--- /dev/null
+/*
+ * Copyright (C) 2020 Google, Inc.
+ *
+ * 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"
+
+/* Lower mediump FS outputs to fp16 */
+
+static bool
+lower_output_var(nir_shader *nir, int location)
+{
+ nir_foreach_variable (var, &nir->outputs) {
+ if (var->data.driver_location == location &&
+ ((var->data.precision == GLSL_PRECISION_MEDIUM) ||
+ (var->data.precision == GLSL_PRECISION_LOW))) {
+ if (glsl_get_base_type(var->type) == GLSL_TYPE_FLOAT)
+ var->type = glsl_float16_type(var->type);
+
+ return glsl_get_base_type(var->type) == GLSL_TYPE_FLOAT16;
+ }
+ }
+
+ return false;
+}
+
+void
+nir_lower_mediump_outputs(nir_shader *nir)
+{
+ nir_function_impl *impl = nir_shader_get_entrypoint(nir);
+ assert(impl);
+
+ /* Get rid of old derefs before we change the types of the variables */
+ nir_opt_dce(nir);
+
+ nir_builder b;
+ nir_builder_init(&b, impl);
+
+ nir_foreach_block_safe (block, impl) {
+ nir_foreach_instr_safe (instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+ if (intr->intrinsic != nir_intrinsic_store_output)
+ continue;
+
+ if (!lower_output_var(nir, nir_intrinsic_base(intr)))
+ continue;
+
+ b.cursor = nir_before_instr(&intr->instr);
+ nir_instr_rewrite_src(&intr->instr, &intr->src[0],
+ nir_src_for_ssa(nir_f2f16(&b, intr->src[0].ssa)));
+
+ nir_intrinsic_set_type(intr, nir_type_float16);
+ }
+ }
+}