150 lines
5.0 KiB
C
150 lines
5.0 KiB
C
/*
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* Copyright © 2019 Broadcom
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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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/**
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* @file v3d_opt_redundant_flags.c
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*
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* This eliminates the APF/MPF flags for redundant flags updates. These are
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* often produced by our channel masking in nonuniform control flow.
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*/
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#include "v3d_compiler.h"
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static bool debug;
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static void
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vir_dce_pf(struct v3d_compile *c, struct qinst *inst)
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{
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if (debug) {
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fprintf(stderr,
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"Removing flags write from: ");
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vir_dump_inst(c, inst);
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fprintf(stderr, "\n");
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}
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assert(inst->qpu.type == V3D_QPU_INSTR_TYPE_ALU);
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inst->qpu.flags.apf = V3D_QPU_PF_NONE;
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inst->qpu.flags.mpf = V3D_QPU_PF_NONE;
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}
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static bool
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vir_sources_modified(struct qinst *srcs, struct qinst *write)
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{
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for (int i = 0; i < vir_get_nsrc(srcs); i++) {
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if (write->dst.file == QFILE_TEMP &&
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srcs->src[i].file == QFILE_TEMP &&
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srcs->src[i].index == write->dst.index) {
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return true;
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}
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/* assume magic regs may be modified by basically anything. */
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if (srcs->src[i].file != QFILE_TEMP &&
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srcs->src[i].file != QFILE_SMALL_IMM)
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return true;
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}
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return false;
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}
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static bool
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vir_instr_flags_op_equal(struct qinst *a, struct qinst *b)
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{
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for (int i = 0; i < vir_get_nsrc(a); i++) {
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if (a->src[i].file != b->src[i].file ||
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a->src[i].index != b->src[i].index) {
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return false;
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}
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}
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if (a->qpu.flags.apf != b->qpu.flags.apf ||
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a->qpu.flags.mpf != b->qpu.flags.mpf ||
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a->qpu.alu.add.op != b->qpu.alu.add.op ||
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a->qpu.alu.mul.op != b->qpu.alu.mul.op ||
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a->qpu.alu.add.a_unpack != b->qpu.alu.add.a_unpack ||
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a->qpu.alu.add.b_unpack != b->qpu.alu.add.b_unpack ||
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a->qpu.alu.add.output_pack != b->qpu.alu.add.output_pack ||
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a->qpu.alu.mul.a_unpack != b->qpu.alu.mul.a_unpack ||
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a->qpu.alu.mul.b_unpack != b->qpu.alu.mul.b_unpack ||
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a->qpu.alu.mul.output_pack != b->qpu.alu.mul.output_pack) {
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return false;
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}
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return true;
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}
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static bool
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vir_opt_redundant_flags_block(struct v3d_compile *c, struct qblock *block)
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{
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struct qinst *last_flags = NULL;
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bool progress = false;
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c->cur_block = block;
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vir_for_each_inst(inst, block) {
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if (inst->qpu.type != V3D_QPU_INSTR_TYPE_ALU ||
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inst->qpu.flags.auf != V3D_QPU_UF_NONE ||
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inst->qpu.flags.muf != V3D_QPU_UF_NONE) {
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last_flags = NULL;
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continue;
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}
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/* Flags aren't preserved across a thrsw.
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*
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* In V3D 4.2+ flags are preserved across thread switches.
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*/
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if (c->devinfo->ver < 42) {
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if (inst->qpu.sig.thrsw)
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last_flags = NULL;
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}
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if (inst->qpu.flags.apf != V3D_QPU_PF_NONE ||
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inst->qpu.flags.mpf != V3D_QPU_PF_NONE) {
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if (last_flags &&
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vir_instr_flags_op_equal(inst, last_flags)) {
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vir_dce_pf(c, inst);
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progress = true;
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} else {
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last_flags = inst;
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}
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}
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if (last_flags && vir_sources_modified(last_flags, inst)) {
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last_flags = NULL;
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}
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}
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return progress;
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}
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bool
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vir_opt_redundant_flags(struct v3d_compile *c)
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{
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bool progress = false;
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vir_for_each_block(block, c) {
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progress = vir_opt_redundant_flags_block(c, block) || progress;
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}
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return progress;
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}
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