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/*
* Copyright (C) 2019-2020 Collabora, Ltd.
*
* 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.
*/
#include "pan_ir.h"
#include "util/u_memory.h"
#include "util/list.h"
#include "util/set.h"
/* Routines for liveness analysis. Liveness is tracked per byte per node. Per
* byte granularity is necessary for proper handling of int8 */
void
pan_liveness_gen(uint16_t *live, unsigned node, unsigned max, uint16_t mask)
{
if (node >= max)
return;
live[node] |= mask;
}
void
pan_liveness_kill(uint16_t *live, unsigned node, unsigned max, uint16_t mask)
{
if (node >= max)
return;
live[node] &= ~mask;
}
bool
pan_liveness_get(uint16_t *live, unsigned node, uint16_t max)
{
if (node >= max)
return false;
return live[node];
}
/* live_out[s] = sum { p in succ[s] } ( live_in[p] ) */
static void
liveness_block_live_out(pan_block *blk, unsigned temp_count)
{
pan_foreach_successor(blk, succ) {
for (unsigned i = 0; i < temp_count; ++i)
blk->live_out[i] |= succ->live_in[i];
}
}
/* Liveness analysis is a backwards-may dataflow analysis pass. Within a block,
* we compute live_out from live_in. The intrablock pass is linear-time. It
* returns whether progress was made. */
static bool
liveness_block_update(
pan_block *blk, unsigned temp_count,
pan_liveness_update callback)
{
bool progress = false;
liveness_block_live_out(blk, temp_count);
uint16_t *live = ralloc_array(blk, uint16_t, temp_count);
memcpy(live, blk->live_out, temp_count * sizeof(uint16_t));
pan_foreach_instr_in_block_rev(blk, ins)
callback(live, (void *) ins, temp_count);
/* To figure out progress, diff live_in */
for (unsigned i = 0; (i < temp_count) && !progress; ++i)
progress |= (blk->live_in[i] != live[i]);
ralloc_free(blk->live_in);
blk->live_in = live;
return progress;
}
/* Globally, liveness analysis uses a fixed-point algorithm based on a
* worklist. We initialize a work list with the exit block. We iterate the work
* list to compute live_in from live_out for each block on the work list,
* adding the predecessors of the block to the work list if we made progress.
*/
void
pan_compute_liveness(
struct list_head *blocks,
unsigned temp_count,
pan_liveness_update callback)
{
/* Set of pan_block */
struct set *work_list = _mesa_set_create(NULL,
_mesa_hash_pointer,
_mesa_key_pointer_equal);
struct set *visited = _mesa_set_create(NULL,
_mesa_hash_pointer,
_mesa_key_pointer_equal);
/* Allocate */
list_for_each_entry(pan_block, block, blocks, link) {
block->live_in = rzalloc_array(NULL, uint16_t, temp_count);
block->live_out = rzalloc_array(NULL, uint16_t, temp_count);
}
/* Initialize the work list with the exit block */
struct set_entry *cur;
cur = _mesa_set_add(work_list, pan_exit_block(blocks));
/* Iterate the work list */
do {
/* Pop off a block */
pan_block *blk = (struct pan_block *) cur->key;
_mesa_set_remove(work_list, cur);
/* Update its liveness information */
bool progress = liveness_block_update(blk, temp_count, callback);
/* If we made progress, we need to process the predecessors */
if (progress || !_mesa_set_search(visited, blk)) {
pan_foreach_predecessor(blk, pred)
_mesa_set_add(work_list, pred);
}
_mesa_set_add(visited, blk);
} while((cur = _mesa_set_next_entry(work_list, NULL)) != NULL);
_mesa_set_destroy(visited, NULL);
_mesa_set_destroy(work_list, NULL);
}
void
pan_free_liveness(struct list_head *blocks)
{
list_for_each_entry(pan_block, block, blocks, link) {
if (block->live_in)
ralloc_free(block->live_in);
if (block->live_out)
ralloc_free(block->live_out);
block->live_in = NULL;
block->live_out = NULL;
}
}
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