nir/tests: Add tests for opt_if_merge

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30629>

src/compiler/nir/tests/opt_if_tests.cpp

@@ -168,3 +168,172 @@ TEST_F(nir_opt_if_test, opt_if_alu_of_phi_progress)
    EXPECT_LE(progress_count, 2);
    ASSERT_FALSE(progress);
 }
+
+static const struct nir_opt_if_merge_test_config {
+   template <class ParamType>
+   std::string
+   operator()(const ::testing::TestParamInfo<ParamType> &info) const
+   {
+      return info.param.name;
+   }
+
+   const char *name;
+
+   /* Test parameter: Location of a return statement within the control flow */
+   enum return_location {
+      NO_RETURN,
+      RETURN_IN_1ST_THEN,
+      RETURN_IN_1ST_ELSE,
+      RETURN_IN_2ND_THEN,
+      RETURN_IN_2ND_ELSE,
+   } return_location;
+} nir_opt_if_merge_test_configs [] = {
+   { "no_return",          nir_opt_if_merge_test_config::NO_RETURN, },
+   { "return_in_1st_then", nir_opt_if_merge_test_config::RETURN_IN_1ST_THEN, },
+   { "return_in_1st_else", nir_opt_if_merge_test_config::RETURN_IN_1ST_ELSE, },
+   { "return_in_2nd_then", nir_opt_if_merge_test_config::RETURN_IN_2ND_THEN, },
+   { "return_in_2nd_else", nir_opt_if_merge_test_config::RETURN_IN_2ND_ELSE, },
+};
+
+class nir_opt_if_merge_test
+   : public nir_opt_if_test
+   , public ::testing::WithParamInterface<struct nir_opt_if_merge_test_config>
+{
+protected:
+   virtual void SetUp();
+
+   enum nir_opt_if_merge_test_config::return_location return_location;
+};
+
+void
+nir_opt_if_merge_test::SetUp()
+{
+   struct nir_opt_if_merge_test_config config = GetParam();
+   return_location = config.return_location;
+}
+
+INSTANTIATE_TEST_SUITE_P(
+   nir_opt_if, nir_opt_if_merge_test,
+   ::testing::ValuesIn(nir_opt_if_merge_test_configs),
+   nir_opt_if_merge_test_config()
+);
+
+TEST_P(nir_opt_if_merge_test, opt_if_merge)
+{
+   /* Tests that opt_if_merge correctly merges if statements with the same
+    * condition, parameterized on the location of a return statement added
+    * within the control-flow.
+    *
+    * block b0:   // preds:
+    * 32     %0 = deref_var &in (shader_in int)
+    * 32     %1 = @load_deref (%0) (access=none)
+    * 32     %2 = load_const (0x00000001)
+    * 32     %3 = load_const (0x00000002)
+    * 32     %4 = load_const (0x00000006)
+    * 1      %5 = ige %1, %2 (0x1)
+    *             // succs: b1 b2
+    * if %5 {
+    *     block b1:   // preds: b0
+    *     32     %6 = iadd %1, %2 (0x1)
+    *                 // succs: b3
+    * } else {
+    *     block b2:   // preds: b0
+    *     32     %7 = iadd %1, %3 (0x2)
+    *                 // succs: b3
+    * }
+    * block b3:  // preds: b1 b2, succs: b4 b5
+    * if %5 {
+    *     block b4:   // preds: b3
+    *     32     %8 = imul %6, %3 (0x2)
+    *                 // succs: b6
+    * } else {
+    *     block b5:   // preds: b3
+    *     32     %9 = imul %7, %4 (0x6)
+    *                 // succs: b6
+    * }
+    * block b6:   // preds: b4 b5
