Adding upstream version 1.16.10.upstream/1.16.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 861 insertions, 0 deletions

diff --git a/src/cmd/internal/obj/link.go b/src/cmd/internal/obj/link.go
new file mode 100644
index 0000000..8c8ff58
--- /dev/null
+++ b/src/cmd/internal/obj/link.go
@@ -0,0 +1,861 @@
+// Derived from Inferno utils/6l/l.h and related files.
+// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/l.h
+//
+//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
+//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
+//	Portions Copyright © 1997-1999 Vita Nuova Limited
+//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
+//	Portions Copyright © 2004,2006 Bruce Ellis
+//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
+//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
+//	Portions Copyright © 2009 The Go Authors. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package obj
+
+import (
+	"bufio"
+	"cmd/internal/dwarf"
+	"cmd/internal/goobj"
+	"cmd/internal/objabi"
+	"cmd/internal/src"
+	"cmd/internal/sys"
+	"fmt"
+	"sync"
+)
+
+// An Addr is an argument to an instruction.
+// The general forms and their encodings are:
+//
+//	sym±offset(symkind)(reg)(index*scale)
+//		Memory reference at address &sym(symkind) + offset + reg + index*scale.
+//		Any of sym(symkind), ±offset, (reg), (index*scale), and *scale can be omitted.
+//		If (reg) and *scale are both omitted, the resulting expression (index) is parsed as (reg).
+//		To force a parsing as index*scale, write (index*1).
+//		Encoding:
+//			type = TYPE_MEM
+//			name = symkind (NAME_AUTO, ...) or 0 (NAME_NONE)
+//			sym = sym
+//			offset = ±offset
+//			reg = reg (REG_*)
+//			index = index (REG_*)
+//			scale = scale (1, 2, 4, 8)
+//
+//	$<mem>
+//		Effective address of memory reference <mem>, defined above.
+//		Encoding: same as memory reference, but type = TYPE_ADDR.
+//
+//	$<±integer value>
+//		This is a special case of $<mem>, in which only ±offset is present.
+//		It has a separate type for easy recognition.
+//		Encoding:
+//			type = TYPE_CONST
+//			offset = ±integer value
+//
+//	*<mem>
+//		Indirect reference through memory reference <mem>, defined above.
+//		Only used on x86 for CALL/JMP *sym(SB), which calls/jumps to a function
+//		pointer stored in the data word sym(SB), not a function named sym(SB).
+//		Encoding: same as above, but type = TYPE_INDIR.
+//
+//	$*$<mem>
+//		No longer used.
+//		On machines with actual SB registers, $*$<mem> forced the
+//		instruction encoding to use a full 32-bit constant, never a
+//		reference relative to SB.
+//
+//	$<floating point literal>
+//		Floating point constant value.
+//		Encoding:
+//			type = TYPE_FCONST
+//			val = floating point value
+//
+//	$<string literal, up to 8 chars>
+//		String literal value (raw bytes used for DATA instruction).
+//		Encoding:
+//			type = TYPE_SCONST
+//			val = string
+//
+//	<register name>
+//		Any register: integer, floating point, control, segment, and so on.
+//		If looking for specific register kind, must check type and reg value range.
+//		Encoding:
+//			type = TYPE_REG
+//			reg = reg (REG_*)
+//
+//	x(PC)
+//		Encoding:
+//			type = TYPE_BRANCH
+//			val = Prog* reference OR ELSE offset = target pc (branch takes priority)
+//
+//	$±x-±y
+//		Final argument to TEXT, specifying local frame size x and argument size y.
+//		In this form, x and y are integer literals only, not arbitrary expressions.
+//		This avoids parsing ambiguities due to the use of - as a separator.
+//		The ± are optional.
+//		If the final argument to TEXT omits the -±y, the encoding should still
+//		use TYPE_TEXTSIZE (not TYPE_CONST), with u.argsize = ArgsSizeUnknown.
