From: Kenneth Graunke Date: Wed, 4 Nov 2015 01:16:49 +0000 (-0800) Subject: nir: Rename nir_live_variables.c to nir_liveness.c. X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b9f8e729c88ad0d934422976a20a7c765016fcb8;p=mesa.git nir: Rename nir_live_variables.c to nir_liveness.c. It doesn't actually operate on variables. Reviewed-by: Jason Ekstrand --- diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources index ca870367640..0266f290ccb 100644 --- a/src/glsl/Makefile.sources +++ b/src/glsl/Makefile.sources @@ -37,7 +37,7 @@ NIR_FILES = \ nir/nir_intrinsics.h \ nir/nir_instr_set.c \ nir/nir_instr_set.h \ - nir/nir_live_variables.c \ + nir/nir_liveness.c \ nir/nir_lower_alu_to_scalar.c \ nir/nir_lower_atomics.c \ nir/nir_lower_clip.c \ diff --git a/src/glsl/nir/nir_live_variables.c b/src/glsl/nir/nir_live_variables.c deleted file mode 100644 index 05f79d7bc61..00000000000 --- a/src/glsl/nir/nir_live_variables.c +++ /dev/null @@ -1,297 +0,0 @@ -/* - * Copyright © 2014 Intel Corporation - * - * 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. - * - * Authors: - * Jason Ekstrand (jason@jlekstrand.net) - */ - -#include "nir.h" -#include "nir_worklist.h" -#include "nir_vla.h" - -/* - * Basic liveness analysis. This works only in SSA form. - * - * This liveness pass treats phi nodes as being melded to the space between - * blocks so that the destinations of a phi are in the livein of the block - * in which it resides and the sources are in the liveout of the - * corresponding block. By formulating the liveness information in this - * way, we ensure that the definition of any variable dominates its entire - * live range. This is true because the only way that the definition of an - * SSA value may not dominate a use is if the use is in a phi node and the - * uses in phi no are in the live-out of the corresponding predecessor - * block but not in the live-in of the block containing the phi node. - */ - -struct live_ssa_defs_state { - unsigned num_ssa_defs; - unsigned bitset_words; - - nir_block_worklist worklist; -}; - -static bool -index_ssa_def(nir_ssa_def *def, void *void_state) -{ - struct live_ssa_defs_state *state = void_state; - - if (def->parent_instr->type == nir_instr_type_ssa_undef) - def->live_index = 0; - else - def->live_index = state->num_ssa_defs++; - - return true; -} - -static bool -index_ssa_definitions_block(nir_block *block, void *state) -{ - nir_foreach_instr(block, instr) - nir_foreach_ssa_def(instr, index_ssa_def, state); - - return true; -} - -/* Initialize the liveness data to zero and add the given block to the - * worklist. - */ -static bool -init_liveness_block(nir_block *block, void *void_state) -{ - struct live_ssa_defs_state *state = void_state; - - block->live_in = reralloc(block, block->live_in, BITSET_WORD, - state->bitset_words); - memset(block->live_in, 0, state->bitset_words * sizeof(BITSET_WORD)); - - block->live_out = reralloc(block, block->live_out, BITSET_WORD, - state->bitset_words); - memset(block->live_out, 0, state->bitset_words * sizeof(BITSET_WORD)); - - nir_block_worklist_push_head(&state->worklist, block); - - return true; -} - -static bool -set_src_live(nir_src *src, void *void_live) -{ - BITSET_WORD *live = void_live; - - if (!src->is_ssa) - return true; - - if (src->ssa->live_index == 0) - return true; /* undefined variables are never live */ - - BITSET_SET(live, src->ssa->live_index); - - return true; -} - -static bool -set_ssa_def_dead(nir_ssa_def *def, void *void_live) -{ - BITSET_WORD *live = void_live; - - BITSET_CLEAR(live, def->live_index); - - return true; -} - -/** Propagates the live in of succ across the edge to the live out of pred - * - * Phi nodes exist "between" blocks and all the phi nodes at the start of a - * block act "in parallel". When we propagate from the live_in of one - * block to the live out of the other, we have to kill any writes from phis - * and make live any sources. - * - * Returns true if updating live out of pred added anything - */ -static bool -propagate_across_edge(nir_block *pred, nir_block *succ, - struct live_ssa_defs_state *state) -{ - NIR_VLA(BITSET_WORD, live, state->bitset_words); - memcpy(live, succ->live_in, state->bitset_words * sizeof *live); - - nir_foreach_instr(succ, instr) { - if (instr->type != nir_instr_type_phi) - break; - nir_phi_instr *phi = nir_instr_as_phi(instr); - - assert(phi->dest.is_ssa); - set_ssa_def_dead(&phi->dest.ssa, live); - } - - nir_foreach_instr(succ, instr) { - if (instr->type != nir_instr_type_phi) - break; - nir_phi_instr *phi = nir_instr_as_phi(instr); - - nir_foreach_phi_src(phi, src) { - if (src->pred == pred) { - set_src_live(&src->src, live); - break; - } - } - } - - BITSET_WORD progress = 0; - for (unsigned i = 0; i < state->bitset_words; ++i) { - progress |= live[i] & ~pred->live_out[i]; - pred->live_out[i] |= live[i]; - } - return progress != 0; -} - -void -nir_live_ssa_defs_impl(nir_function_impl *impl) -{ - struct live_ssa_defs_state state; - - /* We start at 1 because we reserve the index value of 0 for ssa_undef - * instructions. Those are never live, so their liveness information - * can be compacted into a single bit. - */ - state.num_ssa_defs = 1; - nir_foreach_block(impl, index_ssa_definitions_block, &state); - - nir_block_worklist_init(&state.worklist, impl->num_blocks, NULL); - - /* We now know how many unique ssa definitions we have and we can go - * ahead and allocate live_in and live_out sets and add all of the - * blocks to the worklist. - */ - state.bitset_words = BITSET_WORDS(state.num_ssa_defs); - nir_foreach_block(impl, init_liveness_block, &state); - - /* We're now ready to work through the worklist and update the liveness - * sets of each of the blocks. By the time we get to this point, every - * block in the function implementation has been pushed onto the - * worklist in reverse order. As long as we keep the worklist - * up-to-date as we go, everything will get covered. - */ - while (!nir_block_worklist_is_empty(&state.worklist)) { - /* We pop them off in the reverse order we pushed them on. This way - * the first walk of the instructions is backwards so we only walk - * once in the case of no control flow. - */ - nir_block *block = nir_block_worklist_pop_head(&state.worklist); - - memcpy(block->live_in, block->live_out, - state.bitset_words * sizeof(BITSET_WORD)); - - nir_if *following_if = nir_block_get_following_if(block); - if (following_if) - set_src_live(&following_if->condition, block->live_in); - - nir_foreach_instr_reverse(block, instr) { - /* Phi nodes are handled seperately so we want to skip them. Since - * we are going backwards and they are at the beginning, we can just - * break as soon as we see one. - */ - if (instr->type == nir_instr_type_phi) - break; - - nir_foreach_ssa_def(instr, set_ssa_def_dead, block->live_in); - nir_foreach_src(instr, set_src_live, block->live_in); - } - - /* Walk over all of the predecessors of the current block updating - * their live in with the live out of this one. If anything has - * changed, add the predecessor to the work list so that we ensure - * that the new information is used. - */ - struct set_entry *entry; - set_foreach(block->predecessors, entry) { - nir_block *pred = (nir_block *)entry->key; - if (propagate_across_edge(pred, block, &state)) - nir_block_worklist_push_tail(&state.worklist, pred); - } - } - - nir_block_worklist_fini(&state.worklist); -} - -static bool -src_does_not_use_def(nir_src *src, void *def) -{ - return !src->is_ssa || src->ssa != (nir_ssa_def *)def; -} - -static bool -search_for_use_after_instr(nir_instr *start, nir_ssa_def *def) -{ - /* Only look for a use strictly after the given instruction */ - struct exec_node *node = start->node.next; - while (!exec_node_is_tail_sentinel(node)) { - nir_instr *instr = exec_node_data(nir_instr, node, node); - if (!nir_foreach_src(instr, src_does_not_use_def, def)) - return true; - node = node->next; - } - return false; -} - -/* Returns true if def is live at instr assuming that def comes before - * instr in a pre DFS search of the dominance tree. - */ -static bool -nir_ssa_def_is_live_at(nir_ssa_def *def, nir_instr *instr) -{ - if (BITSET_TEST(instr->block->live_out, def->live_index)) { - /* Since def dominates instr, if def is in the liveout of the block, - * it's live at instr - */ - return true; - } else { - if (BITSET_TEST(instr->block->live_in, def->live_index) || - def->parent_instr->block == instr->block) { - /* In this case it is either live coming into instr's block or it - * is defined in the same block. In this case, we simply need to - * see if it is used after instr. - */ - return search_for_use_after_instr(instr, def); - } else { - return false; - } - } -} - -bool -nir_ssa_defs_interfere(nir_ssa_def *a, nir_ssa_def *b) -{ - if (a->parent_instr == b->parent_instr) { - /* Two variables defined at the same