package standard library
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Published: Dec 7, 2023 License: BSD-3-Clause Imports: 2 Imported by: 0




View Source
const (

	// RAX, RBX, RCX, RDI, RSI, R8, R9, R10, R11.
	IntArgRegs = 9

	// X0 -> X14.
	FloatArgRegs = 15

	// We use SSE2 registers which support 64-bit float operations.
	EffectiveFloatRegSize = 8
View Source
const (
	MapBucketCountBits = 3 // log2 of number of elements in a bucket.
	MapBucketCount     = 1 << MapBucketCountBits
	MapMaxKeyBytes     = 128 // Must fit in a uint8.
	MapMaxElemBytes    = 128 // Must fit in a uint8.

Map constants common to several packages runtime/runtime-gdb.py:MapTypePrinter contains its own copy

View Source
const (
	// StackNosplitBase is the base maximum number of bytes that a chain of
	// NOSPLIT functions can use.
	// This value must be multiplied by the stack guard multiplier, so do not
	// use it directly. See runtime/stack.go:stackNosplit and
	// cmd/internal/objabi/stack.go:StackNosplit.
	StackNosplitBase = 800

	// After a stack split check the SP is allowed to be StackSmall bytes below
	// the stack guard.
	// Functions that need frames <= StackSmall can perform the stack check
	// using a single comparison directly between the stack guard and the SP
	// because we ensure that StackSmall bytes of stack space are available
	// beyond the stack guard.
	StackSmall = 128

	// Functions that need frames <= StackBig can assume that neither
	// SP-framesize nor stackGuard-StackSmall will underflow, and thus use a
	// more efficient check. In order to ensure this, StackBig must be <= the
	// size of the unmapped space at zero.
	StackBig = 4096
View Source
const (
	PCDATA_UnsafePoint   = 0
	PCDATA_StackMapIndex = 1
	PCDATA_InlTreeIndex  = 2
	PCDATA_ArgLiveIndex  = 3

	FUNCDATA_ArgsPointerMaps    = 0
	FUNCDATA_LocalsPointerMaps  = 1
	FUNCDATA_StackObjects       = 2
	FUNCDATA_InlTree            = 3
	FUNCDATA_OpenCodedDeferInfo = 4
	FUNCDATA_ArgInfo            = 5
	FUNCDATA_ArgLiveInfo        = 6
	FUNCDATA_WrapInfo           = 7

IDs for PCDATA and FUNCDATA tables in Go binaries.

These must agree with ../../../runtime/funcdata.h.

View Source
const (
	UnsafePointSafe   = -1 // Safe for async preemption
	UnsafePointUnsafe = -2 // Unsafe for async preemption

	// UnsafePointRestart1(2) apply on a sequence of instructions, within
	// which if an async preemption happens, we should back off the PC
	// to the start of the sequence when resuming.
	// We need two so we can distinguish the start/end of the sequence
	// in case that two sequences are next to each other.
	UnsafePointRestart1 = -3
	UnsafePointRestart2 = -4

	// Like UnsafePointRestart1, but back to function entry if async preempted.
	UnsafePointRestartAtEntry = -5

Special values for the PCDATA_UnsafePoint table.

View Source
const (
	// TODO (khr, drchase) why aren't these in TFlag?  Investigate, fix if possible.
	KindDirectIface = 1 << 5
	KindGCProg      = 1 << 6 // Type.gc points to GC program
	KindMask        = (1 << 5) - 1
View Source
const ArgsSizeUnknown = -0x80000000

ArgsSizeUnknown is set in Func.argsize to mark all functions whose argument size is unknown (C vararg functions, and assembly code without an explicit specification). This value is generated by the compiler, assembler, or linker.

View Source
const ZeroValSize = 1024

ZeroValSize is the size in bytes of runtime.zeroVal.


This section is empty.


func CommonSize added in go1.21.0

func CommonSize(ptrSize int) int

CommonSize returns sizeof(Type) for a compilation target with a given ptrSize

func FuncPCABI0

func FuncPCABI0(f interface{}) uintptr

FuncPCABI0 returns the entry PC of the function f, which must be a direct reference of a function defined as ABI0. Otherwise it is a compile-time error.

Implemented as a compile intrinsic.

func FuncPCABIInternal

func FuncPCABIInternal(f interface{}) uintptr

FuncPCABIInternal returns the entry PC of the function f. If f is a direct reference of a function, it must be defined as ABIInternal. Otherwise it is a compile-time error. If f is not a direct reference of a defined function, it assumes that f is a func value. Otherwise the behavior is undefined.

