go name 源码
golang name 代码
文件路径：/src/cmd/compile/internal/ir/name.go
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ir
import (
"cmd/compile/internal/base"
"cmd/compile/internal/types"
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/src"
"fmt"
"go/constant"
)
// An Ident is an identifier, possibly qualified.
type Ident struct {
miniExpr
sym *types.Sym
}
func NewIdent(pos src.XPos, sym *types.Sym) *Ident {
n := new(Ident)
n.op = ONONAME
n.pos = pos
n.sym = sym
return n
}
func (n *Ident) Sym() *types.Sym { return n.sym }
// Name holds Node fields used only by named nodes (ONAME, OTYPE, some OLITERAL).
type Name struct {
miniExpr
BuiltinOp Op // uint8
Class Class // uint8
pragma PragmaFlag // int16
flags bitset16
DictIndex uint16 // index of the dictionary entry describing the type of this variable declaration plus 1
sym *types.Sym
Func *Func // TODO(austin): nil for I.M, eqFor, hashfor, and hashmem
Offset_ int64
val constant.Value
Opt interface{} // for use by escape analysis
Embed *[]Embed // list of embedded files, for ONAME var
// For a local variable (not param) or extern, the initializing assignment (OAS or OAS2).
// For a closure var, the ONAME node of the outer captured variable.
// For the case-local variables of a type switch, the type switch guard (OTYPESW).
// For a range variable, the range statement (ORANGE)
// For a recv variable in a case of a select statement, the receive assignment (OSELRECV2)
// For the name of a function, points to corresponding Func node.
Defn Node
// The function, method, or closure in which local variable or param is declared.
Curfn *Func
Heapaddr *Name // temp holding heap address of param
// ONAME closure linkage
// Consider:
//
// func f() {
// x := 1 // x1
// func() {
// use(x) // x2
// func() {
// use(x) // x3
// --- parser is here ---
// }()
// }()
// }
//
// There is an original declaration of x and then a chain of mentions of x
// leading into the current function. Each time x is mentioned in a new closure,
// we create a variable representing x for use in that specific closure,
// since the way you get to x is different in each closure.
//
// Let's number the specific variables as shown in the code:
// x1 is the original x, x2 is when mentioned in the closure,
// and x3 is when mentioned in the closure in the closure.
//
// We keep these linked (assume N > 1):
//
// - x1.Defn = original declaration statement for x (like most variables)
// - x1.Innermost = current innermost closure x (in this case x3), or nil for none
// - x1.IsClosureVar() = false
//
// - xN.Defn = x1, N > 1
// - xN.IsClosureVar() = true, N > 1
// - x2.Outer = nil
// - xN.Outer = x(N-1), N > 2
//
//
// When we look up x in the symbol table, we always get x1.
// Then we can use x1.Innermost (if not nil) to get the x
// for the innermost known closure function,
// but the first reference in a closure will find either no x1.Innermost
// or an x1.Innermost with .Funcdepth < Funcdepth.
// In that case, a new xN must be created, linked in with:
//
// xN.Defn = x1
// xN.Outer = x1.Innermost
// x1.Innermost = xN
//
// When we finish the function, we'll process its closure variables
// and find xN and pop it off the list using:
//
// x1 := xN.Defn
// x1.Innermost = xN.Outer
//
// We leave x1.Innermost set so that we can still get to the original
// variable quickly. Not shown here, but once we're
// done parsing a function and no longer need xN.Outer for the
// lexical x reference links as described above, funcLit
// recomputes xN.Outer as the semantic x reference link tree,
// even filling in x in intermediate closures that might not
// have mentioned it along the way to inner closures that did.
// See funcLit for details.
//
// During the eventual compilation, then, for closure variables we have:
//
// xN.Defn = original variable
// xN.Outer = variable captured in next outward scope
// to make closure where xN appears
//
// Because of the sharding of pieces of the node, x.Defn means x.Name.Defn
// and x.Innermost/Outer means x.Name.Param.Innermost/Outer.
Innermost *Name
Outer *Name
}
func (n *Name) isExpr() {}
func (n *Name) copy() Node { panic(n.no("copy")) }
func (n *Name) doChildren(do func(Node) bool) bool { return false }
func (n *Name) editChildren(edit func(Node) Node) {}
// RecordFrameOffset records the frame offset for the name.
// It is used by package types when laying out function arguments.
func (n *Name) RecordFrameOffset(offset int64) {
n.SetFrameOffset(offset)
}
// NewNameAt returns a new ONAME Node associated with symbol s at position pos.
