Mesa (master): u_upload_mgr: rework the application of alignment

[Marek Olšák]

Module: Mesa
Branch: master
Commit: ffc4716e9730ca162ce5dfcf0298125269c6d908
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ffc4716e9730ca162ce5dfcf0298125269c6d908

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Sat Dec 19 16:44:52 2015 +0100

u_upload_mgr: rework the application of alignment

The function only aligned the size, but not the offset.
The offset was aligned only when the previous suballocation was aligned.
That yielded the correct offset alignment if the alignment was constant
for all suballocations.

Instead, directly align the offset, but allow an unaligned size.
There is no change in behavior, because the alignment is constant
at the moment.

This a prerequisite for allowing a variable alignment for suballocations.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>

---

 src/gallium/auxiliary/util/u_upload_mgr.c |   24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/src/gallium/auxiliary/util/u_upload_mgr.c b/src/gallium/auxiliary/util/u_upload_mgr.c
index b672fad..4148bae 100644
--- a/src/gallium/auxiliary/util/u_upload_mgr.c
+++ b/src/gallium/auxiliary/util/u_upload_mgr.c
@@ -185,15 +185,20 @@ u_upload_alloc(struct u_upload_mgr *upload,
                struct pipe_resource **outbuf,
                void **ptr)
 {
-   unsigned alloc_size = align(size, upload->alignment);
-   unsigned alloc_offset = align(min_out_offset, upload->alignment);
+   unsigned alignment = upload->alignment;
    unsigned buffer_size = upload->buffer ? upload->buffer->width0 : 0;
    unsigned offset;
 
+   min_out_offset = align(min_out_offset, alignment);
+
+   offset = align(upload->offset, alignment);
+   offset = MAX2(offset, min_out_offset);
+
    /* Make sure we have enough space in the upload buffer
-    * for the sub-allocation. */
-   if (unlikely(MAX2(upload->offset, alloc_offset) + alloc_size > buffer_size)) {
-      u_upload_alloc_buffer(upload, alloc_offset + alloc_size);
+    * for the sub-allocation.
+    */
+   if (unlikely(!upload->buffer || offset + size > buffer_size)) {
+      u_upload_alloc_buffer(upload, min_out_offset + size);
 
       if (unlikely(!upload->buffer)) {
          *out_offset = ~0;
@@ -202,11 +207,10 @@ u_upload_alloc(struct u_upload_mgr *upload,
          return;
       }
 
+      offset = min_out_offset;
       buffer_size = upload->buffer->width0;
    }
 
-   offset = MAX2(upload->offset, alloc_offset);
-
    if (unlikely(!upload->map)) {
       upload->map = pipe_buffer_map_range(upload->pipe, upload->buffer,
                                           offset,
@@ -224,8 +228,8 @@ u_upload_alloc(struct u_upload_mgr *upload,
       upload->map -= offset;
    }
 
-   assert(offset < upload->buffer->width0);
-   assert(offset + size <= upload->buffer->width0);
+   assert(offset < buffer_size);
+   assert(offset + size <= buffer_size);
    assert(size);
 
    /* Emit the return values: */
@@ -233,7 +237,7 @@ u_upload_alloc(struct u_upload_mgr *upload,
    pipe_resource_reference(outbuf, upload->buffer);
    *out_offset = offset;
 
-   upload->offset = offset + alloc_size;
+   upload->offset = offset + size;
 }
 
 void u_upload_data(struct u_upload_mgr *upload,