On Thu, Jan 11, 2024 at 12:12:59PM +0100, Jakub Jelinek wrote:
> So, the problem was that in 2 spots I was comparing TYPE_SIZE of large/huge
> BITINT_TYPEs to determine if it can be handled cheaply.
> On x86_64 with limb_mode == abi_limb_mode (both DImode) that works fine,
> if TYPE_SIZE is equal, it means it has the same number of limbs.
> But on aarch64 TYPE_SIZE of say _BitInt(135) and _BitInt(193) is the same,
> both are 256-bit storage, but because DImode is used as limb_mode, the
> former actually needs just 3 limbs, while the latter needs 4 limbs.
> And limb_access_type was asserting that we don't try to access 4th limb
> on types which actually have a precision which needs just 3 limbs.
>
> The following patch (so far tested on x86_64 with all the bitint tests plus
> on the bitint-7.c testcase in a cross to aarch64) should fix that.
>
> Note, for the info.extended targets (currently none, but I think arm 32-bit
> in the ABI is meant like that), we'll need to do something different,
> because the upper bits aren't just padding and should be zero/sign extended,
> so if we say have limb_mode SImode, abi_limb_mode DImode, we'll need to
> treat _BitInt(135) not as 5 SImode limbs, but 6. For !info.extended targets
> I think treating _BitInt(135) as 3 DImode limbs rather than 4 is fine.
>
> 2024-01-11 Jakub Jelinek <ja...@redhat.com>
>
> * gimple-lower-bitint.cc (mergeable_op): Instead of comparing
> TYPE_SIZE (t) of large/huge BITINT_TYPEs, compare
> CEIL (TYPE_PRECISION (t), limb_prec).
> (bitint_large_huge::handle_cast): Likewise.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> --- gcc/gimple-lower-bitint.cc.jj 2024-01-08 13:58:21.448176859 +0100
> +++ gcc/gimple-lower-bitint.cc 2024-01-11 11:46:49.147779946 +0100
> @@ -231,7 +231,8 @@ mergeable_op (gimple *stmt)
> && TREE_CODE (rhs_type) == BITINT_TYPE
> && bitint_precision_kind (lhs_type) >= bitint_prec_large
> && bitint_precision_kind (rhs_type) >= bitint_prec_large
> - && tree_int_cst_equal (TYPE_SIZE (lhs_type), TYPE_SIZE (rhs_type)))
> + && (CEIL (TYPE_PRECISION (lhs_type), limb_prec)
> + == CEIL (TYPE_PRECISION (rhs_type), limb_prec)))
> {
> if (TYPE_PRECISION (rhs_type) >= TYPE_PRECISION (lhs_type))
> return true;
> @@ -1263,8 +1264,8 @@ bitint_large_huge::handle_cast (tree lhs
> if m_upwards_2limb * limb_prec is equal to
> lhs precision that is not the case. */
> || (!m_var_msb
> - && tree_int_cst_equal (TYPE_SIZE (rhs_type),
> - TYPE_SIZE (lhs_type))
> + && (CEIL (TYPE_PRECISION (lhs_type), limb_prec)
> + == CEIL (TYPE_PRECISION (rhs_type), limb_prec))
> && (!m_upwards_2limb
> || (m_upwards_2limb * limb_prec
> < TYPE_PRECISION (lhs_type)))))
>
> Jakub
Jakub
