/* * Copyright © 2012 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. */ #include "brw_fs.h" #include "brw_cfg.h" /** @file brw_fs_cse.cpp * * Support for local common subexpression elimination. * * See Muchnick's Advanced Compiler Design and Implementation, section * 13.1 (p378). */ namespace { struct aeb_entry : public exec_node { /** The instruction that generates the expression value. */ fs_inst *generator; /** The temporary where the value is stored. */ fs_reg tmp; }; } static bool is_copy_payload(const fs_inst *inst) { const int reg = inst->src[0].reg; if (inst->src[0].reg_offset != 0) return false; for (int i = 1; i < inst->sources; i++) { if (inst->src[i].reg != reg || inst->src[i].reg_offset != i) { return false; } } return true; } static bool is_expression(const fs_inst *const inst) { switch (inst->opcode) { case BRW_OPCODE_SEL: case BRW_OPCODE_NOT: case BRW_OPCODE_AND: case BRW_OPCODE_OR: case BRW_OPCODE_XOR: case BRW_OPCODE_SHR: case BRW_OPCODE_SHL: case BRW_OPCODE_ASR: case BRW_OPCODE_CMP: case BRW_OPCODE_CMPN: case BRW_OPCODE_ADD: case BRW_OPCODE_MUL: case BRW_OPCODE_FRC: case BRW_OPCODE_RNDU: case BRW_OPCODE_RNDD: case BRW_OPCODE_RNDE: case BRW_OPCODE_RNDZ: case BRW_OPCODE_LINE: case BRW_OPCODE_PLN: case BRW_OPCODE_MAD: case BRW_OPCODE_LRP: case FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD: case FS_OPCODE_VARYING_PULL_CONSTANT_LOAD_GEN7: case FS_OPCODE_VARYING_PULL_CONSTANT_LOAD: case FS_OPCODE_CINTERP: case FS_OPCODE_LINTERP: return true; case SHADER_OPCODE_RCP: case SHADER_OPCODE_RSQ: case SHADER_OPCODE_SQRT: case SHADER_OPCODE_EXP2: case SHADER_OPCODE_LOG2: case SHADER_OPCODE_POW: case SHADER_OPCODE_INT_QUOTIENT: case SHADER_OPCODE_INT_REMAINDER: case SHADER_OPCODE_SIN: case SHADER_OPCODE_COS: return inst->mlen < 2; case SHADER_OPCODE_LOAD_PAYLOAD: return !is_copy_payload(inst); default: return inst->is_send_from_grf() && !inst->has_side_effects(); } } static bool is_expression_commutative(enum opcode op) { switch (op) { case BRW_OPCODE_AND: case BRW_OPCODE_OR: case BRW_OPCODE_XOR: case BRW_OPCODE_ADD: case BRW_OPCODE_MUL: return true; default: return false; } } static bool operands_match(fs_inst *a, fs_inst *b) { fs_reg *xs = a->src; fs_reg *ys = b->src; if (a->opcode == BRW_OPCODE_MAD) { return xs[0].equals(ys[0]) && ((xs[1].equals(ys[1]) && xs[2].equals(ys[2])) || (xs[2].equals(ys[1]) && xs[1].equals(ys[2]))); } else if (!is_expression_commutative(a->opcode)) { bool match = true; for (int i = 0; i < a->sources; i++) { if (!xs[i].equals(ys[i])) { match = false; break; } } return match; } else { return (xs[0].equals(ys[0]) && xs[1].equals(ys[1])) || (xs[1].equals(ys[0]) && xs[0].equals(ys[1])); } } static bool instructions_match(fs_inst *a, fs_inst *b) { return a->opcode == b->opcode && a->saturate == b->saturate && a->predicate == b->predicate && a->predicate_inverse == b->predicate_inverse && a->conditional_mod == b->conditional_mod && a->dst.type == b->dst.type && a->sources == b->sources && (a->is_tex() ? (a->texture_offset == b->texture_offset && a->mlen == b->mlen && a->regs_written == b->regs_written && a->base_mrf == b->base_mrf && a->eot == b->eot && a->header_present == b->header_present && a->shadow_compare == b->shadow_compare) : true) && operands_match(a, b); } bool fs_visitor::opt_cse_local(bblock_t *block) { bool progress = false; exec_list aeb; void *cse_ctx = ralloc_context(NULL); int ip = block->start_ip; foreach_inst_in_block(fs_inst, inst, block) { /* Skip some cases. */ if (is_expression(inst) && !inst->is_partial_write() && (inst->dst.file != HW_REG || inst->dst.is_null())) { bool found = false; foreach_in_list_use_after(aeb_entry, entry, &aeb) { /* Match current instruction's expression against those in AEB. */ if (instructions_match(inst, entry->generator)) { found = true; progress = true; break; } } if (!found) { /* Our first sighting of this expression. Create an entry. */ aeb_entry *entry = ralloc(cse_ctx, aeb_entry); entry->tmp = reg_undef; entry->generator = inst; aeb.push_tail(entry); } else { /* This is at least our second sighting of this expression. * If we don't have a temporary already, make one. */ bool no_existing_temp = entry->tmp.file == BAD_FILE; if (no_existing_temp && !entry->generator->dst.is_null()) { int written = entry->generator->regs_written; int dst_width = entry->generator->dst.width / 8; assert(written % dst_width == 0); fs_reg orig_dst = entry->generator->dst; fs_reg tmp = fs_reg(GRF, virtual_grf_alloc(written), orig_dst.type, orig_dst.width); entry->tmp = tmp; entry->generator->dst = tmp; fs_inst *copy; if (written > dst_width) { fs_reg *sources = ralloc_array(mem_ctx, fs_reg, written / dst_width); for (int i = 0; i < written / dst_width; i++) sources[i] = offset(tmp, i); copy = LOAD_PAYLOAD(orig_dst, sources, written / dst_width); } else { copy = MOV(orig_dst, tmp); copy->force_writemask_all = entry->generator->force_writemask_all; } entry->generator->insert_after(block, copy); } /* dest <- temp */ if (!inst->dst.is_null()) { int written = inst->regs_written; int dst_width = inst->dst.width / 8; assert(written == entry->generator->regs_written); assert(dst_width == entry->generator->dst.width / 8); assert(inst->dst.type == entry->tmp.type); fs_reg dst = inst->dst; fs_reg tmp = entry->tmp; fs_inst *copy; if (written > dst_width) { fs_reg *sources = ralloc_array(mem_ctx, fs_reg, written / dst_width); for (int i = 0; i < written / dst_width; i++) sources[i] = offset(tmp, i); copy = LOAD_PAYLOAD(dst, sources, written / dst_width); } else { copy = MOV(dst, tmp); copy->force_writemask_all = inst->force_writemask_all; } inst->insert_before(block, copy); } /* Set our iterator so that next time through the loop inst->next * will get the instruction in the basic block after the one we've * removed. */ fs_inst *prev = (fs_inst *)inst->prev; inst->remove(block); inst = prev; } } foreach_in_list_safe(aeb_entry, entry, &aeb) { /* Kill all AEB entries that write a different value to or read from * the flag register if we just wrote it. */ if (inst->writes_flag()) { if (entry->generator->reads_flag() || (entry->generator->writes_flag() && !instructions_match(inst, entry->generator))) { entry->remove(); ralloc_free(entry); continue; } } for (int i = 0; i < entry->generator->sources; i++) { fs_reg *src_reg = &entry->generator->src[i]; /* Kill all AEB entries that use the destination we just * overwrote. */ if (inst->overwrites_reg(entry->generator->src[i])) { entry->remove(); ralloc_free(entry); break; } /* Kill any AEB entries using registers that don't get reused any * more -- a sure sign they'll fail operands_match(). */ if (src_reg->file == GRF && virtual_grf_end[src_reg->reg] < ip) { entry->remove(); ralloc_free(entry); break; } } } ip++; } ralloc_free(cse_ctx); return progress; } bool fs_visitor::opt_cse() { bool progress = false; calculate_live_intervals(); foreach_block (block, cfg) { progress = opt_cse_local(block) || progress; } if (progress) invalidate_live_intervals(); return progress; }