lkml.org 
[lkml]   [2020]   [Feb]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2] drm/i915: Disable -Wtautological-constant-out-of-range-compare
Date
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
\
 
 \ /
  Last update: 2020-02-11 07:16    [W:0.048 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site