On Fri, 8 Dec 2023, Jakub Jelinek wrote:
> Hi!
>
> For casts from integers to floating point,
> simplify_float_conversion_using_ranges uses SCALAR_INT_TYPE_MODE
> and queries optabs on the optimization it wants to make.
>
> That doesn't really work for large/huge BITINT_TYPE, those have BLKmode
> which is not scalar int mode. Querying an optab is not useful for that
> either.
>
> I think it is best to just skip this optimization for those bitints,
> after all, bitint lowering uses ranges already to determine minimum
> precision for bitint operands of the integer to float casts.
>
> Bootstrapped/regrtested on x86_64-linux and i686-linux, ok for trunk?
OK.
> 2023-12-08 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/112901
> * vr-values.cc
> (simplify_using_ranges::simplify_float_conversion_using_ranges):
> Return false if rhs1 has BITINT_TYPE type with BLKmode TYPE_MODE.
>
> * gcc.dg/bitint-51.c: New test.
>
> --- gcc/vr-values.cc.jj 2023-09-06 17:28:24.240977329 +0200
> +++ gcc/vr-values.cc 2023-12-07 14:34:36.935121459 +0100
> @@ -1656,6 +1656,11 @@ simplify_using_ranges::simplify_float_co
> || vr.undefined_p ())
> return false;
>
> + /* The code below doesn't work for large/huge _BitInt, nor is really
> + needed for those, bitint lowering does use ranges already. */
> + if (TREE_CODE (TREE_TYPE (rhs1)) == BITINT_TYPE
> + && TYPE_MODE (TREE_TYPE (rhs1)) == BLKmode)
> + return false;
> /* First check if we can use a signed type in place of an unsigned. */
> scalar_int_mode rhs_mode = SCALAR_INT_TYPE_MODE (TREE_TYPE (rhs1));
> if (TYPE_UNSIGNED (TREE_TYPE (rhs1))
> --- gcc/testsuite/gcc.dg/bitint-51.c.jj 2023-12-07 15:10:20.500384705
> +0100
> +++ gcc/testsuite/gcc.dg/bitint-51.c 2023-12-07 15:09:54.159750006 +0100
> @@ -0,0 +1,14 @@
> +/* PR tree-optimization/112901 */
> +/* { dg-do compile { target bitint } } */
> +/* { dg-options "-O2" } */
> +
> +float f;
> +#if __BITINT_MAXWIDTH__ >= 256
> +_BitInt(256) i;
> +
> +void
> +foo (void)
> +{
> + f *= 4 * i;
> +}
> +#endif
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
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