On Sat, Jul 1, 2023 at 10:23 AM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The problem here is we might produce some values out of the type's
> min/max (and/or valid values, e.g. signed booleans). The fix is to
> use an integer type which has the same precision and signedness
> as the original type.
>
> Note two_value_replacement in phiopt had the same issue in previous
> versions; though I don't know if a problem will show up there.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu.
OK.
> gcc/ChangeLog:
>
> PR tree-optimization/110487
> * match.pd (a !=/== CST1 ? CST2 : CST3): Always
> build a nonstandard integer and use that.
> ---
> gcc/match.pd | 24 ++++++++----------------
> 1 file changed, 8 insertions(+), 16 deletions(-)
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index a0d114f6a16..9748ad8466e 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -4797,24 +4797,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> tree type1;
> if ((eqne == EQ_EXPR) ^ (wi::to_wide (@1) == min))
> std::swap (arg0, arg1);
> - if (TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (type))
> - {
> - /* Avoid performing the arithmetics in bool type which has
> different
> - semantics, otherwise prefer unsigned types from the two with
> - the same precision. */
> - if (TREE_CODE (TREE_TYPE (arg0)) == BOOLEAN_TYPE
> - || !TYPE_UNSIGNED (type))
> - type1 = TREE_TYPE (@0);
> - else
> - type1 = TREE_TYPE (arg0);
> - }
> - else if (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (type))
> + if (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (type))
> type1 = TREE_TYPE (@0);
> else
> type1 = type;
> - min = wide_int::from (min, TYPE_PRECISION (type1),
> + auto prec = TYPE_PRECISION (type1);
> + auto unsign = TYPE_UNSIGNED (type1);
> + type1 = build_nonstandard_integer_type (prec, unsign);
> + min = wide_int::from (min, prec,
> TYPE_SIGN (TREE_TYPE (@0)));
> - wide_int a = wide_int::from (wi::to_wide (arg0), TYPE_PRECISION
> (type1),
> + wide_int a = wide_int::from (wi::to_wide (arg0), prec,
> TYPE_SIGN (type));
> enum tree_code code;
> wi::overflow_type ovf;
> @@ -4822,7 +4814,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> {
> code = PLUS_EXPR;
> a -= min;
> - if (!TYPE_UNSIGNED (type1))
> + if (!unsign)
> {
> /* lhs is known to be in range [min, min+1] and we want to add
> a
> to it. Check if that operation can overflow for those 2
> values
> @@ -4836,7 +4828,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> {
> code = MINUS_EXPR;
> a += min;
> - if (!TYPE_UNSIGNED (type1))
> + if (!unsign)
> {
> /* lhs is known to be in range [min, min+1] and we want to
> subtract
> it from a. Check if that operation can overflow for those 2
> --
> 2.31.1
>