Implemented as a compile intrinsic.

func StructFieldSize added in go1.21.0

func StructFieldSize(ptrSize int) int

StructFieldSize returns sizeof(StructField) for a compilation target with a given ptrSize

func TFlagOff added in go1.21.0

func TFlagOff(ptrSize int) int

TFlagOff returns the offset of Type.TFlag for a compilation target with a given ptrSize

func UncommonSize added in go1.21.0

func UncommonSize() uint64

UncommonSize returns sizeof(UncommonType). This currently does not depend on ptrSize. This exported function is in an internal package, so it may change to depend on ptrSize in the future.

func UseInterfaceSwitchCache

func UseInterfaceSwitchCache(goarch string) bool


type ArrayType added in go1.21.0

type ArrayType struct {
	Elem  *Type // array element type
	Slice *Type // slice type
	Len   uintptr

ArrayType represents a fixed array type.

type ChanDir added in go1.21.0

type ChanDir int
const (
	RecvDir    ChanDir = 1 << iota         // <-chan
	SendDir                                // chan<-
	BothDir            = RecvDir | SendDir // chan
	InvalidDir ChanDir = 0

type ChanType added in go1.21.0

type ChanType struct {
	Elem *Type
	Dir  ChanDir

ChanType represents a channel type

type FuncFlag added in go1.21.0

type FuncFlag uint8

A FuncFlag records bits about a function, passed to the runtime.

const (
	// FuncFlagTopFrame indicates a function that appears at the top of its stack.
	// The traceback routine stop at such a function and consider that a
	// successful, complete traversal of the stack.
	// Examples of TopFrame functions include goexit, which appears
	// at the top of a user goroutine stack, and mstart, which appears
	// at the top of a system goroutine stack.
	FuncFlagTopFrame FuncFlag = 1 << iota

	// FuncFlagSPWrite indicates a function that writes an arbitrary value to SP
	// (any write other than adding or subtracting a constant amount).
	// The traceback routines cannot encode such changes into the
	// pcsp tables, so the function traceback cannot safely unwind past
	// SPWrite functions. Stopping at an SPWrite function is considered
	// to be an incomplete unwinding of the stack. In certain contexts
	// (in particular garbage collector stack scans) that is a fatal error.

	// FuncFlagAsm indicates that a function was implemented in assembly.

type FuncID added in go1.21.0

type FuncID uint8

A FuncID identifies particular functions that need to be treated specially by the runtime. Note that in some situations involving plugins, there may be multiple copies of a particular special runtime function.

const (
	FuncIDNormal FuncID = iota // not a special function
	FuncIDWrapper // any autogenerated code (hash/eq algorithms, method wrappers, etc.)

type FuncType added in go1.21.0

type FuncType struct {
	InCount  uint16
	OutCount uint16 // top bit is set if last input parameter is ...

funcType represents a function type.

A *Type for each in and out parameter is stored in an array that directly follows the funcType (and possibly its uncommonType). So a function type with one method, one input, and one output is:

struct {
	[2]*rtype    // [0] is in, [1] is out

func (*FuncType) In added in go1.21.0

func (t *FuncType) In(i int) *Type

func (*FuncType) InSlice added in go1.21.0

func (t *FuncType) InSlice() []*Type

func (*FuncType) IsVariadic added in go1.21.0

func (t *FuncType) IsVariadic() bool

func (*FuncType) NumIn added in go1.21.0

func (t *FuncType) NumIn() int

func (*FuncType) NumOut added in go1.21.0

func (t *FuncType) NumOut() int

func (*FuncType) Out added in go1.21.0

func (t *FuncType) Out(i int) *Type

func (*FuncType) OutSlice added in go1.21.0

func (t *FuncType) OutSlice() []*Type

type Imethod added in go1.21.0

type Imethod struct {
	Name NameOff // name of method
	Typ  TypeOff // .(*FuncType) underneath

Imethod represents a method on an interface type

type IntArgRegBitmap

type IntArgRegBitmap [(IntArgRegs + 7) / 8]uint8

IntArgRegBitmap is a bitmap large enough to hold one bit per integer argument/return register.

func (*IntArgRegBitmap) Get

func (b *IntArgRegBitmap) Get(i int) bool

Get returns whether the i'th bit of the bitmap is set.

nosplit because it's called in extremely sensitive contexts, like on the reflectcall return path.

func (*IntArgRegBitmap) Set

func (b *IntArgRegBitmap) Set(i int)

Set sets the i'th bit of the bitmap to 1.

