pan/bi: Add back custom algebraic opts

Right now just do a trivial one to test the infrastructure. In the next
commit we'll use this for a more interesting optimization that's a bit
painful in BIR but trivial with nir_search.

total instructions in shared programs: 149566 -> 149562 (<.01%)
instructions in affected programs: 502 -> 498 (-0.80%)
helped: 3
HURT: 0
helped stats (abs) min: 1 max: 2 x̄: 1.33 x̃: 1
helped stats (rel) min: 0.38% max: 1.30% x̄: 0.97% x̃: 1.21%

total tuples in shared programs: 130957 -> 130487 (-0.36%)
tuples in affected programs: 54752 -> 54282 (-0.86%)
helped: 303
HURT: 2
helped stats (abs) min: 1 max: 29 x̄: 1.56 x̃: 1
helped stats (rel) min: 0.13% max: 7.14% x̄: 1.08% x̃: 0.92%
HURT stats (abs)   min: 1 max: 2 x̄: 1.50 x̃: 1
HURT stats (rel)   min: 1.89% max: 2.99% x̄: 2.44% x̃: 2.44%
95% mean confidence interval for tuples value: -1.79 -1.30
95% mean confidence interval for tuples %-change: -1.17% -0.95%
Tuples are helped.

total clauses in shared programs: 27877 -> 27827 (-0.18%)
clauses in affected programs: 1556 -> 1506 (-3.21%)
helped: 45
HURT: 0
helped stats (abs) min: 1 max: 2 x̄: 1.11 x̃: 1
helped stats (rel) min: 1.43% max: 9.52% x̄: 3.88% x̃: 3.57%
95% mean confidence interval for clauses value: -1.21 -1.02
95% mean confidence interval for clauses %-change: -4.38% -3.39%
Clauses are helped.

total quadwords in shared programs: 119058 -> 118563 (-0.42%)
quadwords in affected programs: 33777 -> 33282 (-1.47%)
helped: 250
HURT: 2
helped stats (abs) min: 1 max: 29 x̄: 1.99 x̃: 1
helped stats (rel) min: 0.23% max: 11.11% x̄: 1.67% x̃: 1.40%
HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 1.64% max: 2.00% x̄: 1.82% x̃: 1.82%
95% mean confidence interval for quadwords value: -2.27 -1.66
95% mean confidence interval for quadwords %-change: -1.80% -1.49%
Quadwords are helped.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11327>

src/panfrost/bifrost/bifrost_compile.c

@@ -35,6 +35,7 @@
 #include "compiler.h"
 #include "bi_quirks.h"
 #include "bi_builder.h"
+#include "bifrost_nir.h"
 
 static const struct debug_named_value bifrost_debug_options[] = {
         {"msgs",      BIFROST_DBG_MSGS,		"Print debug messages"},
@@ -3119,6 +3120,9 @@ bi_optimize_nir(nir_shader *nir, unsigned gpu_id, bool is_blend)
         NIR_PASS(progress, nir, nir_lower_load_const_to_scalar);
         NIR_PASS(progress, nir, nir_opt_dce);
 
+        /* Prepass to simplify instruction selection */
+        NIR_PASS(progress, nir, bifrost_nir_lower_algebraic_late);
+
         /* Backend scheduler is purely local, so do some global optimizations
          * to reduce register pressure. */
         nir_move_options move_all =

src/panfrost/bifrost/bifrost_nir.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2021 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 <stdbool.h>
+#include "nir.h"
+
+bool bifrost_nir_lower_algebraic_late(nir_shader *shader);

src/panfrost/bifrost/bifrost_nir_algebraic.py

@@ -0,0 +1,55 @@
+# Copyright (C) 2021 Collabora, Ltd.
+# Copyright (C) 2016 Intel Corporation
+#
+# 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.
+
+import argparse
+import sys
+import math
+
+a = 'a'
+b = 'b'
+c = 'c'
+
+algebraic_late = [
+    # Canonical form. The scheduler will convert back if it makes sense.
+    (('fmul', a, 2.0), ('fadd', a, a)),
+]
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-p', '--import-path', required=True)
+    args = parser.parse_args()
+    sys.path.insert(0, args.import_path)
+    run()
+
+
+def run():
+    import nir_algebraic  # pylint: disable=import-error
+
+    print('#include "bifrost_nir.h"')
+
+    print(nir_algebraic.AlgebraicPass("bifrost_nir_lower_algebraic_late",
+                                      algebraic_late).render())
+
+
+if __name__ == '__main__':
+    main()

src/panfrost/bifrost/meson.build

@@ -103,6 +103,18 @@ idep_bi_builder_h = declare_dependency(
   include_directories : include_directories('.'),
 )
 
+bifrost_nir_algebraic_c = custom_target(
+  'bifrost_nir_algebraic.c',
+  input : 'bifrost_nir_algebraic.py',
+  output : 'bifrost_nir_algebraic.c',
+  command : [
+    prog_python, '@INPUT@',
+    '-p', join_paths(meson.source_root(), 'src/compiler/nir/'),
+  ],
+  capture : true,
+  depend_files : nir_algebraic_py,
+)
+
 libpanfrost_bifrost_disasm = static_library(
   'panfrost_bifrost_disasm',
   ['disassemble.c', 'bi_print_common.c', bifrost_gen_disasm_c],
@@ -116,7 +128,7 @@ libpanfrost_bifrost_disasm = static_library(
 
 libpanfrost_bifrost = static_library(
   'panfrost_bifrost',
-  [libpanfrost_bifrost_files, bi_opcodes_c, bi_printer_c, bi_packer_c],
+  [libpanfrost_bifrost_files, bi_opcodes_c, bi_printer_c, bi_packer_c, bifrost_nir_algebraic_c],
   include_directories : [inc_include, inc_src, inc_mapi, inc_mesa, inc_gallium, inc_gallium_aux, inc_panfrost_hw],
   dependencies: [idep_nir, idep_bi_opcodes_h, idep_bi_builder_h],
   link_with: [libpanfrost_util, libpanfrost_bifrost_disasm],