nir: Add tests for dead write elimination
Note at the moment the pass called is nir_opt_copy_prop_vars, because dead write elimination is implemented there. Also added tests that involve identifying dead writes in multiple blocks (e.g. the overwrite happens in another block). Those currently fail as expected, so are marked to be skipped. Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This commit is contained in:
Caio Marcelo de Oliveira Filho
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bbda2a17f7
commit
a02fd7000d
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@ -26,6 +26,9 @@
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#include "nir.h"
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#include "nir_builder.h"
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/* This optimization is done together with copy propagation. */
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#define nir_opt_dead_write_vars nir_opt_copy_prop_vars
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namespace {
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class nir_vars_test : public ::testing::Test {
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@ -132,6 +135,7 @@ nir_vars_test::find_next_intrinsic(nir_intrinsic_op intrinsic,
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/* Allow grouping the tests while still sharing the helpers. */
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class nir_copy_prop_vars_test : public nir_vars_test {};
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class nir_dead_write_vars_test : public nir_vars_test {};
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} // namespace
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@ -188,3 +192,240 @@ TEST_F(nir_copy_prop_vars_test, simple_store_load)
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EXPECT_EQ(store->src[1].ssa, stored_value);
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}
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}
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TEST_F(nir_dead_write_vars_test, no_dead_writes_in_block)
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{
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nir_variable **v = create_many_int(nir_var_shader_storage, "v", 2);
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_FALSE(progress);
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}
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TEST_F(nir_dead_write_vars_test, no_dead_writes_different_components_in_block)
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{
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nir_variable **v = create_many_ivec2(nir_var_shader_storage, "v", 3);
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1 << 0);
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nir_store_var(b, v[0], nir_load_var(b, v[2]), 1 << 1);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_FALSE(progress);
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}
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TEST_F(nir_dead_write_vars_test, no_dead_writes_in_if_statement)
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{
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nir_variable **v = create_many_int(nir_var_shader_storage, "v", 6);
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nir_store_var(b, v[2], nir_load_var(b, v[0]), 1);
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nir_store_var(b, v[3], nir_load_var(b, v[1]), 1);
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/* Each arm of the if statement will overwrite one store. */
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nir_if *if_stmt = nir_push_if(b, nir_imm_int(b, 0));
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nir_store_var(b, v[2], nir_load_var(b, v[4]), 1);
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nir_push_else(b, if_stmt);
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nir_store_var(b, v[3], nir_load_var(b, v[5]), 1);
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nir_pop_if(b, if_stmt);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_FALSE(progress);
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}
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TEST_F(nir_dead_write_vars_test, no_dead_writes_in_loop_statement)
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{
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nir_variable **v = create_many_int(nir_var_shader_storage, "v", 3);
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1);
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/* Loop will write other value. Since it might not be executed, it doesn't
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* kill the first write.
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*/
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nir_loop *loop = nir_push_loop(b);
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nir_if *if_stmt = nir_push_if(b, nir_imm_int(b, 0));
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nir_jump(b, nir_jump_break);
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nir_pop_if(b, if_stmt);
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nir_store_var(b, v[0], nir_load_var(b, v[2]), 1);
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nir_pop_loop(b, loop);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_FALSE(progress);
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}
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TEST_F(nir_dead_write_vars_test, dead_write_in_block)
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{
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nir_variable **v = create_many_int(nir_var_shader_storage, "v", 3);
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1);
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nir_ssa_def *load_v2 = nir_load_var(b, v[2]);
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nir_store_var(b, v[0], load_v2, 1);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_TRUE(progress);
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EXPECT_EQ(1, count_intrinsics(nir_intrinsic_store_deref));
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nir_intrinsic_instr *store = find_next_intrinsic(nir_intrinsic_store_deref, NULL);
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ASSERT_TRUE(store->src[1].is_ssa);
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EXPECT_EQ(store->src[1].ssa, load_v2);
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}
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TEST_F(nir_dead_write_vars_test, dead_write_components_in_block)
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{
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nir_variable **v = create_many_ivec2(nir_var_shader_storage, "v", 3);
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1 << 0);
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nir_ssa_def *load_v2 = nir_load_var(b, v[2]);
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nir_store_var(b, v[0], load_v2, 1 << 0);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_TRUE(progress);
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EXPECT_EQ(1, count_intrinsics(nir_intrinsic_store_deref));
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nir_intrinsic_instr *store = find_next_intrinsic(nir_intrinsic_store_deref, NULL);
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ASSERT_TRUE(store->src[1].is_ssa);
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EXPECT_EQ(store->src[1].ssa, load_v2);
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}
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/* TODO: The DISABLED tests below depend on the dead write removal be able to
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* identify dead writes between multiple blocks. This is still not
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* implemented.