+//		Encoding:
+//			type = TYPE_TEXTSIZE
+//			offset = x
+//			val = int32(y)
+//
+//	reg<<shift, reg>>shift, reg->shift, reg@>shift
+//		Shifted register value, for ARM and ARM64.
+//		In this form, reg must be a register and shift can be a register or an integer constant.
+//		Encoding:
+//			type = TYPE_SHIFT
+//		On ARM:
+//			offset = (reg&15) | shifttype<<5 | count
+//			shifttype = 0, 1, 2, 3 for <<, >>, ->, @>
+//			count = (reg&15)<<8 | 1<<4 for a register shift count, (n&31)<<7 for an integer constant.
+//		On ARM64:
+//			offset = (reg&31)<<16 | shifttype<<22 | (count&63)<<10
+//			shifttype = 0, 1, 2 for <<, >>, ->
+//
+//	(reg, reg)
+//		A destination register pair. When used as the last argument of an instruction,
+//		this form makes clear that both registers are destinations.
+//		Encoding:
+//			type = TYPE_REGREG
+//			reg = first register
+//			offset = second register
+//
+//	[reg, reg, reg-reg]
+//		Register list for ARM, ARM64, 386/AMD64.
+//		Encoding:
+//			type = TYPE_REGLIST
+//		On ARM:
+//			offset = bit mask of registers in list; R0 is low bit.
+//		On ARM64:
+//			offset = register count (Q:size) | arrangement (opcode) | first register
+//		On 386/AMD64:
+//			reg = range low register
+//			offset = 2 packed registers + kind tag (see x86.EncodeRegisterRange)
+//
+//	reg, reg
+//		Register pair for ARM.
+//		TYPE_REGREG2
+//
+//	(reg+reg)
+//		Register pair for PPC64.
+//		Encoding:
+//			type = TYPE_MEM
+//			reg = first register
+//			index = second register
+//			scale = 1
+//
+//	reg.[US]XT[BHWX]
+//		Register extension for ARM64
+//		Encoding:
+//			type = TYPE_REG
+//			reg = REG_[US]XT[BHWX] + register + shift amount
+//			offset = ((reg&31) << 16) | (exttype << 13) | (amount<<10)
+//
+//	reg.<T>
+//		Register arrangement for ARM64 SIMD register
+//		e.g.: V1.S4, V2.S2, V7.D2, V2.H4, V6.B16
+//		Encoding:
+//			type = TYPE_REG
+//			reg = REG_ARNG + register + arrangement
+//
+//	reg.<T>[index]
+//		Register element for ARM64
+//		Encoding:
+//			type = TYPE_REG
+//			reg = REG_ELEM + register + arrangement
+//			index = element index
+
+type Addr struct {
+	Reg    int16
+	Index  int16
+	Scale  int16 // Sometimes holds a register.
+	Type   AddrType
+	Name   AddrName
+	Class  int8
+	Offset int64
+	Sym    *LSym
+
+	// argument value:
+	//	for TYPE_SCONST, a string
+	//	for TYPE_FCONST, a float64
+	//	for TYPE_BRANCH, a *Prog (optional)
+	//	for TYPE_TEXTSIZE, an int32 (optional)
+	Val interface{}
+}
+
+type AddrName int8
+
+const (
+	NAME_NONE AddrName = iota
+	NAME_EXTERN
+	NAME_STATIC
+	NAME_AUTO
+	NAME_PARAM
+	// A reference to name@GOT(SB) is a reference to the entry in the global offset
+	// table for 'name'.
+	NAME_GOTREF
+	// Indicates that this is a reference to a TOC anchor.