// The caller is responsible for setting Curfn.
func NewNameAt(pos src.XPos, sym *types.Sym) *Name {
if sym == nil {
base.Fatalf("NewNameAt nil")
}
return newNameAt(pos, ONAME, sym)
}
// NewDeclNameAt returns a new Name associated with symbol s at position pos.
// The caller is responsible for setting Curfn.
func NewDeclNameAt(pos src.XPos, op Op, sym *types.Sym) *Name {
if sym == nil {
base.Fatalf("NewDeclNameAt nil")
}
switch op {
case ONAME, OTYPE, OLITERAL:
// ok
default:
base.Fatalf("NewDeclNameAt op %v", op)
}
return newNameAt(pos, op, sym)
}
// NewConstAt returns a new OLITERAL Node associated with symbol s at position pos.
func NewConstAt(pos src.XPos, sym *types.Sym, typ *types.Type, val constant.Value) *Name {
if sym == nil {
base.Fatalf("NewConstAt nil")
}
n := newNameAt(pos, OLITERAL, sym)
n.SetType(typ)
n.SetVal(val)
return n
}
// newNameAt is like NewNameAt but allows sym == nil.
func newNameAt(pos src.XPos, op Op, sym *types.Sym) *Name {
n := new(Name)
n.op = op
n.pos = pos
n.sym = sym
return n
}
func (n *Name) Name() *Name { return n }
func (n *Name) Sym() *types.Sym { return n.sym }
func (n *Name) SetSym(x *types.Sym) { n.sym = x }
func (n *Name) SubOp() Op { return n.BuiltinOp }
func (n *Name) SetSubOp(x Op) { n.BuiltinOp = x }
func (n *Name) SetFunc(x *Func) { n.Func = x }
func (n *Name) Offset() int64 { panic("Name.Offset") }
func (n *Name) SetOffset(x int64) {
if x != 0 {
panic("Name.SetOffset")
}
}
func (n *Name) FrameOffset() int64 { return n.Offset_ }
func (n *Name) SetFrameOffset(x int64) { n.Offset_ = x }
func (n *Name) Linksym() *obj.LSym { return n.sym.Linksym() }
func (n *Name) LinksymABI(abi obj.ABI) *obj.LSym { return n.sym.LinksymABI(abi) }
func (*Name) CanBeNtype() {}
func (*Name) CanBeAnSSASym() {}
func (*Name) CanBeAnSSAAux() {}
// Pragma returns the PragmaFlag for p, which must be for an OTYPE.
func (n *Name) Pragma() PragmaFlag { return n.pragma }
// SetPragma sets the PragmaFlag for p, which must be for an OTYPE.
func (n *Name) SetPragma(flag PragmaFlag) { n.pragma = flag }
// Alias reports whether p, which must be for an OTYPE, is a type alias.
func (n *Name) Alias() bool { return n.flags&nameAlias != 0 }
// SetAlias sets whether p, which must be for an OTYPE, is a type alias.
func (n *Name) SetAlias(alias bool) { n.flags.set(nameAlias, alias) }
const (
nameReadonly = 1 << iota
nameByval // is the variable captured by value or by reference
nameNeedzero // if it contains pointers, needs to be zeroed on function entry
nameAutoTemp // is the variable a temporary (implies no dwarf info. reset if escapes to heap)
nameUsed // for variable declared and not used error
nameIsClosureVar // PAUTOHEAP closure pseudo-variable; original (if any) at n.Defn
nameIsOutputParamHeapAddr // pointer to a result parameter's heap copy
nameIsOutputParamInRegisters // output parameter in registers spills as an auto
nameAddrtaken // address taken, even if not moved to heap
nameInlFormal // PAUTO created by inliner, derived from callee formal
nameInlLocal // PAUTO created by inliner, derived from callee local
nameOpenDeferSlot // if temporary var storing info for open-coded defers
nameLibfuzzer8BitCounter // if PEXTERN should be assigned to __sancov_cntrs section
nameAlias // is type name an alias
)
func (n *Name) Readonly() bool { return n.flags&nameReadonly != 0 }
func (n *Name) Needzero() bool { return n.flags&nameNeedzero != 0 }
func (n *Name) AutoTemp() bool { return n.flags&nameAutoTemp != 0 }
func (n *Name) Used() bool { return n.flags&nameUsed != 0 }
func (n *Name) IsClosureVar() bool { return n.flags&nameIsClosureVar != 0 }
func (n *Name) IsOutputParamHeapAddr() bool { return n.flags&nameIsOutputParamHeapAddr != 0 }
func (n *Name) IsOutputParamInRegisters() bool { return n.flags&nameIsOutputParamInRegisters != 0 }
func (n *Name) Addrtaken() bool { return n.flags&nameAddrtaken != 0 }
func (n *Name) InlFormal() bool { return n.flags&nameInlFormal != 0 }
func (n *Name) InlLocal() bool { return n.flags&nameInlLocal != 0 }
func (n *Name) OpenDeferSlot() bool { return n.flags&nameOpenDeferSlot != 0 }
