[Bug target/65373] New: [SH] Implement bit counting built-in functions

[olegendo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65373

            Bug ID: 65373
           Summary: [SH] Implement bit counting built-in functions
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: olegendo at gcc dot gnu.org
            Target: sh*-*-*

In linux/arch/sh/include/asm there's following code:

static inline unsigned long ffz(unsigned long word)
{
    unsigned long result;

    __asm__("1:\n\t"
        "shlr    %1\n\t"
        "bt/s    1b\n\t"
        " add    #1, %0"
        : "=r" (result), "=r" (word)
        : "0" (~0L), "1" (word)
        : "t");
    return result;
}

static inline unsigned long __ffs(unsigned long word)
{
    unsigned long result;

    __asm__("1:\n\t"
        "shlr    %1\n\t"
        "bf/s    1b\n\t"
        " add    #1, %0"
        : "=r" (result), "=r" (word)
        : "0" (~0L), "1" (word)
        : "t");
    return result;
}

The respective GCC built-in functions such as __builtin_ffs should be
implemented.  The code snippets above result in quite compact code, which could
be used for -Os.

Otherwise, it could be interesting to see whether it makes sense to expand some
inline code as found in include/longlong.h.