/* * 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). */ using namespace brw; 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_expression(const fs_visitor *v, const fs_inst *const inst) { switch (inst->opcode) { case BRW_OPCODE_MOV: 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: case SHADER_OPCODE_FIND_LIVE_CHANNEL: case SHADER_OPCODE_BROADCAST: 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 !inst->is_copy_payload(v->alloc); default: return inst->is_send_from_grf() && !inst->has_side_effects(); } } static bool operands_match(const fs_inst *a, const fs_inst *b, bool *negate) { 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 (a->opcode == BRW_OPCODE_MUL && a->dst.type == BRW_REGISTER_TYPE_F) { bool xs0_negate = xs[0].negate; bool xs1_negate = xs[1].file == IMM ? xs[1].fixed_hw_reg.dw1.f < 0.0f : xs[1].negate; bool ys0_negate = ys[0].negate; bool ys1_negate = ys[1].file == IMM ? ys[1].fixed_hw_reg.dw1.f < 0.0f : ys[1].negate; float xs1_imm = xs[1].fixed_hw_reg.dw1.f; float ys1_imm = ys[1].fixed_hw_reg.dw1.f; xs[0].negate = false; xs[1].negate = false; ys[0].negate = false; ys[1].negate = false; xs[1].fixed_hw_reg.dw1.f = fabsf(xs[1].fixed_hw_reg.dw1.f); ys[1].fixed_hw_reg.dw1.f = fabsf(ys[1].fixed_hw_reg.dw1.f); bool ret = (xs[0].equals(ys[0]) && xs[1].equals(ys[1])) || (xs[1].equals(ys[0]) && xs[0].equals(ys[1])); xs[0].negate = xs0_negate; xs[1].negate = xs[1].file == IMM ? false : xs1_negate; ys[0].negate = ys0_negate; ys[1].negate = ys[1].file == IMM ? false : ys1_negate; xs[1].fixed_hw_reg.dw1.f = xs1_imm; ys[1].fixed_hw_reg.dw1.f = ys1_imm; *negate = (xs0_negate != xs1_negate) != (ys0_negate != ys1_negate); return ret; } else if (!a->is_commutative()) { 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, bool *negate) { return a->opcode == b->opcode && a->force_writemask_all == b->force_writemask_all && a->exec_size == b->exec_size && a->force_sechalf == b->force_sechalf && a->saturate == b->saturate && a->predicate == b->predicate && a->predicate_inverse == b->predicate_inverse && a->conditional_mod == b->conditional_mod && a->flag_subreg == b->flag_subreg && a->dst.type == b->dst.type && a->offset == b->offset && a->mlen == b->mlen && a->regs_written == b->regs_written && a->base_mrf == b->base_mrf && a->eot == b->eot && a->header_size == b->header_size && a->shadow_compare == b->shadow_compare && a->pi_noperspective == b->pi_noperspective && a->sources == b->sources && operands_match(a, b, negate); } static void create_copy_instr(const fs_builder &bld, fs_inst *inst, fs_reg src, bool negate) { int written = inst->regs_written; int dst_width = inst->exec_size / 8; const fs_builder ubld = bld.exec_all(inst->force_writemask_all) .group(inst->exec_size, inst->force_sechalf); fs_inst *copy; if (written > dst_width) { fs_reg *payload; int sources, header_size; if (inst->opcode == SHADER_OPCODE_LOAD_PAYLOAD) { sources = inst->sources; header_size = inst->header_size; } else { assert(written % dst_width == 0); sources = written / dst_width; header_size = 0; } assert(src.file == GRF); payload = ralloc_array(bld.shader->mem_ctx, fs_reg, sources); for (int i = 0; i < header_size; i++) { payload[i] = src; src.reg_offset++; } for (int i = header_size; i < sources; i++) { payload[i] = src; src = offset(src, ubld, 1); } copy = ubld.LOAD_PAYLOAD(inst->dst, payload, sources, header_size); } else { copy = ubld.MOV(inst->dst, src); copy->src[0].negate = negate; } assert(copy->regs_written == written); } 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(this, inst) && !inst->is_partial_write() && (inst->dst.file != HW_REG || inst->dst.is_null())) { bool found = false; bool negate = false; foreach_in_list_use_after(aeb_entry, entry, &aeb) { /* Match current instruction's expression against those in AEB. */ if (!(entry->generator->dst.is_null() && !inst->dst.is_null()) && instructions_match(inst, entry->generator, &negate)) { found = true; progress = true; break; } } if (!found) { if (inst->opcode != BRW_OPCODE_MOV || (inst->opcode == BRW_OPCODE_MOV && inst->src[0].file == IMM && inst->src[0].type == BRW_REGISTER_TYPE_VF)) { /* 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; entry->tmp = fs_reg(GRF, alloc.allocate(written), entry->generator->dst.type); create_copy_instr(bld.at(block, entry->generator->next), entry->generator, entry->tmp, false); entry->generator->dst = entry->tmp; } /* dest <- temp */ if (!inst->dst.is_null()) { assert(inst->regs_written == entry->generator->regs_written); assert(inst->dst.type == entry->tmp.type); create_copy_instr(bld.at(block, inst), inst, entry->tmp, negate); } /* 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()) { bool negate; /* dummy */ if (entry->generator->reads_flag() || (entry->generator->writes_flag() && !instructions_match(inst, entry->generator, &negate))) { 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; }