9a3cb6f5fe
None of the current code knows what to do with swizzles. Take the safe
option for now and bail if we see one. This does have a small shader-db
impact but it is at least safe.
Shader-db results on Kaby Lake:
total loops in shared programs: 4364 -> 4388 (0.55%)
loops in affected programs: 5 -> 29 (480.00%)
helped: 5
HURT: 29
Shader-db results on Haswell:
total loops in shared programs: 4373 -> 4370 (-0.07%)
loops in affected programs: 5 -> 2 (-60.00%)
helped: 5
HURT: 2
Fixes: 6772a17acc "nir: Add a loop analysis pass"
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
1229 lines
39 KiB
C
1229 lines
39 KiB
C
/*
|
||
* Copyright © 2015 Thomas Helland
|
||
*
|
||
* 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.
|
||
*/
|
||
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||
#include "nir.h"
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#include "nir_constant_expressions.h"
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#include "nir_loop_analyze.h"
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||
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||
typedef enum {
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undefined,
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invariant,
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not_invariant,
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basic_induction
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} nir_loop_variable_type;
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struct nir_basic_induction_var;
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typedef struct {
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/* A link for the work list */
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struct list_head process_link;
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bool in_loop;
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/* The ssa_def associated with this info */
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nir_ssa_def *def;
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/* The type of this ssa_def */
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nir_loop_variable_type type;
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/* If this is of type basic_induction */
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struct nir_basic_induction_var *ind;
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/* True if variable is in an if branch */
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bool in_if_branch;
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/* True if variable is in a nested loop */
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bool in_nested_loop;
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} nir_loop_variable;
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typedef struct nir_basic_induction_var {
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nir_op alu_op; /* The type of alu-operation */
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nir_loop_variable *alu_def; /* The def of the alu-operation */
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nir_loop_variable *invariant; /* The invariant alu-operand */
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nir_loop_variable *def_outside_loop; /* The phi-src outside the loop */
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} nir_basic_induction_var;
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typedef struct {
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/* The loop we store information for */
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nir_loop *loop;
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/* Loop_variable for all ssa_defs in function */
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nir_loop_variable *loop_vars;
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/* A list of the loop_vars to analyze */
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struct list_head process_list;
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nir_variable_mode indirect_mask;
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} loop_info_state;
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static nir_loop_variable *
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get_loop_var(nir_ssa_def *value, loop_info_state *state)
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{
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return &(state->loop_vars[value->index]);
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}
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typedef struct {
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loop_info_state *state;
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bool in_if_branch;
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bool in_nested_loop;
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} init_loop_state;
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static bool
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init_loop_def(nir_ssa_def *def, void *void_init_loop_state)
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{
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init_loop_state *loop_init_state = void_init_loop_state;
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nir_loop_variable *var = get_loop_var(def, loop_init_state->state);
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if (loop_init_state->in_nested_loop) {
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var->in_nested_loop = true;
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} else if (loop_init_state->in_if_branch) {
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var->in_if_branch = true;
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} else {
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/* Add to the tail of the list. That way we start at the beginning of
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* the defs in the loop instead of the end when walking the list. This
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* means less recursive calls. Only add defs that are not in nested
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* loops or conditional blocks.
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*/
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list_addtail(&var->process_link, &loop_init_state->state->process_list);
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}
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var->in_loop = true;
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return true;
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}
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/** Calculate an estimated cost in number of instructions
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*
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* We do this so that we don't unroll loops which will later get massively
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* inflated due to int64 or fp64 lowering. The estimates provided here don't
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* have to be massively accurate; they just have to be good enough that loop
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* unrolling doesn't cause things to blow up too much.
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*/
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static unsigned
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instr_cost(nir_instr *instr, const nir_shader_compiler_options *options)
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{
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if (instr->type == nir_instr_type_intrinsic ||
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instr->type == nir_instr_type_tex)
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return 1;
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if (instr->type != nir_instr_type_alu)
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return 0;
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nir_alu_instr *alu = nir_instr_as_alu(instr);
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const nir_op_info *info = &nir_op_infos[alu->op];
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/* Assume everything 16 or 32-bit is cheap.
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*
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* There are no 64-bit ops that don't have a 64-bit thing as their
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* destination or first source.