+	NAME_TOCREF
+)
+
+//go:generate stringer -type AddrType
+
+type AddrType uint8
+
+const (
+	TYPE_NONE AddrType = iota
+	TYPE_BRANCH
+	TYPE_TEXTSIZE
+	TYPE_MEM
+	TYPE_CONST
+	TYPE_FCONST
+	TYPE_SCONST
+	TYPE_REG
+	TYPE_ADDR
+	TYPE_SHIFT
+	TYPE_REGREG
+	TYPE_REGREG2
+	TYPE_INDIR
+	TYPE_REGLIST
+)
+
+func (a *Addr) Target() *Prog {
+	if a.Type == TYPE_BRANCH && a.Val != nil {
+		return a.Val.(*Prog)
+	}
+	return nil
+}
+func (a *Addr) SetTarget(t *Prog) {
+	if a.Type != TYPE_BRANCH {
+		panic("setting branch target when type is not TYPE_BRANCH")
+	}
+	a.Val = t
+}
+
+// Prog describes a single machine instruction.
+//
+// The general instruction form is:
+//
+//	(1) As.Scond From [, ...RestArgs], To
+//	(2) As.Scond From, Reg [, ...RestArgs], To, RegTo2
+//
+// where As is an opcode and the others are arguments:
+// From, Reg are sources, and To, RegTo2 are destinations.
+// RestArgs can hold additional sources and destinations.
+// Usually, not all arguments are present.
+// For example, MOVL R1, R2 encodes using only As=MOVL, From=R1, To=R2.
+// The Scond field holds additional condition bits for systems (like arm)
+// that have generalized conditional execution.
+// (2) form is present for compatibility with older code,
+// to avoid too much changes in a single swing.
+// (1) scheme is enough to express any kind of operand combination.
+//
+// Jump instructions use the To.Val field to point to the target *Prog,
+// which must be in the same linked list as the jump instruction.
+//
+// The Progs for a given function are arranged in a list linked through the Link field.
+//
+// Each Prog is charged to a specific source line in the debug information,
+// specified by Pos.Line().
+// Every Prog has a Ctxt field that defines its context.
+// For performance reasons, Progs usually are usually bulk allocated, cached, and reused;
+// those bulk allocators should always be used, rather than new(Prog).
+//
+// The other fields not yet mentioned are for use by the back ends and should
+// be left zeroed by creators of Prog lists.
+type Prog struct {
+	Ctxt     *Link     // linker context
+	Link     *Prog     // next Prog in linked list
+	From     Addr      // first source operand
+	RestArgs []AddrPos // can pack any operands that not fit into {Prog.From, Prog.To}
+	To       Addr      // destination operand (second is RegTo2 below)
+	Pool     *Prog     // constant pool entry, for arm,arm64 back ends
+	Forwd    *Prog     // for x86 back end
+	Rel      *Prog     // for x86, arm back ends
+	Pc       int64     // for back ends or assembler: virtual or actual program counter, depending on phase
+	Pos      src.XPos  // source position of this instruction
+	Spadj    int32     // effect of instruction on stack pointer (increment or decrement amount)
+	As       As        // assembler opcode
+	Reg      int16     // 2nd source operand
+	RegTo2   int16     // 2nd destination operand
+	Mark     uint16    // bitmask of arch-specific items
+	Optab    uint16    // arch-specific opcode index
+	Scond    uint8     // bits that describe instruction suffixes (e.g. ARM conditions)
+	Back     uint8     // for x86 back end: backwards branch state
+	Ft       uint8     // for x86 back end: type index of Prog.From
+	Tt       uint8     // for x86 back end: type index of Prog.To
+	Isize    uint8     // for x86 back end: size of the instruction in bytes
+}
+
+// Pos indicates whether the oprand is the source or the destination.
+type AddrPos struct {
+	Addr
+	Pos OperandPos
+}
+
+type OperandPos int8
+
+const (
+	Source OperandPos = iota
+	Destination
+)
+
+// From3Type returns p.GetFrom3().Type, or TYPE_NONE when
+// p.GetFrom3() returns nil.
+//
+// Deprecated: for the same reasons as Prog.GetFrom3.
+func (p *Prog) From3Type() AddrType {
+	if p.RestArgs == nil {
+		return TYPE_NONE
+	}
+	return p.RestArgs[0].Type
+}
+
+// GetFrom3 returns second source operand (the first is Prog.From).
