From 8cacf38f527d42e41441ef8c25d95d4b2f4e8602 Mon Sep 17 00:00:00 2001 From: Bas Nieuwenhuizen Date: Sun, 15 Jul 2018 01:19:17 +0200 Subject: [PATCH] nir: Do not use continue block after removing it. Reinserting code directly before a jump means the block gets split and merged, removing the original block and replacing it in the process. Hence keeping a pointer to the continue block over a reinsert causes issues. This code changes nir_opt_if to simply look for the new continue block. Reviewed-by: Jason Ekstrand Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107275 CC: 18.1 --- src/compiler/nir/nir_opt_if.c | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-) diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c index a52de120ad6..49ba5de09e9 100644 --- a/src/compiler/nir/nir_opt_if.c +++ b/src/compiler/nir/nir_opt_if.c @@ -27,6 +27,26 @@ #include "nir_loop_analyze.h" /** + * Gets the single block that jumps back to the loop header. Already assumes + * there is exactly one such block. + */ +static nir_block* +find_continue_block(nir_loop *loop) +{ + nir_block *header_block = nir_loop_first_block(loop); + nir_block *prev_block = + nir_cf_node_as_block(nir_cf_node_prev(&loop->cf_node)); + + assert(header_block->predecessors->entries == 2); + + struct set_entry *pred_entry; + set_foreach(header_block->predecessors, pred_entry) { + if (pred_entry->key != prev_block) + return (nir_block*)pred_entry->key; + } +} + +/** * This optimization detects if statements at the tops of loops where the * condition is a phi node of two constants and moves half of the if to above * the loop and the other half of the if to the end of the loop. A simple for @@ -97,12 +117,7 @@ opt_peel_loop_initial_if(nir_loop *loop) if (header_block->predecessors->entries != 2) return false; - nir_block *continue_block = NULL; - struct set_entry *pred_entry; - set_foreach(header_block->predecessors, pred_entry) { - if (pred_entry->key != prev_block) - continue_block = (void *)pred_entry->key; - } + nir_block *continue_block = find_continue_block(loop); nir_cf_node *if_node = nir_cf_node_next(&header_block->cf_node); if (!if_node || if_node->type != nir_cf_node_if) @@ -193,6 +208,10 @@ opt_peel_loop_initial_if(nir_loop *loop) nir_cf_reinsert(&tmp, nir_before_cf_node(&loop->cf_node)); nir_cf_reinsert(&header, nir_after_block_before_jump(continue_block)); + + /* Get continue block again as the previous reinsert might have removed the block. */ + continue_block = find_continue_block(loop); + nir_cf_extract(&tmp, nir_before_cf_list(continue_list), nir_after_cf_list(continue_list)); nir_cf_reinsert(&tmp, nir_after_block_before_jump(continue_block)); -- 2.11.0