bee/vendor/github.com/derekparker/delve/dwarf/line/state_machine.go

253 lines
5.8 KiB
Go

package line
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"github.com/derekparker/delve/dwarf/util"
)
type Location struct {
File string
Line int
Address uint64
Delta int
}
type StateMachine struct {
dbl *DebugLineInfo
file string
line int
address uint64
column uint
isStmt bool
basicBlock bool
endSeq bool
lastWasStandard bool
lastDelta int
}
type opcodefn func(*StateMachine, *bytes.Buffer)
// Special opcodes
const (
DW_LNS_copy = 1
DW_LNS_advance_pc = 2
DW_LNS_advance_line = 3
DW_LNS_set_file = 4
DW_LNS_set_column = 5
DW_LNS_negate_stmt = 6
DW_LNS_set_basic_block = 7
DW_LNS_const_add_pc = 8
DW_LNS_fixed_advance_pc = 9
)
// Extended opcodes
const (
DW_LINE_end_sequence = 1
DW_LINE_set_address = 2
DW_LINE_define_file = 3
)
var standardopcodes = map[byte]opcodefn{
DW_LNS_copy: copyfn,
DW_LNS_advance_pc: advancepc,
DW_LNS_advance_line: advanceline,
DW_LNS_set_file: setfile,
DW_LNS_set_column: setcolumn,
DW_LNS_negate_stmt: negatestmt,
DW_LNS_set_basic_block: setbasicblock,
DW_LNS_const_add_pc: constaddpc,
DW_LNS_fixed_advance_pc: fixedadvancepc,
}
var extendedopcodes = map[byte]opcodefn{
DW_LINE_end_sequence: endsequence,
DW_LINE_set_address: setaddress,
DW_LINE_define_file: definefile,
}
func newStateMachine(dbl *DebugLineInfo) *StateMachine {
return &StateMachine{dbl: dbl, file: dbl.FileNames[0].Name, line: 1}
}
// Returns all PCs for a given file/line. Useful for loops where the 'for' line
// could be split amongst 2 PCs.
func (dbl *DebugLines) AllPCsForFileLine(f string, l int) (pcs []uint64) {
var (
foundFile bool
lastAddr uint64
lineInfo = dbl.GetLineInfo(f)
sm = newStateMachine(lineInfo)
buf = bytes.NewBuffer(lineInfo.Instructions)
)
for b, err := buf.ReadByte(); err == nil; b, err = buf.ReadByte() {
findAndExecOpcode(sm, buf, b)
if foundFile && sm.file != f {
return
}
if sm.line == l && sm.file == f && sm.address != lastAddr {
foundFile = true
pcs = append(pcs, sm.address)
line := sm.line
// Keep going until we're on a different line. We only care about
// when a line comes back around (i.e. for loop) so get to next line,
// and try to find the line we care about again.
for b, err := buf.ReadByte(); err == nil; b, err = buf.ReadByte() {
findAndExecOpcode(sm, buf, b)
if line < sm.line {
break
}
}
}
}
return
}
var NoSourceError = errors.New("no source available")
func (dbl *DebugLines) AllPCsBetween(begin, end uint64, filename string) ([]uint64, error) {
lineInfo := dbl.GetLineInfo(filename)
if lineInfo == nil {
return nil, NoSourceError
}
var (
pcs []uint64
lastaddr uint64
sm = newStateMachine(lineInfo)
buf = bytes.NewBuffer(lineInfo.Instructions)
)
for b, err := buf.ReadByte(); err == nil; b, err = buf.ReadByte() {
findAndExecOpcode(sm, buf, b)
if sm.address > end {
break
}
if sm.address >= begin && sm.address > lastaddr {
lastaddr = sm.address
pcs = append(pcs, sm.address)
}
}
return pcs, nil
}
func findAndExecOpcode(sm *StateMachine, buf *bytes.Buffer, b byte) {
switch {
case b == 0:
execExtendedOpcode(sm, b, buf)
case b < sm.dbl.Prologue.OpcodeBase:
execStandardOpcode(sm, b, buf)
default:
execSpecialOpcode(sm, b)
}
}
func execSpecialOpcode(sm *StateMachine, instr byte) {
var (
opcode = uint8(instr)
decoded = opcode - sm.dbl.Prologue.OpcodeBase
)
if sm.dbl.Prologue.InitialIsStmt == uint8(1) {
sm.isStmt = true
}
sm.lastDelta = int(sm.dbl.Prologue.LineBase + int8(decoded%sm.dbl.Prologue.LineRange))
sm.line += sm.lastDelta
sm.address += uint64(decoded / sm.dbl.Prologue.LineRange)
sm.basicBlock = false
sm.lastWasStandard = false
}
func execExtendedOpcode(sm *StateMachine, instr byte, buf *bytes.Buffer) {
_, _ = util.DecodeULEB128(buf)
b, _ := buf.ReadByte()
fn, ok := extendedopcodes[b]
if !ok {
panic(fmt.Sprintf("Encountered unknown extended opcode %#v\n", b))
}
sm.lastWasStandard = false
fn(sm, buf)
}
func execStandardOpcode(sm *StateMachine, instr byte, buf *bytes.Buffer) {
fn, ok := standardopcodes[instr]
if !ok {
panic(fmt.Sprintf("Encountered unknown standard opcode %#v\n", instr))
}
sm.lastWasStandard = true
fn(sm, buf)
}
func copyfn(sm *StateMachine, buf *bytes.Buffer) {
sm.basicBlock = false
}
func advancepc(sm *StateMachine, buf *bytes.Buffer) {
addr, _ := util.DecodeULEB128(buf)
sm.address += addr * uint64(sm.dbl.Prologue.MinInstrLength)
}
func advanceline(sm *StateMachine, buf *bytes.Buffer) {
line, _ := util.DecodeSLEB128(buf)
sm.line += int(line)
sm.lastDelta = int(line)
}
func setfile(sm *StateMachine, buf *bytes.Buffer) {
i, _ := util.DecodeULEB128(buf)
sm.file = sm.dbl.FileNames[i-1].Name
}
func setcolumn(sm *StateMachine, buf *bytes.Buffer) {
c, _ := util.DecodeULEB128(buf)
sm.column = uint(c)
}
func negatestmt(sm *StateMachine, buf *bytes.Buffer) {
sm.isStmt = !sm.isStmt
}
func setbasicblock(sm *StateMachine, buf *bytes.Buffer) {
sm.basicBlock = true
}
func constaddpc(sm *StateMachine, buf *bytes.Buffer) {
sm.address += (255 / uint64(sm.dbl.Prologue.LineRange))
}
func fixedadvancepc(sm *StateMachine, buf *bytes.Buffer) {
var operand uint16
binary.Read(buf, binary.LittleEndian, &operand)
sm.address += uint64(operand)
}
func endsequence(sm *StateMachine, buf *bytes.Buffer) {
sm.endSeq = true
}
func setaddress(sm *StateMachine, buf *bytes.Buffer) {
var addr uint64
binary.Read(buf, binary.LittleEndian, &addr)
sm.address = addr
}
func definefile(sm *StateMachine, buf *bytes.Buffer) {
var (
_, _ = util.ParseString(buf)
_, _ = util.DecodeULEB128(buf)
_, _ = util.DecodeULEB128(buf)
_, _ = util.DecodeULEB128(buf)
)
// Don't do anything here yet.
}