diff options
Diffstat (limited to 'src/compiler')
| -rw-r--r-- | src/compiler/nir/nir_opt_dead_cf.c | 44 |
1 files changed, 30 insertions, 14 deletions
diff --git a/src/compiler/nir/nir_opt_dead_cf.c b/src/compiler/nir/nir_opt_dead_cf.c index b15dfdd0c91..a652bcd99bb 100644 --- a/src/compiler/nir/nir_opt_dead_cf.c +++ b/src/compiler/nir/nir_opt_dead_cf.c @@ -60,12 +60,12 @@ * } * ... * - * Finally, we also handle removing useless loops, i.e. loops with no side - * effects and without any definitions that are used elsewhere. This case is a - * little different from the first two in that the code is actually run (it - * just never does anything), but there are similar issues with needing to - * be careful with restarting after deleting the cf_node (see dead_cf_list()) - * so this is a convenient place to remove them. + * Finally, we also handle removing useless loops and ifs, i.e. loops and ifs + * with no side effects and without any definitions that are used + * elsewhere. This case is a little different from the first two in that the + * code is actually run (it just never does anything), but there are similar + * issues with needing to be careful with restarting after deleting the + * cf_node (see dead_cf_list()) so this is a convenient place to remove them. */ static void @@ -136,6 +136,12 @@ static bool cf_node_has_side_effects(nir_cf_node *node) { nir_foreach_block_in_cf_node(block, node) { + bool inside_loop = node->type == nir_cf_node_loop; + for (nir_cf_node *n = &block->cf_node; !inside_loop && n != node; n = n->parent) { + if (n->type == nir_cf_node_loop) + inside_loop = true; + } + nir_foreach_instr(instr, block) { if (instr->type == nir_instr_type_call) return true; @@ -143,10 +149,13 @@ cf_node_has_side_effects(nir_cf_node *node) /* Return instructions can cause us to skip over other side-effecting * instructions after the loop, so consider them to have side effects * here. + * + * When the block is not inside a loop, break and continue might also + * cause a skip. */ if (instr->type == nir_instr_type_jump && - nir_instr_as_jump(instr)->type == nir_jump_return) + (!inside_loop || nir_instr_as_jump(instr)->type == nir_jump_return)) return true; if (instr->type != nir_instr_type_intrinsic) @@ -171,7 +180,7 @@ def_not_live_out(nir_ssa_def *def, void *state) } /* - * Test if a loop is dead. A loop node is dead if: + * Test if a loop node or if node is dead. Such nodes are dead if: * * 1) It has no side effects (i.e. intrinsics which could possibly affect the * state of the program aside from producing an SSA value, indicated by a lack @@ -187,19 +196,21 @@ def_not_live_out(nir_ssa_def *def, void *state) */ static bool -loop_is_dead(nir_loop *loop) +node_is_dead(nir_cf_node *node) { - nir_block *before = nir_cf_node_as_block(nir_cf_node_prev(&loop->cf_node)); - nir_block *after = nir_cf_node_as_block(nir_cf_node_next(&loop->cf_node)); + assert(node->type == nir_cf_node_loop || node->type == nir_cf_node_if); + + nir_block *before = nir_cf_node_as_block(nir_cf_node_prev(node)); + nir_block *after = nir_cf_node_as_block(nir_cf_node_next(node)); if (!exec_list_is_empty(&after->instr_list) && nir_block_first_instr(after)->type == nir_instr_type_phi) return false; - if (cf_node_has_side_effects(&loop->cf_node)) + if (cf_node_has_side_effects(node)) return false; - nir_function_impl *impl = nir_cf_node_get_function(&loop->cf_node); + nir_function_impl *impl = nir_cf_node_get_function(node); nir_metadata_require(impl, nir_metadata_live_ssa_defs | nir_metadata_dominance); @@ -219,6 +230,11 @@ dead_cf_block(nir_block *block) { nir_if *following_if = nir_block_get_following_if(block); if (following_if) { + if (node_is_dead(&following_if->cf_node)) { + nir_cf_node_remove(&following_if->cf_node); + return true; + } + nir_const_value *const_value = nir_src_as_const_value(following_if->condition); @@ -233,7 +249,7 @@ dead_cf_block(nir_block *block) if (!following_loop) return false; - if (!loop_is_dead(following_loop)) + if (!node_is_dead(&following_loop->cf_node)) return false; nir_cf_node_remove(&following_loop->cf_node); |