> Am 22.12.2023 um 09:12 schrieb Jakub Jelinek <ja...@redhat.com>:
>
> Hi!
>
> My recent change to use m_data[save_data_cnt] instead of
> m_data[save_data_cnt + 1] when inside of a loop (m_bb is non-NULL)
> broke the following testcase. When we create a PHI node on the loop
> using prepare_data_in_out, both m_data[save_data_cnt{, + 1}] are
> computed and the fix was right, but there are also cases when we in
> a loop (m_bb non-NULL) emit a nested cast with too few limbs and
> then just use constant indexes for all accesses - in that case
> only m_data[save_data_cnt + 1] is initialized and m_data[save_data_cnt]
> is NULL. In those cases, we want to use the former.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Ok
> 2023-12-22 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/113102
> * gimple-lower-bitint.cc (bitint_large_huge::handle_cast): Only
> use m_data[save_data_cnt] if it is non-NULL.
>
> * gcc.dg/bitint-58.c: New test.
>
> --- gcc/gimple-lower-bitint.cc.jj 2023-12-21 11:13:32.000000000 +0100
> +++ gcc/gimple-lower-bitint.cc 2023-12-21 13:28:56.953120687 +0100
> @@ -1491,7 +1491,7 @@ bitint_large_huge::handle_cast (tree lhs
> m_data_cnt = tree_to_uhwi (m_data[save_data_cnt + 2]);
> if (TYPE_UNSIGNED (rhs_type))
> t = build_zero_cst (m_limb_type);
> - else if (m_bb)
> + else if (m_bb && m_data[save_data_cnt])
> t = m_data[save_data_cnt];
> else
> t = m_data[save_data_cnt + 1];
> --- gcc/testsuite/gcc.dg/bitint-58.c.jj 2023-12-21 13:33:25.882383838 +0100
> +++ gcc/testsuite/gcc.dg/bitint-58.c 2023-12-21 13:32:54.408821172 +0100
> @@ -0,0 +1,31 @@
> +/* PR tree-optimization/113102 */
> +/* { dg-do compile { target bitint } } */
> +/* { dg-options "-std=c23 -O2" } */
> +
> +_BitInt(3) a;
> +#if __BITINT_MAXWIDTH__ >= 4097
> +_BitInt(8) b;
> +_BitInt(495) c;
> +_BitInt(513) d;
> +_BitInt(1085) e;
> +_BitInt(4096) f;
> +
> +void
> +foo (void)
> +{
> + a -= (_BitInt(4097)) d >> b;
> +}
> +
> +void
> +bar (void)
> +{
> + __builtin_sub_overflow ((_BitInt(767)) c >> e, 0, &a);
> +}
> +
> +void
> +baz (void)
> +{
> + _BitInt(768) x = (_BitInt(257))f;
> + b /= x >> 0 / 0; /* { dg-warning "division by zero" } */
> +}
> +#endif
>
> Jakub
>