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*/
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if (nir_dest_bit_size(alu->dest.dest) < 64 &&
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nir_src_bit_size(alu->src[0].src) < 64)
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return 1;
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bool is_fp64 = nir_dest_bit_size(alu->dest.dest) == 64 &&
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nir_alu_type_get_base_type(info->output_type) == nir_type_float;
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for (unsigned i = 0; i < info->num_inputs; i++) {
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if (nir_src_bit_size(alu->src[i].src) == 64 &&
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nir_alu_type_get_base_type(info->input_types[i]) == nir_type_float)
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is_fp64 = true;
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}
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if (is_fp64) {
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/* If it's something lowered normally, it's expensive. */
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unsigned cost = 1;
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if (options->lower_doubles_options &
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nir_lower_doubles_op_to_options_mask(alu->op))
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cost *= 20;
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/* If it's full software, it's even more expensive */
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if (options->lower_doubles_options & nir_lower_fp64_full_software)
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cost *= 100;
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return cost;
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} else {
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if (options->lower_int64_options &
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nir_lower_int64_op_to_options_mask(alu->op)) {
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/* These require a doing the division algorithm. */
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if (alu->op == nir_op_idiv || alu->op == nir_op_udiv ||
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alu->op == nir_op_imod || alu->op == nir_op_umod ||
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alu->op == nir_op_irem)
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return 100;
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/* Other int64 lowering isn't usually all that expensive */
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return 5;
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}
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return 1;
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}
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}
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static bool
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init_loop_block(nir_block *block, loop_info_state *state,
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bool in_if_branch, bool in_nested_loop,
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const nir_shader_compiler_options *options)
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{
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init_loop_state init_state = {.in_if_branch = in_if_branch,
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.in_nested_loop = in_nested_loop,
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.state = state };
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nir_foreach_instr(instr, block) {
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state->loop->info->instr_cost += instr_cost(instr, options);
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nir_foreach_ssa_def(instr, init_loop_def, &init_state);
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}
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return true;
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}
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static inline bool
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is_var_alu(nir_loop_variable *var)
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{
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return var->def->parent_instr->type == nir_instr_type_alu;
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}
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static inline bool
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is_var_constant(nir_loop_variable *var)
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{
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return var->def->parent_instr->type == nir_instr_type_load_const;
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}
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static inline bool
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is_var_phi(nir_loop_variable *var)
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{
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return var->def->parent_instr->type == nir_instr_type_phi;
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}
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static inline bool
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mark_invariant(nir_ssa_def *def, loop_info_state *state)
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{
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nir_loop_variable *var = get_loop_var(def, state);
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if (var->type == invariant)
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return true;
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if (!var->in_loop) {
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var->type = invariant;
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return true;
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}
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if (var->type == not_invariant)
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return false;
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if (is_var_alu(var)) {
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nir_alu_instr *alu = nir_instr_as_alu(def->parent_instr);
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for (unsigned i = 0; i < nir_op_infos[alu->op].num_inputs; i++) {
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if (!mark_invariant(alu->src[i].src.ssa, state)) {
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var->type = not_invariant;
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return false;
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}
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}
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var->type = invariant;
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return true;
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}
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/* Phis shouldn't be invariant except if one operand is invariant, and the
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* other is the phi itself. These should be removed by opt_remove_phis.
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* load_consts are already set to invariant and constant during init,
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* and so should return earlier. Remaining op_codes are set undefined.
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*/
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var->type = not_invariant;
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return false;
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}
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static void
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compute_invariance_information(loop_info_state *state)
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{
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/* An expression is invariant in a loop L if:
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* (base cases)
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* – it’s a constant
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* – it’s a variable use, all of whose single defs are outside of L
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* (inductive cases)
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* – it’s a pure computation all of whose args are loop invariant
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* – it’s a variable use whose single reaching def, and the
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* rhs of that def is loop-invariant
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*/
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list_for_each_entry_safe(nir_loop_variable, var, &state->process_list,
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process_link) {
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assert(!var->in_if_branch && !var->in_nested_loop);
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if (mark_invariant(var->def, state))
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list_del(&var->process_link);
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}
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}
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|
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/* If all of the instruction sources point to identical ALU instructions (as
|
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* per nir_instrs_equal), return one of the ALU instructions. Otherwise,
|
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* return NULL.
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*/
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static nir_alu_instr *
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phi_instr_as_alu(nir_phi_instr *phi)
|
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{
|
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nir_alu_instr *first = NULL;
|
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nir_foreach_phi_src(src, phi) {
|
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assert(src->src.is_ssa);
|
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if (src->src.ssa->parent_instr->type != nir_instr_type_alu)
|
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return NULL;
|
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|
||
nir_alu_instr *alu = nir_instr_as_alu(src->src.ssa->parent_instr);
|
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if (first == NULL) {
|
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first = alu;
|
||
} else {
|
||
if (!nir_instrs_equal(&first->instr, &alu->instr))
|
||
return NULL;
|
||
}
|
||
}
|
||
|
||
return first;
|
||
}
|
||
|
||
static bool
|
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compute_induction_information(loop_info_state *state)
|
||
{
|
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bool found_induction_var = false;
|
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list_for_each_entry_safe(nir_loop_variable, var, &state->process_list,
|
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process_link) {
|
||
|
||
/* It can't be an induction variable if it is invariant. Invariants and
|
||
* things in nested loops or conditionals should have been removed from
|
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* the list by compute_invariance_information().
|
||
*/
|
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assert(!var->in_if_branch && !var->in_nested_loop &&
|
||
var->type != invariant);
|
||
|
||
/* We are only interested in checking phis for the basic induction
|
||
* variable case as its simple to detect. All basic induction variables
|
||
* have a phi node
|
||
*/
|
||
if (!is_var_phi(var))
|
||
continue;
|
||
|
||
/* We only handle scalars because none of the rest of the loop analysis
|
||
* code can properly handle swizzles.
|
||
*/
|
||
if (var->def->num_components > 1)
|
||
continue;
|
||
|
||
nir_phi_instr *phi = nir_instr_as_phi(var->def->parent_instr);
|
||
nir_basic_induction_var *biv = rzalloc(state, nir_basic_induction_var);
|
||
|
||
nir_foreach_phi_src(src, phi) {
|
||
nir_loop_variable *src_var = get_loop_var(src->src.ssa, state);
|
||
|
||
/* If one of the sources is in an if branch or nested loop then don't
|
||
* attempt to go any further.
|
||
*/
|
||
if (src_var->in_if_branch || src_var->in_nested_loop)
|
||
break;
|
||
|
||
/* Detect inductions variables that are incremented in both branches
|
||
* of an unnested if rather than in a loop block.
