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middle-end/108500 - replace recursive domtree DFS traversal

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The following replaces the recursive DFS traversal of the dominator
tree in assign_dfs_numbers with a tree traversal using the fact
that we have recorded parents.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

This makes r13-5325 somewhat obsolete, though not computing the
DFS numbers at all is beneficial in the cases where we perform
immediate CFG manipulations.

OK for trunk and later branch(es)?

Thanks,
Richard.

	PR middle-end/108500
	* dominance.cc (assign_dfs_numbers): Replace recursive DFS
	with tree traversal algorithm.
This commit is contained in:
Richard Biener 2023-01-31 15:45:43 +01:00
parent e2f939d30f
commit 9725848043
1 changed files with 17 additions and 10 deletions
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27
gcc/dominance.cc
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@ -639,18 +639,25 @@ dom_info::calc_idoms ()
static void
assign_dfs_numbers (struct et_node *node, int *num)
{
struct et_node *son;
node->dfs_num_in = (*num)++;
if (node->son)
et_node *n = node;
while (1)
{
assign_dfs_numbers (node->son, num);
for (son = node->son->right; son != node->son; son = son->right)
assign_dfs_numbers (son, num);
n->dfs_num_in = (*num)++;
if (n->son)
n = n->son;
else
{
while (!n->right || n->right == n->father->son)
{
n->dfs_num_out = (*num)++;
if (n == node)
return;
n = n->father;
}
n->dfs_num_out = (*num)++;
n = n->right;
}
}
node->dfs_num_out = (*num)++;
}
/* Compute the data necessary for fast resolving of dominator queries in a