Messages in this thread Patch in this message | | | From | Nathan Chancellor <> | Subject | [PATCH v2] drm/i915: Disable -Wtautological-constant-out-of-range-compare | Date | Mon, 10 Feb 2020 23:13:39 -0700 |
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A recent commit in clang added -Wtautological-compare to -Wall, which is enabled for i915 so we see the following warning:
../drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c:1485:22: warning: result of comparison of constant 576460752303423487 with expression of type 'unsigned int' is always false [-Wtautological-constant-out-of-range-compare] if (unlikely(remain > N_RELOC(ULONG_MAX))) ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
This warning only happens on x86_64 but that check is relevant for 32-bit x86 so we cannot remove it. -Wtautological-compare on a whole has good warnings but this one is not really relevant for the kernel because of all of the different configurations that are used to build the kernel. When -Wtautological-compare is enabled for the kernel, this option will remain disabled so do that for i915 now.
Link: https://github.com/ClangBuiltLinux/linux/issues/778 Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> ---
v1 -> v2: https://lore.kernel.org/lkml/20200211050808.29463-1-natechancellor@gmail.com/
* Fix patch application due to basing on a local tree that had -Wuninitialized turned on. Can confirm that patch applies on latest -next now.
drivers/gpu/drm/i915/Makefile | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile index b8c5f8934dbd..159355eb43a9 100644 --- a/drivers/gpu/drm/i915/Makefile +++ b/drivers/gpu/drm/i915/Makefile @@ -22,6 +22,7 @@ subdir-ccflags-y += $(call cc-disable-warning, sign-compare) subdir-ccflags-y += $(call cc-disable-warning, sometimes-uninitialized) subdir-ccflags-y += $(call cc-disable-warning, initializer-overrides) subdir-ccflags-y += $(call cc-disable-warning, uninitialized) +subdir-ccflags-y += $(call cc-disable-warning, tautological-constant-out-of-range-compare) subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror # Fine grained warnings disable -- 2.25.0
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