+    * 32    %10 = phi b4: %8, b5: %9
+    * 32    %11 = deref_var &out (shader_out int)
+    *             @store_deref (%11, %10) (wrmask=x, access=none)
+    *             // succs: b7
+    * block b7:
+    */
+
+   int instr_in_1st_then = 1, instr_in_1st_else = 1;
+   int instr_in_2nd_then = 1, instr_in_2nd_else = 1;
+
+   nir_def *one = nir_imm_int(b, 1);
+   nir_def *two = nir_imm_int(b, 2);
+   nir_def *six = nir_imm_int(b, 6);
+
+   nir_def *cmp_result = nir_ige(b, in_def, one);
+
+   nir_if *nif = nir_push_if(b, cmp_result);
+
+   nir_def *x1 = nir_iadd(b, in_def, one);
+   if (return_location == nir_opt_if_merge_test_config::RETURN_IN_1ST_THEN) {
+      nir_jump(b, nir_jump_return);
+      instr_in_1st_then++;
+   }
+
+   nir_push_else(b, NULL);
+
+   nir_def *x2 = nir_iadd(b, in_def, two);
+   if (return_location == nir_opt_if_merge_test_config::RETURN_IN_1ST_ELSE) {
+      nir_jump(b, nir_jump_return);
+      instr_in_1st_else++;
+   }
+
+   nir_pop_if(b, NULL);
+
+   nir_phi_instr *phi = nir_phi_instr_create(b->shader);
+   nir_def_init(&phi->instr, &phi->def,
+                one->num_components, one->bit_size);
+
+   nir_if *next_if = nir_push_if(b, cmp_result);
+
+   nir_def *y1 = nir_imul(b, x1, two);
+   if (return_location == nir_opt_if_merge_test_config::RETURN_IN_2ND_THEN) {
+      nir_jump(b, nir_jump_return);
+      instr_in_2nd_then++;
+   } else {
+      nir_phi_instr_add_src(phi, nir_cursor_current_block(b->cursor), y1);
+   }
+
+   nir_push_else(b, NULL);
+
+   nir_def *y2 = nir_imul(b, x2, six);
+   if (return_location == nir_opt_if_merge_test_config::RETURN_IN_2ND_ELSE) {
+      nir_jump(b, nir_jump_return);
+      instr_in_2nd_else++;
+   } else {
+      nir_phi_instr_add_src(phi, nir_cursor_current_block(b->cursor), y2);
+   }
+
+   nir_pop_if(b, NULL);
+
+   nir_builder_instr_insert(b, &phi->instr);
+
+   // do_work
+   nir_store_var(b, out_var, &phi->def, 1);
+
+   if (return_location == nir_opt_if_merge_test_config::RETURN_IN_2ND_THEN ||
+       return_location == nir_opt_if_merge_test_config::RETURN_IN_2ND_ELSE) {
+      ASSERT_FALSE(nir_opt_if(b->shader, nir_opt_if_optimize_phi_true_false));
+   } else if (return_location == nir_opt_if_merge_test_config::NO_RETURN) {
+      ASSERT_TRUE(nir_opt_if(b->shader, nir_opt_if_optimize_phi_true_false));
+      instr_in_1st_then = 2;
+      instr_in_1st_else = 2;
+      instr_in_2nd_then = 0;
+      instr_in_2nd_else = 0;
+   } else {
+      ASSERT_TRUE(nir_opt_if(b->shader, nir_opt_if_optimize_phi_true_false));
+   }
+
+   nir_validate_shader(b->shader, NULL);
+
+   ASSERT_EQ(exec_list_length((&nir_if_first_then_block(nif)->instr_list)), instr_in_1st_then);
+   ASSERT_EQ(exec_list_length((&nir_if_first_else_block(nif)->instr_list)), instr_in_1st_else);
+   ASSERT_EQ(exec_list_length((&nir_if_first_then_block(next_if)->instr_list)), instr_in_2nd_then);
+   ASSERT_EQ(exec_list_length((&nir_if_first_else_block(next_if)->instr_list)), instr_in_2nd_else);
+}