nir: add a pass to lower system value reads

v2: Jason Ekstrand <[email protected]>:
   whitespace fixes

2 files changed, 108 insertions, 0 deletions

diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
index 0595b221442..cb63a129a57 100644
--- a/src/glsl/nir/nir.h
+++ b/src/glsl/nir/nir.h
@@ -1259,6 +1259,8 @@ void nir_lower_samplers(nir_shader *shader,
                         struct gl_shader_program *shader_program,
                         struct gl_program *prog);
 
+void nir_lower_system_values(nir_shader *shader);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/src/glsl/nir/nir_lower_system_values.c b/src/glsl/nir/nir_lower_system_values.c
new file mode 100644
index 00000000000..cbd1dace9c6
--- /dev/null
+++ b/src/glsl/nir/nir_lower_system_values.c
@@ -0,0 +1,106 @@
+/*
+ * Copyright © 2014 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Connor Abbott ([email protected])
+ *
+ */
+
+#include "nir.h"
+
+static void
+convert_instr(nir_intrinsic_instr *instr)
+{
+   if (instr->intrinsic != nir_intrinsic_load_var_vec1 &&
+       instr->intrinsic != nir_intrinsic_load_var_vec2)
+      return;
+
+   nir_variable *var = instr->variables[0]->var;
+   if (var->data.mode != nir_var_system_value)
+      return;
+
+   void *mem_ctx = ralloc_parent(instr);
+
+   nir_intrinsic_op op;
+
+   switch (var->data.location) {
+   case SYSTEM_VALUE_FRONT_FACE:
+      op = nir_intrinsic_load_front_face;
+      break;
+   case SYSTEM_VALUE_VERTEX_ID:
+      op = nir_intrinsic_load_vertex_id;
+      break;
+   case SYSTEM_VALUE_INSTANCE_ID:
+      op = nir_intrinsic_load_instance_id;
+      break;
+   case SYSTEM_VALUE_SAMPLE_ID:
+      op = nir_intrinsic_load_sample_id;
+      break;
+   case SYSTEM_VALUE_SAMPLE_POS:
+      op = nir_intrinsic_load_sample_pos;
+      break;
+   case SYSTEM_VALUE_SAMPLE_MASK_IN:
+      op = nir_intrinsic_load_sample_mask_in;
+      break;
+   case SYSTEM_VALUE_INVOCATION_ID:
+      op = nir_intrinsic_load_invocation_id;
+      break;
+   default:
+      assert(0);
+      break;
+   }
+
+   nir_intrinsic_instr *new_instr = nir_intrinsic_instr_create(mem_ctx, op);
+   new_instr->dest = nir_dest_copy(instr->dest, mem_ctx);
+   nir_instr_insert_before(&instr->instr, &new_instr->instr);
+   nir_instr_remove(&instr->instr);
+}
+
+static bool
+convert_block(nir_block *block, void *state)
+{
+   (void) state;
+
+   nir_foreach_instr_safe(block, instr) {
+      if (instr->type == nir_instr_type_intrinsic)
+         convert_instr(nir_instr_as_intrinsic(instr));
+   }
+
+   return true;
+}
+
+static void
+convert_impl(nir_function_impl *impl)
+{
+   nir_foreach_block(impl, convert_block, NULL);
+}
+
+void
+nir_lower_system_values(nir_shader *shader)
+{
+   nir_foreach_overload(shader, overload) {
+      if (overload->impl)
+         convert_impl(overload->impl);
+   }
+
+   exec_list_make_empty(&shader->system_values);
+}