| /* |
| * Copyright (C) 2018-2019 Alyssa Rosenzweig <alyssa@rosenzweig.io> |
| * |
| * 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 "compiler.h" |
| #include "util/u_memory.h" |
| |
| /* Routines for liveness analysis. Liveness is tracked per byte per node. Per |
| * byte granularity is necessary for proper handling of int8 */ |
| |
| static void |
| liveness_gen(uint16_t *live, unsigned node, unsigned max, uint16_t mask) |
| { |
| if (node >= max) |
| return; |
| |
| live[node] |= mask; |
| } |
| |
| static void |
| liveness_kill(uint16_t *live, unsigned node, unsigned max, uint16_t mask) |
| { |
| if (node >= max) |
| return; |
| |
| live[node] &= ~mask; |
| } |
| |
| static bool |
| liveness_get(uint16_t *live, unsigned node, uint16_t max) { |
| if (node >= max) |
| return false; |
| |
| return live[node]; |
| } |
| |
| /* Updates live_in for a single instruction */ |
| |
| void |
| mir_liveness_ins_update(uint16_t *live, midgard_instruction *ins, unsigned max) |
| { |
| /* live_in[s] = GEN[s] + (live_out[s] - KILL[s]) */ |
| |
| liveness_kill(live, ins->dest, max, mir_bytemask(ins)); |
| |
| mir_foreach_src(ins, src) { |
| unsigned node = ins->src[src]; |
| unsigned bytemask = mir_bytemask_of_read_components(ins, node); |
| |
| liveness_gen(live, node, max, bytemask); |
| } |
| } |
| |
| /* live_out[s] = sum { p in succ[s] } ( live_in[p] ) */ |
| |
| static void |
| liveness_block_live_out(compiler_context *ctx, midgard_block *blk) |
| { |
| mir_foreach_successor(blk, succ) { |
| for (unsigned i = 0; i < ctx->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(compiler_context *ctx, midgard_block *blk) |
| { |
| bool progress = false; |
| |
| liveness_block_live_out(ctx, blk); |
| |
| uint16_t *live = ralloc_array(ctx, uint16_t, ctx->temp_count); |
| memcpy(live, blk->live_out, ctx->temp_count * sizeof(uint16_t)); |
| |
| mir_foreach_instr_in_block_rev(blk, ins) |
| mir_liveness_ins_update(live, ins, ctx->temp_count); |
| |
| /* To figure out progress, diff live_in */ |
| |
| for (unsigned i = 0; (i < ctx->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 |
| mir_compute_liveness(compiler_context *ctx) |
| { |
| /* If we already have fresh liveness, nothing to do */ |
| if (ctx->metadata & MIDGARD_METADATA_LIVENESS) |
| return; |
| |
| mir_compute_temp_count(ctx); |
| |
| /* List of midgard_block */ |
| struct set *work_list = _mesa_set_create(ctx, |
| _mesa_hash_pointer, |
| _mesa_key_pointer_equal); |
| |
| /* Allocate */ |
| |
| mir_foreach_block(ctx, block) { |
| block->live_in = rzalloc_array(ctx, uint16_t, ctx->temp_count); |
| block->live_out = rzalloc_array(ctx, uint16_t, ctx->temp_count); |
| } |
| |
| /* Initialize the work list with the exit block */ |
| struct set_entry *cur; |
| |
| midgard_block *exit = mir_exit_block(ctx); |
| cur = _mesa_set_add(work_list, exit); |
| |
| /* Iterate the work list */ |
| |
| do { |
| /* Pop off a block */ |
| midgard_block *blk = (struct midgard_block *) cur->key; |
| _mesa_set_remove(work_list, cur); |
| |
| /* Update its liveness information */ |
| bool progress = liveness_block_update(ctx, blk); |
| |
| /* If we made progress, we need to process the predecessors */ |
| |
| if (progress || !blk->visited) { |
| mir_foreach_predecessor(blk, pred) |
| _mesa_set_add(work_list, pred); |
| } |
| |
| blk->visited = true; |
| } while((cur = _mesa_set_next_entry(work_list, NULL)) != NULL); |
| |
| /* Liveness is now valid */ |
| ctx->metadata |= MIDGARD_METADATA_LIVENESS; |
| |
| mir_foreach_block(ctx, block) { |
| block->visited = false; |
| } |
| } |
| |
| /* Once liveness data is no longer valid, call this */ |
| |
| void |
| mir_invalidate_liveness(compiler_context *ctx) |
| { |
| /* If we didn't already compute liveness, there's nothing to do */ |
| if (!(ctx->metadata & MIDGARD_METADATA_LIVENESS)) |
| return; |
| |
| /* It's now invalid regardless */ |
| ctx->metadata &= ~MIDGARD_METADATA_LIVENESS; |
| |
| mir_foreach_block(ctx, block) { |
| 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; |
| } |
| } |
| |
| bool |
| mir_is_live_after(compiler_context *ctx, midgard_block *block, midgard_instruction *start, int src) |
| { |
| mir_compute_liveness(ctx); |
| |
| /* Check whether we're live in the successors */ |
| |
| if (liveness_get(block->live_out, src, ctx->temp_count)) |
| return true; |
| |
| /* Check the rest of the block for liveness */ |
| |
| mir_foreach_instr_in_block_from(block, ins, mir_next_op(start)) { |
| if (mir_has_arg(ins, src)) |
| return true; |
| } |
| |
| return false; |
| } |