+// In combination with Prog.From and Prog.To it makes common 3 operand
+// case easier to use.
+//
+// Should be used only when RestArgs is set with SetFrom3.
+//
+// Deprecated: better use RestArgs directly or define backend-specific getters.
+// Introduced to simplify transition to []Addr.
+// Usage of this is discouraged due to fragility and lack of guarantees.
+func (p *Prog) GetFrom3() *Addr {
+	if p.RestArgs == nil {
+		return nil
+	}
+	return &p.RestArgs[0].Addr
+}
+
+// SetFrom3 assigns []Args{{a, 0}} to p.RestArgs.
+// In pair with Prog.GetFrom3 it can help in emulation of Prog.From3.
+//
+// Deprecated: for the same reasons as Prog.GetFrom3.
+func (p *Prog) SetFrom3(a Addr) {
+	p.RestArgs = []AddrPos{{a, Source}}
+}
+
+// SetTo2 assings []Args{{a, 1}} to p.RestArgs when the second destination
+// operand does not fit into prog.RegTo2.
+func (p *Prog) SetTo2(a Addr) {
+	p.RestArgs = []AddrPos{{a, Destination}}
+}
+
+// GetTo2 returns the second destination operand.
+func (p *Prog) GetTo2() *Addr {
+	if p.RestArgs == nil {
+		return nil
+	}
+	return &p.RestArgs[0].Addr
+}
+
+// SetRestArgs assigns more than one source operands to p.RestArgs.
+func (p *Prog) SetRestArgs(args []Addr) {
+	for i := range args {
+		p.RestArgs = append(p.RestArgs, AddrPos{args[i], Source})
+	}
+}
+
+// An As denotes an assembler opcode.
+// There are some portable opcodes, declared here in package obj,
+// that are common to all architectures.
+// However, the majority of opcodes are arch-specific
+// and are declared in their respective architecture's subpackage.
+type As int16
+
+// These are the portable opcodes.
+const (
+	AXXX As = iota
+	ACALL
+	ADUFFCOPY
+	ADUFFZERO
+	AEND
+	AFUNCDATA
+	AJMP
+	ANOP
+	APCALIGN
+	APCDATA
+	ARET
+	AGETCALLERPC
+	ATEXT
+	AUNDEF
+	A_ARCHSPECIFIC
+)
+
+// Each architecture is allotted a distinct subspace of opcode values
+// for declaring its arch-specific opcodes.
+// Within this subspace, the first arch-specific opcode should be
+// at offset A_ARCHSPECIFIC.
+//
+// Subspaces are aligned to a power of two so opcodes can be masked
+// with AMask and used as compact array indices.
+const (
+	ABase386 = (1 + iota) << 11
+	ABaseARM
+	ABaseAMD64
+	ABasePPC64
+	ABaseARM64
+	ABaseMIPS
+	ABaseRISCV
+	ABaseS390X
+	ABaseWasm
+
+	AllowedOpCodes = 1 << 11            // The number of opcodes available for any given architecture.
+	AMask          = AllowedOpCodes - 1 // AND with this to use the opcode as an array index.
+)
+
+// An LSym is the sort of symbol that is written to an object file.
+// It represents Go symbols in a flat pkg+"."+name namespace.
+type LSym struct {
+	Name string
+	Type objabi.SymKind
+	Attribute
+
+	Size   int64
+	Gotype *LSym
+	P      []byte
+	R      []Reloc
+
+	Extra *interface{} // *FuncInfo or *FileInfo, if present
+
+	Pkg    string
+	PkgIdx int32
+	SymIdx int32
+}
+
+// A FuncInfo contains extra fields for STEXT symbols.