type InterfaceSwitch

type InterfaceSwitch struct {
	Cache  *InterfaceSwitchCache
	NCases int

	// Array of NCases elements.
	// Each case must be a non-empty interface type.
	Cases [1]*InterfaceType

type InterfaceSwitchCache

type InterfaceSwitchCache struct {
	Mask    uintptr                      // mask for index. Must be a power of 2 minus 1
	Entries [1]InterfaceSwitchCacheEntry // Mask+1 entries total

type InterfaceSwitchCacheEntry

type InterfaceSwitchCacheEntry struct {
	// type of source value (a *Type)
	Typ uintptr
	// case # to dispatch to
	Case int
	// itab to use for resulting case variable (a *runtime.itab)
	Itab uintptr

type InterfaceType added in go1.21.0

type InterfaceType struct {
	PkgPath Name      // import path
	Methods []Imethod // sorted by hash

func (*InterfaceType) NumMethod added in go1.21.0

func (t *InterfaceType) NumMethod() int

NumMethod returns the number of interface methods in the type's method set.

type Kind added in go1.21.0

type Kind uint

A Kind represents the specific kind of type that a Type represents. The zero Kind is not a valid kind.

const (
	Invalid Kind = iota

func (Kind) String added in go1.21.0

func (k Kind) String() string

String returns the name of k.

type MapType added in go1.21.0

type MapType struct {
	Key    *Type
	Elem   *Type
	Bucket *Type // internal type representing a hash bucket
	// function for hashing keys (ptr to key, seed) -> hash
	Hasher     func(unsafe.Pointer, uintptr) uintptr
	KeySize    uint8  // size of key slot
	ValueSize  uint8  // size of elem slot
	BucketSize uint16 // size of bucket
	Flags      uint32

func (*MapType) HashMightPanic added in go1.21.0

func (mt *MapType) HashMightPanic() bool

func (*MapType) IndirectElem added in go1.21.0

func (mt *MapType) IndirectElem() bool

func (*MapType) IndirectKey added in go1.21.0

func (mt *MapType) IndirectKey() bool

Note: flag values must match those used in the TMAP case in ../cmd/compile/internal/reflectdata/reflect.go:writeType.

func (*MapType) NeedKeyUpdate added in go1.21.0

func (mt *MapType) NeedKeyUpdate() bool

func (*MapType) ReflexiveKey added in go1.21.0

func (mt *MapType) ReflexiveKey() bool

type Method added in go1.21.0

type Method struct {
	Name NameOff // name of method
	Mtyp TypeOff // method type (without receiver)
	Ifn  TextOff // fn used in interface call (one-word receiver)
	Tfn  TextOff // fn used for normal method call

Method on non-interface type

type Name added in go1.21.0

type Name struct {
	Bytes *byte

func NewName added in go1.21.0

func NewName(n, tag string, exported, embedded bool) Name

func (Name) Data added in go1.21.0

func (n Name) Data(off int) *byte

Data does pointer arithmetic on n's Bytes, and that arithmetic is asserted to be safe because the runtime made the call (other packages use DataChecked)

func (Name) DataChecked added in go1.21.0

func (n Name) DataChecked(off int, whySafe string) *byte

DataChecked does pointer arithmetic on n's Bytes, and that arithmetic is asserted to be safe for the reason in whySafe (which can appear in a backtrace, etc.)

func (Name) HasTag added in go1.21.0

func (n Name) HasTag() bool

HasTag returns true iff there is tag data following this name

func (Name) IsBlank added in go1.21.0

func (n Name) IsBlank() bool

IsBlank indicates whether n is "_".

func (Name) IsEmbedded added in go1.21.0

func (n Name) IsEmbedded() bool

IsEmbedded returns true iff n is embedded (an anonymous field).

func (Name) IsExported added in go1.21.0

func (n Name) IsExported() bool

IsExported returns "is n exported?"

func (Name) Name added in go1.21.0

func (n Name) Name() string

Name returns the tag string for n, or empty if there is none.

func (Name) ReadVarint added in go1.21.0

func (n Name) ReadVarint(off int) (int, int)

ReadVarint parses a varint as encoded by encoding/binary. It returns the number of encoded bytes and the encoded value.

func (Name) Tag added in go1.21.0

func (n Name) Tag() string

Tag returns the tag string for n, or empty if there is none.

type NameOff added in go1.21.0

type NameOff int32

NameOff is the offset to a name from moduledata.types. See resolveNameOff in runtime.

