From 2bf0d26706f899e124a2b340dc0529386bb2b235 Mon Sep 17 00:00:00 2001
From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Date: Tue, 13 Dec 2016 14:37:27 +0000
Subject: [PATCH] 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
---
drivers/gpu/drm/i915/i915_vma.h | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index 21be74c61065a..e3b2b3b1e0568 100644
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -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;
--
2.30.2