From 7972e74f40f7e69085f551c200b3fd30bd97c9fe Mon Sep 17 00:00:00 2001 From: Alyssa Rosenzweig Date: Sat, 19 Jun 2021 13:48:03 -0400 Subject: [PATCH] agx: Add liveness analysis pass Based on the Panfrost one, scalarized and with some silly things fixed. Signed-off-by: Alyssa Rosenzweig Part-of: --- src/asahi/compiler/agx_compiler.h | 9 +++ src/asahi/compiler/agx_liveness.c | 135 ++++++++++++++++++++++++++++++++++++++ src/asahi/compiler/meson.build | 1 + 3 files changed, 145 insertions(+) create mode 100644 src/asahi/compiler/agx_liveness.c diff --git a/src/asahi/compiler/agx_compiler.h b/src/asahi/compiler/agx_compiler.h index f261c42..5a396b1 100644 --- a/src/asahi/compiler/agx_compiler.h +++ b/src/asahi/compiler/agx_compiler.h @@ -322,6 +322,9 @@ typedef struct agx_block { /* Offset of the block in the emitted binary */ off_t offset; + + /** Available for passes to use for metadata */ + uint8_t pass_flags; } agx_block; typedef struct { @@ -346,6 +349,9 @@ typedef struct { /* Has r0l been zeroed yet due to control flow? */ bool any_cf; + /** Computed metadata */ + bool has_liveness; + /* Number of nested control flow structures within the innermost loop. Since * NIR is just loop and if-else, this is the number of nested if-else * statements in the loop */ @@ -602,4 +608,7 @@ void agx_dce(agx_context *ctx); void agx_ra(agx_context *ctx); void agx_pack_binary(agx_context *ctx, struct util_dynarray *emission); +void agx_compute_liveness(agx_context *ctx); +void agx_liveness_ins_update(BITSET_WORD *live, agx_instr *I); + #endif diff --git a/src/asahi/compiler/agx_liveness.c b/src/asahi/compiler/agx_liveness.c new file mode 100644 index 0000000..d309b0c --- /dev/null +++ b/src/asahi/compiler/agx_liveness.c @@ -0,0 +1,135 @@ +/* + * Copyright (C) 2021 Alyssa Rosenzweig + * 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 "agx_compiler.h" +#include "util/u_memory.h" +#include "util/list.h" +#include "util/set.h" + +/* 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. */ + +/* live_in[s] = GEN[s] + (live_out[s] - KILL[s]) */ + +void +agx_liveness_ins_update(BITSET_WORD *live, agx_instr *I) +{ + agx_foreach_dest(I, d) { + if (I->dest[d].type == AGX_INDEX_NORMAL) + BITSET_CLEAR(live, I->dest[d].value); + } + + agx_foreach_src(I, s) { + if (I->src[s].type == AGX_INDEX_NORMAL) + BITSET_SET(live, I->src[s].value); + } +} + +static bool +liveness_block_update(agx_block *blk, unsigned words) +{ + bool progress = false; + + /* live_out[s] = sum { p in succ[s] } ( live_in[p] ) */ + agx_foreach_successor(blk, succ) { + for (unsigned i = 0; i < words; ++i) + blk->live_out[i] |= succ->live_in[i]; + } + + /* live_in is live_out after iteration */ + BITSET_WORD *live = ralloc_array(blk, BITSET_WORD, words); + memcpy(live, blk->live_out, words * sizeof(BITSET_WORD)); + + agx_foreach_instr_in_block_rev(blk, I) + agx_liveness_ins_update(live, I); + + /* To figure out progress, diff live_in */ + for (unsigned i = 0; i < words; ++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 +agx_compute_liveness(agx_context *ctx) +{ + if (ctx->has_liveness) + return; + + /* Set of agx_block */ + struct set *work_list = _mesa_set_create(NULL, _mesa_hash_pointer, + _mesa_key_pointer_equal); + + /* Free any previous liveness, and allocate */ + unsigned words = BITSET_WORDS(ctx->alloc); + + agx_foreach_block(ctx, block) { + if (block->live_in) + ralloc_free(block->live_in); + + if (block->live_out) + ralloc_free(block->live_out); + + block->pass_flags = false; + block->live_in = rzalloc_array(block, BITSET_WORD, words); + block->live_out = rzalloc_array(block, BITSET_WORD, words); + } + + /* Initialize the work list with the exit block */ + struct set_entry *cur = _mesa_set_add(work_list, agx_exit_block(ctx)); + + /* Iterate the work list */ + do { + /* Pop off a block */ + agx_block *blk = (struct agx_block *) cur->key; + _mesa_set_remove(work_list, cur); + + /* Update its liveness information */ + bool progress = liveness_block_update(blk, words); + + /* If we made progress, we need to process the predecessors */ + + if (progress || !blk->pass_flags) { + agx_foreach_predecessor(blk, pred) + _mesa_set_add(work_list, pred); + } + + /* Use pass flags to communicate that we've visited this block */ + blk->pass_flags = true; + } while((cur = _mesa_set_next_entry(work_list, NULL)) != NULL); + + _mesa_set_destroy(work_list, NULL); + + ctx->has_liveness = true; +} diff --git a/src/asahi/compiler/meson.build b/src/asahi/compiler/meson.build index a023dfa..bce79d7 100644 --- a/src/asahi/compiler/meson.build +++ b/src/asahi/compiler/meson.build @@ -22,6 +22,7 @@ libasahi_agx_files = files( 'agx_compile.c', 'agx_dce.c', + 'agx_liveness.c', 'agx_pack.c', 'agx_print.c', 'agx_optimizer.c', -- 2.7.4