zink: lower b2b to b2i

Zink requires 1-bit booleans, but this requirement was missed before
b2b1s started getting automatically inserted. Let's lower these away, to
avoid piglit regressions.

Fixes the following piglits:
- shaders@glsl-vs-if-bool
- spec@!opengl 2.0@vertex-program-two-side

Fixes: c217ee8d35 ("nir: Insert b2b1s around booleans in nir_lower_to")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/2902
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4903>

src/gallium/drivers/zink/meson.build

@@ -39,9 +39,21 @@ files_libzink = files(
   'zink_surface.c',
 )
 
+zink_nir_algebraic_c = custom_target(
+  'zink_nir_algebraic.c',
+  input : 'nir_to_spirv/zink_nir_algebraic.py',
+  output : 'zink_nir_algebraic.c',
+  command : [
+    prog_python, '@INPUT@',
+    '-p', join_paths(meson.source_root(), 'src/compiler/nir/'),
+  ],
+  capture : true,
+  depend_files : nir_algebraic_py,
+)
+
 libzink = static_library(
   'zink',
-  files_libzink,
+  [files_libzink, zink_nir_algebraic_c],
   c_args : c_vis_args,
   include_directories : [inc_include, inc_src, inc_mapi, inc_mesa, inc_gallium, inc_gallium_aux],
   dependencies: [dep_vulkan, idep_nir_headers],

src/gallium/drivers/zink/nir_to_spirv/nir_to_spirv.h

@@ -46,4 +46,9 @@ spirv_shader_delete(struct spirv_shader *s);
 uint32_t
 zink_binding(gl_shader_stage stage, VkDescriptorType type, int index);
 
+struct nir_shader;
+
+bool
+zink_nir_lower_b2b(struct nir_shader *shader);
+
 #endif

src/gallium/drivers/zink/nir_to_spirv/zink_nir_algebraic.py

@@ -0,0 +1,48 @@
+#
+# 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.
+
+import argparse
+import sys
+
+lower_b2b = [
+   (('b2b32', 'a'), ('b2i32', 'a')),
+   (('b2b1', 'a'), ('i2b1', '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 "nir_to_spirv/nir_to_spirv.h"')
+
+    print(nir_algebraic.AlgebraicPass("zink_nir_lower_b2b",
+                                      lower_b2b).render())
+
+if __name__ == '__main__':
+    main()

src/gallium/drivers/zink/zink_compiler.c

@@ -127,6 +127,7 @@ optimize_nir(struct nir_shader *s)
       NIR_PASS(progress, s, nir_opt_algebraic);
       NIR_PASS(progress, s, nir_opt_constant_folding);
       NIR_PASS(progress, s, nir_opt_undef);
+      NIR_PASS(progress, s, zink_nir_lower_b2b);
    } while (progress);
 }