|
||
*/
|
||
if (is_var_phi(src_var)) {
|
||
nir_phi_instr *src_phi =
|
||
nir_instr_as_phi(src_var->def->parent_instr);
|
||
nir_alu_instr *src_phi_alu = phi_instr_as_alu(src_phi);
|
||
if (src_phi_alu) {
|
||
src_var = get_loop_var(&src_phi_alu->dest.dest.ssa, state);
|
||
if (!src_var->in_if_branch)
|
||
break;
|
||
}
|
||
}
|
||
|
||
if (!src_var->in_loop) {
|
||
biv->def_outside_loop = src_var;
|
||
} else if (is_var_alu(src_var)) {
|
||
nir_alu_instr *alu = nir_instr_as_alu(src_var->def->parent_instr);
|
||
|
||
if (nir_op_infos[alu->op].num_inputs == 2) {
|
||
biv->alu_def = src_var;
|
||
biv->alu_op = alu->op;
|
||
|
||
for (unsigned i = 0; i < 2; i++) {
|
||
/* Is one of the operands const, and the other the phi */
|
||
if (alu->src[i].src.ssa->parent_instr->type == nir_instr_type_load_const &&
|
||
alu->src[i].swizzle[0] == 0 &&
|
||
alu->src[1-i].src.ssa == &phi->dest.ssa)
|
||
assert(alu->src[1-i].swizzle[0] == 0);
|
||
biv->invariant = get_loop_var(alu->src[i].src.ssa, state);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
if (biv->alu_def && biv->def_outside_loop && biv->invariant &&
|
||
is_var_constant(biv->def_outside_loop)) {
|
||
assert(is_var_constant(biv->invariant));
|
||
biv->alu_def->type = basic_induction;
|
||
biv->alu_def->ind = biv;
|
||
var->type = basic_induction;
|
||
var->ind = biv;
|
||
|
||
found_induction_var = true;
|
||
} else {
|
||
ralloc_free(biv);
|
||
}
|
||
}
|
||
return found_induction_var;
|
||
}
|
||
|
||
static bool
|
||
initialize_ssa_def(nir_ssa_def *def, void *void_state)
|
||
{
|
||
loop_info_state *state = void_state;
|
||
nir_loop_variable *var = get_loop_var(def, state);
|
||
|
||
var->in_loop = false;
|
||
var->def = def;
|
||
|
||
if (def->parent_instr->type == nir_instr_type_load_const) {
|
||
var->type = invariant;
|
||
} else {
|
||
var->type = undefined;
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
static bool
|
||
find_loop_terminators(loop_info_state *state)
|
||
{
|
||
bool success = false;
|
||
foreach_list_typed_safe(nir_cf_node, node, node, &state->loop->body) {
|
||
if (node->type == nir_cf_node_if) {
|
||
nir_if *nif = nir_cf_node_as_if(node);
|
||
|
||
nir_block *break_blk = NULL;
|
||
nir_block *continue_from_blk = NULL;
|
||
bool continue_from_then = true;
|
||
|
||
nir_block *last_then = nir_if_last_then_block(nif);
|
||
nir_block *last_else = nir_if_last_else_block(nif);
|
||
if (nir_block_ends_in_break(last_then)) {
|
||
break_blk = last_then;
|
||
continue_from_blk = last_else;
|
||
continue_from_then = false;
|
||
} else if (nir_block_ends_in_break(last_else)) {
|
||
break_blk = last_else;
|
||
continue_from_blk = last_then;
|
||
}
|
||
|
||
/* If there is a break then we should find a terminator. If we can
|
||
* not find a loop terminator, but there is a break-statement then
|
||
* we should return false so that we do not try to find trip-count
|
||
*/
|
||
if (!nir_is_trivial_loop_if(nif, break_blk)) {
|
||
state->loop->info->complex_loop = true;
|
||
return false;
|
||
}
|
||
|
||
/* Continue if the if contained no jumps at all */
|
||
if (!break_blk)
|
||
continue;
|
||
|
||
if (nif->condition.ssa->parent_instr->type == nir_instr_type_phi) {
|
||
state->loop->info->complex_loop = true;
|
||
return false;
|
||
}
|
||
|
||
nir_loop_terminator *terminator =
|
||
rzalloc(state->loop->info, nir_loop_terminator);
|
||
|
||
list_addtail(&terminator->loop_terminator_link,
|
||
&state->loop->info->loop_terminator_list);
|
||
|
||
terminator->nif = nif;
|
||
terminator->break_block = break_blk;
|
||
terminator->continue_from_block = continue_from_blk;
|
||
terminator->continue_from_then = continue_from_then;
|
||
terminator->conditional_instr = nif->condition.ssa->parent_instr;
|
||
|
||
success = true;
|
||
}
|
||
}
|
||
|
||
return success;
|
||
}
|
||
|
||
/* This function looks for an array access within a loop that uses an
|
||
* induction variable for the array index. If found it returns the size of the
|
||
* array, otherwise 0 is returned. If we find an induction var we pass it back
|
||
* to the caller via array_index_out.