type PtrType added in go1.21.0

type PtrType struct {
	Elem *Type // pointer element (pointed at) type

type RegArgs

type RegArgs struct {
	// Values in these slots should be precisely the bit-by-bit
	// representation of how they would appear in a register.
	// This means that on big endian arches, integer values should
	// be in the top bits of the slot. Floats are usually just
	// directly represented, but some architectures treat narrow
	// width floating point values specially (e.g. they're promoted
	// first, or they need to be NaN-boxed).
	Ints   [IntArgRegs]uintptr  // untyped integer registers
	Floats [FloatArgRegs]uint64 // untyped float registers

	// Ptrs is a space that duplicates Ints but with pointer type,
	// used to make pointers passed or returned  in registers
	// visible to the GC by making the type unsafe.Pointer.
	Ptrs [IntArgRegs]unsafe.Pointer

	// ReturnIsPtr is a bitmap that indicates which registers
	// contain or will contain pointers on the return path from
	// a reflectcall. The i'th bit indicates whether the i'th
	// register contains or will contain a valid Go pointer.
	ReturnIsPtr IntArgRegBitmap

RegArgs is a struct that has space for each argument and return value register on the current architecture.

Assembly code knows the layout of the first two fields of RegArgs.

RegArgs also contains additional space to hold pointers when it may not be safe to keep them only in the integer register space otherwise.

func (*RegArgs) Dump added in go1.17.6

func (r *RegArgs) Dump()

func (*RegArgs) IntRegArgAddr added in go1.18

func (r *RegArgs) IntRegArgAddr(reg int, argSize uintptr) unsafe.Pointer

IntRegArgAddr returns a pointer inside of r.Ints[reg] that is appropriately offset for an argument of size argSize.

argSize must be non-zero, fit in a register, and a power-of-two.

This method is a helper for dealing with the endianness of different CPU architectures, since sub-word-sized arguments in big endian architectures need to be "aligned" to the upper edge of the register to be interpreted by the CPU correctly.

type SliceType added in go1.21.0

type SliceType struct {
	Elem *Type // slice element type

type StructField added in go1.21.0

type StructField struct {
	Name   Name    // name is always non-empty
	Typ    *Type   // type of field
	Offset uintptr // byte offset of field

func (*StructField) Embedded added in go1.21.0

func (f *StructField) Embedded() bool

type StructType added in go1.21.0

type StructType struct {
	PkgPath Name
	Fields  []StructField

type TFlag added in go1.21.0

type TFlag uint8

TFlag is used by a Type to signal what extra type information is available in the memory directly following the Type value.

const (
	// TFlagUncommon means that there is a data with a type, UncommonType,
	// just beyond the shared-per-type common data.  That is, the data
	// for struct types will store their UncommonType at one offset, the
	// data for interface types will store their UncommonType at a different
	// offset.  UncommonType is always accessed via a pointer that is computed
	// using trust-us-we-are-the-implementors pointer arithmetic.
	// For example, if t.Kind() == Struct and t.tflag&TFlagUncommon != 0,
	// then t has UncommonType data and it can be accessed as:
	//	type structTypeUncommon struct {
	//		structType
	//		u UncommonType
	//	}
	//	u := &(*structTypeUncommon)(unsafe.Pointer(t)).u
	TFlagUncommon TFlag = 1 << 0

	// TFlagExtraStar means the name in the str field has an
	// extraneous '*' prefix. This is because for most types T in
	// a program, the type *T also exists and reusing the str data
	// saves binary size.
	TFlagExtraStar TFlag = 1 << 1

	// TFlagNamed means the type has a name.
	TFlagNamed TFlag = 1 << 2

	// TFlagRegularMemory means that equal and hash functions can treat
	// this type as a single region of t.size bytes.
	TFlagRegularMemory TFlag = 1 << 3

type TextOff added in go1.21.0

type TextOff int32

TextOff is an offset from the top of a text section. See (rtype).textOff in runtime.

type Type added in go1.21.0

type Type struct {
	Size_       uintptr
	PtrBytes    uintptr // number of (prefix) bytes in the type that can contain pointers
	Hash        uint32  // hash of type; avoids computation in hash tables
	TFlag       TFlag   // extra type information flags
	Align_      uint8   // alignment of variable with this type
	FieldAlign_ uint8   // alignment of struct field with this type
	Kind_       uint8   // enumeration for C
	// function for comparing objects of this type
	// (ptr to object A, ptr to object B) -> ==?
	Equal func(unsafe.Pointer, unsafe.Pointer) bool
	// GCData stores the GC type data for the garbage collector.
	// If the KindGCProg bit is set in kind, GCData is a GC program.
	// Otherwise it is a ptrmask bitmap. See mbitmap.go for details.
	GCData    *byte
	Str       NameOff // string form
	PtrToThis TypeOff // type for pointer to this type, may be zero

Type is the runtime representation of a Go type.

