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glsl: move loop analysis helpers to loop_analysis.cpp

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Reviewed-by: Thomas Helland <thomashelland90@gmail.com>
This commit is contained in:
Timothy Arceri 2017-09-19 12:14:11 +10:00
parent d8eede1697
commit e7424b2d73
3 changed files with 139 additions and 146 deletions
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139
src/compiler/glsl/loop_analysis.cpp
View file

@ -32,6 +32,145 @@ static bool all_expression_operands_are_loop_constant(ir_rvalue *,
static ir_rvalue *get_basic_induction_increment(ir_assignment *, hash_table *);
/**
* Find an initializer of a variable outside a loop
*
* Works backwards from the loop to find the pre-loop value of the variable.
* This is used, for example, to find the initial value of loop induction
* variables.
*
* \param loop Loop where \c var is an induction variable
* \param var Variable whose initializer is to be found
*
* \return
* The \c ir_rvalue assigned to the variable outside the loop. May return
* \c NULL if no initializer can be found.
*/
static ir_rvalue *
find_initial_value(ir_loop *loop, ir_variable *var)
{
for (exec_node *node = loop->prev; !node->is_head_sentinel();
node = node->prev) {
ir_instruction *ir = (ir_instruction *) node;
switch (ir->ir_type) {
case ir_type_call:
case ir_type_loop:
case ir_type_loop_jump:
case ir_type_return:
case ir_type_if:
return NULL;
case ir_type_function:
case ir_type_function_signature:
assert(!"Should not get here.");
return NULL;
case ir_type_assignment: {
ir_assignment *assign = ir->as_assignment();
ir_variable *assignee = assign->lhs->whole_variable_referenced();
if (assignee == var)
return (assign->condition != NULL) ? NULL : assign->rhs;
break;
}
default:
break;
}
}
return NULL;
}
static int
calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment,
enum ir_expression_operation op)
{
if (from == NULL || to == NULL || increment == NULL)
return -1;
void *mem_ctx = ralloc_context(NULL);
ir_expression *const sub =
new(mem_ctx) ir_expression(ir_binop_sub, from->type, to, from);
ir_expression *const div =
new(mem_ctx) ir_expression(ir_binop_div, sub->type, sub, increment);
ir_constant *iter = div->constant_expression_value(mem_ctx);
if (iter == NULL) {
ralloc_free(mem_ctx);
return -1;
}
if (!iter->type->is_integer()) {
const ir_expression_operation op = iter->type->is_double()
? ir_unop_d2i : ir_unop_f2i;
ir_rvalue *cast =
new(mem_ctx) ir_expression(op, glsl_type::int_type, iter, NULL);
iter = cast->constant_expression_value(mem_ctx);
}
int iter_value = iter->get_int_component(0);
/* Make sure that the calculated number of iterations satisfies the exit
* condition. This is needed to catch off-by-one errors and some types of
* ill-formed loops. For example, we need to detect that the following
* loop does not have a maximum iteration count.
*
* for (float x = 0.0; x != 0.9; x += 0.2)
* ;
*/
const int bias[] = { -1, 0, 1 };
bool valid_loop = false;
for (unsigned i = 0; i < ARRAY_SIZE(bias); i++) {
/* Increment may be of type int, uint or float. */
switch (increment->type->base_type) {
case GLSL_TYPE_INT:
iter = new(mem_ctx) ir_constant(iter_value + bias[i]);
break;
case GLSL_TYPE_UINT:
iter = new(mem_ctx) ir_constant(unsigned(iter_value + bias[i]));
break;
case GLSL_TYPE_FLOAT:
iter = new(mem_ctx) ir_constant(float(iter_value + bias[i]));
break;
case GLSL_TYPE_DOUBLE:
iter = new(mem_ctx) ir_constant(double(iter_value + bias[i]));
break;
default:
unreachable("Unsupported type for loop iterator.");
}
ir_expression *const mul =
new(mem_ctx) ir_expression(ir_binop_mul, increment->type, iter,
increment);
ir_expression *const add =
new(mem_ctx) ir_expression(ir_binop_add, mul->type, mul, from);
ir_expression *const cmp =
new(mem_ctx) ir_expression(op, glsl_type::bool_type, add, to);
ir_constant *const cmp_result = cmp->constant_expression_value(mem_ctx);
assert(cmp_result != NULL);
if (cmp_result->get_bool_component(0)) {
iter_value += bias[i];
valid_loop = true;
break;
}
}
ralloc_free(mem_ctx);
return (valid_loop) ? iter_value : -1;
}
/**
* Record the fact that the given loop variable was referenced inside the loop.

