nir/tests: Add tests for opt_if_simplification

Test cases:

opt_if_simplification - the most trivial test case.

opt_if_simplification_single_source_phi_after_if - tests that
opt_if_simplification correctly handles single-source phis after
the if, found in https://gitlab.freedesktop.org/mesa/mesa/-/issues/3282

Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5945>

src/compiler/nir/meson.build

@@ -381,4 +381,17 @@ if with_tests
     ),
     suite : ['compiler', 'nir'],
   )
+
+  test(
+    'nir_opt_if',
+    executable(
+      'nir_opt_if_tests',
+      files('tests/opt_if_tests.cpp'),
+      cpp_args : [cpp_msvc_compat_args],
+      gnu_symbol_visibility : 'hidden',
+      include_directories : [inc_include, inc_src, inc_mapi, inc_mesa, inc_gallium, inc_gallium_aux],
+      dependencies : [dep_thread, idep_gtest, idep_nir, idep_mesautil],
+    ),
+    suite : ['compiler', 'nir'],
+  )
 endif

src/compiler/nir/tests/opt_if_tests.cpp

@@ -0,0 +1,143 @@
+/*
+ * Copyright © 2020 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.
+ */
+#include <gtest/gtest.h>
+#include "nir.h"
+#include "nir_builder.h"
+
+class nir_opt_if_test : public ::testing::Test {
+protected:
+   nir_opt_if_test();
+   ~nir_opt_if_test();
+
+   nir_builder bld;
+
+   nir_ssa_def *in_def;
+   nir_variable *out_var;
+};
+
+nir_opt_if_test::nir_opt_if_test()
+{
+   glsl_type_singleton_init_or_ref();
+
+   static const nir_shader_compiler_options options = { };
+   nir_builder_init_simple_shader(&bld, NULL, MESA_SHADER_VERTEX, &options);
+
+   nir_variable *var = nir_variable_create(bld.shader, nir_var_shader_in, glsl_int_type(), "in");
+   in_def = nir_load_var(&bld, var);
+
+   out_var = nir_variable_create(bld.shader, nir_var_shader_out, glsl_int_type(), "out");
+}
+
+nir_opt_if_test::~nir_opt_if_test()
+{
+   ralloc_free(bld.shader);
+   glsl_type_singleton_decref();
+}
+
+TEST_F(nir_opt_if_test, opt_if_simplification)
+{
+   /* Tests that opt_if_simplification correctly optimizes a simple case:
+    *
+    * vec1 1 ssa_2 = ieq ssa_0, ssa_1
+    * if ssa_2 {
+    *    block block_2:
+    * } else {
+    *    block block_3:
+    *    do_work()
+    * }
+    */
+
+   nir_ssa_def *one = nir_imm_int(&bld, 1);
+
+   nir_ssa_def *cmp_result = nir_ieq(&bld, in_def, one);
+   nir_if *nif = nir_push_if(&bld, cmp_result);
+
+   nir_push_else(&bld, NULL);
+
+   // do_work
+   nir_store_var(&bld, out_var, one, 1);
+
+   nir_pop_if(&bld, NULL);
+
+   ASSERT_TRUE(nir_opt_if(bld.shader, false));
+
+   nir_validate_shader(bld.shader, NULL);
+
+   ASSERT_TRUE(!exec_list_is_empty((&nir_if_first_then_block(nif)->instr_list)));
+   ASSERT_TRUE(exec_list_is_empty((&nir_if_first_else_block(nif)->instr_list)));
+}
+
+TEST_F(nir_opt_if_test, opt_if_simplification_single_source_phi_after_if)
+{
+   /* Tests that opt_if_simplification correctly handles single-source
+    * phis after the if.
+    *
+    * vec1 1 ssa_2 = ieq ssa_0, ssa_1
+    * if ssa_2 {
+    *    block block_2:
+    * } else {
+    *    block block_3:
+    *    do_work()
+    *    return
+    * }
+    * block block_4:
+    * vec1 32 ssa_3 = phi block_2: ssa_0
+    */
+
+   nir_ssa_def *one = nir_imm_int(&bld, 1);
+
+   nir_ssa_def *cmp_result = nir_ieq(&bld, in_def, one);
+   nir_if *nif = nir_push_if(&bld, cmp_result);
+
+   nir_push_else(&bld, NULL);
+
+   // do_work
+   nir_store_var(&bld, out_var, one, 1);
+
+   nir_jump_instr *jump = nir_jump_instr_create(bld.shader, nir_jump_return);
+   nir_builder_instr_insert(&bld, &jump->instr);
+
+   nir_pop_if(&bld, NULL);
+
+   nir_block *then_block = nir_if_last_then_block(nif);
+
+   nir_phi_instr *const phi = nir_phi_instr_create(bld.shader);
+
+   nir_phi_src *phi_src;
+   phi_src = ralloc(phi, nir_phi_src);
+   phi_src->pred = then_block;
+   phi_src->src = nir_src_for_ssa(one);
+   exec_list_push_tail(&phi->srcs, &phi_src->node);
+
+   nir_ssa_dest_init(&phi->instr, &phi->dest,
+                     one->num_components, one->bit_size, NULL);
+
+   nir_builder_instr_insert(&bld, &phi->instr);
+
+   ASSERT_TRUE(nir_opt_if(bld.shader, false));
+
+   nir_validate_shader(bld.shader, NULL);
+
+   ASSERT_TRUE(nir_block_ends_in_jump(nir_if_last_then_block(nif)));
+   ASSERT_TRUE(exec_list_is_empty((&nir_if_first_else_block(nif)->instr_list)));
+}