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*/
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TEST_F(nir_dead_write_vars_test, DISABLED_dead_write_in_two_blocks)
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{
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nir_variable **v = create_many_int(nir_var_shader_storage, "v", 3);
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1);
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nir_ssa_def *load_v2 = nir_load_var(b, v[2]);
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/* Causes the stores to be in different blocks. */
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nir_pop_if(b, nir_push_if(b, nir_imm_int(b, 0)));
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nir_store_var(b, v[0], load_v2, 1);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_TRUE(progress);
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EXPECT_EQ(1, count_intrinsics(nir_intrinsic_store_deref));
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nir_intrinsic_instr *store = find_next_intrinsic(nir_intrinsic_store_deref, NULL);
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ASSERT_TRUE(store->src[1].is_ssa);
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EXPECT_EQ(store->src[1].ssa, load_v2);
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}
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TEST_F(nir_dead_write_vars_test, DISABLED_dead_write_components_in_two_blocks)
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{
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nir_variable **v = create_many_ivec2(nir_var_shader_storage, "v", 3);
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1 << 0);
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/* Causes the stores to be in different blocks. */
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nir_pop_if(b, nir_push_if(b, nir_imm_int(b, 0)));
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nir_ssa_def *load_v2 = nir_load_var(b, v[2]);
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nir_store_var(b, v[0], load_v2, 1 << 0);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_TRUE(progress);
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EXPECT_EQ(1, count_intrinsics(nir_intrinsic_store_deref));
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nir_intrinsic_instr *store = find_next_intrinsic(nir_intrinsic_store_deref, NULL);
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ASSERT_TRUE(store->src[1].is_ssa);
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EXPECT_EQ(store->src[1].ssa, load_v2);
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}
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TEST_F(nir_dead_write_vars_test, DISABLED_dead_writes_in_if_statement)
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{
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nir_variable **v = create_many_int(nir_var_shader_storage, "v", 4);
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/* Both branches will overwrite, making the previous store dead. */
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1);
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nir_if *if_stmt = nir_push_if(b, nir_imm_int(b, 0));
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nir_ssa_def *load_v2 = nir_load_var(b, v[2]);
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nir_store_var(b, v[0], load_v2, 1);
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nir_push_else(b, if_stmt);
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nir_ssa_def *load_v3 = nir_load_var(b, v[3]);
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nir_store_var(b, v[0], load_v3, 1);
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nir_pop_if(b, if_stmt);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_TRUE(progress);
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EXPECT_EQ(2, count_intrinsics(nir_intrinsic_store_deref));
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nir_intrinsic_instr *store = NULL;
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store = find_next_intrinsic(nir_intrinsic_store_deref, store);
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ASSERT_TRUE(store->src[1].is_ssa);
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EXPECT_EQ(store->src[1].ssa, load_v2);
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store = find_next_intrinsic(nir_intrinsic_store_deref, store);
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ASSERT_TRUE(store->src[1].is_ssa);
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EXPECT_EQ(store->src[1].ssa, load_v3);
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}
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TEST_F(nir_dead_write_vars_test, DISABLED_memory_barrier_in_two_blocks)
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{
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nir_variable **v = create_many_int(nir_var_shader_storage, "v", 2);
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nir_store_var(b, v[0], nir_imm_int(b, 1), 1);
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nir_store_var(b, v[1], nir_imm_int(b, 2), 1);
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/* Split into many blocks. */
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nir_pop_if(b, nir_push_if(b, nir_imm_int(b, 0)));
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/* Because it is before the barrier, this will kill the previous store to that target. */
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nir_store_var(b, v[0], nir_imm_int(b, 3), 1);
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nir_builder_instr_insert(b, &nir_intrinsic_instr_create(b->shader, nir_intrinsic_memory_barrier)->instr);
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nir_store_var(b, v[1], nir_imm_int(b, 4), 1);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_TRUE(progress);
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EXPECT_EQ(3, count_intrinsics(nir_intrinsic_store_deref));
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}
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TEST_F(nir_dead_write_vars_test, DISABLED_unrelated_barrier_in_two_blocks)
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{
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nir_variable **v = create_many_int(nir_var_shader_storage, "v", 3);
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nir_variable *out = create_int(nir_var_shader_out, "out");
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nir_store_var(b, out, nir_load_var(b, v[1]), 1);
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nir_store_var(b, v[0], nir_load_var(b, v[1]), 1);
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/* Split into many blocks. */
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nir_pop_if(b, nir_push_if(b, nir_imm_int(b, 0)));
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/* Emit vertex will ensure writes to output variables are considered used,
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* but should not affect other types of variables. */
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nir_builder_instr_insert(b, &nir_intrinsic_instr_create(b->shader, nir_intrinsic_emit_vertex)->instr);
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nir_store_var(b, out, nir_load_var(b, v[2]), 1);
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nir_store_var(b, v[0], nir_load_var(b, v[2]), 1);
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bool progress = nir_opt_dead_write_vars(b->shader);
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ASSERT_TRUE(progress);
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/* Verify the first write to v[0] was removed. */
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EXPECT_EQ(3, count_intrinsics(nir_intrinsic_store_deref));
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nir_intrinsic_instr *store = NULL;
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store = find_next_intrinsic(nir_intrinsic_store_deref, store);
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EXPECT_EQ(nir_intrinsic_get_var(store, 0), out);
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store = find_next_intrinsic(nir_intrinsic_store_deref, store);
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EXPECT_EQ(nir_intrinsic_get_var(store, 0), out);
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store = find_next_intrinsic(nir_intrinsic_store_deref, store);
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EXPECT_EQ(nir_intrinsic_get_var(store, 0), v[0]);
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}
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