|
||
*/
|
||
static unsigned
|
||
find_array_access_via_induction(loop_info_state *state,
|
||
nir_deref_instr *deref,
|
||
nir_loop_variable **array_index_out)
|
||
{
|
||
for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
|
||
if (d->deref_type != nir_deref_type_array)
|
||
continue;
|
||
|
||
assert(d->arr.index.is_ssa);
|
||
nir_loop_variable *array_index = get_loop_var(d->arr.index.ssa, state);
|
||
|
||
if (array_index->type != basic_induction)
|
||
continue;
|
||
|
||
if (array_index_out)
|
||
*array_index_out = array_index;
|
||
|
||
nir_deref_instr *parent = nir_deref_instr_parent(d);
|
||
if (glsl_type_is_array_or_matrix(parent->type)) {
|
||
return glsl_get_length(parent->type);
|
||
} else {
|
||
assert(glsl_type_is_vector(parent->type));
|
||
return glsl_get_vector_elements(parent->type);
|
||
}
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
static bool
|
||
guess_loop_limit(loop_info_state *state, nir_const_value *limit_val,
|
||
nir_loop_variable *basic_ind)
|
||
{
|
||
unsigned min_array_size = 0;
|
||
|
||
nir_foreach_block_in_cf_node(block, &state->loop->cf_node) {
|
||
nir_foreach_instr(instr, block) {
|
||
if (instr->type != nir_instr_type_intrinsic)
|
||
continue;
|
||
|
||
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
|
||
|
||
/* Check for arrays variably-indexed by a loop induction variable. */
|
||
if (intrin->intrinsic == nir_intrinsic_load_deref ||
|
||
intrin->intrinsic == nir_intrinsic_store_deref ||
|
||
intrin->intrinsic == nir_intrinsic_copy_deref) {
|
||
|
||
nir_loop_variable *array_idx = NULL;
|
||
unsigned array_size =
|
||
find_array_access_via_induction(state,
|
||
nir_src_as_deref(intrin->src[0]),
|
||
&array_idx);
|
||
if (basic_ind == array_idx &&
|
||
(min_array_size == 0 || min_array_size > array_size)) {
|
||
min_array_size = array_size;
|
||
}
|
||
|
||
if (intrin->intrinsic != nir_intrinsic_copy_deref)
|
||
continue;
|
||
|
||
array_size =
|
||
find_array_access_via_induction(state,
|
||
nir_src_as_deref(intrin->src[1]),
|
||
&array_idx);
|
||
if (basic_ind == array_idx &&
|
||
(min_array_size == 0 || min_array_size > array_size)) {
|
||
min_array_size = array_size;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
if (min_array_size) {
|
||
*limit_val = nir_const_value_for_uint(min_array_size,
|
||
basic_ind->def->bit_size);
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static bool
|
||
try_find_limit_of_alu(nir_loop_variable *limit, nir_const_value *limit_val,
|
||
nir_loop_terminator *terminator, loop_info_state *state)
|
||
{
|
||
if(!is_var_alu(limit))
|
||
return false;
|
||
|
||
nir_alu_instr *limit_alu = nir_instr_as_alu(limit->def->parent_instr);
|
||
|
||
if (limit_alu->op == nir_op_imin ||
|
||
limit_alu->op == nir_op_fmin) {
|
||
/* We don't handle swizzles here */
|
||
if (limit_alu->src[0].swizzle[0] > 0 || limit_alu->src[1].swizzle[0] > 0)
|
||
return false;
|
||
|
||
limit = get_loop_var(limit_alu->src[0].src.ssa, state);
|
||
|
||
if (!is_var_constant(limit))
|
||
limit = get_loop_var(limit_alu->src[1].src.ssa, state);
|
||
|
||
if (!is_var_constant(limit))
|
||
return false;
|
||
|
||
*limit_val = nir_instr_as_load_const(limit->def->parent_instr)->value[0];
|
||
|
||
terminator->exact_trip_count_unknown = true;
|
||
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static nir_const_value
|
||
eval_const_unop(nir_op op, unsigned bit_size, nir_const_value src0)
|
||
{
|
||
assert(nir_op_infos[op].num_inputs == 1);
|
||
nir_const_value dest;
|
||
nir_const_value *src[1] = { &src0 };
|
||
nir_eval_const_opcode(op, &dest, 1, bit_size, src);
|
||
return dest;
|
||
}
|
||
|
||
static nir_const_value
|
||
eval_const_binop(nir_op op, unsigned bit_size,
|
||
nir_const_value src0, nir_const_value src1)
|
||
{
|
||
assert(nir_op_infos[op].num_inputs == 2);
|
||
nir_const_value dest;
|
||
nir_const_value *src[2] = { &src0, &src1 };
|
||
nir_eval_const_opcode(op, &dest, 1, bit_size, src);
|
||
return dest;
|
||
}
|
||
|
||
static int32_t
|
||
get_iteration(nir_op cond_op, nir_const_value initial, nir_const_value step,
|
||
nir_const_value limit, unsigned bit_size)
|
||
{
|
||
nir_const_value span, iter;
|
||
|
||
switch (cond_op) {
|
||
case nir_op_ige:
|
||
case nir_op_ilt:
|
||
case nir_op_ieq:
|
||
case nir_op_ine:
|
||
span = eval_const_binop(nir_op_isub, bit_size, limit, initial);
|
||
iter = eval_const_binop(nir_op_idiv, bit_size, span, step);
|
||
break;
|
||
|
||
case nir_op_uge:
|
||
case nir_op_ult:
|
||
span = eval_const_binop(nir_op_isub, bit_size, limit, initial);
|
||
iter = eval_const_binop(nir_op_udiv, bit_size, span, step);
|
||
break;
|
||
|
||
case nir_op_fge:
|
||
case nir_op_flt:
|
||
case nir_op_feq:
|
||
case nir_op_fne:
|
||
span = eval_const_binop(nir_op_fsub, bit_size, limit, initial);
|
||
iter = eval_const_binop(nir_op_fdiv, bit_size, span, step);
|
||
iter = eval_const_unop(nir_op_f2i64, bit_size, iter);
|
||
break;
|
||
|
||
default:
|
||
return -1;
|
||
}
|
||
|
||
uint64_t iter_u64 = nir_const_value_as_uint(iter, bit_size);
|
||
return iter_u64 > INT_MAX ? -1 : (int)iter_u64;
|
||
}
|
||
|
||
static bool
|
||
test_iterations(int32_t iter_int, nir_const_value *step,
|
||
nir_const_value *limit, nir_op cond_op, unsigned bit_size,
|
||
nir_alu_type induction_base_type,
|
||
nir_const_value *initial, bool limit_rhs, bool invert_cond)
|
||
{
|
||
assert(nir_op_infos[cond_op].num_inputs == 2);
|
||
|
||
nir_const_value iter_src;
|
||
nir_op mul_op;
|
||
nir_op add_op;
|
||
switch (induction_base_type) {
|
||
case nir_type_float:
|
||
iter_src = nir_const_value_for_float(iter_int, bit_size);
|
||
mul_op = nir_op_fmul;
|
||
add_op = nir_op_fadd;
|
||
break;
|
||
case nir_type_int:
|
||
case nir_type_uint:
|
||
iter_src = nir_const_value_for_int(iter_int, bit_size);
|
||
mul_op = nir_op_imul;
|
||
add_op = nir_op_iadd;
|
||
break;
|
||
default:
|
||
unreachable("Unhandled induction variable base type!");
|
||
}
|
||
|
||
/* Multiple the iteration count we are testing by the number of times we
|
||
* step the induction variable each iteration.
