nir: add lowering-pass for point-size mov

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/compiler/Makefile.sources

@@ -269,6 +269,7 @@ NIR_FILES = \
 	nir/nir_lower_passthrough_edgeflags.c \
 	nir/nir_lower_patch_vertices.c \
 	nir/nir_lower_phis_to_scalar.c \
+	nir/nir_lower_point_size_mov.c \
 	nir/nir_lower_regs_to_ssa.c \
 	nir/nir_lower_returns.c \
 	nir/nir_lower_samplers.c \

src/compiler/nir/meson.build

@@ -151,6 +151,7 @@ files_libnir = files(
   'nir_lower_patch_vertices.c',
   'nir_lower_phis_to_scalar.c',
   'nir_lower_point_size.c',
+  'nir_lower_point_size_mov.c',
   'nir_lower_regs_to_ssa.c',
   'nir_lower_returns.c',
   'nir_lower_samplers.c',

src/compiler/nir/nir.h

@@ -3911,6 +3911,9 @@ bool nir_lower_clip_gs(nir_shader *shader, unsigned ucp_enables);
 bool nir_lower_clip_fs(nir_shader *shader, unsigned ucp_enables);
 bool nir_lower_clip_cull_distance_arrays(nir_shader *nir);
 
+void nir_lower_point_size_mov(nir_shader *shader,
+                              const gl_state_index16 *pointsize_state_tokens);
+
 bool nir_lower_frexp(nir_shader *nir);
 
 void nir_lower_two_sided_color(nir_shader *shader);

src/compiler/nir/nir_lower_point_size_mov.c

@@ -0,0 +1,69 @@
+/*
+ * Copyright © 2019 Collabora Ltd
+ *
+ * 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 "nir.h"
+#include "nir_builder.h"
+
+/** nir_lower_point_size_mov.c
+ *
+ * This pass lowers glPointSize into gl_PointSize, by adding a uniform
+ * and a move from that uniform to VARYING_SLOT_PSIZ. This is useful for
+ * OpenGL ES level hardware that lack constant point-size hardware state.
+ */
+
+static bool
+lower_impl(nir_function_impl *impl,
+           const gl_state_index16 *pointsize_state_tokens)
+{
+   nir_shader *shader = impl->function->shader;
+   nir_builder b;
+   nir_variable *in, *out;
+
+   nir_builder_init(&b, impl);
+   b.cursor = nir_before_cf_list(&impl->body);
+
+   in = nir_variable_create(shader, nir_var_uniform,
+                            glsl_float_type(), "gl_PointSizeClampedMESA");
+   in->num_state_slots = 1;
+   in->state_slots = ralloc_array(in, nir_state_slot, 1);
+   memcpy(in->state_slots[0].tokens,
+         pointsize_state_tokens,
+         sizeof(in->state_slots[0].tokens));
+
+   out = nir_variable_create(shader, nir_var_shader_out,
+                             glsl_float_type(), "gl_PointSize");
+   out->data.location = VARYING_SLOT_PSIZ;
+
+   nir_copy_var(&b, out, in);
+
+   nir_metadata_preserve(impl, nir_metadata_block_index |
+                               nir_metadata_dominance);
+   return true;
+}
+
+void
+nir_lower_point_size_mov(nir_shader *shader,
+                         const gl_state_index16 *pointsize_state_tokens)
+{
+   lower_impl(nir_shader_get_entrypoint(shader), pointsize_state_tokens);
+}