199 lines
5.9 KiB
C
199 lines
5.9 KiB
C
/*
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* Copyright © 2019 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include "nir.h"
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#include "nir/nir_builder.h"
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#include "nir_constant_expressions.h"
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#include "nir_control_flow.h"
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#include "nir_loop_analyze.h"
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static bool
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is_two_src_comparison(const nir_alu_instr *instr)
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{
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switch (instr->op) {
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case nir_op_flt:
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case nir_op_flt32:
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case nir_op_fge:
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case nir_op_fge32:
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case nir_op_feq:
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case nir_op_feq32:
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case nir_op_fneu:
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case nir_op_fneu32:
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case nir_op_ilt:
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case nir_op_ilt32:
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case nir_op_ult:
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case nir_op_ult32:
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case nir_op_ige:
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case nir_op_ige32:
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case nir_op_uge:
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case nir_op_uge32:
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case nir_op_ieq:
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case nir_op_ieq32:
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case nir_op_ine:
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case nir_op_ine32:
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return true;
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default:
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return false;
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}
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}
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static bool
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all_srcs_are_ssa(const nir_alu_instr *instr)
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{
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for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
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if (!instr->src[i].src.is_ssa)
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return false;
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}
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return true;
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}
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static bool
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all_uses_are_bcsel(const nir_alu_instr *instr)
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{
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if (!instr->dest.dest.is_ssa)
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return false;
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nir_foreach_use(use, &instr->dest.dest.ssa) {
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if (use->parent_instr->type != nir_instr_type_alu)
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return false;
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nir_alu_instr *const alu = nir_instr_as_alu(use->parent_instr);
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if (alu->op != nir_op_bcsel &&
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alu->op != nir_op_b32csel)
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return false;
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/* Not only must the result be used by a bcsel, but it must be used as
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* the first source (the condition).
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*/
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if (alu->src[0].src.ssa != &instr->dest.dest.ssa)
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return false;
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}
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return true;
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}
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static bool
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nir_opt_rematerialize_compares_impl(nir_shader *shader, nir_function_impl *impl)
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{
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bool progress = false;
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nir_foreach_block(block, impl) {
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nir_foreach_instr(instr, block) {
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if (instr->type != nir_instr_type_alu)
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continue;
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nir_alu_instr *const alu = nir_instr_as_alu(instr);
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if (!is_two_src_comparison(alu))
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continue;
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if (!all_srcs_are_ssa(alu))
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continue;
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if (!all_uses_are_bcsel(alu))
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continue;
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/* At this point it is known that alu is a comparison instruction
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* that is only used by nir_op_bcsel and possibly by if-statements
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* (though the latter has not been explicitly checked).
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*
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* Iterate through each use of the comparison. For every use (or use
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* by an if-statement) that is in a different block, emit a copy of
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* the comparison. Care must be taken here. The original
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* instruction must be duplicated only once in each block because CSE
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* cannot be run after this pass.
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*/
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nir_foreach_use_safe(use, &alu->dest.dest.ssa) {
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nir_instr *const use_instr = use->parent_instr;
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/* If the use is in the same block as the def, don't
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* rematerialize.
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*/
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if (use_instr->block == alu->instr.block)
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continue;
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nir_alu_instr *clone = nir_alu_instr_clone(shader, alu);
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nir_instr_insert_before(use_instr, &clone->instr);
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nir_alu_instr *const use_alu = nir_instr_as_alu(use_instr);
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for (unsigned i = 0; i < nir_op_infos[use_alu->op].num_inputs; i++) {
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if (use_alu->src[i].src.ssa == &alu->dest.dest.ssa) {
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nir_instr_rewrite_src(&use_alu->instr,
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&use_alu->src[i].src,
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nir_src_for_ssa(&clone->dest.dest.ssa));
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progress = true;
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}
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}
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}
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nir_foreach_if_use_safe(use, &alu->dest.dest.ssa) {
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nir_if *const if_stmt = use->parent_if;
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nir_block *const prev_block =
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nir_cf_node_as_block(nir_cf_node_prev(&if_stmt->cf_node));
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/* If the compare is from the previous block, don't
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* rematerialize.
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*/
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if (prev_block == alu->instr.block)
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continue;
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nir_alu_instr *clone = nir_alu_instr_clone(shader, alu);
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nir_instr_insert_after_block(prev_block, &clone->instr);
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nir_if_rewrite_condition(if_stmt,
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nir_src_for_ssa(&clone->dest.dest.ssa));
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progress = true;
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}
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}
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}
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if (progress) {
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nir_metadata_preserve(impl, nir_metadata_block_index |
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nir_metadata_dominance);
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} else {
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nir_metadata_preserve(impl, nir_metadata_all);
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}
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return progress;
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}
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bool
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nir_opt_rematerialize_compares(nir_shader *shader)
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{
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bool progress = false;
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nir_foreach_function(function, shader) {
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if (function->impl == NULL)
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continue;
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progress = nir_opt_rematerialize_compares_impl(shader, function->impl)
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|| progress;
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}
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return progress;
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}
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