|
||
*/
|
||
nir_const_value mul_result =
|
||
eval_const_binop(mul_op, bit_size, iter_src, *step);
|
||
|
||
/* Add the initial value to the accumulated induction variable total */
|
||
nir_const_value add_result =
|
||
eval_const_binop(add_op, bit_size, mul_result, *initial);
|
||
|
||
nir_const_value *src[2];
|
||
src[limit_rhs ? 0 : 1] = &add_result;
|
||
src[limit_rhs ? 1 : 0] = limit;
|
||
|
||
/* Evaluate the loop exit condition */
|
||
nir_const_value result;
|
||
nir_eval_const_opcode(cond_op, &result, 1, bit_size, src);
|
||
|
||
return invert_cond ? !result.b : result.b;
|
||
}
|
||
|
||
static int
|
||
calculate_iterations(nir_const_value *initial, nir_const_value *step,
|
||
nir_const_value *limit, nir_loop_variable *alu_def,
|
||
nir_alu_instr *cond_alu, nir_op alu_op, bool limit_rhs,
|
||
bool invert_cond)
|
||
{
|
||
assert(initial != NULL && step != NULL && limit != NULL);
|
||
|
||
nir_alu_instr *alu = nir_instr_as_alu(alu_def->def->parent_instr);
|
||
|
||
/* nir_op_isub should have been lowered away by this point */
|
||
assert(alu->op != nir_op_isub);
|
||
|
||
/* Make sure the alu type for our induction variable is compatible with the
|
||
* conditional alus input type. If its not something has gone really wrong.
|
||
*/
|
||
nir_alu_type induction_base_type =
|
||
nir_alu_type_get_base_type(nir_op_infos[alu->op].output_type);
|
||
if (induction_base_type == nir_type_int || induction_base_type == nir_type_uint) {
|
||
assert(nir_alu_type_get_base_type(nir_op_infos[alu_op].input_types[1]) == nir_type_int ||
|
||
nir_alu_type_get_base_type(nir_op_infos[alu_op].input_types[1]) == nir_type_uint);
|
||
} else {
|
||
assert(nir_alu_type_get_base_type(nir_op_infos[alu_op].input_types[0]) ==
|
||
induction_base_type);
|
||
}
|
||
|
||
/* Check for nsupported alu operations */
|
||
if (alu->op != nir_op_iadd && alu->op != nir_op_fadd)
|
||
return -1;
|
||
|
||
/* do-while loops can increment the starting value before the condition is
|
||
* checked. e.g.
|
||
*
|
||
* do {
|
||
* ndx++;
|
||
* } while (ndx < 3);
|
||
*
|
||
* Here we check if the induction variable is used directly by the loop
|
||
* condition and if so we assume we need to step the initial value.
|
||
*/
|
||
unsigned trip_offset = 0;
|
||
if (cond_alu->src[0].src.ssa == alu_def->def ||
|
||
cond_alu->src[1].src.ssa == alu_def->def) {
|
||
trip_offset = 1;
|
||
}
|
||
|
||
assert(nir_src_bit_size(alu->src[0].src) ==
|
||
nir_src_bit_size(alu->src[1].src));
|
||
unsigned bit_size = nir_src_bit_size(alu->src[0].src);
|
||
int iter_int = get_iteration(alu_op, *initial, *step, *limit, bit_size);
|
||
|
||
/* If iter_int is negative the loop is ill-formed or is the conditional is
|
||
* unsigned with a huge iteration count so don't bother going any further.
