go/gcimporter: update importer to match latest gc export data changes
Adjustments taken from https://golang.org/cl/22580.
Change-Id: Ic88137b410767bd17e3d6142cec2b5a112df56be
Reviewed-on: https://go-review.googlesource.com/22582
Reviewed-by: Alan Donovan <adonovan@google.com>
diff --git a/go/gcimporter15/bexport.go b/go/gcimporter15/bexport.go
index 4a9cd2d..9cb46f9 100644
--- a/go/gcimporter15/bexport.go
+++ b/go/gcimporter15/bexport.go
@@ -37,14 +37,6 @@
// (suspected) format errors, and whenever a change is made to the format.
const debugFormat = false // default: false
-// If posInfoFormat is set, position information (file, lineno) is written
-// for each exported object, including methods and struct fields. Currently
-// disabled because it may lead to different object files depending on which
-// directory they are built under, which causes tests checking for hermetic
-// builds to fail (e.g. TestCgoConsistentResults for cmd/go).
-// TODO(gri) determine what to do here.
-const posInfoFormat = false
-
// If trace is set, debugging output is printed to std out.
const trace = false // default: false
@@ -60,8 +52,9 @@
typIndex map[types.Type]int
// position encoding
- prevFile string
- prevLine int
+ posInfoFormat bool
+ prevFile string
+ prevLine int
// debugging support
written int // bytes written
@@ -72,10 +65,11 @@
// If no file set is provided, position info will be missing.
func BExportData(fset *token.FileSet, pkg *types.Package) []byte {
p := exporter{
- fset: fset,
- strIndex: map[string]int{"": 0}, // empty string is mapped to 0
- pkgIndex: make(map[*types.Package]int),
- typIndex: make(map[types.Type]int),
+ fset: fset,
+ strIndex: map[string]int{"": 0}, // empty string is mapped to 0
+ pkgIndex: make(map[*types.Package]int),
+ typIndex: make(map[types.Type]int),
+ posInfoFormat: true, // TODO(gri) might become a flag, eventually
}
// first byte indicates low-level encoding format
@@ -86,7 +80,7 @@
p.rawByte(format)
// posInfo exported or not?
- p.bool(posInfoFormat)
+ p.bool(p.posInfoFormat)
// --- generic export data ---
@@ -211,29 +205,56 @@
}
func (p *exporter) pos(obj types.Object) {
- if !posInfoFormat {
+ if !p.posInfoFormat {
return
}
- var file string
- var line int
+ file, line := p.fileLine(obj)
+ if file == p.prevFile {
+ // common case: write line delta
+ // delta == 0 means different file or no line change
+ delta := line - p.prevLine
+ p.int(delta)
+ if delta == 0 {
+ p.int(-1) // -1 means no file change
+ }
+ } else {
+ // different file
+ p.int(0)
+ // Encode filename as length of common prefix with previous
+ // filename, followed by (possibly empty) suffix. Filenames
+ // frequently share path prefixes, so this can save a lot
+ // of space and make export data size less dependent on file
+ // path length. The suffix is unlikely to be empty because
+ // file names tend to end in ".go".
+ n := commonPrefixLen(p.prevFile, file)
+ p.int(n) // n >= 0
+ p.string(file[n:]) // write suffix only
+ p.prevFile = file
+ p.int(line)
+ }
+ p.prevLine = line
+}
+
+func (p *exporter) fileLine(obj types.Object) (file string, line int) {
if p.fset != nil {
pos := p.fset.Position(obj.Pos())
file = pos.Filename
line = pos.Line
}
+ return
+}
- if file == p.prevFile && line != p.prevLine {
- // common case: write delta-encoded line number
- p.int(line - p.prevLine) // != 0
- } else {
- // uncommon case: filename changed, or line didn't change
- p.int(0)
- p.string(file)
- p.int(line)
- p.prevFile = file
+func commonPrefixLen(a, b string) int {
+ if len(a) > len(b) {
+ a, b = b, a
}
- p.prevLine = line
+ // len(a) <= len(b)
+ i := 0
+ for i < len(a) && a[i] == b[i] {
+ i++
+ }
+ return i
}
func (p *exporter) qualifiedName(obj types.Object) {
diff --git a/go/gcimporter15/bimport.go b/go/gcimporter15/bimport.go
index 4cae220..22a6f60 100644
--- a/go/gcimporter15/bimport.go
+++ b/go/gcimporter15/bimport.go
@@ -208,13 +208,14 @@
file := p.prevFile
line := p.prevLine
-
if delta := p.int(); delta != 0 {
+ // line changed
line += delta
- } else {
- file = p.string()
- line = p.int()
+ } else if n := p.int(); n >= 0 {
+ // file changed
+ file = p.prevFile[:n] + p.string()
p.prevFile = file
+ line = p.int()
}
p.prevLine = line
