panfrost: Add theory for new framebuffer lowering

We take a somewhat different strategy that should be more flexible.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5265>

diff --git a/src/panfrost/Makefile.sources b/src/panfrost/Makefile.sources
index 865812e82a9f2cdd7cc32a0f82c046fae9b9fcfd..945c8f4e04282a7d660e100a170d40a9084d256e 100644 (file)
--- a/src/panfrost/Makefile.sources
+++ b/src/panfrost/Makefile.sources
@@ -87,4 +87,5 @@ util_FILES := \
         util/pan_ir.c \
         util/pan_ir.h \
         util/pan_liveness.c \
+        util/pan_lower_framebuffer.c \
         util/pan_sysval.c \

diff --git a/src/panfrost/util/meson.build b/src/panfrost/util/meson.build
index aa3b5decbc888c08c16bf1567e63e44196af440a..04271a6bb021ebe1db975aeff5daff1a6f6ae394 100644 (file)
--- a/src/panfrost/util/meson.build
+++ b/src/panfrost/util/meson.build
@@ -26,6 +26,7 @@ libpanfrost_util_files = files(
   'pan_ir.c',
   'pan_ir.h',
   'pan_liveness.c',
+  'pan_lower_framebuffer.c',
   'pan_sysval.c',
 )
 

diff --git a/src/panfrost/util/pan_lower_framebuffer.c b/src/panfrost/util/pan_lower_framebuffer.c
new file mode 100644 (file)
index 0000000..1df763c
--- /dev/null
+++ b/src/panfrost/util/pan_lower_framebuffer.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2020 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@collabora.com>
+ */
+
+/**
+ * Implements framebuffer format conversions in software for Midgard/Bifrost
+ * blend shaders. This pass is designed for a single render target; Midgard
+ * duplicates blend shaders for MRT to simplify everything. A particular
+ * framebuffer format may be categorized as 1) typed load available, 2) typed
+ * unpack available, or 3) software unpack only, and likewise for stores. The
+ * first two types are handled in the compiler backend directly, so this module
+ * is responsible for identifying type 3 formats (hardware dependent) and
+ * inserting appropriate ALU code to perform the conversion from the packed
+ * type to a designated unpacked type, and vice versa.
+ *
+ * The unpacked type depends on the format:
+ *
+ *      - For 32-bit float formats, 32-bit floats.
+ *      - For other floats, 16-bit floats.
+ *      - For 32-bit ints, 32-bit ints.
+ *      - For 8-bit ints, 8-bit ints.
+ *      - For other ints, 16-bit ints.
+ *
+ * The rationale is to optimize blending and logic op instructions by using the
+ * smallest precision necessary to store the pixel losslessly.
+ */
+
+#include "compiler/nir/nir.h"
+#include "compiler/nir/nir_builder.h"
+#include "compiler/nir/nir_format_convert.h"
+#include "util/format/u_format.h"