On August 31, 2019 7:41:17 PM GMT+02:00, Jakub Jelinek <ja...@redhat.com> wrote:
>On Sat, Aug 31, 2019 at 07:23:35PM +0200, Richard Biener wrote:
>> Hmm, couldn't we make range_check_type_for take an argument whether
>signed
>> or unsigned type is required? That is, what do we do if the caller
>wants
>> a signed type? Leaving it unspecified what the function returns is
>odd.
>
>I think we never want specially signed type, either we don't care
>whether it
>is signed or not, in that case we want just some type that wraps
>around, or we
>do want an unsigned type.
So why not always return an unsigned type then by telling type_for_size?
>
>So something like below, with using range_check_type (x, true) in some
>places.
>
>Note it will be more compile time expensive than just calling
>unsigned_type_for after the range_check_type call, due to all the
>wrap-around verification it does.
>
>--- gcc/fold-const.h.jj 2019-08-08 08:34:28.010306157 +0200
>+++ gcc/fold-const.h 2019-08-31 19:39:13.436366420 +0200
>@@ -182,7 +182,7 @@ extern bool tree_expr_nonnegative_warnv_
> extern tree make_range (tree, int *, tree *, tree *, bool *);
>extern tree make_range_step (location_t, enum tree_code, tree, tree,
>tree,
> tree *, tree *, int *, bool *);
>-extern tree range_check_type (tree);
>+extern tree range_check_type (tree, bool = false);
>extern tree build_range_check (location_t, tree, tree, int, tree,
>tree);
> extern bool merge_ranges (int *, tree *, tree *, int, tree, tree, int,
> tree, tree);
>--- gcc/fold-const.c.jj 2019-08-27 12:26:39.303884758 +0200
>+++ gcc/fold-const.c 2019-08-31 19:39:06.235470312 +0200
>@@ -4930,10 +4930,12 @@ maskable_range_p (const_tree low, const_
> }
> >
>/* Helper routine for build_range_check and match.pd. Return the type
>to
>- perform the check or NULL if it shouldn't be optimized. */
>+ perform the check or NULL if it shouldn't be optimized.
>+ If UNSIGNEDP is true, the returned type must be unsigned, otherwise
>+ it can be some INTEGER_TYPE that wraps around. */
>
> tree
>-range_check_type (tree etype)
>+range_check_type (tree etype, bool unsignedp)
> {
>/* First make sure that arithmetics in this type is valid, then make
>sure
> that it wraps around. */
>@@ -4941,7 +4943,8 @@ range_check_type (tree etype)
> etype = lang_hooks.types.type_for_size (TYPE_PRECISION (etype),
> TYPE_UNSIGNED (etype));
>
>- if (TREE_CODE (etype) == INTEGER_TYPE && !TYPE_OVERFLOW_WRAPS
>(etype))
>+ if (unsignedp
>+ || (TREE_CODE (etype) == INTEGER_TYPE && !TYPE_OVERFLOW_WRAPS
>(etype)))
> {
> tree utype, minv, maxv;
>
>
>
> Jakub
