On Fri, 17 Feb 2017, Marek Polacek wrote:
> For "(int) -x", which is a NOP_EXPR, negate_expr_p returns true, which means
> that fold_negate_expr cannot return NULL_TREE. But that's what happens here,
> leading to a crash in fold_build2. negate_expr_p has (as well as negate_expr)
> STRIP_SIGN_NOPS, so the "(int) -x" becomes "-x", but fold_negate_expr doesn't
> have any STRIP_SIGN_NOPS. Richi suggested to add a wrapper for
> fold_negate_expr
> that strips/restores such NOP_EXPRs, much like negate_expr, which is what this
> patch does.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk? And 6 after a while?
Ok.
Thanks,
Richard.
> 2017-02-16 Marek Polacek <pola...@redhat.com>
>
> PR middle-end/79536
> * fold-const.c (fold_negate_expr_1): Renamed from fold_negate_expr.
> (fold_negate_expr): New wrapper.
>
> * gcc.dg/torture/pr79536.c: New test.
>
> diff --git gcc/fold-const.c gcc/fold-const.c
> index a8bb8af..ad4770b 100644
> --- gcc/fold-const.c
> +++ gcc/fold-const.c
> @@ -139,6 +139,7 @@ static tree fold_relational_const (enum tree_code, tree,
> tree, tree);
> static tree fold_convert_const (enum tree_code, tree, tree);
> static tree fold_view_convert_expr (tree, tree);
> static bool vec_cst_ctor_to_array (tree, tree *);
> +static tree fold_negate_expr (location_t, tree);
>
>
> /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
> @@ -522,7 +523,7 @@ negate_expr_p (tree t)
> returned. */
>
> static tree
> -fold_negate_expr (location_t loc, tree t)
> +fold_negate_expr_1 (location_t loc, tree t)
> {
> tree type = TREE_TYPE (t);
> tree tem;
> @@ -533,7 +534,7 @@ fold_negate_expr (location_t loc, tree t)
> case BIT_NOT_EXPR:
> if (INTEGRAL_TYPE_P (type))
> return fold_build2_loc (loc, PLUS_EXPR, type, TREE_OPERAND (t, 0),
> - build_one_cst (type));
> + build_one_cst (type));
> break;
>
> case INTEGER_CST:
> @@ -581,14 +582,14 @@ fold_negate_expr (location_t loc, tree t)
> case COMPLEX_EXPR:
> if (negate_expr_p (t))
> return fold_build2_loc (loc, COMPLEX_EXPR, type,
> - fold_negate_expr (loc, TREE_OPERAND (t, 0)),
> - fold_negate_expr (loc, TREE_OPERAND (t, 1)));
> + fold_negate_expr (loc, TREE_OPERAND (t, 0)),
> + fold_negate_expr (loc, TREE_OPERAND (t, 1)));
> break;
>
> case CONJ_EXPR:
> if (negate_expr_p (t))
> return fold_build1_loc (loc, CONJ_EXPR, type,
> - fold_negate_expr (loc, TREE_OPERAND (t, 0)));
> + fold_negate_expr (loc, TREE_OPERAND (t, 0)));
> break;
>
> case NEGATE_EXPR:
> @@ -605,7 +606,7 @@ fold_negate_expr (location_t loc, tree t)
> {
> tem = negate_expr (TREE_OPERAND (t, 1));
> return fold_build2_loc (loc, MINUS_EXPR, type,
> - tem, TREE_OPERAND (t, 0));
> + tem, TREE_OPERAND (t, 0));
> }
>
> /* -(A + B) -> (-A) - B. */
> @@ -613,7 +614,7 @@ fold_negate_expr (location_t loc, tree t)
> {
> tem = negate_expr (TREE_OPERAND (t, 0));
> return fold_build2_loc (loc, MINUS_EXPR, type,
> - tem, TREE_OPERAND (t, 1));
> + tem, TREE_OPERAND (t, 1));
> }
> }
> break;
> @@ -623,7 +624,7 @@ fold_negate_expr (location_t loc, tree t)
> if (!HONOR_SIGN_DEPENDENT_ROUNDING (element_mode (type))
> && !HONOR_SIGNED_ZEROS (element_mode (type)))
> return fold_build2_loc (loc, MINUS_EXPR, type,
> - TREE_OPERAND (t, 1), TREE_OPERAND (t, 0));
> + TREE_OPERAND (t, 1), TREE_OPERAND (t, 0));
> break;
>
> case MULT_EXPR:
> @@ -638,11 +639,11 @@ fold_negate_expr (location_t loc, tree t)
> tem = TREE_OPERAND (t, 1);
> if (negate_expr_p (tem))
> return fold_build2_loc (loc, TREE_CODE (t), type,
> - TREE_OPERAND (t, 0), negate_expr (tem));
> + TREE_OPERAND (t, 0), negate_expr (tem));
> tem = TREE_OPERAND (t, 0);
> if (negate_expr_p (tem))
> return fold_build2_loc (loc, TREE_CODE (t), type,
> - negate_expr (tem), TREE_OPERAND (t, 1));
> + negate_expr (tem), TREE_OPERAND (t, 1));
> }
> break;
>
> @@ -715,6 +716,19 @@ fold_negate_expr (location_t loc, tree t)
> return NULL_TREE;
> }
>
> +/* A wrapper for fold_negate_expr_1. */
> +
> +static tree
> +fold_negate_expr (location_t loc, tree t)
> +{
> + tree type = TREE_TYPE (t);
> + STRIP_SIGN_NOPS (t);
> + tree tem = fold_negate_expr_1 (loc, t);
> + if (tem == NULL_TREE)
> + return NULL_TREE;
> + return fold_convert_loc (loc, type, tem);
> +}
> +
> /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
> negated in a simpler way. Also allow for T to be NULL_TREE, in which case
> return NULL_TREE. */
> diff --git gcc/testsuite/gcc.dg/torture/pr79536.c
> gcc/testsuite/gcc.dg/torture/pr79536.c
> index e69de29..6f05ca7 100644
> --- gcc/testsuite/gcc.dg/torture/pr79536.c
> +++ gcc/testsuite/gcc.dg/torture/pr79536.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +
> +typedef int A;
> +int
> +fn1 (A x, A y)
> +{
> + if ((x + (x - y) * 1i) != -(-x + (y - x) * 1i))
> + return 1;
> + return 0;
> +}
>
> Marek
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
