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Re: [PATCH] Fix canonicalization of addresses
> Indeed. But we canonicalize u - 2 to u + -2u. So how about the following
> (untested apart from on the testcase)?
>
> Index: fold-const.c
> ===================================================================
> --- fold-const.c (revision 143138)
> +++ fold-const.c (working copy)
> @@ -7439,7 +7439,17 @@ fold_plusminus_mult_expr (enum tree_code
> else if (TREE_CODE (arg1) == INTEGER_CST)
> {
> arg10 = build_one_cst (type);
> - arg11 = arg1;
> + /* As we canonicalize A - 2 to A + -2 get rid of that sign for
> + the purpose of this canonicalization. */
> + if (TREE_INT_CST_HIGH (arg1) == -1
> + && negate_expr_p (arg1)
> + && code == PLUS_EXPR)
> + {
> + arg11 = negate_expr (arg1);
> + code = MINUS_EXPR;
> + }
> + else
> + arg11 = arg1;
> }
> else
> {
This should indeed be equivalent to the first part of the patch.
--
Eric Botcazou