[PATCH] Check headers in verify_loop_structure

Richard Biener rguenther@suse.de
Thu Feb 7 13:56:00 GMT 2013


On Thu, 7 Feb 2013, Marek Polacek wrote:

> On Thu, Feb 07, 2013 at 10:14:14AM +0100, Richard Biener wrote:
> > I'd say "loop with header %d not in loop tree" here.  Eventually
> > the header detection should be shared with the code in flow_loops_find
> > to avoid divergence.  I'm making changes to the flow_loops_find code
> > at the moment and will look at splitting out that part properly to
> > be re-used by the verifier.
> 
> Ok, thanks.  This version, on top of your PR56181 fix, uses
> bb_loop_header_p then.  Regtested/bootstrapped on x86_64-linux,
> ok for trunk after you commit your patch?
> 
> Maybe I should try bootstrap-O3 on it as well...
> 
> 2013-02-07  Marek Polacek  <polacek@redhat.com>
> 
> 	* cfgloop.c (verify_loop_structure): Add more checking
> 	of headers.
> 
> --- gcc/cfgloop.c.mp	2013-02-07 14:07:24.580864372 +0100
> +++ gcc/cfgloop.c	2013-02-07 14:11:42.005604064 +0100
> @@ -1353,6 +1353,21 @@ verify_loop_structure (void)
>  	}
>      }
>  
> +  /* Check the headers.  */
> +  FOR_EACH_BB (bb)
> +    {
> +      /* Skip BBs in the root tree.  */
> +      if (bb->loop_father == current_loops->tree_root)
> +	continue;

You shouldn't need this ... it will miss missing toplevel loops

> +      if (bb_loop_header_p (bb))
> +	if (bb->loop_father->header != bb)

  && bb->loop_father->header != bb)

Richard.

> +	  {
> +	    error ("loop with header %d not in loop tree", bb->index);
> +	    err = 1;
> +	  }
> +    }
> +
>    /* Check get_loop_body.  */
>    visited = sbitmap_alloc (last_basic_block);
>    bitmap_clear (visited);



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