[Mesa-dev] [PATCH 04/42] panfrost/midgard: Passthrough nir_lower_framebuffer

[Alyssa Rosenzweig]

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
---
 src/gallium/drivers/panfrost/meson.build      |   1 +
 .../panfrost/midgard/nir_lower_blend.h        |   3 +
 .../panfrost/midgard/nir_lower_framebuffer.c  | 102 ++++++++++++++++++
 .../drivers/panfrost/pan_blend_shaders.c      |   2 +
 4 files changed, 108 insertions(+)
 create mode 100644 src/gallium/drivers/panfrost/midgard/nir_lower_framebuffer.c

diff --git a/src/gallium/drivers/panfrost/meson.build b/src/gallium/drivers/panfrost/meson.build
index b69b41bfd90..cc49903aaac 100644
--- a/src/gallium/drivers/panfrost/meson.build
+++ b/src/gallium/drivers/panfrost/meson.build
@@ -37,6 +37,7 @@ files_panfrost = files(
   'midgard/midgard_ops.c',
 
   'midgard/nir_lower_blend.c',
+  'midgard/nir_lower_framebuffer.c',
   'midgard/cppwrap.cpp',
   'midgard/disassemble.c',
 
diff --git a/src/gallium/drivers/panfrost/midgard/nir_lower_blend.h b/src/gallium/drivers/panfrost/midgard/nir_lower_blend.h
index f8075768e7a..2805ca25d97 100644
--- a/src/gallium/drivers/panfrost/midgard/nir_lower_blend.h
+++ b/src/gallium/drivers/panfrost/midgard/nir_lower_blend.h
@@ -53,4 +53,7 @@ typedef struct {
 
 void nir_lower_blend(nir_shader *shader, nir_lower_blend_options options);
 
+void
+nir_lower_framebuffer(nir_shader *shader);
+
 #endif
diff --git a/src/gallium/drivers/panfrost/midgard/nir_lower_framebuffer.c b/src/gallium/drivers/panfrost/midgard/nir_lower_framebuffer.c
new file mode 100644
index 00000000000..67fdf012c04
--- /dev/null
+++ b/src/gallium/drivers/panfrost/midgard/nir_lower_framebuffer.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 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.
+ *
+ * Authors (Collabora):
+ *      Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
+ */
+
+/**
+ * @file
+ *
+ * Implements framebuffer format conversions in software, specifically for
+ * blend shaders on Midgard/Bifrost. load_output/store_output (derefs more
+ * correctly -- pre I/O lowering) normally for the fragment stage within the
+ * blend shader will operate with purely vec4 float ("nir") encodings. This
+ * lowering stage, to be run before I/O is lowered, converts the native
+ * framebuffer format to a NIR encoding after loads and vice versa before
+ * stores. This pass is designed for a single render target; Midgard duplicates
+ * blend shaders for MRT to simplify everything.
+ */
+
+#include "compiler/nir/nir.h"
+#include "compiler/nir/nir_builder.h"
+#include "nir_lower_blend.h"
+
+static nir_ssa_def *
+nir_float_to_native(nir_builder *b, nir_ssa_def *c_float)
+{
+   /* TODO */
+   return c_float;
+}
+
+void
+nir_lower_framebuffer(nir_shader *shader)
+{
+   /* Blend shaders are represented as special fragment shaders */
+   assert(shader->info.stage == MESA_SHADER_FRAGMENT);
+
+   nir_foreach_function(func, shader) {
+      nir_foreach_block(block, func->impl) {
+         nir_foreach_instr_safe(instr, block) {
+            if (instr->type != nir_instr_type_intrinsic)
+               continue;
+
+            nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+
+            bool is_load = intr->intrinsic == nir_intrinsic_load_deref;
+            bool is_store = intr->intrinsic == nir_intrinsic_store_deref;
+
+            if (!(is_load || is_store))
+               continue;
+
+            /* Don't worry about MRT */
+            nir_variable *var = nir_intrinsic_get_var(intr, 0);
+
+            if (var->data.location != FRAG_RESULT_COLOR)
+               continue;
+
+            nir_builder b;
+            nir_builder_init(&b, func->impl);
+
+            if (is_store) {
+               /* For stores, add conversion before */
+               b.cursor = nir_before_instr(instr);
+
+               /* Grab the input color */
+               nir_ssa_def *c_nir = nir_ssa_for_src(&b, intr->src[1], 4);
+
+               /* Format convert */
+               nir_ssa_def *converted = nir_float_to_native(&b, c_nir);
+
+               /* Write out the converted color instead of the input */
+               nir_instr_rewrite_src(instr, &intr->src[1],
+               nir_src_for_ssa(converted));
+            } else {
+               /* TODO loads */
+            }
+         }
+      }
+
+      nir_metadata_preserve(func->impl, nir_metadata_block_index |
+                            nir_metadata_dominance);
+   }
+}
diff --git a/src/gallium/drivers/panfrost/pan_blend_shaders.c b/src/gallium/drivers/panfrost/pan_blend_shaders.c
index b458f42d720..640ddc86847 100644
--- a/src/gallium/drivers/panfrost/pan_blend_shaders.c
+++ b/src/gallium/drivers/panfrost/pan_blend_shaders.c
@@ -149,6 +149,8 @@ panfrost_make_blend_shader(struct panfrost_context *ctx, struct panfrost_blend_s
                 nir_make_options(&cso->base, 1);
         NIR_PASS_V(shader, nir_lower_blend, options);
 
+        NIR_PASS_V(shader, nir_lower_framebuffer);
+
         /* Compile the built shader */
 
         midgard_program program;
-- 
2.20.1