Re: [PATCH, 4.3] Fix PR 37861 - Remove bogus "subscript is above array bounds" warning

[Richard Guenther <rguenther at suse dot de>]

On Sat, 28 Feb 2009, Martin Jambor wrote:

> Hi,
> 
> the fix have been on trunk for a few months now and so I have prepared
> a fix for 4.3 against which the bug was filed so that I can close it.
> 
> I have bootstapped  and tested the patch without  any problems, I have
> also verified it does fix the problem.
> 
> OK for the 4.3 branch?

Ok.

Thanks,
Richard.

> Thansk,
> 
> Martin
> 
> 
> 2009-02-29  Martin Jambor  <mjambor@suse.cz>
> 
> 	PR middle-end/37861
> 	* tree-ssa-forwprop.c 
> 	(forward_propagate_addr_into_variable_array_index): Check that the
> 	offset is not computed from a MULT_EXPR if element size is one.
> 
> Index: gcc/tree-ssa-forwprop.c
> ===================================================================
> --- gcc/tree-ssa-forwprop.c	(revision 144464)
> +++ gcc/tree-ssa-forwprop.c	(working copy)
> @@ -487,28 +487,36 @@
>  forward_propagate_addr_into_variable_array_index (tree offset,
>  						  tree def_rhs, tree use_stmt)
>  {
> -  tree index;
> +  tree index, offset_def;
>  
> -  /* Try to find an expression for a proper index.  This is either
> -     a multiplication expression by the element size or just the
> -     ssa name we came along in case the element size is one.  */
> +  /* Get the offset's defining statement.  */
> +  offset_def = SSA_NAME_DEF_STMT (offset);
> +
> +  /* Try to find an expression for a proper index.  This is either a
> +     multiplication expression by the element size or just the ssa name we came
> +     along in case the element size is one. In that case, however, we do not
> +     allow multiplications because they can be computing index to a higher
> +     level dimension (PR 37861). */
>    if (integer_onep (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (def_rhs)))))
> -    index = offset;
> +    {
> +      if (TREE_CODE (offset_def) == GIMPLE_MODIFY_STMT
> +	  && TREE_CODE (GIMPLE_STMT_OPERAND (offset_def, 1)) == MULT_EXPR)
> +	return false;
> +
> +      index = offset;
> +    }
>    else
>      {
> -      /* Get the offset's defining statement.  */
> -      offset = SSA_NAME_DEF_STMT (offset);
> -
>        /* The statement which defines OFFSET before type conversion
>           must be a simple GIMPLE_MODIFY_STMT.  */
> -      if (TREE_CODE (offset) != GIMPLE_MODIFY_STMT)
> +      if (TREE_CODE (offset_def) != GIMPLE_MODIFY_STMT)
>  	return false;
>  
>        /* The RHS of the statement which defines OFFSET must be a
>  	 multiplication of an object by the size of the array elements. 
>  	 This implicitly verifies that the size of the array elements
>  	 is constant.  */
> -     offset = GIMPLE_STMT_OPERAND (offset, 1);
> +     offset = GIMPLE_STMT_OPERAND (offset_def, 1);
>        if (TREE_CODE (offset) != MULT_EXPR
>  	  || TREE_CODE (TREE_OPERAND (offset, 1)) != INTEGER_CST
>  	  || !simple_cst_equal (TREE_OPERAND (offset, 1),
> 
> 

-- 
Richard Guenther <rguenther@suse.de>
Novell / SUSE Labs
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