https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102989
--- Comment #101 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:2ce182e258d3ab11310442d5f4dd1d063018aca9 commit r14-3750-g2ce182e258d3ab11310442d5f4dd1d063018aca9 Author: Jakub Jelinek <ja...@redhat.com> Date: Wed Sep 6 17:33:05 2023 +0200 libgcc _BitInt support [PR102989] This patch adds the library helpers for multiplication, division + modulo and casts from and to floating point (both binary and decimal). As described in the intro, the first step is try to reduce further the passed in precision by skipping over most significant limbs with just zeros or sign bit copies. For multiplication and division I've implemented a simple algorithm, using something smarter like Karatsuba or Toom N-Way might be faster for very large _BitInts (which we don't support right now anyway), but could mean more code in libgcc, which maybe isn't what people are willing to accept. For the to/from floating point conversions the patch uses soft-fp, because it already has tons of handy macros which can be used for that. In theory it could be implemented using {,unsigned} long long or {,unsigned} __int128 to/from floating point conversions with some frexp before/after, but at that point we already need to force it into integer registers and analyze it anyway. Plus, for 32-bit arches there is no __int128 that could be used for XF/TF mode stuff. I know that soft-fp is owned by glibc and I think the op-common.h change should be propagated there, but the bitint stuff is really GCC specific and IMHO doesn't belong into the glibc copy. 2023-09-06 Jakub Jelinek <ja...@redhat.com> PR c/102989 libgcc/ * config/aarch64/t-softfp (softfp_extras): Use += rather than :=. * config/i386/64/t-softfp (softfp_extras): Likewise. * config/i386/libgcc-glibc.ver (GCC_14.0.0): Export _BitInt support routines. * config/i386/t-softfp (softfp_extras): Add fixxfbitint and bf, hf and xf mode floatbitint. (CFLAGS-floatbitintbf.c, CFLAGS-floatbitinthf.c): Add -msse2. * config/riscv/t-softfp32 (softfp_extras): Use += rather than :=. * config/rs6000/t-e500v1-fp (softfp_extras): Likewise. * config/rs6000/t-e500v2-fp (softfp_extras): Likewise. * config/t-softfp (softfp_floatbitint_funcs): New. (softfp_bid_list): New. (softfp_func_list): Add sf and df mode from and to _BitInt libcalls. (softfp_bid_file_list): New. (LIB2ADD_ST): Add $(softfp_bid_file_list). * config/t-softfp-sfdftf (softfp_extras): Add fixtfbitint and floatbitinttf. * config/t-softfp-tf (softfp_extras): Likewise. * libgcc2.c (bitint_reduce_prec): New inline function. (BITINT_INC, BITINT_END): Define. (bitint_mul_1, bitint_addmul_1): New helper functions. (__mulbitint3): New function. (bitint_negate, bitint_submul_1): New helper functions. (__divmodbitint4): New function. * libgcc2.h (LIBGCC2_UNITS_PER_WORD): When building _BitInt support libcalls, redefine depending on __LIBGCC_BITINT_LIMB_WIDTH__. (__mulbitint3, __divmodbitint4): Declare. * libgcc-std.ver.in (GCC_14.0.0): Export _BitInt support routines. * Makefile.in (lib2funcs): Add _mulbitint3. (LIB2_DIVMOD_FUNCS): Add _divmodbitint4. * soft-fp/bitint.h: New file. * soft-fp/fixdfbitint.c: New file. * soft-fp/fixsfbitint.c: New file. * soft-fp/fixtfbitint.c: New file. * soft-fp/fixxfbitint.c: New file. * soft-fp/floatbitintbf.c: New file. * soft-fp/floatbitintdf.c: New file. * soft-fp/floatbitinthf.c: New file. * soft-fp/floatbitintsf.c: New file. * soft-fp/floatbitinttf.c: New file. * soft-fp/floatbitintxf.c: New file. * soft-fp/op-common.h (_FP_FROM_INT): Add support for rsize up to 4 * _FP_W_TYPE_SIZE rather than just 2 * _FP_W_TYPE_SIZE. * soft-fp/bitintpow10.c: New file. * soft-fp/fixsdbitint.c: New file. * soft-fp/fixddbitint.c: New file. * soft-fp/fixtdbitint.c: New file. * soft-fp/floatbitintsd.c: New file. * soft-fp/floatbitintdd.c: New file. * soft-fp/floatbitinttd.c: New file.
