On Wed, 11 Mar 2020, Jakub Jelinek wrote:
> Hi!
>
> As e.g. decimal_from_decnumber shows, the REAL_VALUE_TYPE representation
> contains a decimal128 embedded in ->sig only if it is rvc_normal, for
> other kinds like rvc_inf or rvc_nan, ->sig is ignored and everything is
> contained in the REAL_VALUE_TYPE flags (cl, sign, signalling and decimal).
> decimal_to_binary which is used when folding a decimal{32,64,128} constant
> to a binary floating point type ignores this and thus folds infinities and
> NaNs into +0.0.
> The following patch fixes that by only doing that for rvc_normal.
> Similarly to the binary to decimal folding, it goes through a string, in
> order to e.g. deal with canonical NaN mantissas, or binary float formats
> that don't support infinities and/or NaNs.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Thanks,
Richard.
> 2020-03-11 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/94111
> * dfp.c (decimal_to_binary): Only use decimal128ToString if from->cl
> is rvc_normal, otherwise use real_to_decimal to print the number to
> string.
>
> * gcc.dg/dfp/pr94111.c: New test.
>
> --- gcc/dfp.c.jj 2020-01-12 11:54:36.530411644 +0100
> +++ gcc/dfp.c 2020-03-10 12:32:07.246961100 +0100
> @@ -342,9 +342,13 @@ decimal_to_binary (REAL_VALUE_TYPE *to,
> const real_format *fmt)
> {
> char string[256];
> - const decimal128 *const d128 = (const decimal128 *) from->sig;
> -
> - decimal128ToString (d128, string);
> + if (from->cl == rvc_normal)
> + {
> + const decimal128 *const d128 = (const decimal128 *) from->sig;
> + decimal128ToString (d128, string);
> + }
> + else
> + real_to_decimal (string, from, sizeof (string), 0, 1);
> real_from_string3 (to, string, fmt);
> }
>
> --- gcc/testsuite/gcc.dg/dfp/pr94111.c.jj 2020-03-10 12:38:20.175451924
> +0100
> +++ gcc/testsuite/gcc.dg/dfp/pr94111.c 2020-03-10 12:38:12.832560341
> +0100
> @@ -0,0 +1,12 @@
> +/* PR middle-end/94111 */
> +/* { dg-do run } */
> +/* { dg-options "-O2" } */
> +
> +int
> +main ()
> +{
> + _Decimal32 d = (_Decimal32) __builtin_inff ();
> + if (!__builtin_isinf ((double) d))
> + __builtin_abort ();
> + return 0;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
