- return NULL;
-}
-
-
-/**
- * \name Control flow modification
- *
- * These functions modify the control flow tree while keeping the control flow
- * graph up-to-date. The invariants respected are:
- * 1. Each then statement, else statement, or loop body must have at least one
- * control flow node.
- * 2. Each if-statement and loop must have one basic block before it and one
- * after.
- * 3. Two basic blocks cannot be directly next to each other.
- * 4. If a basic block has a jump instruction, there must be only one and it
- * must be at the end of the block.
- * 5. The CFG must always be connected - this means that we must insert a fake
- * CFG edge for loops with no break statement.
- *
- * The purpose of the second one is so that we have places to insert code during
- * GCM, as well as eliminating the possibility of critical edges.
- */
-/*@{*/
-
-static void
-link_non_block_to_block(nir_cf_node *node, nir_block *block)
-{
- if (node->type == nir_cf_node_if) {
- /*
- * We're trying to link an if to a block after it; this just means linking
- * the last block of the then and else branches.
- */
-
- nir_if *if_stmt = nir_cf_node_as_if(node);
-
- nir_cf_node *last_then = nir_if_last_then_node(if_stmt);
- assert(last_then->type == nir_cf_node_block);
- nir_block *last_then_block = nir_cf_node_as_block(last_then);
-
- nir_cf_node *last_else = nir_if_last_else_node(if_stmt);
- assert(last_else->type == nir_cf_node_block);
- nir_block *last_else_block = nir_cf_node_as_block(last_else);
-
- if (exec_list_is_empty(&last_then_block->instr_list) ||
- nir_block_last_instr(last_then_block)->type != nir_instr_type_jump) {
- unlink_block_successors(last_then_block);
- link_blocks(last_then_block, block, NULL);
- }
-
- if (exec_list_is_empty(&last_else_block->instr_list) ||
- nir_block_last_instr(last_else_block)->type != nir_instr_type_jump) {
- unlink_block_successors(last_else_block);
- link_blocks(last_else_block, block, NULL);
- }
- } else {
- assert(node->type == nir_cf_node_loop);
-
- /*
- * We can only get to this codepath if we're inserting a new loop, or
- * at least a loop with no break statements; we can't insert break
- * statements into a loop when we haven't inserted it into the CFG
- * because we wouldn't know which block comes after the loop
- * and therefore, which block should be the successor of the block with
- * the break). Therefore, we need to insert a fake edge (see invariant
- * #5).
- */
-
- nir_loop *loop = nir_cf_node_as_loop(node);
-
- 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] = block;
- block_add_pred(block, last_block);
- }
-}
-
-static void
-link_block_to_non_block(nir_block *block, nir_cf_node *node)
-{
- if (node->type == nir_cf_node_if) {
- /*
- * We're trying to link a block to an if after it; this just means linking
- * the block to the first block of the then and else branches.
- */
-
- nir_if *if_stmt = nir_cf_node_as_if(node);
-
- nir_cf_node *first_then = nir_if_first_then_node(if_stmt);
- assert(first_then->type == nir_cf_node_block);
- nir_block *first_then_block = nir_cf_node_as_block(first_then);
-
- nir_cf_node *first_else = nir_if_first_else_node(if_stmt);
- assert(first_else->type == nir_cf_node_block);
- nir_block *first_else_block = nir_cf_node_as_block(first_else);
-
- unlink_block_successors(block);
- link_blocks(block, first_then_block, first_else_block);
- } else {
- /*
- * For similar reasons as the corresponding case in
- * link_non_block_to_block(), don't worry about if the loop header has
- * any predecessors that need to be unlinked.
- */
-
- assert(node->type == nir_cf_node_loop);
-
- nir_loop *loop = nir_cf_node_as_loop(node);
-
- nir_cf_node *loop_header = nir_loop_first_cf_node(loop);
- assert(loop_header->type == nir_cf_node_block);
- nir_block *loop_header_block = nir_cf_node_as_block(loop_header);
-
- unlink_block_successors(block);
- link_blocks(block, loop_header_block, NULL);
- }
-
-}
-
-/**
- * Takes a basic block and inserts a new empty basic block before it, making its
- * predecessors point to the new block. This essentially splits the block into
- * an empty header and a body so that another non-block CF node can be inserted
- * between the two. Note that this does *not* link the two basic blocks, so
- * some kind of cleanup *must* be performed after this call.