+type FuncInfo struct {
+	Args     int32
+	Locals   int32
+	Align    int32
+	FuncID   objabi.FuncID
+	Text     *Prog
+	Autot    map[*LSym]struct{}
+	Pcln     Pcln
+	InlMarks []InlMark
+
+	dwarfInfoSym       *LSym
+	dwarfLocSym        *LSym
+	dwarfRangesSym     *LSym
+	dwarfAbsFnSym      *LSym
+	dwarfDebugLinesSym *LSym
+
+	GCArgs             *LSym
+	GCLocals           *LSym
+	StackObjects       *LSym
+	OpenCodedDeferInfo *LSym
+
+	FuncInfoSym *LSym
+}
+
+// NewFuncInfo allocates and returns a FuncInfo for LSym.
+func (s *LSym) NewFuncInfo() *FuncInfo {
+	if s.Extra != nil {
+		panic(fmt.Sprintf("invalid use of LSym - NewFuncInfo with Extra of type %T", *s.Extra))
+	}
+	f := new(FuncInfo)
+	s.Extra = new(interface{})
+	*s.Extra = f
+	return f
+}
+
+// Func returns the *FuncInfo associated with s, or else nil.
+func (s *LSym) Func() *FuncInfo {
+	if s.Extra == nil {
+		return nil
+	}
+	f, _ := (*s.Extra).(*FuncInfo)
+	return f
+}
+
+// A FileInfo contains extra fields for SDATA symbols backed by files.
+// (If LSym.Extra is a *FileInfo, LSym.P == nil.)
+type FileInfo struct {
+	Name string // name of file to read into object file
+	Size int64  // length of file
+}
+
+// NewFileInfo allocates and returns a FileInfo for LSym.
+func (s *LSym) NewFileInfo() *FileInfo {
+	if s.Extra != nil {
+		panic(fmt.Sprintf("invalid use of LSym - NewFileInfo with Extra of type %T", *s.Extra))
+	}
+	f := new(FileInfo)
+	s.Extra = new(interface{})
+	*s.Extra = f
+	return f
+}
+
+// File returns the *FileInfo associated with s, or else nil.
+func (s *LSym) File() *FileInfo {
+	if s.Extra == nil {
+		return nil
+	}
+	f, _ := (*s.Extra).(*FileInfo)
+	return f
+}
+
+type InlMark struct {
+	// When unwinding from an instruction in an inlined body, mark
+	// where we should unwind to.
+	// id records the global inlining id of the inlined body.
+	// p records the location of an instruction in the parent (inliner) frame.
+	p  *Prog
+	id int32
+}
+
+// Mark p as the instruction to set as the pc when
+// "unwinding" the inlining global frame id. Usually it should be
+// instruction with a file:line at the callsite, and occur
+// just before the body of the inlined function.
+func (fi *FuncInfo) AddInlMark(p *Prog, id int32) {
+	fi.InlMarks = append(fi.InlMarks, InlMark{p: p, id: id})
+}
+
+// Record the type symbol for an auto variable so that the linker
+// an emit DWARF type information for the type.
+func (fi *FuncInfo) RecordAutoType(gotype *LSym) {
+	if fi.Autot == nil {
+		fi.Autot = make(map[*LSym]struct{})
+	}
+	fi.Autot[gotype] = struct{}{}
+}
+
+//go:generate stringer -type ABI
+
+// ABI is the calling convention of a text symbol.
+type ABI uint8
+
+const (
+	// ABI0 is the stable stack-based ABI. It's important that the
+	// value of this is "0": we can't distinguish between
+	// references to data and ABI0 text symbols in assembly code,
+	// and hence this doesn't distinguish between symbols without
+	// an ABI and text symbols with ABI0.
+	ABI0 ABI = iota
+
+	// ABIInternal is the internal ABI that may change between Go
+	// versions. All Go functions use the internal ABI and the
+	// compiler generates wrappers for calls to and from other
+	// ABIs.
+	ABIInternal
+
+	ABICount
+)
+
+// ParseABI converts from a string representation in 'abistr' to the
+// corresponding ABI value. Second return value is TRUE if the
+// abi string is recognized, FALSE otherwise.
