241 lines
7.7 KiB
C
241 lines
7.7 KiB
C
/*
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* Copyright © 2018 Red Hat
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* Copyright © 2019 Valve 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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* Authors:
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* Rob Clark (robdclark@gmail.com>
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* Daniel Schürmann (daniel.schuermann@campus.tu-berlin.de)
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* Rhys Perry (pendingchaos02@gmail.com)
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*
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*/
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#include "nir.h"
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/*
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* A simple pass that moves some instructions into the least common
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* anscestor of consuming instructions.
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*/
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bool
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nir_can_move_instr(nir_instr *instr, nir_move_options options)
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{
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switch (instr->type) {
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case nir_instr_type_load_const:
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case nir_instr_type_ssa_undef: {
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return options & nir_move_const_undef;
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}
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case nir_instr_type_alu: {
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if (nir_op_is_vec(nir_instr_as_alu(instr)->op) ||
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nir_instr_as_alu(instr)->op == nir_op_b2i32)
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return options & nir_move_copies;
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if (nir_alu_instr_is_comparison(nir_instr_as_alu(instr)))
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return options & nir_move_comparisons;
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return false;
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}
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case nir_instr_type_intrinsic: {
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nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
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switch (intrin->intrinsic) {
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case nir_intrinsic_load_ubo:
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case nir_intrinsic_load_ubo_vec4:
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return options & nir_move_load_ubo;
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case nir_intrinsic_load_ssbo:
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return (options & nir_move_load_ssbo) && nir_intrinsic_can_reorder(intrin);
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case nir_intrinsic_load_input:
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case nir_intrinsic_load_interpolated_input:
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case nir_intrinsic_load_per_vertex_input:
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return options & nir_move_load_input;
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case nir_intrinsic_load_uniform:
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return options & nir_move_load_uniform;
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default:
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return false;
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}
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}
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default:
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return false;
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}
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}
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static nir_loop *
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get_innermost_loop(nir_cf_node *node)
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{
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for (; node != NULL; node = node->parent) {
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if (node->type == nir_cf_node_loop)
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return (nir_loop*)node;
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}
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return NULL;
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}
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static bool
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loop_contains_block(nir_loop *loop, nir_block *block)
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{
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nir_block *before = nir_cf_node_as_block(nir_cf_node_prev(&loop->cf_node));
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nir_block *after = nir_cf_node_as_block(nir_cf_node_next(&loop->cf_node));
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return block->index > before->index && block->index < after->index;
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}
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/* Given the LCA of all uses and the definition, find a block on the path
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* between them in the dominance tree that is outside of as many loops as
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* possible. If "sink_out_of_loops" is false, then we disallow sinking the
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* definition outside of the loop it's defined in (if any).
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*/
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static nir_block *
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adjust_block_for_loops(nir_block *use_block, nir_block *def_block,
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bool sink_out_of_loops)
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{
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nir_loop *def_loop = NULL;
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if (!sink_out_of_loops)
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def_loop = get_innermost_loop(&def_block->cf_node);
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for (nir_block *cur_block = use_block; cur_block != def_block->imm_dom;
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cur_block = cur_block->imm_dom) {
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if (!sink_out_of_loops && def_loop &&
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!loop_contains_block(def_loop, use_block)) {
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use_block = cur_block;
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continue;
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}
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nir_cf_node *next = nir_cf_node_next(&cur_block->cf_node);
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if (next && next->type == nir_cf_node_loop) {
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nir_loop *following_loop = nir_cf_node_as_loop(next);
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if (loop_contains_block(following_loop, use_block)) {
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use_block = cur_block;
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continue;
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}
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}
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}
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return use_block;
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}
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/* iterate a ssa def's use's and try to find a more optimal block to
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* move it to, using the dominance tree. In short, if all of the uses
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* are contained in a single block, the load will be moved there,
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* otherwise it will be move to the least common ancestor block of all
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* the uses
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*/
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static nir_block *
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get_preferred_block(nir_ssa_def *def, bool sink_out_of_loops)
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{
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nir_block *lca = NULL;
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nir_foreach_use(use, def) {
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nir_instr *instr = use->parent_instr;
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nir_block *use_block = instr->block;
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/*
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* Kind of an ugly special-case, but phi instructions
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* need to appear first in the block, so by definition
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* we can't move an instruction into a block where it is
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* consumed by a phi instruction. We could conceivably
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* move it into a dominator block.
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*/
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if (instr->type == nir_instr_type_phi) {
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nir_phi_instr *phi = nir_instr_as_phi(instr);
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nir_block *phi_lca = NULL;
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nir_foreach_phi_src(src, phi) {
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if (&src->src == use)
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phi_lca = nir_dominance_lca(phi_lca, src->pred);
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}
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use_block = phi_lca;
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}
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lca = nir_dominance_lca(lca, use_block);
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}
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nir_foreach_if_use(use, def) {
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nir_block *use_block =
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nir_cf_node_as_block(nir_cf_node_prev(&use->parent_if->cf_node));
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lca = nir_dominance_lca(lca, use_block);
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}
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/* return in case, we didn't find a reachable user */
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if (!lca)
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return NULL;
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/* We don't sink any instructions into loops to avoid repeated executions
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* This might occasionally increase register pressure, but seems overall
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* the better choice.
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*/
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lca = adjust_block_for_loops(lca, def->parent_instr->block,
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sink_out_of_loops);
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assert(nir_block_dominates(def->parent_instr->block, lca));
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return lca;
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}
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static bool
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can_sink_out_of_loop(nir_intrinsic_instr *intrin)
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{
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/* Don't sink buffer loads out of loops because that can make its
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* resource divergent and break code like that which is generated
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* by nir_lower_non_uniform_access.
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*/
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return intrin->intrinsic != nir_intrinsic_load_ubo &&
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intrin->intrinsic != nir_intrinsic_load_ssbo;
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}
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bool
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nir_opt_sink(nir_shader *shader, nir_move_options options)
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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)
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continue;
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nir_metadata_require(function->impl,
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nir_metadata_block_index | nir_metadata_dominance);
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nir_foreach_block_reverse(block, function->impl) {
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nir_foreach_instr_reverse_safe(instr, block) {
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if (!nir_can_move_instr(instr, options))
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continue;
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nir_ssa_def *def = nir_instr_ssa_def(instr);
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bool sink_out_of_loops =
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instr->type != nir_instr_type_intrinsic ||
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can_sink_out_of_loop(nir_instr_as_intrinsic(instr));
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nir_block *use_block =
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get_preferred_block(def, sink_out_of_loops);
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if (!use_block || use_block == instr->block)
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continue;
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nir_instr_remove(instr);
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nir_instr_insert(nir_after_phis(use_block), instr);
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progress = true;
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}
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}
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nir_metadata_preserve(function->impl,
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nir_metadata_block_index | nir_metadata_dominance);
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}
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return progress;
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}
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