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nir: Consider pointer initializers in nir_remove_dead_variables 

Between the creation of a shader (from GLSL or SPIRV frontends) and
nir_lower_variable_initializers is called, variables may refer to
other variables for initialization.  Those referred variables need to
be kept alive, so consider that in the pass.

Fixes: 7acc81056f ("compiler/nir: Add support for variable initialization from a pointer")
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8133>
This commit is contained in:
Caio Marcelo de Oliveira Filho 2020-12-15 23:25:51 -08:00 committed by Marge Bot
parent 577bfba959
commit acce4ce04e
2 changed files with 62 additions and 7 deletions
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21
src/compiler/nir/nir_remove_dead_variables.c
View File

@ -67,14 +67,21 @@ add_var_use_deref(nir_deref_instr *deref, struct set *live)
if (deref->deref_type != nir_deref_type_var)
return;
/* If it's not a local that never escapes the shader, then any access at
* all means we need to keep it alive.
/* Since these local variables don't escape the shader, writing doesn't
* make them live. Only keep them if they are used by some intrinsic.
*/
if (!(deref->var->data.mode & (nir_var_function_temp |
nir_var_shader_temp |
nir_var_mem_shared)) ||
deref_used_for_not_store(deref))
_mesa_set_add(live, deref->var);
if ((deref->var->data.mode & (nir_var_function_temp |
nir_var_shader_temp |
nir_var_mem_shared)) &&
!deref_used_for_not_store(deref))
return;
nir_variable *var = deref->var;
do {
_mesa_set_add(live, var);
/* Also mark the chain of variables used to initialize it. */
var = var->pointer_initializer;
} while (var);
}
static void

48
src/compiler/nir/tests/vars_tests.cpp
View File

@ -196,6 +196,7 @@ class nir_copy_prop_vars_test : public nir_vars_test {};
class nir_dead_write_vars_test : public nir_vars_test {};
class nir_combine_stores_test : public nir_vars_test {};
class nir_split_vars_test : public nir_vars_test {};
class nir_remove_dead_variables_test : public nir_vars_test {};
} // namespace
@ -2184,3 +2185,50 @@ TEST_F(nir_split_vars_test, split_wildcard_copy)
ASSERT_EQ(count_function_temp_vars(), 8);
ASSERT_EQ(count_intrinsics(nir_intrinsic_copy_deref), 4);
}
TEST_F(nir_remove_dead_variables_test, pointer_initializer_used)
{
nir_variable *x = create_int(nir_var_shader_temp, "x");
nir_variable *y = create_int(nir_var_shader_temp, "y");
y->pointer_initializer = x;
nir_variable *out = create_int(nir_var_shader_out, "out");
nir_validate_shader(b->shader, NULL);
nir_copy_var(b, out, y);
bool progress = nir_remove_dead_variables(b->shader, nir_var_all, NULL);
EXPECT_FALSE(progress);
nir_validate_shader(b->shader, NULL);
unsigned count = 0;
nir_foreach_variable_in_shader(var, b->shader)
count++;
ASSERT_EQ(count, 3);
}
TEST_F(nir_remove_dead_variables_test, pointer_initializer_dead)
{
nir_variable *x = create_int(nir_var_shader_temp, "x");
nir_variable *y = create_int(nir_var_shader_temp, "y");
nir_variable *z = create_int(nir_var_shader_temp, "z");
y->pointer_initializer = x;
z->pointer_initializer = y;
nir_validate_shader(b->shader, NULL);
bool progress = nir_remove_dead_variables(b->shader, nir_var_all, NULL);
EXPECT_TRUE(progress);
nir_validate_shader(b->shader, NULL);
unsigned count = 0;
nir_foreach_variable_in_shader(var, b->shader)
count++;
ASSERT_EQ(count, 0);
}