+func ParseABI(abistr string) (ABI, bool) {
+	switch abistr {
+	default:
+		return ABI0, false
+	case "ABI0":
+		return ABI0, true
+	case "ABIInternal":
+		return ABIInternal, true
+	}
+}
+
+// Attribute is a set of symbol attributes.
+type Attribute uint32
+
+const (
+	AttrDuplicateOK Attribute = 1 << iota
+	AttrCFunc
+	AttrNoSplit
+	AttrLeaf
+	AttrWrapper
+	AttrNeedCtxt
+	AttrNoFrame
+	AttrOnList
+	AttrStatic
+
+	// MakeTypelink means that the type should have an entry in the typelink table.
+	AttrMakeTypelink
+
+	// ReflectMethod means the function may call reflect.Type.Method or
+	// reflect.Type.MethodByName. Matching is imprecise (as reflect.Type
+	// can be used through a custom interface), so ReflectMethod may be
+	// set in some cases when the reflect package is not called.
+	//
+	// Used by the linker to determine what methods can be pruned.
+	AttrReflectMethod
+
+	// Local means make the symbol local even when compiling Go code to reference Go
+	// symbols in other shared libraries, as in this mode symbols are global by
+	// default. "local" here means in the sense of the dynamic linker, i.e. not
+	// visible outside of the module (shared library or executable) that contains its
+	// definition. (When not compiling to support Go shared libraries, all symbols are
+	// local in this sense unless there is a cgo_export_* directive).
+	AttrLocal
+
+	// For function symbols; indicates that the specified function was the
+	// target of an inline during compilation
+	AttrWasInlined
+
+	// TopFrame means that this function is an entry point and unwinders should not
+	// keep unwinding beyond this frame.
+	AttrTopFrame
+
+	// Indexed indicates this symbol has been assigned with an index (when using the
+	// new object file format).
+	AttrIndexed
+
+	// Only applied on type descriptor symbols, UsedInIface indicates this type is
+	// converted to an interface.
+	//
+	// Used by the linker to determine what methods can be pruned.
+	AttrUsedInIface
+
+	// ContentAddressable indicates this is a content-addressable symbol.
+	AttrContentAddressable
+
+	// attrABIBase is the value at which the ABI is encoded in
+	// Attribute. This must be last; all bits after this are
+	// assumed to be an ABI value.
+	//
+	// MUST BE LAST since all bits above this comprise the ABI.
+	attrABIBase
+)
+
+func (a Attribute) DuplicateOK() bool        { return a&AttrDuplicateOK != 0 }
+func (a Attribute) MakeTypelink() bool       { return a&AttrMakeTypelink != 0 }
+func (a Attribute) CFunc() bool              { return a&AttrCFunc != 0 }
+func (a Attribute) NoSplit() bool            { return a&AttrNoSplit != 0 }
+func (a Attribute) Leaf() bool               { return a&AttrLeaf != 0 }
+func (a Attribute) OnList() bool             { return a&AttrOnList != 0 }
+func (a Attribute) ReflectMethod() bool      { return a&AttrReflectMethod != 0 }
+func (a Attribute) Local() bool              { return a&AttrLocal != 0 }
+func (a Attribute) Wrapper() bool            { return a&AttrWrapper != 0 }
+func (a Attribute) NeedCtxt() bool           { return a&AttrNeedCtxt != 0 }
+func (a Attribute) NoFrame() bool            { return a&AttrNoFrame != 0 }
+func (a Attribute) Static() bool             { return a&AttrStatic != 0 }
+func (a Attribute) WasInlined() bool         { return a&AttrWasInlined != 0 }
+func (a Attribute) TopFrame() bool           { return a&AttrTopFrame != 0 }
+func (a Attribute) Indexed() bool            { return a&AttrIndexed != 0 }
+func (a Attribute) UsedInIface() bool        { return a&AttrUsedInIface != 0 }
+func (a Attribute) ContentAddressable() bool { return a&AttrContentAddressable != 0 }
+
+func (a *Attribute) Set(flag Attribute, value bool) {
+	if value {
+		*a |= flag
+	} else {
+		*a &^= flag
+	}
+}
+
+func (a Attribute) ABI() ABI { return ABI(a / attrABIBase) }
+func (a *Attribute) SetABI(abi ABI) {
+	const mask = 1 // Only one ABI bit for now.