|
||
*/
|
||
if (iter_int < 0)
|
||
return -1;
|
||
|
||
/* An explanation from the GLSL unrolling pass:
|
||
*
|
||
* 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);
|
||
*/
|
||
for (int bias = -1; bias <= 1; bias++) {
|
||
const int iter_bias = iter_int + bias;
|
||
|
||
if (test_iterations(iter_bias, step, limit, alu_op, bit_size,
|
||
induction_base_type, initial,
|
||
limit_rhs, invert_cond)) {
|
||
return iter_bias > 0 ? iter_bias - trip_offset : iter_bias;
|
||
}
|
||
}
|
||
|
||
return -1;
|
||
}
|
||
|
||
static nir_op
|
||
inverse_comparison(nir_alu_instr *alu)
|
||
{
|
||
switch (alu->op) {
|
||
case nir_op_fge:
|
||
return nir_op_flt;
|
||
case nir_op_ige:
|
||
return nir_op_ilt;
|
||
case nir_op_uge:
|
||
return nir_op_ult;
|
||
case nir_op_flt:
|
||
return nir_op_fge;
|
||
case nir_op_ilt:
|
||
return nir_op_ige;
|
||
case nir_op_ult:
|
||
return nir_op_uge;
|
||
case nir_op_feq:
|
||
return nir_op_fne;
|
||
case nir_op_ieq:
|
||
return nir_op_ine;
|
||
case nir_op_fne:
|
||
return nir_op_feq;
|
||
case nir_op_ine:
|
||
return nir_op_ieq;
|
||
default:
|
||
unreachable("Unsuported comparison!");
|
||
}
|
||
}
|
||
|
||
static bool
|
||
is_supported_terminator_condition(nir_alu_instr *alu)
|
||
{
|
||
return nir_alu_instr_is_comparison(alu) &&
|
||
nir_op_infos[alu->op].num_inputs == 2;
|
||
}
|
||
|
||
static bool
|
||
get_induction_and_limit_vars(nir_alu_instr *alu, nir_loop_variable **ind,
|
||
nir_loop_variable **limit,
|
||
loop_info_state *state)
|
||
{
|
||
bool limit_rhs = true;
|
||
|
||
/* We assume that the limit is the "right" operand */
|
||
*ind = get_loop_var(alu->src[0].src.ssa, state);
|
||
*limit = get_loop_var(alu->src[1].src.ssa, state);
|
||
|
||
if ((*ind)->type != basic_induction) {
|
||
/* We had it the wrong way, flip things around */
|
||
*ind = get_loop_var(alu->src[1].src.ssa, state);
|
||
*limit = get_loop_var(alu->src[0].src.ssa, state);
|
||
limit_rhs = false;
|
||
}
|
||
|
||
return limit_rhs;
|
||
}
|
||
|
||
static void
|
||
try_find_trip_count_vars_in_iand(nir_alu_instr **alu,
|
||
nir_loop_variable **ind,
|
||
nir_loop_variable **limit,
|
||
bool *limit_rhs,
|
||
loop_info_state *state)
|
||
{
|
||
assert((*alu)->op == nir_op_ieq || (*alu)->op == nir_op_inot);
|
||
|
||
nir_ssa_def *iand_def = (*alu)->src[0].src.ssa;
|
||
/* This is used directly in an if condition so it must be a scalar */
|
||
assert(iand_def->num_components == 1);
|
||
|
||
if ((*alu)->op == nir_op_ieq) {
|
||
nir_ssa_def *zero_def = (*alu)->src[1].src.ssa;
|
||
|
||
/* We don't handle swizzles here */
|
||
if ((*alu)->src[0].swizzle[0] > 0 || (*alu)->src[1].swizzle[0] > 0)
|
||
return;
|
||
|
||
if (iand_def->parent_instr->type != nir_instr_type_alu ||
|
||
zero_def->parent_instr->type != nir_instr_type_load_const) {
|
||
|
||
/* Maybe we had it the wrong way, flip things around */
|
||
iand_def = (*alu)->src[1].src.ssa;
|
||
zero_def = (*alu)->src[0].src.ssa;
|
||
|
||
/* If we still didn't find what we need then return */
|
||
if (zero_def->parent_instr->type != nir_instr_type_load_const)
|
||
return;
|
||
}
|
||
|
||
/* If the loop is not breaking on (x && y) == 0 then return */
|
||
nir_const_value *zero =
|
||
nir_instr_as_load_const(zero_def->parent_instr)->value;
|
||
if (zero[0].i32 != 0)
|
||
return;
|
||
}
|
||
|
||
if (iand_def->parent_instr->type != nir_instr_type_alu)
|
||
return;
|
||
|
||
nir_alu_instr *iand = nir_instr_as_alu(iand_def->parent_instr);
|
||
if (iand->op != nir_op_iand)
|
||
return;
|
||
|
||
/* We don't handle swizzles here */
|
||
if ((*alu)->src[0].swizzle[0] > 0 || (*alu)->src[1].swizzle[0] > 0)
|
||
return;
|
||
|
||
/* Check if iand src is a terminator condition and try get induction var
|
||
* and trip limit var.
|
||
*/
|
||
nir_ssa_def *src = iand->src[0].src.ssa;
|
||
if (src->parent_instr->type == nir_instr_type_alu) {
|
||
*alu = nir_instr_as_alu(src->parent_instr);
|
||
if (is_supported_terminator_condition(*alu))
|
||
*limit_rhs = get_induction_and_limit_vars(*alu, ind, limit, state);
|
||
}
|
||
|
||
/* Try the other iand src if needed */
|
||
if (*ind == NULL || (*ind && (*ind)->type != basic_induction) ||
|
||
!is_var_constant(*limit)) {
|
||
src = iand->src[1].src.ssa;
|
||
if (src->parent_instr->type == nir_instr_type_alu) {
|
||
nir_alu_instr *tmp_alu = nir_instr_as_alu(src->parent_instr);
|
||
if (is_supported_terminator_condition(tmp_alu)) {
|
||
*alu = tmp_alu;
|
||
*limit_rhs = get_induction_and_limit_vars(*alu, ind, limit, state);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Run through each of the terminators of the loop and try to infer a possible
|
||
* trip-count. We need to check them all, and set the lowest trip-count as the
|
||
* trip-count of our loop. If one of the terminators has an undecidable
|
||
* trip-count we can not safely assume anything about the duration of the
|
||
* loop.
|
||
*/
|
||
static void
|
||
find_trip_count(loop_info_state *state)
|
||
{
|
||
bool trip_count_known = true;
|
||
bool guessed_trip_count = false;
|
||
nir_loop_terminator *limiting_terminator = NULL;
|
||
int max_trip_count = -1;
|
||
|
||
list_for_each_entry(nir_loop_terminator, terminator,
|
||
&state->loop->info->loop_terminator_list,
|
||
loop_terminator_link) {
|
||
|
||
if (terminator->conditional_instr->type != nir_instr_type_alu) {
|
||
/* If we get here the loop is dead and will get cleaned up by the
|
||
* nir_opt_dead_cf pass.
