go/src/internal/runtime/sys/intrinsics.go

var deBruijn32tab …

const deBruijn32 …

var deBruijn64tab …

const deBruijn64 …

const ntz8tab …

// TrailingZeros32 returns the number of trailing zero bits in x; the result is 32 for x == 0.
func TrailingZeros32(x uint32) int { … }

// TrailingZeros64 returns the number of trailing zero bits in x; the result is 64 for x == 0.
func TrailingZeros64(x uint64) int { … }

// TrailingZeros8 returns the number of trailing zero bits in x; the result is 8 for x == 0.
func TrailingZeros8(x uint8) int { … }

const len8tab …

// Len64 returns the minimum number of bits required to represent x; the result is 0 for x == 0.
//
// nosplit because this is used in src/runtime/histogram.go, which make run in sensitive contexts.
//
//go:nosplit
func Len64(x uint64) (n int) { … }

const m0 …

const m1 …

const m2 …

// OnesCount64 returns the number of one bits ("population count") in x.
func OnesCount64(x uint64) int { … }

// LeadingZeros64 returns the number of leading zero bits in x; the result is 64 for x == 0.
func LeadingZeros64(x uint64) int { … }

// LeadingZeros8 returns the number of leading zero bits in x; the result is 8 for x == 0.
func LeadingZeros8(x uint8) int { … }

// Len8 returns the minimum number of bits required to represent x; the result is 0 for x == 0.
func Len8(x uint8) int { … }

// Bswap64 returns its input with byte order reversed
// 0x0102030405060708 -> 0x0807060504030201
func Bswap64(x uint64) uint64 { … }

// Bswap32 returns its input with byte order reversed
// 0x01020304 -> 0x04030201
func Bswap32(x uint32) uint32 { … }

// Prefetch prefetches data from memory addr to cache
//
// AMD64: Produce PREFETCHT0 instruction
//
// ARM64: Produce PRFM instruction with PLDL1KEEP option
func Prefetch(addr uintptr) { … }

// PrefetchStreamed prefetches data from memory addr, with a hint that this data is being streamed.
// That is, it is likely to be accessed very soon, but only once. If possible, this will avoid polluting the cache.
//
// AMD64: Produce PREFETCHNTA instruction
//
// ARM64: Produce PRFM instruction with PLDL1STRM option
func PrefetchStreamed(addr uintptr) { … }

func GetCallerPC() uintptr

func GetCallerSP() uintptr

// GetClosurePtr returns the pointer to the current closure.
// GetClosurePtr can only be used in an assignment statement
// at the entry of a function. Moreover, go:nosplit directive
// must be specified at the declaration of caller function,
// so that the function prolog does not clobber the closure register.
// for example:
//
//	//go:nosplit
//	func f(arg1, arg2, arg3 int) {
//		dx := GetClosurePtr()
//	}
//
// The compiler rewrites calls to this function into instructions that fetch the
// pointer from a well-known register (DX on x86 architecture, etc.) directly.
//
// WARNING: PGO-based devirtualization cannot detect that caller of
// GetClosurePtr requires closure context, and thus must maintain a list of
// these functions, which is in
// cmd/compile/internal/devirtualize/pgo.maybeDevirtualizeFunctionCall.
func GetClosurePtr() uintptr