svga: eliminiate unnecessary constant buffer updates

Currently if the texture binding is changed, emit_fs_consts()
is triggered to update texture scaling factor for
rectangle texture or texture buffer size in the constant buffer.
But the update is only relevant if the texture binding includes
a rectangle texture or a texture buffer.

To eliminate the unnecessary constant buffer updates due to other texture
binding changes, a new flag SVGA_NEW_TEXTURE_CONSTS will be used
to trigger fragment shader constant buffer update when a rectangle texture
or a texture buffer is bound.

With this patch, the number of constant buffer updates in Lightsmark2008
reduces from hundreds per frame to about 28 per frame.

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

src/gallium/drivers/svga/svga_context.h

@@ -291,6 +291,8 @@ struct svga_state
    struct {
       unsigned flag_1d;
       unsigned flag_srgb;
+      unsigned flag_rect;  /* sampler views with rectangular texture target */
+      unsigned flag_buf;   /* sampler views with texture buffer target */
    } tex_flags;
 
    unsigned sample_mask;
@@ -586,6 +588,7 @@ struct svga_context
 #define SVGA_NEW_GS                  0x10000000
 #define SVGA_NEW_GS_CONST_BUFFER     0x20000000
 #define SVGA_NEW_GS_VARIANT          0x40000000
+#define SVGA_NEW_TEXTURE_CONSTS      0x80000000
 
 
 

src/gallium/drivers/svga/svga_pipe_sampler.c

@@ -421,6 +421,8 @@ svga_set_sampler_views(struct pipe_context *pipe,
    struct svga_context *svga = svga_context(pipe);
    unsigned flag_1d = 0;
    unsigned flag_srgb = 0;
+   unsigned flag_rect = 0;
+   unsigned flag_buf = 0;
    uint i;
    boolean any_change = FALSE;
 
@@ -432,6 +434,8 @@ svga_set_sampler_views(struct pipe_context *pipe,
       return;
 
    for (i = 0; i < num; i++) {
+      enum pipe_texture_target target;
+
       if (svga->curr.sampler_views[shader][start + i] != views[i]) {
          /* Note: we're using pipe_sampler_view_release() here to work around
           * a possible crash when the old view belongs to another context that
@@ -449,8 +453,13 @@ svga_set_sampler_views(struct pipe_context *pipe,
       if (util_format_is_srgb(views[i]->format))
          flag_srgb |= 1 << (start + i);
 
-      if (views[i]->texture->target == PIPE_TEXTURE_1D)
+      target = views[i]->texture->target;
+      if (target == PIPE_TEXTURE_1D)
          flag_1d |= 1 << (start + i);
+      else if (target == PIPE_TEXTURE_RECT)
+         flag_rect |= 1 << (start + i);
+      else if (target == PIPE_BUFFER)
+         flag_buf |= 1 << (start + i);
    }
 
    if (!any_change) {
@@ -474,6 +483,15 @@ svga_set_sampler_views(struct pipe_context *pipe,
       svga->curr.tex_flags.flag_srgb = flag_srgb;
    }
 
+   if (flag_rect != svga->curr.tex_flags.flag_rect ||
+       flag_buf != svga->curr.tex_flags.flag_buf)
+   {
+      /* Need to re-emit texture constants */
+      svga->dirty |= SVGA_NEW_TEXTURE_CONSTS;
+      svga->curr.tex_flags.flag_rect = flag_rect;
+      svga->curr.tex_flags.flag_buf = flag_buf;
+   }
+
    /* Check if any of the sampler view resources collide with the framebuffer
     * color buffers or depth stencil resource. If so, enable the NEW_FRAME_BUFFER
     * dirty bit so that emit_framebuffer can be invoked to create backed view

src/gallium/drivers/svga/svga_state_constants.c

@@ -788,7 +788,7 @@ struct svga_tracked_state svga_hw_fs_constants =
    "hw fs params",
    (SVGA_NEW_FS_CONST_BUFFER |
     SVGA_NEW_FS_VARIANT |
-    SVGA_NEW_TEXTURE_BINDING),
+    SVGA_NEW_TEXTURE_CONSTS),
    emit_fs_consts
 };