Eric Anholt
72 lines
2.6 KiB
C
72 lines
2.6 KiB
C
/*
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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_dead_code.c
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*
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* This is a simmple dead code eliminator for QIR with no control flow.
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*
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* It walks from the bottom of the instruction list, removing instructions
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* with a destination that is never used, and marking the sources of non-dead
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* instructions as used.
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*/
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#include "vc4_qir.h"
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bool
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qir_opt_dead_code(struct vc4_compile *c)
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{
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bool progress = false;
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bool debug = false;
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bool *used = calloc(c->num_temps, sizeof(bool));
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struct simple_node *node, *t;
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for (node = c->instructions.prev, t = node->prev;
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&c->instructions != node;
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node = t, t = t->prev) {
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struct qinst *inst = (struct qinst *)node;
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if (inst->dst.file == QFILE_TEMP &&
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!used[inst->dst.index] &&
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!qir_has_side_effects(inst)) {
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if (debug) {
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fprintf(stderr, "Removing: ");
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qir_dump_inst(inst);
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fprintf(stderr, "\n");
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}
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qir_remove_instruction(inst);
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progress = true;
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continue;
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}
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for (int i = 0; i < qir_get_op_nsrc(inst->op); i++) {
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if (inst->src[i].file == QFILE_TEMP)
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used[inst->src[i].index] = true;
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}
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}
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free(used);
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return progress;
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}
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