+	*a = (*a &^ (mask * attrABIBase)) | Attribute(abi)*attrABIBase
+}
+
+var textAttrStrings = [...]struct {
+	bit Attribute
+	s   string
+}{
+	{bit: AttrDuplicateOK, s: "DUPOK"},
+	{bit: AttrMakeTypelink, s: ""},
+	{bit: AttrCFunc, s: "CFUNC"},
+	{bit: AttrNoSplit, s: "NOSPLIT"},
+	{bit: AttrLeaf, s: "LEAF"},
+	{bit: AttrOnList, s: ""},
+	{bit: AttrReflectMethod, s: "REFLECTMETHOD"},
+	{bit: AttrLocal, s: "LOCAL"},
+	{bit: AttrWrapper, s: "WRAPPER"},
+	{bit: AttrNeedCtxt, s: "NEEDCTXT"},
+	{bit: AttrNoFrame, s: "NOFRAME"},
+	{bit: AttrStatic, s: "STATIC"},
+	{bit: AttrWasInlined, s: ""},
+	{bit: AttrTopFrame, s: "TOPFRAME"},
+	{bit: AttrIndexed, s: ""},
+	{bit: AttrContentAddressable, s: ""},
+}
+
+// TextAttrString formats a for printing in as part of a TEXT prog.
+func (a Attribute) TextAttrString() string {
+	var s string
+	for _, x := range textAttrStrings {
+		if a&x.bit != 0 {
+			if x.s != "" {
+				s += x.s + "|"
+			}
+			a &^= x.bit
+		}
+	}
+	switch a.ABI() {
+	case ABI0:
+	case ABIInternal:
+		s += "ABIInternal|"
+		a.SetABI(0) // Clear ABI so we don't print below.
+	}
+	if a != 0 {
+		s += fmt.Sprintf("UnknownAttribute(%d)|", a)
+	}
+	// Chop off trailing |, if present.
+	if len(s) > 0 {
+		s = s[:len(s)-1]
+	}
+	return s
+}
+
+func (s *LSym) String() string {
+	return s.Name
+}
+
+// The compiler needs *LSym to be assignable to cmd/compile/internal/ssa.Sym.
+func (s *LSym) CanBeAnSSASym() {
+}
+
+type Pcln struct {
+	// Aux symbols for pcln
+	Pcsp        *LSym
+	Pcfile      *LSym
+	Pcline      *LSym
+	Pcinline    *LSym
+	Pcdata      []*LSym
+	Funcdata    []*LSym
+	Funcdataoff []int64
+	UsedFiles   map[goobj.CUFileIndex]struct{} // file indices used while generating pcfile
+	InlTree     InlTree                        // per-function inlining tree extracted from the global tree
+}
+
+type Reloc struct {
+	Off  int32
+	Siz  uint8
+	Type objabi.RelocType
+	Add  int64
+	Sym  *LSym
+}
+
+type Auto struct {
+	Asym    *LSym
+	Aoffset int32
+	Name    AddrName
+	Gotype  *LSym
+}
+
+// Link holds the context for writing object code from a compiler
+// to be linker input or for reading that input into the linker.