- */
-
-static nir_block *
-split_block_beginning(nir_block *block)
-{
- nir_block *new_block = nir_block_create(ralloc_parent(block));
- new_block->cf_node.parent = block->cf_node.parent;
- exec_node_insert_node_before(&block->cf_node.node, &new_block->cf_node.node);
-
- struct set_entry *entry;
- set_foreach(block->predecessors, entry) {
- nir_block *pred = (nir_block *) entry->key;
-
- unlink_blocks(pred, block);
- link_blocks(pred, new_block, NULL);
- }
-
- return new_block;
-}
-
-static void
-rewrite_phi_preds(nir_block *block, nir_block *old_pred, nir_block *new_pred)
-{
- nir_foreach_instr_safe(block, instr) {
- if (instr->type != nir_instr_type_phi)
- break;
-
- nir_phi_instr *phi = nir_instr_as_phi(instr);
- foreach_list_typed_safe(nir_phi_src, src, node, &phi->srcs) {
- if (src->pred == old_pred) {
- src->pred = new_pred;
- break;
- }
- }
- }
-}
-
-/**
- * Moves the successors of source to the successors of dest, leaving both
- * successors of source NULL.
- */
-
-static void
-move_successors(nir_block *source, nir_block *dest)
-{
- nir_block *succ1 = source->successors[0];
- nir_block *succ2 = source->successors[1];
-
- if (succ1) {
- unlink_blocks(source, succ1);
- rewrite_phi_preds(succ1, source, dest);
- }
-
- if (succ2) {
- unlink_blocks(source, succ2);
- rewrite_phi_preds(succ2, source, dest);
- }
-
- unlink_block_successors(dest);
- link_blocks(dest, succ1, succ2);
-}
-
-static nir_block *
-split_block_end(nir_block *block)
-{
- nir_block *new_block = nir_block_create(ralloc_parent(block));
- new_block->cf_node.parent = block->cf_node.parent;
- exec_node_insert_after(&block->cf_node.node, &new_block->cf_node.node);
-
- move_successors(block, new_block);
-
- return new_block;
-}
-
-/**
- * Inserts a non-basic block between two basic blocks and links them together.
- */
-
-static void
-insert_non_block(nir_block *before, nir_cf_node *node, nir_block *after)
-{
- node->parent = before->cf_node.parent;
- exec_node_insert_after(&before->cf_node.node, &node->node);
- link_block_to_non_block(before, node);
- link_non_block_to_block(node, after);
-}
-
-/**
- * Inserts a non-basic block before a basic block.
- */
-
-static void
-insert_non_block_before_block(nir_cf_node *node, nir_block *block)
-{
- /* split off the beginning of block into new_block */
- nir_block *new_block = split_block_beginning(block);
-
- /* insert our node in between new_block and block */
- insert_non_block(new_block, node, block);
-}
-
-static void
-insert_non_block_after_block(nir_block *block, nir_cf_node *node)
-{
- /* split off the end of block into new_block */
- nir_block *new_block = split_block_end(block);
-
- /* insert our node in between block and new_block */
- insert_non_block(block, node, new_block);
-}
-
-/* walk up the control flow tree to find the innermost enclosed loop */
-static nir_loop *
-nearest_loop(nir_cf_node *node)
-{
- while (node->type != nir_cf_node_loop) {
- node = node->parent;
- }
-
- return nir_cf_node_as_loop(node);
-}
-
-nir_function_impl *
-nir_cf_node_get_function(nir_cf_node *node)
-{
- while (node->type != nir_cf_node_function) {
- node = node->parent;
- }
-
- return nir_cf_node_as_function(node);
-}
-
-/*
- * update the CFG after a jump instruction has been added to the end of a block
- */
-
-static void
-handle_jump(nir_block *block)
-{
- nir_instr *instr = nir_block_last_instr(block);
- nir_jump_instr *jump_instr = nir_instr_as_jump(instr);
-
- unlink_block_successors(block);
-
- nir_function_impl *impl = nir_cf_node_get_function(&block->cf_node);
- nir_metadata_dirty(impl, nir_metadata_none);
-
- if (jump_instr->type == nir_jump_break ||
- jump_instr->type == nir_jump_continue) {
