[PATCH] comment precising need to use free_dominance_info

[PATCH] comment precising need to use free_dominance_info

[piervit]

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After using function flow_loops_find in cfgloop.c, it is needed to use 
free_dominance_info to clear structure which have beend added by the 
use of calculate_dominance_info.

I have added a comment precising this.

My contributor number is 634276.


ChangeLog:
2011-05-11  Pierre Vittet  <piervit@pvittet.com>

	* cfgloop.c (flow_loops_find): Add comment remembering to call
	free_dominance_info

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Index: gcc/cfgloop.c
===================================================================
--- gcc/cfgloop.c	(revision 173677)
+++ gcc/cfgloop.c	(working copy)
@@ -368,6 +368,11 @@ init_loops_structure (struct loops *loops, unsigne
 
 /* Find all the natural loops in the function and save in LOOPS structure and
    recalculate loop_depth information in basic block structures.
+
+   This function calls calculate_dominance_info which allocates a structure to
+   handle dominance. It must be freed after use with the function
+   free_dominance_info.
+
    Return the number of natural loops found.  */
 
 int

Re: [PATCH] comment precising need to use free_dominance_info

[Richard Guenther]

On Thu, May 12, 2011 at 12:14 AM,  <piervit@pvittet.com> wrote:
> After using function flow_loops_find in cfgloop.c, it is needed to use
> free_dominance_info to clear structure which have beend added by the use of
> calculate_dominance_info.
>
> I have added a comment precising this.
>
> My contributor number is 634276.

The patch is not correct.  Keeping dom info live is ok.

Richard.

>
> ChangeLog:
> 2011-05-11  Pierre Vittet  <piervit@pvittet.com>
>
>        * cfgloop.c (flow_loops_find): Add comment remembering to call
>        free_dominance_info
>

Re: [PATCH] comment precising need to use free_dominance_info

[Pierre Vittet]

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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


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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)
 {