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123 lines
4.5 KiB
123 lines
4.5 KiB
/******************************************************************************
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* Copyright (C) 2020-2021 Dibyendu Majumdar
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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******************************************************************************/
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/*
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* Calculate variable liveness
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* This will use the Dataflow Framework.
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* Implementation inspired by one in MIR
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*/
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#include "bitset.h"
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#include "dataflow_framework.h"
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#include "linearizer.h"
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#include <allocate.h>
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struct liveness_info {
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nodeId_t node_id;
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BitSet in;
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BitSet out;
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BitSet use;
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BitSet def;
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};
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DECLARE_ARRAY(liveness_info_array, struct liveness_info *);
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struct liveness_data {
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Proc *proc;
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struct liveness_info_array lives;
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};
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static void init_liveness_data(Proc *proc, struct liveness_data *liveness_data)
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{
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memset(liveness_data, 0, sizeof(*liveness_data));
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for (unsigned i = 0; i < proc->node_count; i++) {
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struct liveness_info *liveness_info = (struct liveness_info *)raviX_calloc(1, sizeof(struct liveness_info));
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liveness_info->node_id = i;
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raviX_bitset_create(&liveness_info->use);
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raviX_bitset_create(&liveness_info->def);
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raviX_bitset_create(&liveness_info->in);
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raviX_bitset_create(&liveness_info->out);
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array_push(&liveness_data->lives, struct liveness_info *, liveness_info);
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}
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}
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static void destroy_liveness_data(struct liveness_data *liveness_data)
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{
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for (unsigned i = 0; i < liveness_data->lives.count; i++) {
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raviX_bitset_create(&liveness_data->lives.data[i]->use);
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raviX_bitset_create(&liveness_data->lives.data[i]->def);
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raviX_bitset_create(&liveness_data->lives.data[i]->in);
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raviX_bitset_create(&liveness_data->lives.data[i]->out);
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}
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array_clearmem(&liveness_data->lives);
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}
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static inline struct liveness_info *get_liveness_info(struct liveness_data *liveness_data, nodeId_t id)
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{
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return liveness_data->lives.data[id];
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}
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/* Life analysis */
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static int live_join_func(void *userdata, nodeId_t id, bool init)
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{
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struct liveness_data *liveness_data = (struct liveness_data *)userdata;
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struct liveness_info *liveness_info = get_liveness_info(liveness_data, id);
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if (init) {
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raviX_bitset_clear(&liveness_info->in);
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return 0;
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} else {
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GraphNodeList *successors = raviX_successors(raviX_graph_node(liveness_data->proc->cfg, id));
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int changed = 0;
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// out[n] = Union of in[s] where s in succ[n]
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for (unsigned i = 0; i < raviX_node_list_size(successors); i++) {
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nodeId_t succ_id = raviX_node_list_at(successors, i);
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struct liveness_info *successor_liveness_info = get_liveness_info(liveness_data, succ_id);
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changed |=
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raviX_bitset_ior(&liveness_info->out, &liveness_info->out, &successor_liveness_info->in);
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}
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return changed;
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}
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}
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static int live_transfer_func(void *userdata, nodeId_t id)
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{
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struct liveness_data *liveness_data = (struct liveness_data *)userdata;
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struct liveness_info *liveness_info = get_liveness_info(liveness_data, id);
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// out[n] = use[n] U (out[n] - def[n])
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// In bitset terms out[n] = use[n] | (out[n] & ~def[n])
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return raviX_bitset_ior_and_compl(&liveness_info->in, &liveness_info->use, &liveness_info->out,
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&liveness_info->def);
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}
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// TODO
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// Compute use/def sets of each node
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// If a reg appears as the target of an instruction that's a def
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// If a reg is used as operand then its a use
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// Need to handle ranges / var args too
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// Or should we restrict analysis to certain types of regs?
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// Right now we have disjoint sets for temps / locals - to do this efficiently we need a merged set of regs for each proc
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// Liveness analysis is a backward data flow problem
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// see calculate_func_cfg_live_info in mir_genc.c
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