From patchwork Tue May 17 14:10:31 2011
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Subject: comment precising need to use free_dominance_info
Date: Tue, 17 May 2011 04:10:31 -0000
From: Pierre Vittet <piervit@pvittet.com>
X-Patchwork-Id: 95939
Message-Id: <4DD281D7.6020409@pvittet.com>
To: gcc-patches@gcc.gnu.org

So maybe this patch adding a comment on calculate_dominance_info is more 
adapted.

ChangeLog:
2011-05-17  Pierre Vittet<piervit@pvittet.com>

	* dominance.c (calculate_dominance_info): Add comment
	   precising when to free with free_dominance_info

contributor number: 634276


Index: gcc/dominance.c
===================================================================
--- gcc/dominance.c	(revision 173830)
+++ gcc/dominance.c	(working copy)
@@ -628,8 +628,15 @@ compute_dom_fast_query (enum cdi_direction dir)
 }
 
 /* The main entry point into this module.  DIR is set depending on whether
-   we want to compute dominators or postdominators.  */
+   we want to compute dominators or postdominators.  
 
+   We try to keep dominance info alive as long as possible (to avoid
+   recomputing it often). It has to be freed with free_dominance_info when CFG
+   transformation makes it invalide. 
+   
+   post_dominance info is less often used, and should be freed after each use.
+*/
+
 void
 calculate_dominance_info (enum cdi_direction dir)
 {