On 13/06/2019 15:12, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2019-06-13 14:35:32)
From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
There is a lot of code in i915_gem_gtt.c which repeatadly dereferences
either ggtt or ppgtt in order to get to the vm. Cache those accesses in
local variables for better readability.
There isn't a dereference though, it's just using the base struct. Meh.
I don't really mind, but I chose to write it the other way, specifically
using vm to keep it short.
At the end of the day, the compiler *should* eliminate the redundant
local, so it is merely a matter of which readers prefer. I think I still
have a slight preference to using ppgtt throughout rather than mixing
ppgtt and vm for the same object.
Agreed. I'll drop it. It was a silly ho-hum moment of misguided optimism
how it will save some line wraps and then it didn't even do that.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem_gtt.c | 254 +++++++++++++++-------------
1 file changed, 134 insertions(+), 120 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 516ffc4a521a..d09a4d9b71da 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1004,10 +1004,11 @@ gen8_ppgtt_insert_pte_entries(struct i915_ppgtt *ppgtt,
{
struct i915_page_directory *pd;
const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
+ struct i915_address_space *vm = &ppgtt->vm;
gen8_pte_t *vaddr;
bool ret;
- GEM_BUG_ON(idx->pdpe >= i915_pdpes_per_pdp(&ppgtt->vm));
+ GEM_BUG_ON(idx->pdpe >= i915_pdpes_per_pdp(vm));
pd = pdp->page_directory[idx->pdpe];
vaddr = kmap_atomic_px(pd->page_table[idx->pde]);
do {
@@ -1038,7 +1039,7 @@ gen8_ppgtt_insert_pte_entries(struct i915_ppgtt *ppgtt,
break;
}
- GEM_BUG_ON(idx->pdpe >= i915_pdpes_per_pdp(&ppgtt->vm));
+ GEM_BUG_ON(idx->pdpe >= i915_pdpes_per_pdp(vm));
I don't see any code here. :-p
I don't get it, maybe for the better. :)
Regards,
Tvrtko
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