+type Link struct {
+	Headtype           objabi.HeadType
+	Arch               *LinkArch
+	Debugasm           int
+	Debugvlog          bool
+	Debugpcln          string
+	Flag_shared        bool
+	Flag_dynlink       bool
+	Flag_linkshared    bool
+	Flag_optimize      bool
+	Flag_locationlists bool
+	Retpoline          bool // emit use of retpoline stubs for indirect jmp/call
+	Bso                *bufio.Writer
+	Pathname           string
+	Pkgpath            string           // the current package's import path, "" if unknown
+	hashmu             sync.Mutex       // protects hash, funchash
+	hash               map[string]*LSym // name -> sym mapping
+	funchash           map[string]*LSym // name -> sym mapping for ABIInternal syms
+	statichash         map[string]*LSym // name -> sym mapping for static syms
+	PosTable           src.PosTable
+	InlTree            InlTree // global inlining tree used by gc/inl.go
+	DwFixups           *DwarfFixupTable
+	Imports            []goobj.ImportedPkg
+	DiagFunc           func(string, ...interface{})
+	DiagFlush          func()
+	DebugInfo          func(fn *LSym, info *LSym, curfn interface{}) ([]dwarf.Scope, dwarf.InlCalls) // if non-nil, curfn is a *gc.Node
+	GenAbstractFunc    func(fn *LSym)
+	Errors             int
+
+	InParallel    bool // parallel backend phase in effect
+	UseBASEntries bool // use Base Address Selection Entries in location lists and PC ranges
+	IsAsm         bool // is the source assembly language, which may contain surprising idioms (e.g., call tables)
+
+	// state for writing objects
+	Text []*LSym
+	Data []*LSym
+
+	// ABIAliases are text symbols that should be aliased to all
+	// ABIs. These symbols may only be referenced and not defined
+	// by this object, since the need for an alias may appear in a
+	// different object than the definition. Hence, this
+	// information can't be carried in the symbol definition.
+	//
+	// TODO(austin): Replace this with ABI wrappers once the ABIs
+	// actually diverge.
+	ABIAliases []*LSym
+
+	// Constant symbols (e.g. $i64.*) are data symbols created late
+	// in the concurrent phase. To ensure a deterministic order, we
+	// add them to a separate list, sort at the end, and append it
+	// to Data.
+	constSyms []*LSym
+
+	// pkgIdx maps package path to index. The index is used for
+	// symbol reference in the object file.
+	pkgIdx map[string]int32
+
+	defs         []*LSym // list of defined symbols in the current package
+	hashed64defs []*LSym // list of defined short (64-bit or less) hashed (content-addressable) symbols
+	hasheddefs   []*LSym // list of defined hashed (content-addressable) symbols
+	nonpkgdefs   []*LSym // list of defined non-package symbols
+	nonpkgrefs   []*LSym // list of referenced non-package symbols
+
+	Fingerprint goobj.FingerprintType // fingerprint of symbol indices, to catch index mismatch
+}
+
+func (ctxt *Link) Diag(format string, args ...interface{}) {
+	ctxt.Errors++
+	ctxt.DiagFunc(format, args...)
+}
+
+func (ctxt *Link) Logf(format string, args ...interface{}) {
+	fmt.Fprintf(ctxt.Bso, format, args...)
+	ctxt.Bso.Flush()
+}
+
+// The smallest possible offset from the hardware stack pointer to a local
+// variable on the stack. Architectures that use a link register save its value
+// on the stack in the function prologue and so always have a pointer between
+// the hardware stack pointer and the local variable area.
+func (ctxt *Link) FixedFrameSize() int64 {
+	switch ctxt.Arch.Family {
+	case sys.AMD64, sys.I386, sys.Wasm:
+		return 0
+	case sys.PPC64:
+		// PIC code on ppc64le requires 32 bytes of stack, and it's easier to
+		// just use that much stack always on ppc64x.
+		return int64(4 * ctxt.Arch.PtrSize)
+	default:
+		return int64(ctxt.Arch.PtrSize)
+	}
+}
+
+// LinkArch is the definition of a single architecture.
+type LinkArch struct {
+	*sys.Arch
+	Init           func(*Link)
+	Preprocess     func(*Link, *LSym, ProgAlloc)
+	Assemble       func(*Link, *LSym, ProgAlloc)
+	Progedit       func(*Link, *Prog, ProgAlloc)
+	UnaryDst       map[As]bool // Instruction takes one operand, a destination.
+	DWARFRegisters map[int16]int16
+}