diff options
| -rw-r--r-- | src/glsl/nir/nir_control_flow.c | 44 |
1 files changed, 28 insertions, 16 deletions
diff --git a/src/glsl/nir/nir_control_flow.c b/src/glsl/nir/nir_control_flow.c index 2b23f38a6a2..87bc7163efd 100644 --- a/src/glsl/nir/nir_control_flow.c +++ b/src/glsl/nir/nir_control_flow.c @@ -551,31 +551,43 @@ remove_phi_src(nir_block *block, nir_block *pred) static void unlink_jump(nir_block *block, nir_jump_type type, bool add_normal_successors) { + nir_block *next = block->successors[0]; + if (block->successors[0]) remove_phi_src(block->successors[0], block); if (block->successors[1]) remove_phi_src(block->successors[1], block); - if (type == nir_jump_break) { - nir_block *next = block->successors[0]; + unlink_block_successors(block); + if (add_normal_successors) + block_add_normal_succs(block); - if (next->predecessors->entries == 1) { - nir_loop *loop = - nir_cf_node_as_loop(nir_cf_node_prev(&next->cf_node)); + /* If we've just removed a break, and the block we were jumping to (after + * the loop) now has zero predecessors, we've created a new infinite loop. + * + * NIR doesn't allow blocks (other than the start block) to have zero + * predecessors. In particular, dominance assumes all blocks are reachable. + * So, we insert a "fake link" by making successors[1] point after the loop. + * + * Note that we have to do this after unlinking/recreating the block's + * successors. If we removed a "break" at the end of the loop, then + * block == last_block, so block->successors[0] would already be "next", + * and adding a fake link would create two identical successors. Doing + * this afterward works, as we'll have changed block->successors[0] to + * be the top of the loop. + */ + if (type == nir_jump_break && next->predecessors->entries == 0) { + nir_loop *loop = + nir_cf_node_as_loop(nir_cf_node_prev(&next->cf_node)); - /* insert fake link */ - nir_cf_node *last = nir_loop_last_cf_node(loop); - assert(last->type == nir_cf_node_block); - nir_block *last_block = nir_cf_node_as_block(last); + /* insert fake link */ + nir_cf_node *last = nir_loop_last_cf_node(loop); + assert(last->type == nir_cf_node_block); + nir_block *last_block = nir_cf_node_as_block(last); - last_block->successors[1] = next; - block_add_pred(next, last_block); - } + last_block->successors[1] = next; + block_add_pred(next, last_block); } - - unlink_block_successors(block); - if (add_normal_successors) - block_add_normal_succs(block); } void |