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