Marking SCCs in ipa_reduced_postorder

Message ID
State New
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Commit Message

Martin Jambor May 12, 2011, 4:11 p.m.

in my current efforts to enhance IPA-CP I propagate values in a single
pass over the call graph nodes in the topological order and only
resort to "propagation until no change" in SCCs.

In order to do that I need to quickly figure out whether two nodes on
both sides of a call graph edge are in the same SCC.  I have not found
a way of doing that with the current code (please let me know if I
overlooked something obvious) but with the patch below it becomes as
simple as comparing their 

  ((struct ipa_dfs_info *) node->aux)->low_link

The patch bootstraps and tests fine on x86_64-linux.  Is it OK for



2011-05-02  Martin Jambor  <>

	* ipa-utils.c (searchc): Update low_link to lowest DFN of a SCC.


Index: src/gcc/ipa-utils.c
--- src.orig/gcc/ipa-utils.c
+++ src/gcc/ipa-utils.c
@@ -134,6 +134,7 @@  searchc (struct searchc_env* env, struct
 	x = env->stack[--(env->stack_size)];
 	x_info = (struct ipa_dfs_info *) x->aux;
 	x_info->on_stack = false;
+	x_info->low_link = v_info->dfn_number;
 	if (env->reduce)