|
||
*/
|
||
trip_count_known = false;
|
||
continue;
|
||
}
|
||
|
||
nir_alu_instr *alu = nir_instr_as_alu(terminator->conditional_instr);
|
||
nir_op alu_op = alu->op;
|
||
|
||
bool limit_rhs;
|
||
nir_loop_variable *basic_ind = NULL;
|
||
nir_loop_variable *limit;
|
||
if (alu->op == nir_op_inot || alu->op == nir_op_ieq) {
|
||
nir_alu_instr *new_alu = alu;
|
||
try_find_trip_count_vars_in_iand(&new_alu, &basic_ind, &limit,
|
||
&limit_rhs, state);
|
||
|
||
/* The loop is exiting on (x && y) == 0 so we need to get the
|
||
* inverse of x or y (i.e. which ever contained the induction var) in
|
||
* order to compute the trip count.
|
||
*/
|
||
if (basic_ind && basic_ind->type == basic_induction) {
|
||
alu = new_alu;
|
||
alu_op = inverse_comparison(alu);
|
||
trip_count_known = false;
|
||
terminator->exact_trip_count_unknown = true;
|
||
}
|
||
}
|
||
|
||
if (!basic_ind) {
|
||
if (!is_supported_terminator_condition(alu)) {
|
||
trip_count_known = false;
|
||
continue;
|
||
}
|
||
|
||
limit_rhs = get_induction_and_limit_vars(alu, &basic_ind, &limit,
|
||
state);
|
||
}
|
||
|
||
/* The comparison has to have a basic induction variable for us to be
|
||
* able to find trip counts.
|
||
*/
|
||
if (basic_ind->type != basic_induction) {
|
||
trip_count_known = false;
|
||
continue;
|
||
}
|
||
|
||
terminator->induction_rhs = !limit_rhs;
|
||
|
||
/* Attempt to find a constant limit for the loop */
|
||
nir_const_value limit_val;
|
||
if (is_var_constant(limit)) {
|
||
limit_val =
|
||
nir_instr_as_load_const(limit->def->parent_instr)->value[0];
|
||
} else {
|
||
trip_count_known = false;
|
||
|
||
if (!try_find_limit_of_alu(limit, &limit_val, terminator, state)) {
|
||
/* Guess loop limit based on array access */
|
||
if (!guess_loop_limit(state, &limit_val, basic_ind)) {
|
||
continue;
|
||
}
|
||
|
||
guessed_trip_count = true;
|
||
}
|
||
}
|
||
|
||
/* We have determined that we have the following constants:
|
||
* (With the typical int i = 0; i < x; i++; as an example)
|
||
* - Upper limit.
|
||
* - Starting value
|
||
* - Step / iteration size
|
||
* Thats all thats needed to calculate the trip-count
|
||
*/
|
||
|
||
nir_const_value *initial_val =
|
||
nir_instr_as_load_const(basic_ind->ind->def_outside_loop->
|
||
def->parent_instr)->value;
|
||
|
||
nir_const_value *step_val =
|
||
nir_instr_as_load_const(basic_ind->ind->invariant->def->
|
||
parent_instr)->value;
|
||
|
||
int iterations = calculate_iterations(initial_val, step_val,
|
||
&limit_val,
|
||
basic_ind->ind->alu_def, alu,
|
||
alu_op, limit_rhs,
|
||
terminator->continue_from_then);
|
||
|
||
/* Where we not able to calculate the iteration count */
|
||
if (iterations == -1) {
|
||
trip_count_known = false;
|
||
guessed_trip_count = false;
|
||
continue;
|
||
}
|
||
|
||
if (guessed_trip_count) {
|
||
guessed_trip_count = false;
|
||
if (state->loop->info->guessed_trip_count == 0 ||
|
||
state->loop->info->guessed_trip_count > iterations)
|
||
state->loop->info->guessed_trip_count = iterations;
|
||
|
||
continue;
|
||
}
|
||
|
||
/* If this is the first run or we have found a smaller amount of
|
||
* iterations than previously (we have identified a more limiting
|
||
* terminator) set the trip count and limiting terminator.
|
||
*/
|
||
if (max_trip_count == -1 || iterations < max_trip_count) {
|
||
max_trip_count = iterations;
|
||
limiting_terminator = terminator;
|
||
}
|
||
}
|
||
|
||
state->loop->info->exact_trip_count_known = trip_count_known;
|
||
if (max_trip_count > -1)
|
||
state->loop->info->max_trip_count = max_trip_count;
|
||
state->loop->info->limiting_terminator = limiting_terminator;
|
||
}
|
||
|
||
static bool
|
||
force_unroll_array_access(loop_info_state *state, nir_deref_instr *deref)
|
||
{
|
||
unsigned array_size = find_array_access_via_induction(state, deref, NULL);
|
||
if (array_size) {
|
||
if (array_size == state->loop->info->max_trip_count)
|
||
return true;
|
||
|
||
if (deref->mode & state->indirect_mask)
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static bool
|
||
force_unroll_heuristics(loop_info_state *state, nir_block *block)
|
||
{
|
||
nir_foreach_instr(instr, block) {
|
||
if (instr->type != nir_instr_type_intrinsic)
|
||
continue;
|
||
|
||
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
|
||
|
||
/* Check for arrays variably-indexed by a loop induction variable.
|
||
* Unrolling the loop may convert that access into constant-indexing.
