[Bug other/55899] New: GCC should provide built-ins in <stdint.h> data types flavor/version/variation

[yann at droneaud dot fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55899

             Bug #: 55899
           Summary: GCC should provide built-ins in <stdint.h> data types
                    flavor/version/variation
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: other
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: yann@droneaud.fr


Built-in functions such as 
 __builtin_clz(unsigned int x)
 __builtin_ctz(unsigned int x)
 __builtin_ffs(unsigned int x)
 etc.
are lacking variant based on C99 <stdint.h> data type.

Currently there's
 __builtin_clzl(unsigned long x)
 __builtin_clzll(unsigned long long x)

I'd like to have:
 __builtin_clz32(uint32_t x)
 __builtin_clz64(uint64_t x)

This would help to hard code the number of bits when using such construct to
know the number of bit needed to hold a value:

(8 * sizeof(unsigned int)) - __builtin_clz(value)

when value is of type uint32_t:

 32 - __builtin_clz32(value)

Note: there's already __builtin_bswap32(int32_t x) and
__builtin_bswap64(int64_t x)