On Wed, 20 Mar 2024, Jakub Jelinek wrote:
> Hi!
>
> For the m_var_msb (aka left shift) case of large/huge _BitInt bitfield loads
> handle_load adds a PHI node, but I forgot to actually update the temporary
> the code later on uses, so the PHI result was unused and the code
> incorrectly used something that wasn't valid SSA form.
> In particular, we emitted
> if (_29 != 2)
> goto <bb 4>; [80.00%]
> else
> goto <bb 5>; [20.00%]
>
> <bb 4> [local count: 1073741824]:
> _33 = VIEW_CONVERT_EXPR<unsigned long[3]>(s.D.2771)[_31];
>
> <bb 5> [local count: 1073741824]:
> # _34 = PHI <_33(4), 0(3)>
> _35 = _32 >> 31;
> _36 = _33 << 33;
> _37 = _36 | _35;
> _38 = _37 << _19;
> where instead of _33 the _36 def stmt should be using _34.
>
> Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> trunk?
OK.
Richard.
> 2024-03-20 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/114365
> * gimple-lower-bitint.cc (bitint_large_huge::handle_load): When adding
> a PHI node, set iv2 to its result afterwards.
>
> * gcc.dg/bitint-102.c: New test.
>
> --- gcc/gimple-lower-bitint.cc.jj 2024-03-16 15:15:22.000000000 +0100
> +++ gcc/gimple-lower-bitint.cc 2024-03-19 10:45:31.006649671 +0100
> @@ -2026,6 +2026,7 @@ bitint_large_huge::handle_load (gimple *
> add_phi_arg (phi, build_zero_cst (m_limb_type),
> edge_false, UNKNOWN_LOCATION);
> m_gsi = gsi_after_labels (edge_true->dest);
> + iv2 = iv3;
> }
> }
> g = gimple_build_assign (make_ssa_name (m_limb_type), RSHIFT_EXPR,
> --- gcc/testsuite/gcc.dg/bitint-102.c.jj 2024-03-19 10:54:15.317327543
> +0100
> +++ gcc/testsuite/gcc.dg/bitint-102.c 2024-03-19 10:53:57.162580193 +0100
> @@ -0,0 +1,18 @@
> +/* PR tree-optimization/114365 */
> +/* { dg-do compile { target bitint } } */
> +/* { dg-options "-std=c23 -O2" } */
> +
> +struct S {
> + int : 31;
> +#if __BITINT_MAXWIDTH__ >= 129
> + _BitInt(129) b : 129;
> +#else
> + _BitInt(63) b : 63;
> +#endif
> +} s;
> +
> +void
> +foo (int a)
> +{
> + s.b <<= a;
> +}
>
> 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)