- nir_loop *loop = nearest_loop(&block->cf_node);
-
- if (jump_instr->type == nir_jump_continue) {
- nir_cf_node *first_node = nir_loop_first_cf_node(loop);
- assert(first_node->type == nir_cf_node_block);
- nir_block *first_block = nir_cf_node_as_block(first_node);
- link_blocks(block, first_block, NULL);
- } else {
- nir_cf_node *after = nir_cf_node_next(&loop->cf_node);
- assert(after->type == nir_cf_node_block);
- nir_block *after_block = nir_cf_node_as_block(after);
- link_blocks(block, after_block, NULL);
-
- /* If we inserted a fake link, remove it */
- 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);
- if (last_block->successors[1] != NULL)
- unlink_blocks(last_block, after_block);
- }
- } else {
- assert(jump_instr->type == nir_jump_return);
- link_blocks(block, impl->end_block, NULL);
- }
-}
-
-static void
-handle_remove_jump(nir_block *block, nir_jump_type type)
-{
- unlink_block_successors(block);
-
- if (exec_node_is_tail_sentinel(block->cf_node.node.next)) {
- nir_cf_node *parent = block->cf_node.parent;
- if (parent->type == nir_cf_node_if) {
- nir_cf_node *next = nir_cf_node_next(parent);
- assert(next->type == nir_cf_node_block);
- nir_block *next_block = nir_cf_node_as_block(next);
-
- link_blocks(block, next_block, NULL);
- } else {
- assert(parent->type == nir_cf_node_loop);
- nir_loop *loop = nir_cf_node_as_loop(parent);
-
- nir_cf_node *head = nir_loop_first_cf_node(loop);
- assert(head->type == nir_cf_node_block);
- nir_block *head_block = nir_cf_node_as_block(head);
-
- link_blocks(block, head_block, NULL);
- }
- } else {
- nir_cf_node *next = nir_cf_node_next(&block->cf_node);
- if (next->type == nir_cf_node_if) {
- nir_if *next_if = nir_cf_node_as_if(next);
-
- nir_cf_node *first_then = nir_if_first_then_node(next_if);
- assert(first_then->type == nir_cf_node_block);
- nir_block *first_then_block = nir_cf_node_as_block(first_then);
-
- nir_cf_node *first_else = nir_if_first_else_node(next_if);
- assert(first_else->type == nir_cf_node_block);
- nir_block *first_else_block = nir_cf_node_as_block(first_else);
-
- link_blocks(block, first_then_block, first_else_block);
- } else {
- assert(next->type == nir_cf_node_loop);
- nir_loop *next_loop = nir_cf_node_as_loop(next);
-
- nir_cf_node *first = nir_loop_first_cf_node(next_loop);
- assert(first->type == nir_cf_node_block);
- nir_block *first_block = nir_cf_node_as_block(first);
-
- link_blocks(block, first_block, NULL);
- }
- }
-
- if (type == nir_jump_break) {
- nir_loop *loop = nearest_loop(&block->cf_node);
-
- nir_cf_node *next = nir_cf_node_next(&loop->cf_node);
- assert(next->type == nir_cf_node_block);
- nir_block *next_block = nir_cf_node_as_block(next);
-
- if (next_block->predecessors->entries == 0) {
- /* 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;
- block_add_pred(next_block, last_block);
- }
- }
-
- nir_function_impl *impl = nir_cf_node_get_function(&block->cf_node);
- nir_metadata_dirty(impl, nir_metadata_none);
-}
-
-/**
- * Inserts a basic block before another by merging the instructions.
- *
- * @param block the target of the insertion
- * @param before the block to be inserted - must not have been inserted before
- * @param has_jump whether \before has a jump instruction at the end
- */
-
-static void
-insert_block_before_block(nir_block *block, nir_block *before, bool has_jump)
-{
- assert(!has_jump || exec_list_is_empty(&block->instr_list));
-
- foreach_list_typed(nir_instr, instr, node, &before->instr_list) {
- instr->block = block;
- }
-
- exec_list_prepend(&block->instr_list, &before->instr_list);
-
- if (has_jump)
- handle_jump(block);
-}
-
-/**
- * Inserts a basic block after another by merging the instructions.
