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// Derived from Inferno utils/6l/l.h and related files.
// https://bitbucket.org/inferno-os/inferno-os/src/default/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/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.
// Encoding:
// type = TYPE_REGLIST
// offset = bit mask of registers in list; R0 is low bit.
//
// 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
//
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
)
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
)
// Prog describes a single machine instruction.
//
// The general instruction form is:
//
// As.Scond From, Reg, From3, To, RegTo2
//
// where As is an opcode and the others are arguments:
// From, Reg, From3 are sources, and To, RegTo2 are 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.
//
// Jump instructions use the Pcond field to point to the target instruction,
// 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
From3 *Addr // third source operand (second is Reg below)
To Addr // destination operand (second is RegTo2 below)
Pcond *Prog // target of conditional jump
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 // condition bits for conditional instruction (e.g., on ARM)
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
}
// From3Type returns From3.Type, or TYPE_NONE when From3 is nil.
func (p *Prog) From3Type() AddrType {
if p.From3 == nil {
return TYPE_NONE
}
return p.From3.Type
}
// 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
APCDATA
ARET
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) << 10
ABaseARM
ABaseAMD64
ABasePPC64
ABaseARM64
ABaseMIPS
ABaseS390X
AllowedOpCodes = 1 << 10 // 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.
type LSym struct {
Name string
Type objabi.SymKind
Attribute
RefIdx int // Index of this symbol in the symbol reference list.
Size int64
Gotype *LSym
P []byte
R []Reloc
Func *FuncInfo
}
// A FuncInfo contains extra fields for STEXT symbols.
type FuncInfo struct {
Args int32
Locals int32
Text *Prog
Autom []*Auto
Pcln Pcln
dwarfSym *LSym
GCArgs LSym
GCLocals LSym
}
// Attribute is a set of symbol attributes.
type Attribute int16
const (
AttrDuplicateOK Attribute = 1 << iota
AttrCFunc
AttrNoSplit
AttrLeaf
AttrWrapper
AttrNeedCtxt
AttrNoFrame
AttrSeenGlobl
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
)
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) SeenGlobl() bool { return a&AttrSeenGlobl != 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) Set(flag Attribute, value bool) {
if value {
*a |= flag
} else {
*a &^= flag
}
}
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: AttrSeenGlobl, s: ""},
{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"},
}
// 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
}
}
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
}
// The compiler needs LSym to satisfy fmt.Stringer, because it stores
// an LSym in ssa.ExternSymbol.
func (s *LSym) String() string {
return s.Name
}
type Pcln struct {
Pcsp Pcdata
Pcfile Pcdata
Pcline Pcdata
Pcinline Pcdata
Pcdata []Pcdata
Funcdata []*LSym
Funcdataoff []int64
File []string
Lastfile string
Lastindex int
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
}
type Pcdata struct {
P []byte
}
// 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 bool
Debugvlog bool
Debugpcln string
Flag_shared bool
Flag_dynlink bool
Flag_optimize bool
Bso *bufio.Writer
Pathname string
hashmu sync.Mutex // protects hash
hash map[string]*LSym // name -> sym mapping
statichash map[string]*LSym // name -> sym mapping for static syms
PosTable src.PosTable
InlTree InlTree // global inlining tree used by gc/inl.go
Imports []string
DiagFunc func(string, ...interface{})
DebugInfo func(fn *LSym, curfn interface{}) []*dwarf.Var // if non-nil, curfn is a *gc.Node
Errors int
Framepointer_enabled bool
// state for writing objects
Text []*LSym
Data []*LSym
}
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:
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.
}