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Disable "maybe-uninitialized" warning globally

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Several build configurations had already disabled this warning because
it generates a lot of false positives.  But some had not, and it was
still enabled for "allmodconfig" builds, for example.

Looking at the warnings produced, every single one I looked at was a
false positive, and the warnings are frequent enough (and big enough)
that they can easily hide real problems that you don't notice in the
noise generated by -Wmaybe-uninitialized.

The warning is good in theory, but this is a classic case of a warning
that causes more problems than the warning can solve.

If gcc gets better at avoiding false positives, we may be able to
re-enable this warning.  But as is, we're better off without it, and I
want to be able to see the *real* warnings.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2016-07-27 13:17:41 -07:00
parent 468fc7ed55
commit 6e8d666e92
3 changed files with 5 additions and 10 deletions
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7
Makefile
View File

@ -370,7 +370,7 @@ LDFLAGS_MODULE =
CFLAGS_KERNEL =
AFLAGS_KERNEL =
LDFLAGS_vmlinux =
CFLAGS_GCOV = -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized
CFLAGS_GCOV = -fprofile-arcs -ftest-coverage -fno-tree-loop-im
CFLAGS_KCOV = -fsanitize-coverage=trace-pc
@ -619,12 +619,13 @@ ARCH_CFLAGS :=
include arch/$(SRCARCH)/Makefile
KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
KBUILD_CFLAGS += $(call cc-disable-warning,maybe-uninitialized,)
ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS += -Os $(call cc-disable-warning,maybe-uninitialized,)
KBUILD_CFLAGS += -Os
else
ifdef CONFIG_PROFILE_ALL_BRANCHES
KBUILD_CFLAGS += -O2 $(call cc-disable-warning,maybe-uninitialized,)
KBUILD_CFLAGS += -O2
else
KBUILD_CFLAGS += -O2
endif

4
arch/arc/Makefile
View File

@ -74,9 +74,7 @@ endif
ifndef CONFIG_CC_OPTIMIZE_FOR_SIZE
# Generic build system uses -O2, we want -O3
# Note: No need to add to cflags-y as that happens anyways
#
# Disable the false maybe-uninitialized warings gcc spits out at -O3
ARCH_CFLAGS += -O3 $(call cc-disable-warning,maybe-uninitialized,)
ARCH_CFLAGS += -O3
endif
# small data is default for elf32 tool-chain. If not usable, disable it

4
scripts/Makefile.ubsan
View File

@ -14,8 +14,4 @@ ifdef CONFIG_UBSAN
ifdef CONFIG_UBSAN_ALIGNMENT
CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment)
endif
# -fsanitize=* options makes GCC less smart than usual and
# increase number of 'maybe-uninitialized false-positives
CFLAGS_UBSAN += $(call cc-option, -Wno-maybe-uninitialized)
endif