[Mesa-dev] [PATCH] st/mesa: emit saturates in the vertex shader if Shader Model 3.0 is supported

[Marek Olšák]

v2: change the requirement from GLSL 1.30 to SM 3.0 (R500 can do this)
---
I'd like to know if people are okay with this.


 src/mesa/state_tracker/st_context.c        |    1 +
 src/mesa/state_tracker/st_context.h        |    1 +
 src/mesa/state_tracker/st_glsl_to_tgsi.cpp |    7 ++++---
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/mesa/state_tracker/st_context.c b/src/mesa/state_tracker/st_context.c
index b416319..676fc06 100644
--- a/src/mesa/state_tracker/st_context.c
+++ b/src/mesa/state_tracker/st_context.c
@@ -182,6 +182,7 @@ st_create_context_priv( struct gl_context *ctx, struct pipe_context *pipe,
 
    st->has_stencil_export =
       screen->get_param(screen, PIPE_CAP_SHADER_STENCIL_EXPORT);
+   st->has_shader_model3 = screen->get_param(screen, PIPE_CAP_SM3);
 
    /* GL limits and extensions */
    st_init_limits(st);
diff --git a/src/mesa/state_tracker/st_context.h b/src/mesa/state_tracker/st_context.h
index 70ee671..726c64d 100644
--- a/src/mesa/state_tracker/st_context.h
+++ b/src/mesa/state_tracker/st_context.h
@@ -84,6 +84,7 @@ struct st_context
    GLboolean clamp_vert_color_in_shader;
    boolean has_stencil_export; /**< can do shader stencil export? */
    boolean has_time_elapsed;
+   boolean has_shader_model3;
 
    /* On old libGL's for linux we need to invalidate the drawables
     * on glViewpport calls, this is set via a option.
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 69061a8..f833321 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -1286,11 +1286,12 @@ glsl_to_tgsi_visitor::try_emit_mad_for_and_not(ir_expression *ir, int try_operan
 bool
 glsl_to_tgsi_visitor::try_emit_sat(ir_expression *ir)
 {
-   /* Saturates were only introduced to vertex programs in
-    * NV_vertex_program3, so don't give them to drivers in the VP.
+   /* Emit saturates in the vertex shader only if SM 3.0 is supported.
     */
-   if (this->prog->Target == GL_VERTEX_PROGRAM_ARB)
+   if (this->prog->Target == GL_VERTEX_PROGRAM_ARB &&
+       !st_context(this->ctx)->has_shader_model3) {
       return false;
+   }
 
    ir_rvalue *sat_src = ir->as_rvalue_to_saturate();
    if (!sat_src)
-- 
1.7.10.4