drm/i915: Optimise VMA lookup slightly

Cast VM pointers before substraction to save the compiler
doing a smart one which includes multiplication.

v2: Only keep the first optimisation and prettify it. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1481639847-9214-1-git-send-email-tvrtko.ursulin@linux.intel.com
This commit is contained in:
Tvrtko Ursulin 2016-12-13 14:37:27 +00:00
parent 2ee7dc497e
commit 2bf0d26706

View File

@ -178,15 +178,23 @@ static inline void i915_vma_put(struct i915_vma *vma)
i915_gem_object_put(vma->obj);
}
static __always_inline ptrdiff_t ptrdiff(const void *a, const void *b)
{
return a - b;
}
static inline long
i915_vma_compare(struct i915_vma *vma,
struct i915_address_space *vm,
const struct i915_ggtt_view *view)
{
ptrdiff_t cmp;
GEM_BUG_ON(view && !i915_is_ggtt(vm));
if (vma->vm != vm)
return vma->vm - vm;
cmp = ptrdiff(vma->vm, vm);
if (cmp)
return cmp;
if (!view)
return vma->ggtt_view.type;