cmd/internal/objfile: cache computation of goobj.Arch

Change-Id: I23774cf185e5fa6b89398001cd0655fb0c5bdb46
GitHub-Last-Rev: ca8cae2469b5fad84bd636a3305a484dfdcb0db2
GitHub-Pull-Request: golang/go#40877
Reviewed-on: https://go-review.googlesource.com/c/go/+/249180
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/internal/archive/archive.go b/src/cmd/internal/archive/archive.go
index db67ce424ba60c765dd4ba4e6ae1bd2771a27515..c1661d7711ac901ef1ae73539e38cd2f64c83785 100644 (file)
--- a/src/cmd/internal/archive/archive.go
+++ b/src/cmd/internal/archive/archive.go
@@ -17,6 +17,7 @@ import (
        "log"
        "os"
        "strconv"
+       "strings"
        "time"
        "unicode/utf8"
 )
@@ -83,6 +84,7 @@ func (e *Entry) String() string {
 
 type GoObj struct {
        TextHeader []byte
+       Arch       string
        Data
 }
 
@@ -404,6 +406,10 @@ func (r *objReader) parseObject(o *GoObj, size int64) error {
                }
        }
        o.TextHeader = h
+       hs := strings.Fields(string(h))
+       if len(hs) >= 4 {
+               o.Arch = hs[3]
+       }
        o.Offset = r.offset
        o.Size = size - int64(len(h))
 

diff --git a/src/cmd/internal/objfile/goobj.go b/src/cmd/internal/objfile/goobj.go
index e838f58aed887a85a286c18723cd40984be69bf9..af9ada3324edf14ac3505906ae67bc18c92b2ac5 100644 (file)
--- a/src/cmd/internal/objfile/goobj.go
+++ b/src/cmd/internal/objfile/goobj.go
@@ -17,13 +17,13 @@ import (
        "fmt"
        "io"
        "os"
-       "strings"
 )
 
 type goobjFile struct {
        goobj *archive.GoObj
        r     *goobj.Reader
        f     *os.File
+       arch  *sys.Arch
 }
 
 func openGoFile(f *os.File) (*File, error) {
@@ -45,9 +45,16 @@ L:
                                return nil, err
                        }
                        r := goobj.NewReaderFromBytes(b, false)
+                       var arch *sys.Arch
+                       for _, a := range sys.Archs {
+                               if a.Name == e.Obj.Arch {
+                                       arch = a
+                                       break
+                               }
+                       }
                        entries = append(entries, &Entry{
                                name: e.Name,
-                               raw:  &goobjFile{e.Obj, r, f},
+                               raw:  &goobjFile{e.Obj, r, f, arch},
                        })
                        continue
                case archive.EntryNativeObj:
@@ -223,17 +230,8 @@ func (f *goobjFile) pcln() (textStart uint64, symtab, pclntab []byte, err error)
 // Returns "",0,nil if unknown.
 // This function implements the Liner interface in preference to pcln() above.
 func (f *goobjFile) PCToLine(pc uint64) (string, int, *gosym.Func) {
-       // TODO: this is really inefficient. Binary search? Memoize last result?
        r := f.r
-       var arch *sys.Arch
-       archname := f.goarch()
-       for _, a := range sys.Archs {
-               if a.Name == archname {
-                       arch = a
-                       break
-               }
-       }
-       if arch == nil {
+       if f.arch == nil {
                return "", 0, nil
        }
        pcdataBase := r.PcdataBase()
@@ -264,10 +262,10 @@ func (f *goobjFile) PCToLine(pc uint64) (string, int, *gosym.Func) {
                lengths := info.ReadFuncInfoLengths(b)
                off, end := info.ReadPcline(b)
                pcline := r.BytesAt(pcdataBase+off, int(end-off))
-               line := int(pcValue(pcline, pc-addr, arch))
+               line := int(pcValue(pcline, pc-addr, f.arch))
                off, end = info.ReadPcfile(b)
                pcfile := r.BytesAt(pcdataBase+off, int(end-off))
-               fileID := pcValue(pcfile, pc-addr, arch)
+               fileID := pcValue(pcfile, pc-addr, f.arch)
                globalFileID := info.ReadFile(b, lengths.FileOff, uint32(fileID))
                fileName := r.File(int(globalFileID))
                // Note: we provide only the name in the Func structure.
@@ -332,11 +330,7 @@ func (f *goobjFile) text() (textStart uint64, text []byte, err error) {
 }
 
 func (f *goobjFile) goarch() string {
-       hs := strings.Fields(string(f.goobj.TextHeader))
-       if len(hs) >= 4 {
-               return hs[3]
-       }
-       return ""
+       return f.goobj.Arch
 }
 
 func (f *goobjFile) loadAddress() (uint64, error) {