| /* |
| * Copyright © 2015 Broadcom |
| * |
| * 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. |
| */ |
| |
| #include "nir.h" |
| #include "nir_builder.h" |
| |
| /** @file nir_opt_undef.c |
| * |
| * Handles optimization of operations involving ssa_undef. |
| */ |
| |
| /** |
| * Turn conditional selects between an undef and some other value into a move |
| * of that other value (on the assumption that the condition's going to be |
| * choosing the defined value). This reduces work after if flattening when |
| * each side of the if is defining a variable. |
| */ |
| static bool |
| opt_undef_csel(nir_alu_instr *instr) |
| { |
| if (instr->op != nir_op_bcsel && instr->op != nir_op_fcsel) |
| return false; |
| |
| assert(instr->dest.dest.is_ssa); |
| |
| for (int i = 1; i <= 2; i++) { |
| if (!instr->src[i].src.is_ssa) |
| continue; |
| |
| nir_instr *parent = instr->src[i].src.ssa->parent_instr; |
| if (parent->type != nir_instr_type_ssa_undef) |
| continue; |
| |
| /* We can't just use nir_alu_src_copy, because we need the def/use |
| * updated. |
| */ |
| nir_instr_rewrite_src(&instr->instr, &instr->src[0].src, |
| instr->src[i == 1 ? 2 : 1].src); |
| nir_alu_src_copy(&instr->src[0], &instr->src[i == 1 ? 2 : 1], |
| ralloc_parent(instr)); |
| |
| nir_src empty_src; |
| memset(&empty_src, 0, sizeof(empty_src)); |
| nir_instr_rewrite_src(&instr->instr, &instr->src[1].src, empty_src); |
| nir_instr_rewrite_src(&instr->instr, &instr->src[2].src, empty_src); |
| instr->op = nir_op_mov; |
| |
| return true; |
| } |
| |
| return false; |
| } |
| |
| /** |
| * Replace vecN(undef, undef, ...) with a single undef. |
| */ |
| static bool |
| opt_undef_vecN(nir_builder *b, nir_alu_instr *alu) |
| { |
| if (!nir_op_is_vec(alu->op)) |
| return false; |
| |
| assert(alu->dest.dest.is_ssa); |
| |
| for (unsigned i = 0; i < nir_op_infos[alu->op].num_inputs; i++) { |
| if (!alu->src[i].src.is_ssa || |
| alu->src[i].src.ssa->parent_instr->type != nir_instr_type_ssa_undef) |
| return false; |
| } |
| |
| b->cursor = nir_before_instr(&alu->instr); |
| nir_ssa_def *undef = nir_ssa_undef(b, alu->dest.dest.ssa.num_components, |
| nir_dest_bit_size(alu->dest.dest)); |
| nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa, nir_src_for_ssa(undef)); |
| |
| return true; |
| } |
| |
| static uint32_t |
| nir_get_undef_mask(nir_ssa_def *def) |
| { |
| nir_instr *instr = def->parent_instr; |
| |
| if (instr->type == nir_instr_type_ssa_undef) |
| return BITSET_MASK(def->num_components); |
| |
| if (instr->type != nir_instr_type_alu) |
| return 0; |
| |
| nir_alu_instr *alu = nir_instr_as_alu(instr); |
| unsigned undef = 0; |
| |
| if (nir_op_is_vec(alu->op)) { |
| for (int i = 0; i < nir_op_infos[alu->op].num_inputs; i++) { |
| if (alu->src[i].src.is_ssa && |
| alu->src[i].src.ssa->parent_instr->type == |
| nir_instr_type_ssa_undef) { |
| undef |= BITSET_MASK(nir_ssa_alu_instr_src_components(alu, i)) << i; |
| } |
| } |
| } |
| |
| return undef; |
| } |
| |
| /** |
| * Remove any store intrinsic writemask channels whose value is undefined (the |
| * existing value is a fine representation of "undefined"). |
| */ |
| static bool |
| opt_undef_store(nir_intrinsic_instr *intrin) |
| { |
| int arg_index; |
| switch (intrin->intrinsic) { |
| case nir_intrinsic_store_deref: |
| arg_index = 1; |
| break; |
| case nir_intrinsic_store_output: |
| case nir_intrinsic_store_per_vertex_output: |
| case nir_intrinsic_store_ssbo: |
| case nir_intrinsic_store_shared: |
| case nir_intrinsic_store_global: |
| case nir_intrinsic_store_scratch: |
| arg_index = 0; |
| break; |
| default: |
| return false; |
| } |
| |
| if (!intrin->src[arg_index].is_ssa) |
| return false; |
| |
| nir_ssa_def *def = intrin->src[arg_index].ssa; |
| |
| unsigned write_mask = nir_intrinsic_write_mask(intrin); |
| unsigned undef_mask = nir_get_undef_mask(def); |
| |
| if (!(write_mask & undef_mask)) |
| return false; |
| |
| write_mask &= ~undef_mask; |
| if (!write_mask) |
| nir_instr_remove(&intrin->instr); |
| else |
| nir_intrinsic_set_write_mask(intrin, write_mask); |
| |
| return true; |
| } |
| |
| static bool |
| nir_opt_undef_instr(nir_builder *b, nir_instr *instr, void *data) |
| { |
| if (instr->type == nir_instr_type_alu) { |
| nir_alu_instr *alu = nir_instr_as_alu(instr); |
| return opt_undef_csel(alu) || opt_undef_vecN(b, alu); |
| } else if (instr->type == nir_instr_type_intrinsic) { |
| nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); |
| return opt_undef_store(intrin); |
| } |
| |
| return false; |
| } |
| |
| bool |
| nir_opt_undef(nir_shader *shader) |
| { |
| return nir_shader_instructions_pass(shader, |
| nir_opt_undef_instr, |
| nir_metadata_block_index | |
| nir_metadata_dominance, |
| NULL); |
| } |