* 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 bool
-block_ends_in_jump(nir_block *block)
-{
- return !exec_list_is_empty(&block->instr_list) &&
- nir_block_last_instr(block)->type == nir_instr_type_jump;
-}
-
static inline void
block_add_pred(nir_block *block, nir_block *pred)
{
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);
+ nir_block *last_then_block = nir_if_last_then_block(if_stmt);
+ nir_block *last_else_block = nir_if_last_else_block(if_stmt);
- if (!block_ends_in_jump(last_then_block)) {
+ if (!nir_block_ends_in_jump(last_then_block)) {
unlink_block_successors(last_then_block);
link_blocks(last_then_block, block, NULL);
}
- if (!block_ends_in_jump(last_else_block)) {
+ if (!nir_block_ends_in_jump(last_else_block)) {
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);
}
}
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);
+ nir_block *first_then_block = nir_if_first_then_block(if_stmt);
+ nir_block *first_else_block = nir_if_first_else_block(if_stmt);
unlink_block_successors(block);
link_blocks(block, first_then_block, first_else_block);
* 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);
+ nir_block *loop_header_block = nir_loop_first_block(loop);
unlink_block_successors(block);
link_blocks(block, loop_header_block, NULL);
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;
replace_successor(pred, block, new_block);
}
/* Any phi nodes must stay part of the new block, or else their
- * sourcse will be messed up. This will reverse the order of the phi's, but
- * order shouldn't matter.
+ * sources will be messed up.
*/
- nir_foreach_instr_safe(block, instr) {
+ nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_phi)
break;
exec_node_remove(&instr->node);
instr->block = new_block;
- exec_list_push_head(&new_block->instr_list, &instr->node);
+ exec_list_push_tail(&new_block->instr_list, &instr->node);
}
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) {
+ nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_phi)
break;
nir_phi_instr *phi = nir_instr_as_phi(instr);
- nir_foreach_phi_src(phi, src) {
+ nir_foreach_phi_src(src, phi) {
if (src->pred == old_pred) {
src->pred = new_pred;
break;
insert_phi_undef(nir_block *block, nir_block *pred)
{
nir_function_impl *impl = nir_cf_node_get_function(&block->cf_node);
- nir_foreach_instr(block, instr) {
+ nir_foreach_instr(instr, block) {
if (instr->type != nir_instr_type_phi)
break;
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 if (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);
+ nir_block *head_block = nir_loop_first_block(loop);
link_blocks(block, head_block, NULL);
insert_phi_undef(head_block, block);
} else {
- assert(parent->type == nir_cf_node_function);
nir_function_impl *impl = nir_cf_node_as_function(parent);
link_blocks(block, impl->end_block, NULL);
}
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);
+ nir_block *first_then_block = nir_if_first_then_block(next_if);
+ nir_block *first_else_block = nir_if_first_else_block(next_if);
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);
+ nir_block *first_block = nir_loop_first_block(next_loop);
link_blocks(block, first_block, NULL);
insert_phi_undef(first_block, block);
new_block->cf_node.parent = block->cf_node.parent;
exec_node_insert_after(&block->cf_node.node, &new_block->cf_node.node);
- if (block_ends_in_jump(block)) {
+ if (nir_block_ends_in_jump(block)) {
/* Figure out what successor block would've had if it didn't have a jump
* instruction, and make new_block have that successor.
*/
assert(instr->type != nir_instr_type_phi);
nir_block *new_block = split_block_beginning(instr->block);
- nir_foreach_instr_safe(instr->block, cur_instr) {
+ nir_foreach_instr_safe(cur_instr, instr->block) {
if (cur_instr == instr)
break;
return nir_cf_node_as_loop(node);
}
+static void
+remove_phi_src(nir_block *block, nir_block *pred)
+{
+ nir_foreach_instr(instr, block) {
+ if (instr->type != nir_instr_type_phi)
+ break;
+
+ nir_phi_instr *phi = nir_instr_as_phi(instr);
+ nir_foreach_phi_src_safe(src, phi) {
+ if (src->pred == pred) {
+ list_del(&src->src.use_link);
+ exec_node_remove(&src->node);
+ }
+ }
+ }
+}
+
/*
* update the CFG after a jump instruction has been added to the end of a block
*/
nir_instr *instr = nir_block_last_instr(block);
nir_jump_instr *jump_instr = nir_instr_as_jump(instr);
+ if (block->successors[0])
+ remove_phi_src(block->successors[0], block);
+ if (block->successors[1])
+ remove_phi_src(block->successors[1], block);
unlink_block_successors(block);
nir_function_impl *impl = nir_cf_node_get_function(&block->cf_node);
nir_metadata_preserve(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);
+ switch (jump_instr->type) {
+ case nir_jump_return:
link_blocks(block, impl->end_block, NULL);
+ break;
+
+ case nir_jump_break: {
+ nir_loop *loop = nearest_loop(&block->cf_node);
+ nir_cf_node *after = nir_cf_node_next(&loop->cf_node);
+ nir_block *after_block = nir_cf_node_as_block(after);
+ link_blocks(block, after_block, NULL);
+ break;
}
-}
-static void
-remove_phi_src(nir_block *block, nir_block *pred)
-{
- nir_foreach_instr(block, instr) {
- if (instr->type != nir_instr_type_phi)
- break;
+ case nir_jump_continue: {
+ nir_loop *loop = nearest_loop(&block->cf_node);
+ nir_block *first_block = nir_loop_first_block(loop);
+ link_blocks(block, first_block, NULL);
+ break;
+ }
- nir_phi_instr *phi = nir_instr_as_phi(instr);
- nir_foreach_phi_src_safe(phi, src) {
- if (src->pred == pred) {
- list_del(&src->src.use_link);
- exec_node_remove(&src->node);
- }
- }
+ default:
+ unreachable("Invalid jump type");
}
}
-/* Removes the successor of a block with a jump, and inserts a fake edge for
- * infinite loops. Note that the jump to be eliminated may be free-floating.
+/* Removes the successor of a block with a jump. Note that the jump to be
+ * eliminated may be free-floating.
*/
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])
unlink_block_successors(block);
if (add_normal_successors)
block_add_normal_succs(block);
-
- /* 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);
-
- last_block->successors[1] = next;
- block_add_pred(next, last_block);
- }
}
void
* TODO: special case when before is empty and after isn't?
*/
- if (block_ends_in_jump(before)) {
+ if (nir_block_ends_in_jump(before)) {
assert(exec_list_is_empty(&after->instr_list));
if (after->successors[0])
remove_phi_src(after->successors[0], after);
* already been setup with the correct successors, so we need to set
* up jumps here as the block is being inserted.
*/
- if (block_ends_in_jump(block))
+ if (nir_block_ends_in_jump(block))
nir_handle_add_jump(block);
stitch_blocks(block, after);
case nir_cf_node_block: {
nir_block *block = nir_cf_node_as_block(node);
/* We need to walk the instructions and clean up defs/uses */
- nir_foreach_instr_safe(block, instr) {
+ nir_foreach_instr_safe(instr, block) {
if (instr->type == nir_instr_type_jump) {
nir_jump_type jump_type = nir_instr_as_jump(instr)->type;
unlink_jump(block, jump_type, false);
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