func (n *Name) Libfuzzer8BitCounter() bool { return n.flags&nameLibfuzzer8BitCounter != 0 }
func (n *Name) setReadonly(b bool) { n.flags.set(nameReadonly, b) }
func (n *Name) SetNeedzero(b bool) { n.flags.set(nameNeedzero, b) }
func (n *Name) SetAutoTemp(b bool) { n.flags.set(nameAutoTemp, b) }
func (n *Name) SetUsed(b bool) { n.flags.set(nameUsed, b) }
func (n *Name) SetIsClosureVar(b bool) { n.flags.set(nameIsClosureVar, b) }
func (n *Name) SetIsOutputParamHeapAddr(b bool) { n.flags.set(nameIsOutputParamHeapAddr, b) }
func (n *Name) SetIsOutputParamInRegisters(b bool) { n.flags.set(nameIsOutputParamInRegisters, b) }
func (n *Name) SetAddrtaken(b bool) { n.flags.set(nameAddrtaken, b) }
func (n *Name) SetInlFormal(b bool) { n.flags.set(nameInlFormal, b) }
func (n *Name) SetInlLocal(b bool) { n.flags.set(nameInlLocal, b) }
func (n *Name) SetOpenDeferSlot(b bool) { n.flags.set(nameOpenDeferSlot, b) }
func (n *Name) SetLibfuzzer8BitCounter(b bool) { n.flags.set(nameLibfuzzer8BitCounter, b) }
// OnStack reports whether variable n may reside on the stack.
func (n *Name) OnStack() bool {
if n.Op() == ONAME {
switch n.Class {
case PPARAM, PPARAMOUT, PAUTO:
return n.Esc() != EscHeap
case PEXTERN, PAUTOHEAP:
return false
}
}
// Note: fmt.go:dumpNodeHeader calls all "func() bool"-typed
// methods, but it can only recover from panics, not Fatalf.
panic(fmt.Sprintf("%v: not a variable: %v", base.FmtPos(n.Pos()), n))
}
// MarkReadonly indicates that n is an ONAME with readonly contents.
func (n *Name) MarkReadonly() {
if n.Op() != ONAME {
base.Fatalf("Node.MarkReadonly %v", n.Op())
}
n.setReadonly(true)
// Mark the linksym as readonly immediately
// so that the SSA backend can use this information.
// It will be overridden later during dumpglobls.
n.Linksym().Type = objabi.SRODATA
}
// Val returns the constant.Value for the node.
func (n *Name) Val() constant.Value {
if n.val == nil {
return constant.MakeUnknown()
}
return n.val
}
// SetVal sets the constant.Value for the node.
func (n *Name) SetVal(v constant.Value) {
if n.op != OLITERAL {
panic(n.no("SetVal"))
}
AssertValidTypeForConst(n.Type(), v)
n.val = v
}
// Canonical returns the logical declaration that n represents. If n
// is a closure variable, then Canonical returns the original Name as
// it appears in the function that immediately contains the
// declaration. Otherwise, Canonical simply returns n itself.
func (n *Name) Canonical() *Name {
if n.IsClosureVar() && n.Defn != nil {
n = n.Defn.(*Name)
}
return n
}
func (n *Name) SetByval(b bool) {
if n.Canonical() != n {
base.Fatalf("SetByval called on non-canonical variable: %v", n)
}
n.flags.set(nameByval, b)
}
func (n *Name) Byval() bool {
// We require byval to be set on the canonical variable, but we
// allow it to be accessed from any instance.
return n.Canonical().flags&nameByval != 0
}
// NewClosureVar returns a new closure variable for fn to refer to
// outer variable n.
func NewClosureVar(pos src.XPos, fn *Func, n *Name) *Name {
c := NewNameAt(pos, n.Sym())
c.Curfn = fn
c.Class = PAUTOHEAP
c.SetIsClosureVar(true)
c.Defn = n.Canonical()
c.Outer = n
c.SetType(n.Type())
c.SetTypecheck(n.Typecheck())
fn.ClosureVars = append(fn.ClosureVars, c)
return c
}
// NewHiddenParam returns a new hidden parameter for fn with the given
// name and type.
func NewHiddenParam(pos src.XPos, fn *Func, sym *types.Sym, typ *types.Type) *Name {
if fn.OClosure != nil {
base.FatalfAt(fn.Pos(), "cannot add hidden parameters to closures")
}
fn.SetNeedctxt(true)
// Create a fake parameter, disassociated from any real function, to
// pretend to capture.
fake := NewNameAt(pos, sym)
fake.Class = PPARAM
fake.SetType(typ)
fake.SetByval(true)
return NewClosureVar(pos, fn, fake)
}
// CaptureName returns a Name suitable for referring to n from within function
// fn or from the package block if fn is nil. If n is a free variable declared
// within a function that encloses fn, then CaptureName returns the closure
// variable that refers to n within fn, creating it if necessary.
