[Bug c/122731] Adding __builtin_bswapg for all types that is a multiple of 2 bytes (16 bits)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122731

--- Comment #2 from GCC 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:9ab08d664545bcea9164040e806385369fdaaf0e

commit r17-1367-g9ab08d664545bcea9164040e806385369fdaaf0e
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Jun 5 10:39:55 2026 +0200

    c, c++, bitintlower: Add __builtin_{bswap,bitreverse}g type-generic
builtins [PR122731]

    Clang has added recently type-generic versions of __builtin_bswap{16,32,64}
    and __builtin_bitreverse{8,16,32,64} builtins.

    The following patch adds them to GCC as well.
    Unlike the other __builtin_*g type-generic builtins, these are different in
    that the return type is not fixed (usually int or unsigned int), but is the
    same as the argument type, so these can't be handled as normal builtins
    and are handled in the C and C++ parsers instead.

    For consistency with the other __builtin_*g builtins, these only accept
    unsigned INTEGER_TYPE (or for C BITINT_TYPE) - users can use various ways
    to request unsigned variant of arbitrary types.  For __builtin_bswapg
    additionally this requires the type to have precision which is a multiple
of
    8 (unlike clang, which for some strange reason requires multiple of 16).

    2026-06-05  Jakub Jelinek  <jakub@redhat.com>

            PR c/122731
    gcc/
            * doc/extend.texi (__builtin_bswapg, __builtin_bitreverseg):
Document.
            * internal-fn.def (DEF_INTERNAL_INTSZ_FN): Define.
            (DEF_INTERNAL_INTSZ_EXT_FN): Define.
            (BSWAP): New internal fn.
            (BITREVERSE): Likewise.
            * internal-fn.h (expand_BSWAP, expand_BITREVERSE): Declare.
            * internal-fn.cc (DEF_INTERNAL_INTSZ_EXT_FN): Define.
            (expand_BSWAP, expand_BITREVERSE): New functions.
            * builtins.h (fold_build_builtin_bswapg_bitreverseg): Declare.
            * builtins.cc (fold_build_builtin_bswapg_bitreverseg): New
function.
            * wide-int.h (wi::bswap): Fix up docs that only multiple of 8 bits
            is required.
            * gimple-match-exports.cc (build_call_internal): Handle IFN_BSWAP
            and IFN_BITREVERSE.
            * gencfn-macros.cc (internal_fn_intsz_names): New variable.
            (intsz_suffixes): Likewise.
            (suffix_lists): Add intsz_suffixes.
            (main): Handle internal_fn_intsz_names.
            * match.pd (BSWAP, BITREVERSE): Remove.
            (popcount(bswap(x)) is popcount(x)): Use BSWAP BITREVERSE
            op lists.
            * tree-ssa-phiopt.cc (empty_bb_or_one_feeding_into_p): Use
            CASE_CFN_BSWAP and CASE_CFN_BITREVERSE.
            (cond_removal_in_builtin_zero_pattern): Likewise.
            * fold-const-call.cc (fold_const_call_ss): Likewise.
            * fold-const.cc (tree_call_nonnegative_p): Likewise.
            * gimple-lower-bitint.cc (struct bitint_large_huge): Declare
            lower_bswap_bitreverse method.
            (bitint_large_huge::lower_bswap_bitreverse): New method.
            (bitint_large_huge::lower_call): Call it.
            (build_bitint_stmt_ssa_conflicts): Set muldiv_p for IFN_BSWAP
            and IFN_BITREVERSE.
    gcc/c-family/
            * c-common.h (enum rid): Add RID_BUILTIN_BSWAPG and
            RID_BUILTIN_BITREVERSEG.
            * c-common.cc (c_common_reswords): Add __builtin_bswapg
            and __builtin_bitreverseg.
    gcc/c/
            * c-parser.cc (c_parser_postfix_expression): Parse
            __builtin_bswapg and __builtin_bitreverseg.
    gcc/cp/
            * parser.cc (cp_parser_postfix_expression): Parse
            __builtin_bswapg and __builtin_bitreverseg.
            * typeck.cc (build_x_bswapg_bitreverseg): New function.
            * cp-tree.h (build_x_bswapg_bitreverseg): Declare.
            * pt.cc (tsubst_expr): Handle IFN_BSWAP and IFN_BITREVERSE.
            * constexpr.cc (cxx_eval_internal_function): Likewise.
            (potential_constant_expression_1): Likewise.
            * cp-gimplify.cc (cp_gimplify_expr): Likewise.
    gcc/testsuite/
            * c-c++-common/builtin-bswapg-1.c: New test.
            * c-c++-common/builtin-bswapg-2.c: New test.
            * c-c++-common/builtin-bswapg-3.c: New test.
            * c-c++-common/builtin-bitreverseg-1.c: New test.
            * c-c++-common/builtin-bitreverseg-2.c: New test.

    Reviewed-by: Richard Biener <rguenth@suse.de>
    Reviewed-by: Joseph Myers <josmyers@redhat.com>
    Reviewed-by: Jason Merrill <jason@redhat.com>