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Matt Turner
3382beeda2
gcc supports __int128 on Alpha, and the 64x64 to 128-bit multiply that the users in the scheduler and in lib/ care about maps onto mulq/umulh rather than an out-of-line libgcc helper. Variable 128-bit shifts are another matter. gcc open-codes them when optimizing for speed, but with CONFIG_CC_OPTIMIZE_FOR_SIZE=y it calls the libgcc routines __ashlti3, __ashrti3 and __lshrti3 instead. The kernel does not link against libgcc, so provide the three helpers in C, as s390 does, and export them for modules. They are built into the kernel proper rather than lib.a so the exports are present even when nothing built in references them. Like the s390 versions they are marked noinstr, since the compiler may emit calls to them from noinstr code. Gate the select on CC_HAS_INT128 as the other 64-bit architectures do. Assisted-by: Claude:claude-opus-5-5 Signed-off-by: Matt Turner <mattst88@gmail.com> Tested-by: Magnus Lindholm <linmag7@gmail.com> Reviewed-by: Magnus Lindholm <linmag7@gmail.com> Link: https://lore.kernel.org/r/20261017174007.695344-1-mattst88@gmail.com Signed-off-by: Magnus Lindholm <linmag7@gmail.com>