- *
- * @param block the target of the insertion
- * @param after the block to be inserted - must not have been inserted before
- * @param has_jump whether \after has a jump instruction at the end
- */
-
-static void
-insert_block_after_block(nir_block *block, nir_block *after, bool has_jump)
-{
- foreach_list_typed(nir_instr, instr, node, &after->instr_list) {
- instr->block = block;
- }
-
- exec_list_append(&block->instr_list, &after->instr_list);
-
- if (has_jump)
- handle_jump(block);
-}
-
-static void
-update_if_uses(nir_cf_node *node)
-{
- if (node->type != nir_cf_node_if)
- return;
-
- nir_if *if_stmt = nir_cf_node_as_if(node);
- if (if_stmt->condition.is_ssa)
- return;
-
- nir_register *reg = if_stmt->condition.reg.reg;
- assert(reg != NULL);
-
- _mesa_set_add(reg->if_uses, _mesa_hash_pointer(if_stmt), if_stmt);
-}
-
-void
-nir_cf_node_insert_after(nir_cf_node *node, nir_cf_node *after)
-{
- update_if_uses(after);
-
- if (after->type == nir_cf_node_block) {
- /*
- * either node or the one after it must be a basic block, by invariant #2;
- * in either case, just merge the blocks together.
- */
- nir_block *after_block = nir_cf_node_as_block(after);
-
- bool has_jump = !exec_list_is_empty(&after_block->instr_list) &&
- nir_block_last_instr(after_block)->type == nir_instr_type_jump;
-
- if (node->type == nir_cf_node_block) {
- insert_block_after_block(nir_cf_node_as_block(node), after_block,
- has_jump);
- } else {
- nir_cf_node *next = nir_cf_node_next(node);
- assert(next->type == nir_cf_node_block);
- nir_block *next_block = nir_cf_node_as_block(next);
-
- insert_block_before_block(next_block, after_block, has_jump);
- }
- } else {
- if (node->type == nir_cf_node_block) {
- insert_non_block_after_block(nir_cf_node_as_block(node), after);
- } else {
- /*
- * We have to insert a non-basic block after a non-basic block. Since
- * every non-basic block has a basic block after it, this is equivalent
- * to inserting a non-basic block before a basic block.
- */
-
- nir_cf_node *next = nir_cf_node_next(node);
- assert(next->type == nir_cf_node_block);
- nir_block *next_block = nir_cf_node_as_block(next);
-
- insert_non_block_before_block(after, next_block);
- }
- }
-
- nir_function_impl *impl = nir_cf_node_get_function(node);
- nir_metadata_dirty(impl, nir_metadata_none);
-}
-
-void
-nir_cf_node_insert_before(nir_cf_node *node, nir_cf_node *before)
-{
- update_if_uses(before);
-
- if (before->type == nir_cf_node_block) {
- nir_block *before_block = nir_cf_node_as_block(before);
-
- bool has_jump = !exec_list_is_empty(&before_block->instr_list) &&
- nir_block_last_instr(before_block)->type == nir_instr_type_jump;
-
- if (node->type == nir_cf_node_block) {
- insert_block_before_block(nir_cf_node_as_block(node), before_block,
- has_jump);
- } else {
- nir_cf_node *prev = nir_cf_node_prev(node);
- assert(prev->type == nir_cf_node_block);
- nir_block *prev_block = nir_cf_node_as_block(prev);
-
- insert_block_after_block(prev_block, before_block, has_jump);
- }
- } else {
- if (node->type == nir_cf_node_block) {
- insert_non_block_before_block(before, nir_cf_node_as_block(node));
- } else {
- /*
- * We have to insert a non-basic block before a non-basic block. This
- * is equivalent to inserting a non-basic block after a basic block.
- */
-
- nir_cf_node *prev_node = nir_cf_node_prev(node);
- assert(prev_node->type == nir_cf_node_block);
- nir_block *prev_block = nir_cf_node_as_block(prev_node);
-
- insert_non_block_after_block(prev_block, before);
- }
- }
-
- nir_function_impl *impl = nir_cf_node_get_function(node);
- nir_metadata_dirty(impl, nir_metadata_none);
-}
-
-void
-nir_cf_node_insert_begin(struct exec_list *list, nir_cf_node *node)
-{
- nir_cf_node *begin = exec_node_data(nir_cf_node, list->head, node);
- nir_cf_node_insert_before(begin, node);
-}
-
-void
-nir_cf_node_insert_end(struct exec_list *list, nir_cf_node *node)
-{
- nir_cf_node *end = exec_node_data(nir_cf_node, list->tail_pred, node);
- nir_cf_node_insert_after(end, node);