intrinsics.h File Reference

Easier access to compiler extensions. More...

#include <assert.h>

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Macros
#define	intrinsics_ctz(x)
	Counts the trailing zeros in a base 2 number. More...
#define	intrinsics_clz(x)
	Counts the leading zeros in a base 2 number. More...
#define	intrinsics_popcount(x)
	Counts the set bits in a base 2 number. More...

Detailed Description

Easier access to compiler extensions.

This header defines some macros which allow to easily rely on some compiler optimizations which can be used to produce more efficient code.

Copyright

Copyright (C) 2008-2022 HPDCS Group https://hpdcs.github.io

Macro Definition Documentation

intrinsics_clz

#define intrinsics_clz

(

x

)

Value:

    __extension__({                                                                                                \
        assert((x) != 0);                                                                                      \
        __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned), __builtin_clz(x),         \
            __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned long),                  \
            __builtin_clzl(x),                                                                             \
            __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned long long),         \
                __builtin_clzll(x), (void)0)));                                                            \
    })

Counts the leading zeros in a base 2 number.

Parameters

x	the number on which to compute this operation

Returns

the count of leading zeros in the base 2 representation of x

The argument x may be of one of the supported types of the underlying compiler built-ins. Selection of the matching built-in is done statically at compile time. If no matching built-in is found a compilation error is thrown.

intrinsics_ctz

#define intrinsics_ctz

(

x

)

Value:

    __extension__({                                                                                                \
        assert((x) != 0);                                                                                      \
        __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned), __builtin_ctz(x),         \
            __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned long),                  \
            __builtin_ctzl(x),                                                                             \
            __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned long long),         \
                __builtin_ctzll(x), (void)0)));                                                            \
    })

Counts the trailing zeros in a base 2 number.

Parameters

x	the number on which to compute this operation

Returns

the count of trailing zeros in the base 2 representation of x

The argument x may be of one of the supported types of the underlying compiler built-ins. Selection of the matching built-in is done statically at compile time. If no matching built-in is found a compilation error is thrown.

intrinsics_popcount

#define intrinsics_popcount

(

x

)

Value:

    __extension__({                                                                                                \
        __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned), __builtin_popcount(x),    \
            __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned long),                  \
            __builtin_popcountl(x),                                                                        \
            __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(x), unsigned long long),         \
                __builtin_popcountll(x), (void)0)));                                                       \
    })

Counts the set bits in a base 2 number.

Parameters

x	the number on which to compute this operation

Returns

the count of set bits in the base 2 representation of x

The argument x may be of one of the supported types of the underlying compiler built-ins. Selection of the matching built-in is done statically at compile time. If no matching built-in is found a compilation error is thrown.