/* * Copyright © 2015 Intel Corporation * * 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. * * Authors: * Jason Ekstrand */ #include "brw_nir.h" /* * This file implements an analysis pass that determines when we have to do * a boolean resolve on Gen <= 5. Instructions that need a boolean resolve * will have the booleans portion of the instr->pass_flags field set to * BRW_NIR_BOOLEAN_NEEDS_RESOLVE. */ /** Returns the resolve status for the given source * * If the source has a parent instruction then the resolve status is the * status of the parent instruction. If the source does not have a parent * instruction then we don't know so we return NON_BOOLEAN. */ static uint8_t get_resolve_status_for_src(nir_src *src) { if (src->is_ssa) { nir_instr *src_instr = src->ssa->parent_instr; uint8_t resolve_status = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK; /* If the source instruction needs resolve, then from the perspective * of the user, it's a true boolean. */ if (resolve_status == BRW_NIR_BOOLEAN_NEEDS_RESOLVE) resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE; return resolve_status; } else { return BRW_NIR_NON_BOOLEAN; } } /** Marks the given source as needing a resolve * * If the given source corresponds to an unresolved boolean it marks it as * needing a resolve. Otherwise, we leave it alone. */ static bool src_mark_needs_resolve(nir_src *src, void *void_state) { if (src->is_ssa) { nir_instr *src_instr = src->ssa->parent_instr; uint8_t resolve_status = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK; /* If the source instruction is unresolved, then mark it as needing * to be resolved. */ if (resolve_status == BRW_NIR_BOOLEAN_UNRESOLVED) { src_instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK; src_instr->pass_flags |= BRW_NIR_BOOLEAN_NEEDS_RESOLVE; } } return true; } static bool analyze_boolean_resolves_block(nir_block *block, void *void_state) { nir_foreach_instr(block, instr) { switch (instr->type) { case nir_instr_type_alu: { /* For ALU instructions, the resolve status is handled in a * three-step process. * * 1) Look at the instruction type and sources and determine if it * can be left unresolved. * * 2) Look at the destination and see if we have to resolve * anyway. (This is the case if this instruction is not the * only instruction writing to a given register.) * * 3) If the instruction has a resolve status other than * BOOL_UNRESOLVED or BOOL_NEEDS_RESOLVE then we walk through * the sources and ensure that they are also resolved. This * ensures that we don't end up with any stray unresolved * booleans going into ADDs or something like that. */ uint8_t resolve_status; nir_alu_instr *alu = nir_instr_as_alu(instr); switch (alu->op) { case nir_op_bany2: case nir_op_bany3: case nir_op_bany4: case nir_op_ball_fequal2: case nir_op_ball_iequal2: case nir_op_ball_fequal3: case nir_op_ball_iequal3: case nir_op_ball_fequal4: case nir_op_ball_iequal4: case nir_op_bany_fnequal2: case nir_op_bany_inequal2: case nir_op_bany_fnequal3: case nir_op_bany_inequal3: case nir_op_bany_fnequal4: case nir_op_bany_inequal4: /* These are only implemented by the vec4 backend and its * implementation emits resolved booleans. At some point in the * future, this may change and we'll have to remove some of the * above cases. */ resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE; break; case nir_op_imov: case nir_op_inot: /* This is a single-source instruction. Just copy the resolve * status from the source. */ resolve_status = get_resolve_status_for_src(&alu->src[0].src); break; case nir_op_iand: case nir_op_ior: case nir_op_ixor: { uint8_t src0_status = get_resolve_status_for_src(&alu->src[0].src); uint8_t src1_status = get_resolve_status_for_src(&alu->src[1].src); if (src0_status == src1_status) { resolve_status = src0_status; } else if (src0_status == BRW_NIR_NON_BOOLEAN || src1_status == BRW_NIR_NON_BOOLEAN) { /* If one of the sources is a non-boolean then the whole * thing is a non-boolean. */ resolve_status = BRW_NIR_NON_BOOLEAN; } else { /* At this point one of them is a true boolean and one is a * boolean that needs a resolve. We could either resolve the * unresolved source or we could resolve here. If we resolve * the unresolved source then we get two resolves for the price * of one. Just set this one to BOOLEAN_NO_RESOLVE and we'll * let the code below force a resolve on the unresolved source. */ resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE; } break; } default: if (nir_op_infos[alu->op].output_type == nir_type_bool) { /* This instructions will turn into a CMP when we actually emit * them so the result will have to be resolved before it can be * used. */ resolve_status = BRW_NIR_BOOLEAN_UNRESOLVED; /* Even though the destination is allowed to be left * unresolved, the sources are treated as regular integers or * floats so they need to be resolved. */ nir_foreach_src(instr, src_mark_needs_resolve, NULL); } else { resolve_status = BRW_NIR_NON_BOOLEAN; } } /* If the destination is SSA, go ahead allow unresolved booleans. * If the destination register doesn't have a well-defined parent_instr * we need to resolve immediately. */ if (!alu->dest.dest.is_ssa && resolve_status == BRW_NIR_BOOLEAN_UNRESOLVED) { resolve_status = BRW_NIR_BOOLEAN_NEEDS_RESOLVE; } instr->pass_flags = (instr->pass_flags & ~BRW_NIR_BOOLEAN_MASK) | resolve_status; /* Finally, resolve sources if it's needed */ switch (resolve_status) { case BRW_NIR_BOOLEAN_NEEDS_RESOLVE: case BRW_NIR_BOOLEAN_UNRESOLVED: /* This instruction is either unresolved or we're doing the * resolve here; leave the sources alone. */ break; case BRW_NIR_BOOLEAN_NO_RESOLVE: case BRW_NIR_NON_BOOLEAN: nir_foreach_src(instr, src_mark_needs_resolve, NULL); break; default: unreachable("Invalid boolean flag"); } break; } case nir_instr_type_load_const: { nir_load_const_instr *load = nir_instr_as_load_const(instr); /* For load_const instructions, it's a boolean exactly when it holds * one of the values NIR_TRUE or NIR_FALSE. * * Since load_const instructions don't have any sources, we don't * have to worry about resolving them. */ instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK; if (load->value.u[0] == NIR_TRUE || load->value.u[0] == NIR_FALSE) { instr->pass_flags |= BRW_NIR_BOOLEAN_NO_RESOLVE; } else { instr->pass_flags |= BRW_NIR_NON_BOOLEAN; } continue; } default: /* Everything else is an unknown non-boolean value and needs to * have all sources resolved. */ instr->pass_flags = (instr->pass_flags & ~BRW_NIR_BOOLEAN_MASK) | BRW_NIR_NON_BOOLEAN; nir_foreach_src(instr, src_mark_needs_resolve, NULL); continue; } } nir_if *following_if = nir_block_get_following_if(block); if (following_if) src_mark_needs_resolve(&following_if->condition, NULL); return true; } static void analyze_boolean_resolves_impl(nir_function_impl *impl) { nir_foreach_block(impl, analyze_boolean_resolves_block, NULL); } void brw_nir_analyze_boolean_resolves(nir_shader *shader) { nir_foreach_overload(shader, overload) if (overload->impl) analyze_boolean_resolves_impl(overload->impl); }