i965/nir/vec4: Select between new nir_vec4 or current vec4_visitor code-paths

The NIR->vec4 pass will be activated if both the following conditions are met:

* INTEL_USE_NIR environment variable is defined and is positive (1 or true)
* The stage is vertex shader (support for geometry shaders and
  ARB_vertex_program will be added later).

Reviewed-by: Jason Ekstrand <[email protected]>

2 files changed, 22 insertions, 10 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp
index 58587b24403..524798c6ac6 100644
--- a/src/mesa/drivers/dri/i965/brw_shader.cpp
+++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
@@ -122,12 +122,14 @@ brw_compiler_create(void *mem_ctx, const struct brw_device_info *devinfo)
    compiler->glsl_compiler_options[MESA_SHADER_VERTEX].OptimizeForAOS = true;
    compiler->glsl_compiler_options[MESA_SHADER_GEOMETRY].OptimizeForAOS = true;
 
-   if (compiler->scalar_vs) {
-      /* If we're using the scalar backend for vertex shaders, we need to
-       * configure these accordingly.
-       */
-      compiler->glsl_compiler_options[MESA_SHADER_VERTEX].EmitNoIndirectOutput = true;
-      compiler->glsl_compiler_options[MESA_SHADER_VERTEX].EmitNoIndirectTemp = true;
+   if (compiler->scalar_vs || brw_env_var_as_boolean("INTEL_USE_NIR", false)) {
+      if (compiler->scalar_vs) {
+         /* If we're using the scalar backend for vertex shaders, we need to
+          * configure these accordingly.
+          */
+         compiler->glsl_compiler_options[MESA_SHADER_VERTEX].EmitNoIndirectOutput = true;
+         compiler->glsl_compiler_options[MESA_SHADER_VERTEX].EmitNoIndirectTemp = true;
+      }
       compiler->glsl_compiler_options[MESA_SHADER_VERTEX].OptimizeForAOS = false;
 
       compiler->glsl_compiler_options[MESA_SHADER_VERTEX].NirOptions = nir_options;
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index 53270fb6eba..ce04f1b2173 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -1709,6 +1709,9 @@ vec4_visitor::emit_shader_time_write(int shader_time_subindex, src_reg value)
 bool
 vec4_visitor::run(gl_clip_plane *clip_planes)
 {
+   bool use_vec4_nir =
+      compiler->glsl_compiler_options[MESA_SHADER_VERTEX].NirOptions != NULL;
+
    sanity_param_count = prog->Parameters->NumParameters;
 
    if (shader_time_index >= 0)
@@ -1718,11 +1721,18 @@ vec4_visitor::run(gl_clip_plane *clip_planes)
 
    emit_prolog();
 
-   /* Generate VS IR for main().  (the visitor only descends into
-    * functions called "main").
-    */
    if (shader) {
-      visit_instructions(shader->base.ir);
+      if (use_vec4_nir) {
+         assert(prog->nir != NULL);
+         emit_nir_code();
+         if (failed)
+            return false;
+      } else {
+         /* Generate VS IR for main().  (the visitor only descends into
+          * functions called "main").
+          */
+         visit_instructions(shader->base.ir);
+      }
    } else {
       emit_program_code();
    }