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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2017-05-17 15:09:58 +0300 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2017-05-17 15:38:03 +0300 |
| commit | 991bfc64db096cb924d5d216a9cb469590f00428 (patch) | |
| tree | 834142f298410b00759f48197da53982b57ae467 /drivers/gpu/drm/i915/i915_utils.h | |
| parent | 47624cc3301b6033d51b84a1381c2d69fda9b1a0 (diff) | |
| download | linux-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.h | 2 |
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); \ }) |