i965/nir/gs: Handle geometry shaders inputs

Outputs from the vertex shader become array inputs in the geomtry shader,
but the arrays are interleaved, so we need to map our inputs accordingly.

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>

src/mesa/drivers/dri/i965/Makefile.sources

@@ -126,6 +126,7 @@ i965_FILES = \
 	brw_vec4_live_variables.cpp \
 	brw_vec4_live_variables.h \
 	brw_vec4_nir.cpp \
+	brw_vec4_gs_nir.cpp \
 	brw_vec4_reg_allocate.cpp \
 	brw_vec4_visitor.cpp \
 	brw_vec4_vp.cpp \

src/mesa/drivers/dri/i965/brw_vec4_gs_nir.cpp

@@ -0,0 +1,68 @@
+/*
+ * Copyright © 2015 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.
+ */
+
+#include "brw_nir.h"
+#include "brw_vec4_gs_visitor.h"
+
+namespace brw {
+
+void
+vec4_gs_visitor::nir_setup_inputs(nir_shader *shader)
+{
+   nir_inputs = ralloc_array(mem_ctx, src_reg, shader->num_inputs);
+
+   foreach_list_typed(nir_variable, var, node, &shader->inputs) {
+      int offset = var->data.driver_location;
+      if (var->type->base_type == GLSL_TYPE_ARRAY) {
+         /* Geometry shader inputs are arrays, but they use an unusual array
+          * layout: instead of all array elements for a given geometry shader
+          * input being stored consecutively, all geometry shader inputs are
+          * interleaved into one giant array. At this stage of compilation, we
+          * assume that the stride of the array is BRW_VARYING_SLOT_COUNT.
+          * Later, setup_attributes() will remap our accesses to the actual
+          * input array.
+          */
+         assert(var->type->length > 0);
+         int length = var->type->length;
+         int size = type_size(var->type) / length;
+         for (int i = 0; i < length; i++) {
+            int location = var->data.location + i * BRW_VARYING_SLOT_COUNT;
+            for (int j = 0; j < size; j++) {
+               src_reg src = src_reg(ATTR, location + j, var->type);
+               src = retype(src, brw_type_for_base_type(var->type));
+               nir_inputs[offset] = src;
+               offset++;
+            }
+         }
+      } else {
+         int size = type_size(var->type);
+         for (int i = 0; i < size; i++) {
+            src_reg src = src_reg(ATTR, var->data.location + i, var->type);
+            src = retype(src, brw_type_for_base_type(var->type));
+            nir_inputs[offset] = src;
+            offset++;
+         }
+      }
+   }
+}
+}

src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h

@@ -75,6 +75,8 @@ public:
                    bool no_spills,
                    int shader_time_index);
 
+   virtual void nir_setup_inputs(nir_shader *shader);
+
 protected:
    virtual dst_reg *make_reg_for_system_value(int location,
                                               const glsl_type *type);