On Sat, 13 Jan 2024, Jakub Jelinek wrote:
> Hi!
>
> As the testcase shows, the INTEGER_CST handling in handle_operand_addr
> (i.e. what is used when passing address of an integer to a bitint library
> routine) wasn't correct. If the minimum precision to represent an
> INTEGER_CST is smaller or equal to limb_prec, the code correctly uses
> m_limb_type; if the minimum precision of a _BitInt INTEGER_CST is large
> enough such that the bitint is middle, large or huge, everything is fine
> too. But the code wasn't handling correctly e.g. __int128 constants which
> need more than limb_prec bits or _BitInt constants which on the architecture
> are considered small (say have DImode limb_mode, TImode abi_limb_mode and
> for [65, 128] bits use TImode scalar like the proposed aarch64 patch).
> Best would be to use an array of 2/3/4 limbs in that case, but we'd need to
> convert the INTEGER_CST to a CONSTRUCTOR in the right endianity etc.,
> so the code was using mid_min_prec to enforce a middle _BitInt precision.
> Except that mid_min_prec can be 0 and not computed yet, or it doesn't have
> to be the smallest middle _BitInt precision, just the smallest so far
> encountered. So, on the testcase one possibility was that it used precision
> 65 from mid_min_prec, even when the INTEGER_CST actually needed larger
> minimum precision (96 bits at least), or crashed when mid_min_prec was 0.
>
> The patch fixes it in 2 hunks, the first makes sure we actually try to
> create a BITINT_TYPE for the > limb_prec cases like __int128, and the second
> instead of using mid_min_prec attempts to increase mp precision until it
> isn't small anymore.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
> 2024-01-13 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/113361
> * gimple-lower-bitint.cc (bitint_large_huge::handle_operand_addr):
> Fix up determination of the type for > limb_prec constants.
>
> * gcc.dg/torture/bitint-47.c: New test.
>
> --- gcc/gimple-lower-bitint.cc.jj 2024-01-12 11:23:12.000000000 +0100
> +++ gcc/gimple-lower-bitint.cc 2024-01-13 00:18:19.255889866 +0100
> @@ -2227,7 +2227,9 @@ bitint_large_huge::handle_operand_addr (
> mp = CEIL (min_prec, limb_prec) * limb_prec;
> if (mp == 0)
> mp = 1;
> - if (mp >= (unsigned) TYPE_PRECISION (TREE_TYPE (op)))
> + if (mp >= (unsigned) TYPE_PRECISION (TREE_TYPE (op))
> + && (TREE_CODE (TREE_TYPE (op)) == BITINT_TYPE
> + || TYPE_PRECISION (TREE_TYPE (op)) <= limb_prec))
> type = TREE_TYPE (op);
> else
> type = build_bitint_type (mp, 1);
> @@ -2237,11 +2239,15 @@ bitint_large_huge::handle_operand_addr (
> if (TYPE_PRECISION (type) <= limb_prec)
> type = m_limb_type;
> else
> - /* This case is for targets which e.g. have 64-bit
> - limb but categorize up to 128-bits _BitInts as
> - small. We could use type of m_limb_type[2] and
> - similar instead to save space. */
> - type = build_bitint_type (mid_min_prec, 1);
> + {
> + while (bitint_precision_kind (mp) == bitint_prec_small)
> + mp += limb_prec;
> + /* This case is for targets which e.g. have 64-bit
> + limb but categorize up to 128-bits _BitInts as
> + small. We could use type of m_limb_type[2] and
> + similar instead to save space. */
> + type = build_bitint_type (mp, 1);
> + }
> }
> if (prec_stored)
> {
> --- gcc/testsuite/gcc.dg/torture/bitint-47.c.jj 2024-01-13
> 00:23:40.627562314 +0100
> +++ gcc/testsuite/gcc.dg/torture/bitint-47.c 2024-01-13 00:25:35.571025508
> +0100
> @@ -0,0 +1,31 @@
> +/* PR tree-optimization/113361 */
> +/* { dg-do run { target { bitint && int128 } } } */
> +/* { dg-options "-std=gnu23" } */
> +/* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */
> +/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
> +
> +#if __BITINT_MAXWIDTH__ >= 129
> +int
> +foo (_BitInt(65) x)
> +{
> + return __builtin_mul_overflow_p ((__int128) 0xffffffff << 64, x,
> (_BitInt(129)) 0);
> +}
> +
> +int
> +bar (_BitInt(63) x)
> +{
> + return __builtin_mul_overflow_p ((__int128) 0xffffffff << 64, x,
> (_BitInt(129)) 0);
> +}
> +#endif
> +
> +int
> +main ()
> +{
> +#if __BITINT_MAXWIDTH__ >= 129
> + if (!foo (5167856845))
> + __builtin_abort ();
> + if (!bar (5167856845))
> + __builtin_abort ();
> +#endif
> + return 0;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
