pan/bi: Add bi_layout.c for clause layout helpers

Figuring out what "shapes" of clauses are kosher happens during
scheduling, not packing, but shouldn't distract the scheduler. So let's
add a new file for these sorts of questions.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5260>

src/panfrost/Makefile.sources

@@ -2,6 +2,7 @@ bifrost_FILES := \
         bifrost/bifrost.h \
         bifrost/bifrost_compile.c \
         bifrost/bifrost_compile.h \
+        bifrost/bi_layout.c \
         bifrost/bi_liveness.c \
         bifrost/bi_lower_combine.c \
         bifrost/bi_tables.c \

src/panfrost/bifrost/bi_layout.c

@@ -0,0 +1,51 @@
+/*
+ * 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.
+ */
+
+#include "compiler.h"
+
+/* The scheduler packs multiple instructions into a clause (grouped as bundle),
+ * and the packing code takes in a clause and emits it to the wire. During
+ * scheduling, we need to lay out the instructions (bundles) and constants
+ * within the clause so constraints can be resolved during scheduling instead
+ * of failing packing. These routines will help building clauses from
+ * instructions so the scheduler can focus on the high-level algorithm, and
+ * manipulating clause layouts.
+ */
+
+/* Helper to see if a bundle can be inserted. We must satisfy the invariant:
+ *
+ *      constant_count + bundle_count <= 13
+ *
+ * ...which is equivalent to the clause ending up with 8 or fewer quardwords.
+ * Inserting a bundle increases bundle_count by one, and if it reads a unique
+ * constant, it increases constant_count by one.
+ */
+
+bool
+bi_can_insert_bundle(bi_clause *clause, bool constant)
+{
+        unsigned constant_count = clause->constant_count + (constant ? 1 : 0);
+        unsigned bundle_count = clause->bundle_count + 1;
+
+        return (constant_count + bundle_count) <= 13;
+}

src/panfrost/bifrost/compiler.h

@@ -581,6 +581,10 @@ void bi_liveness_ins_update(uint16_t *live, bi_instruction *ins, unsigned max);
 void bi_invalidate_liveness(bi_context *ctx);
 bool bi_is_live_after(bi_context *ctx, bi_block *block, bi_instruction *start, int src);
 
+/* Layout */
+
+bool bi_can_insert_bundle(bi_clause *clause, bool constant);
+
 /* Code emit */
 
 void bi_pack(bi_context *ctx, struct util_dynarray *emission);

src/panfrost/bifrost/meson.build

@@ -21,6 +21,7 @@
 
 libpanfrost_bifrost_files = files(
   'disassemble.c',
+  'bi_layout.c',
   'bi_liveness.c',
   'bi_lower_combine.c',
   'bi_print.c',