nir/zink: move clip_halfz-lowering to common code

Etnaviv also does the same thing, so let's try to avoid repetition here,
and use the same for it code as well.

Reviewed-by: Jonathan Marek <[email protected]>
Tested-by: Paul Cercueil <[email protected]>

4 files changed, 81 insertions, 0 deletions

diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index c5c1dc62a6b..1b10e3e4bb7 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -242,6 +242,7 @@ NIR_FILES = \
 	nir/nir_lower_clamp_color_outputs.c \
 	nir/nir_lower_clip.c \
 	nir/nir_lower_clip_cull_distance_arrays.c \
+	nir/nir_lower_clip_halfz.c \
 	nir/nir_lower_constant_initializers.c \
 	nir/nir_lower_double_ops.c \
 	nir/nir_lower_drawpixels.c \
diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build
index 43a91769253..b35eb855282 100644
--- a/src/compiler/nir/meson.build
+++ b/src/compiler/nir/meson.build
@@ -123,6 +123,7 @@ files_libnir = files(
   'nir_lower_clamp_color_outputs.c',
   'nir_lower_clip.c',
   'nir_lower_clip_cull_distance_arrays.c',
+  'nir_lower_clip_halfz.c',
   'nir_lower_constant_initializers.c',
   'nir_lower_double_ops.c',
   'nir_lower_drawpixels.c',
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 976fc59bff1..868fe09ca36 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -3633,6 +3633,8 @@ bool nir_lower_vars_to_scratch(nir_shader *shader,
                                int size_threshold,
                                glsl_type_size_align_func size_align);
 
+void nir_lower_clip_halfz(nir_shader *shader);
+
 void nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint);
 
 void nir_gather_ssa_types(nir_function_impl *impl,
diff --git a/src/compiler/nir/nir_lower_clip_halfz.c b/src/compiler/nir/nir_lower_clip_halfz.c
new file mode 100644
index 00000000000..13b7a5b8f1e
--- /dev/null
+++ b/src/compiler/nir/nir_lower_clip_halfz.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2018-2019 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
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHOR(S) AND/OR THEIR SUPPLIERS 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_builder.h"
+
+static void
+lower_pos_write(nir_builder *b, struct nir_instr *instr)
+{
+   if (instr->type != nir_instr_type_intrinsic)
+      return;
+
+   nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+   if (intr->intrinsic != nir_intrinsic_store_deref)
+      return;
+
+   nir_variable *var = nir_intrinsic_get_var(intr, 0);
+   if (var->data.mode != nir_var_shader_out ||
+       var->data.location != VARYING_SLOT_POS)
+      return;
+
+   b->cursor = nir_before_instr(&intr->instr);
+
+   nir_ssa_def *pos = nir_ssa_for_src(b, intr->src[1], 4);
+   nir_ssa_def *def = nir_vec4(b,
+                               nir_channel(b, pos, 0),
+                               nir_channel(b, pos, 1),
+                               nir_fmul_imm(b,
+                                            nir_fadd(b,
+                                                     nir_channel(b, pos, 2),
+                                                     nir_channel(b, pos, 3)),
+                                            0.5),
+                               nir_channel(b, pos, 3));
+   nir_instr_rewrite_src(&intr->instr, intr->src + 1, nir_src_for_ssa(def));
+}
+
+void
+nir_lower_clip_halfz(nir_shader *shader)
+{
+   if (shader->info.stage != MESA_SHADER_VERTEX)
+      return;
+
+   nir_foreach_function(function, shader) {
+      if (function->impl) {
+         nir_builder b;
+         nir_builder_init(&b, function->impl);
+
+         nir_foreach_block(block, function->impl) {
+            nir_foreach_instr_safe(instr, block) {
+               lower_pos_write(&b, instr);
+            }
+         }
+
+         nir_metadata_preserve(function->impl, nir_metadata_block_index |
+                                               nir_metadata_dominance);
+      }
+   }
+}