7
src/compiler/glsl/loop_analysis.h
View file

@ -55,13 +55,6 @@ extern bool
unroll_loops(exec_list *instructions, loop_state *ls,
const struct gl_shader_compiler_options *options);
ir_rvalue *
find_initial_value(ir_loop *loop, ir_variable *var);
int
calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment,
enum ir_expression_operation op);
/**
* Tracking for all variables used in a loop

139
src/compiler/glsl/loop_controls.cpp
View file

@ -27,145 +27,6 @@
#include "loop_analysis.h"
#include "ir_hierarchical_visitor.h"
/**
* Find an initializer of a variable outside a loop
*
* Works backwards from the loop to find the pre-loop value of the variable.
* This is used, for example, to find the initial value of loop induction
* variables.
*
* \param loop Loop where \c var is an induction variable
* \param var Variable whose initializer is to be found
*
* \return
* The \c ir_rvalue assigned to the variable outside the loop. May return
* \c NULL if no initializer can be found.
*/
ir_rvalue *
find_initial_value(ir_loop *loop, ir_variable *var)
{
for (exec_node *node = loop->prev;
!node->is_head_sentinel();
node = node->prev) {
ir_instruction *ir = (ir_instruction *) node;
switch (ir->ir_type) {
case ir_type_call:
case ir_type_loop:
case ir_type_loop_jump:
case ir_type_return:
case ir_type_if:
return NULL;
case ir_type_function:
case ir_type_function_signature:
assert(!"Should not get here.");
return NULL;
case ir_type_assignment: {
ir_assignment *assign = ir->as_assignment();
ir_variable *assignee = assign->lhs->whole_variable_referenced();
if (assignee == var)
return (assign->condition != NULL) ? NULL : assign->rhs;
break;
}
default:
break;
}
}
return NULL;
}
int
calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment,
enum ir_expression_operation op)
{
if (from == NULL || to == NULL || increment == NULL)
return -1;
void *mem_ctx = ralloc_context(NULL);
ir_expression *const sub =
new(mem_ctx) ir_expression(ir_binop_sub, from->type, to, from);
ir_expression *const div =
new(mem_ctx) ir_expression(ir_binop_div, sub->type, sub, increment);
ir_constant *iter = div->constant_expression_value(mem_ctx);
if (iter == NULL) {
ralloc_free(mem_ctx);
return -1;
}
if (!iter->type->is_integer()) {
const ir_expression_operation op = iter->type->is_double()
? ir_unop_d2i : ir_unop_f2i;
ir_rvalue *cast =
new(mem_ctx) ir_expression(op, glsl_type::int_type, iter, NULL);
iter = cast->constant_expression_value(mem_ctx);
}
int iter_value = iter->get_int_component(0);
/* Make sure that the calculated number of iterations satisfies the exit
* condition. This is needed to catch off-by-one errors and some types of
* ill-formed loops. For example, we need to detect that the following
* loop does not have a maximum iteration count.
*
* for (float x = 0.0; x != 0.9; x += 0.2)
* ;
*/
const int bias[] = { -1, 0, 1 };
bool valid_loop = false;
for (unsigned i = 0; i < ARRAY_SIZE(bias); i++) {
/* Increment may be of type int, uint or float. */
switch (increment->type->base_type) {
case GLSL_TYPE_INT:
iter = new(mem_ctx) ir_constant(iter_value + bias[i]);
break;
case GLSL_TYPE_UINT:
iter = new(mem_ctx) ir_constant(unsigned(iter_value + bias[i]));
break;
case GLSL_TYPE_FLOAT:
iter = new(mem_ctx) ir_constant(float(iter_value + bias[i]));
break;
case GLSL_TYPE_DOUBLE:
iter = new(mem_ctx) ir_constant(double(iter_value + bias[i]));
break;
default:
unreachable("Unsupported type for loop iterator.");
}
ir_expression *const mul =
new(mem_ctx) ir_expression(ir_binop_mul, increment->type, iter,
increment);
ir_expression *const add =
new(mem_ctx) ir_expression(ir_binop_add, mul->type, mul, from);
ir_expression *const cmp =
new(mem_ctx) ir_expression(op, glsl_type::bool_type, add, to);
ir_constant *const cmp_result = cmp->constant_expression_value(mem_ctx);
assert(cmp_result != NULL);
if (cmp_result->get_bool_component(0)) {
iter_value += bias[i];
valid_loop = true;
break;
}
}
ralloc_free(mem_ctx);
return (valid_loop) ? iter_value : -1;
}
namespace {