/*
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* Copyright © 2014 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 vc4_opt_vpm.c
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*
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* This modifies instructions that exclusively consume a value read from the
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* VPM to directly read the VPM if other operands allow it.
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*/
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#include "vc4_qir.h"
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bool
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qir_opt_vpm(struct vc4_compile *c)
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{
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if (c->stage == QSTAGE_FRAG)
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return false;
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/* For now, only do this pass when we don't have control flow. */
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struct qblock *block = qir_entry_block(c);
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if (block != qir_exit_block(c))
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return false;
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bool progress = false;
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uint32_t use_count[c->num_temps];
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memset(&use_count, 0, sizeof(use_count));
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qir_for_each_inst_inorder(inst, c) {
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for (int i = 0; i < qir_get_nsrc(inst); i++) {
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if (inst->src[i].file == QFILE_TEMP) {
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uint32_t temp = inst->src[i].index;
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use_count[temp]++;
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}
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}
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}
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/* For instructions reading from a temporary that contains a VPM read
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* result, try to move the instruction up in place of the VPM read.
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*/
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qir_for_each_inst_inorder(inst, c) {
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if (!inst)
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continue;
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if (qir_depends_on_flags(inst) || inst->sf)
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continue;
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if (qir_has_side_effects(c, inst) ||
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qir_has_side_effect_reads(c, inst) ||
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qir_is_tex(inst))
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continue;
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for (int j = 0; j < qir_get_nsrc(inst); j++) {
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if (inst->src[j].file != QFILE_TEMP ||
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inst->src[j].pack)
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continue;
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uint32_t temp = inst->src[j].index;
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/* Since VPM reads pull from a FIFO, we only get to
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* read each VPM entry once (unless we reset the read
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* pointer). That means we can't copy-propagate a VPM
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* read to multiple locations.
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*/
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if (use_count[temp] != 1)
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continue;
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struct qinst *mov = c->defs[temp];
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if (!mov ||
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(mov->op != QOP_MOV &&
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mov->op != QOP_FMOV &&
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mov->op != QOP_MMOV) ||
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mov->src[0].file != QFILE_VPM) {
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continue;
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}
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uint32_t temps = 0;
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for (int k = 0; k < qir_get_nsrc(inst); k++) {
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if (inst->src[k].file == QFILE_TEMP)
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temps++;
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}
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/* The instruction is safe to reorder if its other
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* sources are independent of previous instructions
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*/
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if (temps == 1) {
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inst->src[j] = mov->src[0];
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list_del(&inst->link);
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list_addtail(&inst->link, &mov->link);
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qir_remove_instruction(c, mov);
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progress = true;
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break;
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}
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}
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}
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return progress;
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}
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