type Entry struct {
    Offset   Offset
    Tag      Tag // 描述其類型
    Children bool
    Field    []Field // 包含的字段
}

package s
    func Leaf(lx, ly int) int {
        return (lx << 7) ^ (ly >> uint32(lx&7))
    }
    func Top(tq int) int {
        var tv [10]int
        tr := Leaf(tq-13, tq+13)
        return tr + tv[tr&3]
    }

DW_TAG_complication_unit{ // package s
DW_TAG_subprogram {
      DW_AT_name:            s.Top
      DW_TAG_formal_parameter {
         DW_AT_name:         tq  // 參數(shù)名
         DW_AT_type:         ... // 參數(shù)類型
      }  
   }
}   

// go1.19/src/cmd/pprof/pprof.go:300
func pctoLine(f *elf.File, pc uint64) []driver.Frame {
	dwarf, _ := f.DWARF()
	r := dwarf.Reader()
	unit, _ := r.SeekPC(pc)
	lines, _ := dwarf.LineReader(unit)
	var lentry godwarf.LineEntry
	if err := lines.SeekPC(pc, &lentry); err != nil {
		log.Fatal(err)
	}
	// Try to find the function name.
	name := ""
FindName:
	for entry, err := r.Next(); entry != nil && err == nil; entry, err = r.Next() {
		if entry.Tag == godwarf.TagSubprogram {
			ranges, err := dwarf.Ranges(entry)
			if err != nil {
				log.Fatal(err)
			}
			for _, pcs := range ranges {
				if pcs[0] <= pc && pc < pcs[1] {
					var ok bool
					// TODO: AT_linkage_name, AT_MIPS_linkage_name.
					name, ok = entry.Val(godwarf.AttrName).(string)
					if ok {
						break FindName
					}
				}
			}
		}
	}
	frames := []driver.Frame{
		{
			Func: name,
			File: lentry.File.Name,
			Line: lentry.Line,
		},
	}
	return frames
}

2152: 0x5a51a8 M=1 regexp/syntax.simplify1 /usr/local/go1.18/go/src/regexp/syntax/simplify.go:148 s=0
             regexp/syntax.(*Regexp).Simplify /usr/local/go1.18/go/src/regexp/syntax/simplify.go:100 s=0

regexp/syntax.(*Regexp).Simplify /usr/local/go1.18/go/src/regexp/syntax/simplify.go 148

package s
    func Leaf(lx, ly int) int {
        return (lx << 7) ^ (ly >> uint32(lx&7))
    }
    func Top(tq int) int {
        var tv [10]int
        tr := Leaf(tq-13, tq+13)
        return tr + tv[tr&3]
    }

DW_TAG_subprogram {
      DW_AT_name:            s.Top
      DW_TAG_formal_parameter {
         DW_AT_name:         tq
         DW_AT_type:         ...
      }
// abstract inline function
DW_TAG_subprogram {   // offset: D1
      DW_AT_name:            s.Leaf
      DW_AT_inline : DW_INL_inlined (not declared as inline but inlined)
      ...
      DW_TAG_formal_parameter {   // offset: D2
         DW_AT_name:         lx
         DW_AT_type:         ...
      }
      DW_TAG_formal_parameter {    // offset: D3
         DW_AT_name:         ly
         DW_AT_type:         ...
      }
      ...
   }
      // inlined body of 'Leaf'
      DW_TAG_inlined_subroutine {
         DW_AT_abstract_origin: // reference to D1 above
         DW_AT_call_file: 1
         DW_AT_call_line: 15
         DW_AT_ranges         : ...
         DW_TAG_formal_parameter {
            DW_AT_abstract_origin: // reference to D2 above
            DW_AT_location:        ...
         }
         DW_TAG_formal_parameter {
            DW_AT_abstract_origin: // reference to D3 above
            DW_AT_location:        ...
         }
      }
   }

func inlineStackInternal(stack []*godwarf.Tree, n *godwarf.Tree, pc uint64) []*godwarf.Tree {
	switch n.Tag {
	case dwarf.TagSubprogram, dwarf.TagInlinedSubroutine, dwarf.TagLexDwarfBlock:
		if pc == 0 || n.ContainsPC(pc) {
			for _, child := range n.Children {
				stack = inlineStackInternal(stack, child, pc)
			}
			if n.Tag == dwarf.TagInlinedSubroutine {
				stack = append(stack, n)
			}
		}
	}
	return stack
}

abstractOrigin := f.abstractSubprograms[e.Val(dwarf.AttrAbstractOrigin).(dwarf.Offset)]

package main
import (
	"debug/elf"
	"log"
	"os"
	"strconv"
	parcadwarf "github.com/parca-dev/parca/pkg/symbol/addr2line"
	"github.com/parca-dev/parca/pkg/symbol/demangle"
)
func main() {
	f, _ := elf.Open(os.Args[1])
	debug, _ := parcadwarf.DWARF(nil, f, demangle.NewDemangler("simple", false))
	pc, _ := strconv.ParseUint(os.Args[2], 16, 64)
	log.Println(debug.PCToLines(pc))
}