Mesa (master): svga: avoid redundant SetVertexBuffer/ SetIndexBuffer commands at rebind

[Brian Paul]

Module: Mesa
Branch: master
Commit: c2b4942afcc7389ba99e230ec34eab03d9863205
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=c2b4942afcc7389ba99e230ec34eab03d9863205

Author: Charmaine Lee <charmainel at vmware.com>
Date:   Fri Jul 22 15:05:02 2016 -0700

svga: avoid redundant SetVertexBuffer/SetIndexBuffer commands at rebind

This patch eliminates the redundant SetVertexBuffers and
SetIndexBuffer commands that are emitted for rebind purpose.
With this patch, the set commands will be skipped, but we will still
reference the associated resources to allow the kernel to
bring in the resources.

Tested with Lightsmark2008, Valley, MTT glretrace, piglit, conform.

Reviewed-by: Brian Paul <brianp at vmware.com>

---

 src/gallium/drivers/svga/svga_draw.c | 35 +++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/src/gallium/drivers/svga/svga_draw.c b/src/gallium/drivers/svga/svga_draw.c
index 600df89..14a7406 100644
--- a/src/gallium/drivers/svga/svga_draw.c
+++ b/src/gallium/drivers/svga/svga_draw.c
@@ -440,10 +440,9 @@ draw_vgpu10(struct svga_hwtnl *hwtnl,
    struct svga_winsys_surface *vbuffer_handles[SVGA3D_INPUTREG_MAX];
    struct svga_winsys_surface *ib_handle;
    const unsigned vbuf_count = hwtnl->cmd.vbuf_count;
+   int last_vbuf = -1;
    enum pipe_error ret;
    unsigned i;
-   boolean rebind_ib = FALSE;
-   boolean rebind_vbuf = FALSE;
 
    assert(svga_have_vgpu10(svga));
    assert(hwtnl->cmd.prim_count == 0);
@@ -467,11 +466,11 @@ draw_vgpu10(struct svga_hwtnl *hwtnl,
       if (ret != PIPE_OK)
          return ret;
 
-      /* Force rebinding the index buffer when needed */
-      rebind_ib = TRUE;
-
-      /* Force rebinding the vertex buffers */
-      rebind_vbuf = TRUE;
+      /* No need to explicitly rebind index buffer and vertex buffers here.
+       * Even if the same index buffer or vertex buffers are referenced for this
+       * draw and we skip emitting the redundant set command, we will still
+       * reference the associated resources.
+       */
    }
 
    ret = validate_sampler_resources(svga);
@@ -492,6 +491,7 @@ draw_vgpu10(struct svga_hwtnl *hwtnl,
          if (vbuffer_handles[i] == NULL)
             return PIPE_ERROR_OUT_OF_MEMORY;
          vbuffers[i] = &sbuf->b.b;
+         last_vbuf = i;
       }
       else {
          vbuffers[i] = NULL;
@@ -543,8 +543,7 @@ draw_vgpu10(struct svga_hwtnl *hwtnl,
       /* If we haven't yet emitted a drawing command or if any
        * vertex buffer state is changing, issue that state now.
        */
-      if (rebind_vbuf ||
-          ((hwtnl->cmd.swc->hints & SVGA_HINT_FLAG_CAN_PRE_FLUSH) == 0) ||
+      if (((hwtnl->cmd.swc->hints & SVGA_HINT_FLAG_CAN_PRE_FLUSH) == 0) ||
           vbuf_count != svga->state.hw_draw.num_vbuffers ||
           memcmp(vbuffer_attrs, svga->state.hw_draw.vbuffer_attrs,
                  vbuf_count * sizeof(vbuffer_attrs[0])) ||
@@ -568,7 +567,10 @@ draw_vgpu10(struct svga_hwtnl *hwtnl,
             if (ret != PIPE_OK)
                return ret;
 
-            svga->state.hw_draw.num_vbuffers = num_vbuffers;
+            /* save the number of vertex buffers sent to the device, not
+             * including trailing unbound vertex buffers.
+             */
+            svga->state.hw_draw.num_vbuffers = last_vbuf + 1;
             memcpy(svga->state.hw_draw.vbuffer_attrs, vbuffer_attrs,
                    num_vbuffers * sizeof(vbuffer_attrs[0]));
             for (i = 0; i < num_vbuffers; i++) {
@@ -582,10 +584,12 @@ draw_vgpu10(struct svga_hwtnl *hwtnl,
           * command, we still need to reference the vertex buffers surfaces.
           */
          for (i = 0; i < vbuf_count; i++) {
-            ret = svga->swc->resource_rebind(svga->swc, vbuffer_handles[i],
-                                             NULL, SVGA_RELOC_READ);
-            if (ret != PIPE_OK)
-               return ret;
+            if (vbuffer_handles[i]) {
+               ret = svga->swc->resource_rebind(svga->swc, vbuffer_handles[i],
+                                                NULL, SVGA_RELOC_READ);
+               if (ret != PIPE_OK)
+                  return ret;
+            }
          }
       }
    }
@@ -604,8 +608,7 @@ draw_vgpu10(struct svga_hwtnl *hwtnl,
       SVGA3dSurfaceFormat indexFormat = xlate_index_format(range->indexWidth);
 
       /* setup index buffer */
-      if (rebind_ib ||
-          ib != svga->state.hw_draw.ib ||
+      if (ib != svga->state.hw_draw.ib ||
           indexFormat != svga->state.hw_draw.ib_format ||
           range->indexArray.offset != svga->state.hw_draw.ib_offset) {