this just should be the existing test,
with a comment that it can be removed once gcc-10+ is the minimum.
Will update that in v2.
-- 
Thanks,
~Nick Desaulniers