|
||
*/
|
||
if (intrin->intrinsic == nir_intrinsic_load_deref ||
|
||
intrin->intrinsic == nir_intrinsic_store_deref ||
|
||
intrin->intrinsic == nir_intrinsic_copy_deref) {
|
||
if (force_unroll_array_access(state,
|
||
nir_src_as_deref(intrin->src[0])))
|
||
return true;
|
||
|
||
if (intrin->intrinsic == nir_intrinsic_copy_deref &&
|
||
force_unroll_array_access(state,
|
||
nir_src_as_deref(intrin->src[1])))
|
||
return true;
|
||
}
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static void
|
||
get_loop_info(loop_info_state *state, nir_function_impl *impl)
|
||
{
|
||
nir_shader *shader = impl->function->shader;
|
||
const nir_shader_compiler_options *options = shader->options;
|
||
|
||
/* Initialize all variables to "outside_loop". This also marks defs
|
||
* invariant and constant if they are nir_instr_type_load_consts
|
||
*/
|
||
nir_foreach_block(block, impl) {
|
||
nir_foreach_instr(instr, block)
|
||
nir_foreach_ssa_def(instr, initialize_ssa_def, state);
|
||
}
|
||
|
||
/* Add all entries in the outermost part of the loop to the processing list
|
||
* Mark the entries in conditionals or in nested loops accordingly
|
||
*/
|
||
foreach_list_typed_safe(nir_cf_node, node, node, &state->loop->body) {
|
||
switch (node->type) {
|
||
|
||
case nir_cf_node_block:
|
||
init_loop_block(nir_cf_node_as_block(node), state,
|
||
false, false, options);
|
||
break;
|
||
|
||
case nir_cf_node_if:
|
||
nir_foreach_block_in_cf_node(block, node)
|
||
init_loop_block(block, state, true, false, options);
|
||
break;
|
||
|
||
case nir_cf_node_loop:
|
||
nir_foreach_block_in_cf_node(block, node) {
|
||
init_loop_block(block, state, false, true, options);
|
||
}
|
||
break;
|
||
|
||
case nir_cf_node_function:
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* Try to find all simple terminators of the loop. If we can't find any,
|
||
* or we find possible terminators that have side effects then bail.
|
||
*/
|
||
if (!find_loop_terminators(state)) {
|
||
list_for_each_entry_safe(nir_loop_terminator, terminator,
|
||
&state->loop->info->loop_terminator_list,
|
||
loop_terminator_link) {
|
||
list_del(&terminator->loop_terminator_link);
|
||
ralloc_free(terminator);
|
||
}
|
||
return;
|
||
}
|
||
|
||
/* Induction analysis needs invariance information so get that first */
|
||
compute_invariance_information(state);
|
||
|
||
/* We have invariance information so try to find induction variables */
|
||
if (!compute_induction_information(state))
|
||
return;
|
||
|
||
/* Run through each of the terminators and try to compute a trip-count */
|
||
find_trip_count(state);
|
||
|
||
nir_foreach_block_in_cf_node(block, &state->loop->cf_node) {
|
||
if (force_unroll_heuristics(state, block)) {
|
||
state->loop->info->force_unroll = true;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
static loop_info_state *
|
||
initialize_loop_info_state(nir_loop *loop, void *mem_ctx,
|
||
nir_function_impl *impl)
|
||
{
|
||
loop_info_state *state = rzalloc(mem_ctx, loop_info_state);
|
||
state->loop_vars = rzalloc_array(mem_ctx, nir_loop_variable,
|
||
impl->ssa_alloc);
|
||
state->loop = loop;
|
||
|
||
list_inithead(&state->process_list);
|
||
|
||
if (loop->info)
|
||
ralloc_free(loop->info);
|
||
|
||
loop->info = rzalloc(loop, nir_loop_info);
|
||
|
||
list_inithead(&loop->info->loop_terminator_list);
|
||
|
||
return state;
|
||
}
|
||
|
||
static void
|
||
process_loops(nir_cf_node *cf_node, nir_variable_mode indirect_mask)
|
||
{
|
||
switch (cf_node->type) {
|
||
case nir_cf_node_block:
|
||
return;
|
||
case nir_cf_node_if: {
|
||
nir_if *if_stmt = nir_cf_node_as_if(cf_node);
|
||
foreach_list_typed(nir_cf_node, nested_node, node, &if_stmt->then_list)
|
||
process_loops(nested_node, indirect_mask);
|
||
foreach_list_typed(nir_cf_node, nested_node, node, &if_stmt->else_list)
|
||
process_loops(nested_node, indirect_mask);
|
||
return;
|
||
}
|
||
case nir_cf_node_loop: {
|
||
nir_loop *loop = nir_cf_node_as_loop(cf_node);
|
||
foreach_list_typed(nir_cf_node, nested_node, node, &loop->body)
|
||
process_loops(nested_node, indirect_mask);
|
||
break;
|
||
}
|
||
default:
|
||
unreachable("unknown cf node type");
|
||
}
|
||
|
||
nir_loop *loop = nir_cf_node_as_loop(cf_node);
|
||
nir_function_impl *impl = nir_cf_node_get_function(cf_node);
|
||
void *mem_ctx = ralloc_context(NULL);
|
||
|
||
loop_info_state *state = initialize_loop_info_state(loop, mem_ctx, impl);
|
||
state->indirect_mask = indirect_mask;
|
||
|
||
get_loop_info(state, impl);
|
||
|
||
ralloc_free(mem_ctx);
|
||
}
|
||
|
||
void
|
||
nir_loop_analyze_impl(nir_function_impl *impl,
|
||
nir_variable_mode indirect_mask)
|
||
{
|
||
nir_index_ssa_defs(impl);
|
||
foreach_list_typed(nir_cf_node, node, node, &impl->body)
|
||
process_loops(node, indirect_mask);
|
||
}
|