Re: [PATCH] operand_equal_p checking (PR sanitizer/70683)

[Richard Biener <rguenther@suse.de>]

On Wed, 27 Apr 2016, Jakub Jelinek wrote:

> On Tue, Apr 26, 2016 at 03:02:38PM +0200, Jakub Jelinek wrote:
> > The debugging hack is too ugly and slows down the compiler (by artificially
> > increasing number of collisions), so it is not appropriate, but perhaps we
> > can add some internal only use OEP_* flag, pass it to the recursive calls
> > of operand_equal_p and if not set and flag_checking, verify
> > iterative_hash_expr equality in the outermost call).
> 
> Here is the corresponding checking patch.  It uncovered two further issues
> in the tree.[ch] patch which I'm going to post momentarily.
> Both patches together bootstrapped/regtested on x86_64-linux and i686-linux,
> ok for trunk?

Ok.

Thanks,
Richard.

> 2016-04-27  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR sanitizer/70683
> 	* tree-core.h (enum operand_equal_flag): Add OEP_NO_HASH_CHECK.
> 	* fold-const.c (operand_equal_p): If flag_checking and
> 	OEP_NO_HASH_CHECK is not set in flag, recurse with OEP_NO_HASH_CHECK
> 	and if it returns non-zero, assert iterative_hash_expr on both
> 	args is the same.
> 
> --- gcc/tree-core.h.jj	2016-04-22 18:21:55.000000000 +0200
> +++ gcc/tree-core.h	2016-04-26 17:47:19.875753297 +0200
> @@ -765,7 +765,9 @@ enum operand_equal_flag {
>    OEP_ONLY_CONST = 1,
>    OEP_PURE_SAME = 2,
>    OEP_MATCH_SIDE_EFFECTS = 4,
> -  OEP_ADDRESS_OF = 8
> +  OEP_ADDRESS_OF = 8,
> +  /* Internal within operand_equal_p:  */
> +  OEP_NO_HASH_CHECK = 16
>  };
>  
>  /* Enum and arrays used for tree allocation stats.
> --- gcc/fold-const.c.jj	2016-04-22 18:21:32.000000000 +0200
> +++ gcc/fold-const.c	2016-04-26 18:30:40.919080701 +0200
> @@ -2749,6 +2749,25 @@ combine_comparisons (location_t loc,
>  int
>  operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
>  {
> +  /* When checking, verify at the outermost operand_equal_p call that
> +     if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
> +     hash value.  */
> +  if (flag_checking && !(flags & OEP_NO_HASH_CHECK))
> +    {
> +      if (operand_equal_p (arg0, arg1, flags | OEP_NO_HASH_CHECK))
> +	{
> +	  inchash::hash hstate0 (0), hstate1 (0);
> +	  inchash::add_expr (arg0, hstate0, flags);
> +	  inchash::add_expr (arg1, hstate1, flags);
> +	  hashval_t h0 = hstate0.end ();
> +	  hashval_t h1 = hstate1.end ();
> +	  gcc_assert (h0 == h1);
> +	  return 1;
> +	}
> +      else
> +	return 0;
> +    }
> +
>    /* If either is ERROR_MARK, they aren't equal.  */
>    if (TREE_CODE (arg0) == ERROR_MARK || TREE_CODE (arg1) == ERROR_MARK
>        || TREE_TYPE (arg0) == error_mark_node
> 
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)