time interfere assuming at - * least one isn't dead. - */ - return true; - } else if (a->live_index == 0 || b->live_index == 0) { - /* If either variable is an ssa_undef, then there's no interference */ - return false; - } else if (a->live_index < b->live_index) { - return nir_ssa_def_is_live_at(a, b->parent_instr); - } else { - return nir_ssa_def_is_live_at(b, a->parent_instr); - } -} diff --git a/src/glsl/nir/nir_liveness.c b/src/glsl/nir/nir_liveness.c new file mode 100644 index 00000000000..05f79d7bc61 --- /dev/null +++ b/src/glsl/nir/nir_liveness.c @@ -0,0 +1,297 @@ +/* + * Copyright © 2014 Intel Corporation + * + * 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. + * + * Authors: + * Jason Ekstrand (jason@jlekstrand.net) + */ + +#include "nir.h" +#include "nir_worklist.h" +#include "nir_vla.h" + +/* + * Basic liveness analysis. This works only in SSA form. + * + * This liveness pass treats phi nodes as being melded to the space between + * blocks so that the destinations of a phi are in the livein of the block + * in which it resides and the sources are in the liveout of the + * corresponding block. By formulating the liveness information in this + * way, we ensure that the definition of any variable dominates its entire + * live range. This is true because the only way that the definition of an + * SSA value may not dominate a use is if the use is in a phi node and the + * uses in phi no are in the live-out of the corresponding predecessor + * block but not in the live-in of the block containing the phi node. + */ + +struct live_ssa_defs_state { + unsigned num_ssa_defs; + unsigned bitset_words; + + nir_block_worklist worklist; +}; + +static bool +index_ssa_def(nir_ssa_def *def, void *void_state) +{ + struct live_ssa_defs_state *state = void_state; + + if (def->parent_instr->type == nir_instr_type_ssa_undef) + def->live_index = 0; + else + def->live_index = state->num_ssa_defs++; + + return true; +} + +static bool +index_ssa_definitions_block(nir_block *block, void *state) +{ + nir_foreach_instr(block, instr) + nir_foreach_ssa_def(instr, index_ssa_def, state); + + return true; +} + +/* Initialize the liveness data to zero and add the given block to the + * worklist. + */ +static bool +init_liveness_block(nir_block *block, void *void_state) +{ + struct live_ssa_defs_state *state = void_state; + + block->live_in = reralloc(block, block->live_in, BITSET_WORD, + state->bitset_words); + memset(block->live_in, 0, state->bitset_words * sizeof(BITSET_WORD)); + + block->live_out = reralloc(block, block->live_out, BITSET_WORD, + state->bitset_words); + memset(block->live_out, 0, state->bitset_words * sizeof(BITSET_WORD)); + + nir_block_worklist_push_head(&state->worklist, block); + + return true; +} + +static bool +set_src_live(nir_src *src, void *void_live) +{ + BITSET_WORD *live = void_live; + + if (!src->is_ssa) + return true; + + if (src->ssa->live_index == 0) + return true; /* undefined variables are never live */ + + BITSET_SET(live, src->ssa->live_index); + + return true; +} + +static bool +set_ssa_def_dead(nir_ssa_def *def, void *void_live) +{ + BITSET_WORD *live = void_live; + + BITSET_CLEAR(live, def->live_index); + + return true; +} + +/** Propagates the live in of succ across the edge to the live out of pred + * + * Phi nodes exist "between" blocks and all the phi nodes at the start of a + * block act "in parallel". When we propagate from the live_in of one + * block to the live out of the other, we have to kill any writes from phis + * and make live any sources. + * + * Returns true if updating live out of pred added anything + */ +static bool +propagate_across_edge(nir_block *pred, nir_block *succ, + struct live_ssa_defs_state *state) +{ + NIR_VLA(BITSET_WORD, live, state->bitset_words); + memcpy(live, succ->live_in, state->bitset_words * sizeof *live); + + nir_foreach_instr(succ, instr) { + if (instr->type != nir_instr_type_phi) + break; + nir_phi_instr *phi = nir_instr_as_phi(instr); + + assert(phi->dest.is_ssa); + set_ssa_def_dead(&phi->dest.ssa, live); + } + + nir_foreach_instr(succ, instr) { + if (instr->type != nir_instr_type_phi) + break; + nir_phi_instr *phi = nir_instr_as_phi(instr); + + nir_foreach_phi_src(phi, src) { + if (src->pred == pred) { + set_src_live(&src->src, live); + break; + } + } + } + + BITSET_WORD progress = 0; + for (unsigned i = 0; i < state->bitset_words; ++i) { + progress |= live[i] & ~pred->live_out[i]; + pred->live_out[i] |= live[i]; + } + return progress != 0; +} + +void +nir_live_ssa_defs_impl(nir_function_impl *impl) +{ + struct live_ssa_defs_state state; + + /* We start at 1 because we reserve the index value of 0 for ssa_undef + * instructions. Those are never live, so their liveness information + * can be compacted into a single bit. + */ + state.num_ssa_defs = 1; + nir_foreach_block(impl, index_ssa_definitions_block, &state); + + nir_block_worklist_init(&state.worklist, impl->num_blocks, NULL); + + /* We now know how many unique ssa definitions we have and we can go + * ahead and allocate live_in and live_out sets and add all of the + * blocks to the worklist. + */ + state.bitset_words = BITSET_WORDS(state.num_ssa_defs); + nir_foreach_block(impl, init_liveness_block, &state); + + /* We're now ready to work through the worklist and update the liveness + * sets of each of the blocks. By the time we get to this point, every + * block in the function implementation has been pushed onto the + * worklist in reverse order. As long as we keep the worklist + * up-to-date as we go, everything will get covered. + */ + while (!nir_block_worklist_is_empty(&state.worklist)) { + /* We pop them off in the reverse order we pushed them on. This way + * the first walk of the instructions is backwards so we only walk + * once in the case of no control flow. + */ + nir_block *block = nir_block_worklist_pop_head(&state.worklist); + + memcpy(block->live_in, block->live_out, + state.bitset_words * sizeof(BITSET_WORD)); + + nir_if *following_if = nir_block_get_following_if(block); + if (following_if) + set_src_live(&following_if->condition, block->live_in); + + nir_foreach_instr_reverse(block, instr) { + /* Phi nodes are handled seperately so we want to skip them. Since + * we are going backwards and they are at the beginning, we can just + * break as soon as we see one. + */ + if (instr->type == nir_instr_type_phi) + break; + + nir_foreach_ssa_def(instr, set_ssa_def_dead, block->live_in); + nir_foreach_src(instr, set_src_live, block->live_in); + } + + /* Walk over all of the predecessors of the current block updating + * their live in with the live out of this one. If anything has + * changed, add the predecessor to the work list so that we ensure + * that the new information is used. + */ + struct set_entry *entry; + set_foreach(block->predecessors, entry) { + nir_block *pred = (nir_block *)entry->key; + if (propagate_across_edge(pred, block, &state)) + nir_block_worklist_push_tail(&state.worklist, pred); + } + } + + nir_block_worklist_fini(&state.worklist); +} + +static bool +src_does_not_use_def(nir_src *src, void *def) +{ + return !src->is_ssa || src->ssa != (nir_ssa_def *)def; +} + +static bool +search_for_use_after_instr(nir_instr *start, nir_ssa_def *def) +{ + /* Only look for a use strictly after the given instruction */ + struct exec_node *node = start->node.next; + while (!exec_node_is_tail_sentinel(node)) { + nir_instr *instr = exec_node_data(nir_instr, node, node); + if (!nir_foreach_src(instr, src_does_not_use_def, def)) + return true; + node = node->next; + } + return false; +} + +/* Returns true if def is live at instr assuming that def comes before + * instr in a pre DFS search of the dominance tree. + */ +static bool +nir_ssa_def_is_live_at(nir_ssa_def *def, nir_instr *instr) +{ + if (BITSET_TEST(instr->block->live_out, def->live_index)) { + /* Since def dominates instr, if def is in the liveout of the block, + * it's live at instr + */ + return true; + } else { + if (BITSET_TEST(instr->block->live_in, def->live_index) || + def->parent_instr->block == instr->block) { + /* In this case it is either live coming into instr's block or it + * is defined in the same block. In this case, we simply need to + * see if it is used after instr. + */ + return search_for_use_after_instr(instr, def); + } else { + return false; + } + } +} + +bool +nir_ssa_defs_interfere(nir_ssa_def *a, nir_ssa_def *b) +{ + if (a->parent_instr == b->parent_instr) { + /* Two variables defined at the same time interfere assuming at + * least one isn't dead. + */ + return true; + } else if (a->live_index == 0 || b->live_index == 0) { + /* If either variable is an ssa_undef, then there's no interference */ + return false; + } else if (a->live_index < b->live_index) { + return nir_ssa_def_is_live_at(a, b->parent_instr); + } else { + return nir_ssa_def_is_live_at(b, a->parent_instr); + } +}