// Otherwise, it simply returns n.
func CaptureName(pos src.XPos, fn *Func, n *Name) *Name {
if n.Op() != ONAME || n.Curfn == nil {
return n // okay to use directly
}
if n.IsClosureVar() {
base.FatalfAt(pos, "misuse of CaptureName on closure variable: %v", n)
}
c := n.Innermost
if c == nil {
c = n
}
if c.Curfn == fn {
return c
}
if fn == nil {
base.FatalfAt(pos, "package-block reference to %v, declared in %v", n, n.Curfn)
}
// Do not have a closure var for the active closure yet; make one.
c = NewClosureVar(pos, fn, c)
// Link into list of active closure variables.
// Popped from list in FinishCaptureNames.
n.Innermost = c
return c
}
// FinishCaptureNames handles any work leftover from calling CaptureName
// earlier. outerfn should be the function that immediately encloses fn.
func FinishCaptureNames(pos src.XPos, outerfn, fn *Func) {
// closure-specific variables are hanging off the
// ordinary ones; see CaptureName above.
// unhook them.
// make the list of pointers for the closure call.
for _, cv := range fn.ClosureVars {
// Unlink from n; see comment above on type Name for these fields.
n := cv.Defn.(*Name)
n.Innermost = cv.Outer
// If the closure usage of n is not dense, we need to make it
// dense by recapturing n within the enclosing function.
//
// That is, suppose we just finished parsing the innermost
// closure f4 in this code:
//
// func f() {
// n := 1
// func() { // f2
// use(n)
// func() { // f3
// func() { // f4
// use(n)
// }()
// }()
// }()
// }
//
// At this point cv.Outer is f2's n; there is no n for f3. To
// construct the closure f4 from within f3, we need to use f3's
// n and in this case we need to create f3's n with CaptureName.
//
// We'll decide later in walk whether to use v directly or &v.
cv.Outer = CaptureName(pos, outerfn, n)
}
}
// SameSource reports whether two nodes refer to the same source
// element.
//
// It exists to help incrementally migrate the compiler towards
// allowing the introduction of IdentExpr (#42990). Once we have
// IdentExpr, it will no longer be safe to directly compare Node
// values to tell if they refer to the same Name. Instead, code will
// need to explicitly get references to the underlying Name object(s),
// and compare those instead.
//
// It will still be safe to compare Nodes directly for checking if two
// nodes are syntactically the same. The SameSource function exists to
// indicate code that intentionally compares Nodes for syntactic
// equality as opposed to code that has yet to be updated in
// preparation for IdentExpr.
func SameSource(n1, n2 Node) bool {
return n1 == n2
}
// Uses reports whether expression x is a (direct) use of the given
// variable.
func Uses(x Node, v *Name) bool {
if v == nil || v.Op() != ONAME {
base.Fatalf("RefersTo bad Name: %v", v)
}
return x.Op() == ONAME && x.Name() == v
}
// DeclaredBy reports whether expression x refers (directly) to a
// variable that was declared by the given statement.
func DeclaredBy(x, stmt Node) bool {
if stmt == nil {
base.Fatalf("DeclaredBy nil")
}
return x.Op() == ONAME && SameSource(x.Name().Defn, stmt)
}
// The Class of a variable/function describes the "storage class"
// of a variable or function. During parsing, storage classes are
// called declaration contexts.
type Class uint8
//go:generate stringer -type=Class name.go
const (
Pxxx Class = iota // no class; used during ssa conversion to indicate pseudo-variables
PEXTERN // global variables
PAUTO // local variables
PAUTOHEAP // local variables or parameters moved to heap
PPARAM // input arguments
PPARAMOUT // output results
PTYPEPARAM // type params
PFUNC // global functions
// Careful: Class is stored in three bits in Node.flags.
_ = uint((1 << 3) - iota) // static assert for iota <= (1 << 3)
)
type Embed struct {
Pos src.XPos
Patterns []string
}
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