4 files changed, 26 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 90d9be449c1..623273c260f 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -329,6 +329,8 @@ brw_initialize_context_constants(struct brw_context *brw)
    ctx->Const.MaxTransformFeedbackSeparateComponents =
       BRW_MAX_SOL_BINDINGS / BRW_MAX_SOL_BUFFERS;
 
+   ctx->Const.AlwaysUseGetTransformFeedbackVertexCount = true;
+
    if (brw->gen == 6) {
       ctx->Const.MaxSamples = 4;
       ctx->Const.MaxColorTextureSamples = 4;
diff --git a/src/mesa/main/dd.h b/src/mesa/main/dd.h
index 50119219906..d7c43271355 100644
--- a/src/mesa/main/dd.h
+++ b/src/mesa/main/dd.h
@@ -843,6 +843,14 @@ struct dd_function_table {
                                    struct gl_transform_feedback_object *obj);
 
    /**
+    * Return the number of vertices written to a stream during the last
+    * Begin/EndTransformFeedback block.
+    */
+   GLsizei (*GetTransformFeedbackVertexCount)(struct gl_context *ctx,
+                                              struct gl_transform_feedback_object *obj,
+                                              GLuint stream);
+
+   /**
     * \name GL_NV_texture_barrier interface
     */
    void (*TextureBarrier)(struct gl_context *ctx);
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index a1a5eb4bf13..087bc372707 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -3156,6 +3156,12 @@ struct gl_constants
     */
    GLboolean PrimitiveRestartInSoftware;
 
+   /**
+    * Always use the GetTransformFeedbackVertexCount() driver hook, rather
+    * than passing the transform feedback object to the drawing function.
+    */
+   GLboolean AlwaysUseGetTransformFeedbackVertexCount;
+
    /** GL_ARB_map_buffer_alignment */
    GLuint MinMapBufferAlignment;
 
diff --git a/src/mesa/vbo/vbo_exec_array.c b/src/mesa/vbo/vbo_exec_array.c
index 1670409d48b..f25a9dec308 100644
--- a/src/mesa/vbo/vbo_exec_array.c
+++ b/src/mesa/vbo/vbo_exec_array.c
@@ -1464,6 +1464,16 @@ vbo_draw_transform_feedback(struct gl_context *ctx, GLenum mode,
       return;
    }
 
+   if (ctx->Driver.GetTransformFeedbackVertexCount &&
+       (ctx->Const.AlwaysUseGetTransformFeedbackVertexCount ||
+        (ctx->Const.PrimitiveRestartInSoftware &&
+         ctx->Array._PrimitiveRestart) ||
+        !vbo_all_varyings_in_vbos(exec->array.inputs))) {
+      GLsizei n = ctx->Driver.GetTransformFeedbackVertexCount(ctx, obj, stream);
+      vbo_draw_arrays(ctx, mode, 0, n, numInstances, 0);
+      return;
+   }
+
    vbo_bind_arrays(ctx);
 
    /* init most fields to zero */