[Bug c/102989] Implement C2x's n2763 (_BitInt)

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102989

--- Comment #113 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:cb0119242317c2a6f3127b4acff6aadbfd1dfbc4

commit r14-4635-gcb0119242317c2a6f3127b4acff6aadbfd1dfbc4
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Sat Oct 14 09:35:44 2023 +0200

    middle-end: Allow _BitInt(65535) [PR102989]

    The following patch lifts further restrictions which limited _BitInt to at
    most 16319 bits up to 65535.
    The problem was mainly in INTEGER_CST representation, which had 3
    unsigned char members to describe lengths in number of 64-bit limbs, which
    it wanted to fit into 32 bits.  This patch removes the third one which was
    just a cache to save a few compile time cycles for wi::to_offset and
    enlarges the other two members to unsigned short.
    Furthermore, the same problem has been in some uses of trailing_wide_int*
    (in value-range-storage*) and value-range-storage* itself, while other
    uses of trailing_wide_int* have been fine (e.g. CONST_POLY_INT, where no
    constants will be larger than 3/5/9/11 limbs depending on target, so 255
    limit is plenty).  The patch turns all those length representations to be
    unsigned short for consistency, so value-range-storage* can handle even
    16320-65535 bits BITINT_TYPE ranges.  The cc1plus growth is about 16K,
    so not really significant for 38M .text section.

    Note, the reason for the new limit is
      unsigned int precision : 16;
    TYPE_PRECISION limit, if we wanted to overcome that, TYPE_PRECISION would
    need to use some other member for BITINT_TYPE from all the others and
    we could reach that way 4194239 limit (65535 * 64 - 1, again implied by
    INTEGER_CST and value-range-storage*).  Dunno if that is
    worth it or if it is something we want to do for GCC 14 though.

    2023-10-14  Jakub Jelinek  <jakub@redhat.com>

            PR c/102989
    gcc/
            * tree-core.h (struct tree_base): Remove int_length.offset
            member, change type of int_length.unextended and
int_length.extended
            from unsigned char to unsigned short.
            * tree.h (TREE_INT_CST_OFFSET_NUNITS): Remove.
            (wi::extended_tree <N>::get_len): Don't use
TREE_INT_CST_OFFSET_NUNITS,
            instead compute it at runtime from TREE_INT_CST_EXT_NUNITS and
            TREE_INT_CST_NUNITS.
            * tree.cc (wide_int_to_tree_1): Don't assert
            TREE_INT_CST_OFFSET_NUNITS value.
            (make_int_cst): Don't initialize TREE_INT_CST_OFFSET_NUNITS.
            * wide-int.h (WIDE_INT_MAX_ELTS): Change from 255 to 1024.
            (WIDEST_INT_MAX_ELTS): Change from 510 to 2048, adjust comment.
            (trailing_wide_int_storage): Change m_len type from unsigned char *
            to unsigned short *.
            (trailing_wide_int_storage::trailing_wide_int_storage): Change
second
            argument from unsigned char * to unsigned short *.
            (trailing_wide_ints): Change m_max_len type from unsigned char to
            unsigned short.  Change m_len element type from
            struct{unsigned char len;} to unsigned short.
            (trailing_wide_ints <N>::operator []): Remove .len from m_len
            accesses.
            * value-range-storage.h (irange_storage::lengths_address): Change
            return type from const unsigned char * to const unsigned short *.
            (irange_storage::write_lengths_address): Change return type from
            unsigned char * to unsigned short *.
            * value-range-storage.cc (irange_storage::write_lengths_address):
            Likewise.
            (irange_storage::lengths_address): Change return type from
            const unsigned char * to const unsigned short *.
            (write_wide_int): Change len argument type from unsigned char *&
            to unsigned short *&.
            (irange_storage::set_irange): Change len variable type from
            unsigned char * to unsigned short *.
            (read_wide_int): Change len argument type from unsigned char to
            unsigned short.  Use trailing_wide_int_storage <unsigned short>
            instead of trailing_wide_int_storage and
            trailing_wide_int <unsigned short> instead of trailing_wide_int.
            (irange_storage::get_irange): Change len variable type from
            unsigned char * to unsigned short *.
            (irange_storage::size): Multiply n by sizeof (unsigned short)
            in len_size variable initialization.
            (irange_storage::dump): Change len variable type from
            unsigned char * to unsigned short *.
    gcc/cp/
            * module.cc (trees_out::start, trees_in::start): Remove
            TREE_INT_CST_OFFSET_NUNITS handling.
    gcc/testsuite/
            * gcc.dg/bitint-38.c: Change into dg-do run test, in addition
            to checking the addition, division and right shift results at
compile
            time check it also at runtime.
            * gcc.dg/bitint-39.c: New test.