[PATCH 9/9] glamor: Use buffer_storage

[Eric Anholt]

v2:
  - Make the default buffer size a #define. (by Markus Wick)
  - Fix the return offset for mapping with buffer_storage.  (oops!)
v3:
  - Avoid GL error at first rendering from unmapping no buffer.
  - Rebase on the glBindBuffer(GL_ARRAY_BUFFER, 0) change.
v4: Rebase on Markus's vbo init changes.

Signed-off-by: Eric Anholt <eric at anholt.net>
---
 glamor/glamor.c      |  2 ++
 glamor/glamor_priv.h |  1 +
 glamor/glamor_vbo.c  | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/glamor/glamor.c b/glamor/glamor.c
index dc69c72..e856179 100644
--- a/glamor/glamor.c
+++ b/glamor/glamor.c
@@ -353,6 +353,8 @@ glamor_init(ScreenPtr screen, unsigned int flags)
         glamor_gl_has_extension("GL_MESA_pack_invert");
     glamor_priv->has_fbo_blit =
         glamor_gl_has_extension("GL_EXT_framebuffer_blit");
+    glamor_priv->has_buffer_storage =
+        glamor_gl_has_extension("GL_ARB_buffer_storage");
     glGetIntegerv(GL_MAX_RENDERBUFFER_SIZE, &glamor_priv->max_fbo_size);
 #ifdef MAX_FBO_SIZE
     glamor_priv->max_fbo_size = MAX_FBO_SIZE;
diff --git a/glamor/glamor_priv.h b/glamor/glamor_priv.h
index 986e729..d15eabd 100644
--- a/glamor/glamor_priv.h
+++ b/glamor/glamor_priv.h
@@ -208,6 +208,7 @@ typedef struct glamor_screen_private {
     enum glamor_gl_flavor gl_flavor;
     int has_pack_invert;
     int has_fbo_blit;
+    int has_buffer_storage;
     int max_fbo_size;
 
     struct xorg_list
diff --git a/glamor/glamor_vbo.c b/glamor/glamor_vbo.c
index be2c2af..f736cbe 100644
--- a/glamor/glamor_vbo.c
+++ b/glamor/glamor_vbo.c
@@ -52,7 +52,49 @@ glamor_get_vbo_space(ScreenPtr screen, unsigned size, char **vbo_offset)
 
     glBindBuffer(GL_ARRAY_BUFFER, glamor_priv->vbo);
 
-    if (glamor_priv->gl_flavor == GLAMOR_GL_DESKTOP) {
+    if (glamor_priv->has_buffer_storage) {
+        if (glamor_priv->vbo_size < glamor_priv->vbo_offset + size) {
+            if (glamor_priv->vbo_size)
+                glUnmapBuffer(GL_ARRAY_BUFFER);
+
+            if (size > glamor_priv->vbo_size) {
+                glamor_priv->vbo_size = MAX(GLAMOR_VBO_SIZE, size);
+
+                /* We aren't allowed to resize glBufferStorage()
+                 * buffers, so we need to gen a new one.
+                 */
+                glDeleteBuffers(1, &glamor_priv->vbo);
+                glGenBuffers(1, &glamor_priv->vbo);
+                glBindBuffer(GL_ARRAY_BUFFER, glamor_priv->vbo);
+
+                assert(glGetError() == GL_NO_ERROR);
+                glBufferStorage(GL_ARRAY_BUFFER, glamor_priv->vbo_size, NULL,
+                                GL_MAP_WRITE_BIT |
+                                GL_MAP_PERSISTENT_BIT |
+                                GL_MAP_COHERENT_BIT);
+
+                if (glGetError() != GL_NO_ERROR) {
+                    /* If the driver failed our coherent mapping, fall
+                     * back to the ARB_mbr path.
+                     */
+                    glamor_priv->has_buffer_storage = false;
+                    glamor_priv->vbo_size = 0;
+                    return glamor_get_vbo_space(screen, size, vbo_offset);
+                }
+            }
+
+            glamor_priv->vbo_offset = 0;
+            glamor_priv->vb = glMapBufferRange(GL_ARRAY_BUFFER,
+                                               0, glamor_priv->vbo_size,
+                                               GL_MAP_WRITE_BIT |
+                                               GL_MAP_INVALIDATE_BUFFER_BIT |
+                                               GL_MAP_PERSISTENT_BIT |
+                                               GL_MAP_COHERENT_BIT);
+        }
+        *vbo_offset = (void *)(uintptr_t)glamor_priv->vbo_offset;
+        data = glamor_priv->vb + glamor_priv->vbo_offset;
+        glamor_priv->vbo_offset += size;
+    } else if (glamor_priv->gl_flavor == GLAMOR_GL_DESKTOP) {
         if (glamor_priv->vbo_size < glamor_priv->vbo_offset + size) {
             glamor_priv->vbo_size = MAX(GLAMOR_VBO_SIZE, size);
             glamor_priv->vbo_offset = 0;
@@ -99,7 +141,12 @@ glamor_put_vbo_space(ScreenPtr screen)
 
     glamor_get_context(glamor_priv);
 
-    if (glamor_priv->gl_flavor == GLAMOR_GL_DESKTOP) {
+    if (glamor_priv->has_buffer_storage) {
+        /* If we're in the ARB_buffer_storage path, we have a
+         * persistent mapping, so we can leave it around until we
+         * reach the end of the buffer.
+         */
+    } else if (glamor_priv->gl_flavor == GLAMOR_GL_DESKTOP) {
         glUnmapBuffer(GL_ARRAY_BUFFER);
     } else {
         glBufferData(GL_ARRAY_BUFFER, glamor_priv->vbo_offset,
-- 
1.9.0