compiler.h File Reference

#include <stddef.h>
#include "portability_macros.h"

Go to the source code of this file.

Macros
#define	INLINE_KEYWORD
#define	FORCE_INLINE_ATTR
#define	WIN_CDECL
#define	UNUSED_ATTR
#define	FORCE_INLINE_TEMPLATE   static INLINE_KEYWORD FORCE_INLINE_ATTR UNUSED_ATTR
#define	HINT_INLINE   FORCE_INLINE_TEMPLATE
#define	MEM_STATIC   static /* this version may generate warnings for unused static functions; disable the relevant warning */
#define	FORCE_NOINLINE   static
#define	TARGET_ATTRIBUTE(target)
#define	BMI2_TARGET_ATTRIBUTE   TARGET_ATTRIBUTE("lzcnt,bmi,bmi2")
#define	PREFETCH_L1(ptr)
#define	PREFETCH_L2(ptr)
#define	CACHELINE_SIZE   64
#define	PREFETCH_AREA(p, s)
#define	DONT_VECTORIZE
#define	LIKELY(x)
#define	UNLIKELY(x)
#define	ZSTD_UNREACHABLE   do { assert(0); } while (0)
#define	STATIC_BMI2   0
#define	ZSTD_HAS_C_ATTRIBUTE(x)
#define	ZSTD_HAS_CPP_ATTRIBUTE(x)
#define	ZSTD_FALLTHROUGH
#define	ZSTD_ALIGNOF(T)
#define	ZSTD_ALLOW_POINTER_OVERFLOW_ATTR

Functions
MEM_STATIC ZSTD_ALLOW_POINTER_OVERFLOW_ATTR ptrdiff_t	ZSTD_wrappedPtrDiff (unsigned char const *lhs, unsigned char const *rhs)
MEM_STATIC ZSTD_ALLOW_POINTER_OVERFLOW_ATTR unsigned char const *	ZSTD_wrappedPtrAdd (unsigned char const *ptr, ptrdiff_t add)
MEM_STATIC ZSTD_ALLOW_POINTER_OVERFLOW_ATTR unsigned char const *	ZSTD_wrappedPtrSub (unsigned char const *ptr, ptrdiff_t sub)
MEM_STATIC unsigned char *	ZSTD_maybeNullPtrAdd (unsigned char *ptr, ptrdiff_t add)

Macro Definition Documentation

BMI2_TARGET_ATTRIBUTE

#define BMI2_TARGET_ATTRIBUTE   TARGET_ATTRIBUTE("lzcnt,bmi,bmi2")

CACHELINE_SIZE

#define CACHELINE_SIZE   64

DONT_VECTORIZE

#define DONT_VECTORIZE

FORCE_INLINE_ATTR

#define FORCE_INLINE_ATTR

FORCE_INLINE_TEMPLATE

#define FORCE_INLINE_TEMPLATE   static INLINE_KEYWORD FORCE_INLINE_ATTR UNUSED_ATTR

FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant parameters. They must be inlined for the compiler to eliminate the constant branches.

FORCE_NOINLINE

#define FORCE_NOINLINE   static

HINT_INLINE

#define HINT_INLINE   FORCE_INLINE_TEMPLATE

HINT_INLINE is used to help the compiler generate better code. It is not used for "templates", so it can be tweaked based on the compilers performance.

gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the always_inline attribute.

clang up to 5.0.0 (trunk) benefit tremendously from the always_inline attribute.

INLINE_KEYWORD

#define INLINE_KEYWORD

LIKELY

#define LIKELY

(

x

)

Value:

(x)

MEM_STATIC

#define MEM_STATIC   static /* this version may generate warnings for unused static functions; disable the relevant warning */

PREFETCH_AREA

#define PREFETCH_AREA	(		p,
			s )

Value:

    do {                                                 \
        const char* const _ptr = (const char*)(p);       \
        size_t const _size = (size_t)(s);                \
        size_t _pos;                                     \
        for (_pos=0; _pos<_size; _pos+=CACHELINE_SIZE) { \
            PREFETCH_L2(_ptr + _pos);                    \
        }                                                \
    } while (0)

PREFETCH_L1

#define PREFETCH_L1

(

ptr

)

Value:

do { (void)(ptr); } while (0)  /* disabled */

PREFETCH_L2

#define PREFETCH_L2

(

ptr

)

Value:

do { (void)(ptr); } while (0)  /* disabled */

STATIC_BMI2

#define STATIC_BMI2   0

TARGET_ATTRIBUTE

#define TARGET_ATTRIBUTE

(

target

)

UNLIKELY

#define UNLIKELY

(

x

)

Value:

(x)

UNUSED_ATTR

#define UNUSED_ATTR

WIN_CDECL

#define WIN_CDECL

On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC). This explicitly marks such functions as __cdecl so that the code will still compile if a CC other than __cdecl has been made the default.

ZSTD_ALIGNOF

#define ZSTD_ALIGNOF

(

T

)

Value:

(sizeof(void*) < sizeof(T) ? sizeof(void*) : sizeof(T))

ZSTD_ALLOW_POINTER_OVERFLOW_ATTR

#define ZSTD_ALLOW_POINTER_OVERFLOW_ATTR

Zstd relies on pointer overflow in its decompressor. We add this attribute to functions that rely on pointer overflow.

ZSTD_FALLTHROUGH

#define ZSTD_FALLTHROUGH

ZSTD_HAS_C_ATTRIBUTE

#define ZSTD_HAS_C_ATTRIBUTE

(

x

)

Value:

0

ZSTD_HAS_CPP_ATTRIBUTE

#define ZSTD_HAS_CPP_ATTRIBUTE

(

x

)

Value:

0

ZSTD_UNREACHABLE

#define ZSTD_UNREACHABLE   do { assert(0); } while (0)

Function Documentation

ZSTD_maybeNullPtrAdd()

MEM_STATIC unsigned char * ZSTD_maybeNullPtrAdd	(	unsigned char *	ptr,
		ptrdiff_t	add )

Helper function to add to a pointer that works around C's undefined behavior of adding 0 to NULL.

Returns

ptr + add except it defines NULL + 0 == NULL.

ZSTD_wrappedPtrAdd()

MEM_STATIC ZSTD_ALLOW_POINTER_OVERFLOW_ATTR unsigned char const * ZSTD_wrappedPtrAdd	(	unsigned char const *	ptr,
		ptrdiff_t	add )

Helper function to perform a wrapped pointer add without triggering UBSAN.

Returns

ptr + add with wrapping

ZSTD_wrappedPtrDiff()

MEM_STATIC ZSTD_ALLOW_POINTER_OVERFLOW_ATTR ptrdiff_t ZSTD_wrappedPtrDiff	(	unsigned char const *	lhs,
		unsigned char const *	rhs )

Helper function to perform a wrapped pointer difference without trigging UBSAN.

Returns

lhs - rhs with wrapping

ZSTD_wrappedPtrSub()

MEM_STATIC ZSTD_ALLOW_POINTER_OVERFLOW_ATTR unsigned char const * ZSTD_wrappedPtrSub	(	unsigned char const *	ptr,
		ptrdiff_t	sub )

Helper function to perform a wrapped pointer subtraction without triggering UBSAN.

Returns

ptr - sub with wrapping