Be careful about accessing this type at build time, as the version of this type in the compiler/linker may not have the same layout as the version in the target binary, due to pointer width differences and any experiments. Use cmd/compile/internal/rttype or the functions in compiletype.go to access this type instead. (TODO: this admonition applies to every type in this package. Put it in some shared location?)

func (*Type) Align added in go1.21.0

func (t *Type) Align() int

Align returns the alignment of data with type t.

func (*Type) ArrayType added in go1.21.0

func (t *Type) ArrayType() *ArrayType

ArrayType returns t cast to a *ArrayType, or nil if its tag does not match.

func (*Type) ChanDir added in go1.21.0

func (t *Type) ChanDir() ChanDir

ChanDir returns the direction of t if t is a channel type, otherwise InvalidDir (0).

func (*Type) Common added in go1.21.0

func (t *Type) Common() *Type

func (*Type) Elem added in go1.21.0

func (t *Type) Elem() *Type

Elem returns the element type for t if t is an array, channel, map, pointer, or slice, otherwise nil.

func (*Type) ExportedMethods added in go1.21.0

func (t *Type) ExportedMethods() []Method

func (*Type) FieldAlign added in go1.21.0

func (t *Type) FieldAlign() int

func (*Type) FuncType added in go1.21.0

func (t *Type) FuncType() *FuncType

FuncType returns t cast to a *FuncType, or nil if its tag does not match.

func (*Type) GcSlice added in go1.21.0

func (t *Type) GcSlice(begin, end uintptr) []byte

func (*Type) HasName added in go1.21.0

func (t *Type) HasName() bool

func (*Type) IfaceIndir added in go1.21.0

func (t *Type) IfaceIndir() bool

IfaceIndir reports whether t is stored indirectly in an interface value.

func (*Type) InterfaceType added in go1.21.0

func (t *Type) InterfaceType() *InterfaceType

InterfaceType returns t cast to a *InterfaceType, or nil if its tag does not match.

func (*Type) IsDirectIface added in go1.21.0

func (t *Type) IsDirectIface() bool

isDirectIface reports whether t is stored directly in an interface value.

func (*Type) Key added in go1.21.0

func (t *Type) Key() *Type

func (*Type) Kind added in go1.21.0

func (t *Type) Kind() Kind

func (*Type) Len added in go1.21.0

func (t *Type) Len() int

Len returns the length of t if t is an array type, otherwise 0

func (*Type) MapType added in go1.21.0

func (t *Type) MapType() *MapType

MapType returns t cast to a *MapType, or nil if its tag does not match.

func (*Type) NumMethod added in go1.21.0

func (t *Type) NumMethod() int

func (*Type) Pointers added in go1.21.0

func (t *Type) Pointers() bool

func (*Type) Size added in go1.21.0

func (t *Type) Size() uintptr

Size returns the size of data with type t.

func (*Type) StructType added in go1.21.0

func (t *Type) StructType() *StructType

StructType returns t cast to a *StructType, or nil if its tag does not match.

func (*Type) Uncommon added in go1.21.0

func (t *Type) Uncommon() *UncommonType

Uncommon returns a pointer to T's "uncommon" data if there is any, otherwise nil

type TypeAssert

type TypeAssert struct {
	Cache   *TypeAssertCache
	Inter   *InterfaceType
	CanFail bool

type TypeAssertCache

type TypeAssertCache struct {
	Mask    uintptr
	Entries [1]TypeAssertCacheEntry

type TypeAssertCacheEntry

type TypeAssertCacheEntry struct {
	// type of source value (a *runtime._type)
	Typ uintptr
	// itab to use for result (a *runtime.itab)
	// nil if CanFail is set and conversion would fail.
	Itab uintptr

type TypeOff added in go1.21.0

type TypeOff int32

TypeOff is the offset to a type from moduledata.types. See resolveTypeOff in runtime.

type UncommonType added in go1.21.0

type UncommonType struct {
	PkgPath NameOff // import path; empty for built-in types like int, string
	Mcount  uint16  // number of methods
	Xcount  uint16  // number of exported methods
	Moff    uint32  // offset from this uncommontype to [mcount]Method
	// contains filtered or unexported fields

UncommonType is present only for defined types or types with methods (if T is a defined type, the uncommonTypes for T and *T have methods). Using a pointer to this struct reduces the overall size required to describe a non-defined type with no methods.

func (*UncommonType) ExportedMethods added in go1.21.0

func (t *UncommonType) ExportedMethods() []Method

func (*UncommonType) Methods added in go1.21.0

func (t *UncommonType) Methods() []Method

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