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authorChris Wilson <chris@chris-wilson.co.uk>2017-05-17 15:09:58 +0300
committerChris Wilson <chris@chris-wilson.co.uk>2017-05-17 15:38:03 +0300
commit991bfc64db096cb924d5d216a9cb469590f00428 (patch)
tree834142f298410b00759f48197da53982b57ae467 /drivers/gpu/drm/i915/i915_utils.h
parent47624cc3301b6033d51b84a1381c2d69fda9b1a0 (diff)
downloadlinux-991bfc64db096cb924d5d216a9cb469590f00428.tar.xz
drm/i915: Make ptr_unpack_bits() more function-like
ptr_unpack_bits() is a function-like macro, as such it is meant to be replaceable by a function. In this case, we should be passing in the out-param as a pointer. Bizarrely this does affect code generation: function old new delta i915_gem_object_pin_map 409 389 -20 An improvement(?) in this case, but one can't help wonder what strict-aliasing optimisations we are preventing. The generated code looks identical in using ptr_unpack_bits (no extra motions to stack, the pointer and bits appear to be kept in registers), the difference appears to be code ordering and with a reorder it is able to use smaller forward jumps. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170517121007.27224-3-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/i915_utils.h')
-rw-r--r--drivers/gpu/drm/i915/i915_utils.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index f9d6607ef52f..18630d8f4be8 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -77,7 +77,7 @@
#define ptr_unpack_bits(ptr, bits) ({ \
unsigned long __v = (unsigned long)(ptr); \
- (bits) = __v & ~PAGE_MASK; \
+ *(bits) = __v & ~PAGE_MASK; \
(typeof(ptr))(__v & PAGE_MASK); \
})