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cmd/compile: add explanations to escape-analysis JSON/LSP logging
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For 1.15.

From the test:

{"range":{"start":{"line":7,"character":13},"end":{...},"severity":3,"code":"leaks","source":"go compiler","message":"parameter z leaks to ~r2 with derefs=0","relatedInformation":[
	{"location":{"uri":"file://T/file.go","range":{"start":{"line":9,"character":13},"end":{...}},"message":"escflow:    flow: y = z:"},
	{"location":{"uri":"file://T/file.go","range":{"start":{"line":9,"character":13},"end":{...}},"message":"escflow:      from y = \u003cN\u003e (assign-pair)"},
	{"location":{"uri":"file://T/file.go","range":{"start":{"line":9,"character":13},"end":{...}},"message":"escflow:    flow: ~r1 = y:"},
	{"location":{"uri":"file://T/file.go","range":{"start":{"line":4,"character":11},"end":{...}},"message":"inlineLoc"},

	{"location":{"uri":"file://T/file.go","range":{"start":{"line":9,"character":13},"end":{...}},"message":"escflow:      from y.b (dot of pointer)"},
	{"location":{"uri":"file://T/file.go","range":{"start":{"line":4,"character":11},"end":{...}},"message":"inlineLoc"},

	{"location":{"uri":"file://T/file.go","range":{"start":{"line":9,"character":13},"end":{...}},"message":"escflow:      from \u0026y.b (address-of)"},
	{"location":{"uri":"file://T/file.go","range":{"start":{"line":4,"character":9},"end":...}},"message":"inlineLoc"},

	{"location":{"uri":"file://T/file.go","range":{"start":{"line":9,"character":13},"end":{...}},"message":"escflow:      from ~r1 = \u003cN\u003e (assign-pair)"},
	{"location":{"uri":"file://T/file.go","range":{"start":{"line":9,"character":3},"end":...}},"message":"escflow:    flow: ~r2 = ~r1:"},
	{"location":{"uri":"file://T/file.go","range":{"start":{"line":9,"character":3},"end":...}},"message":"escflow:      from return (*int)(~r1) (return)"}]}

Change-Id: Idf02438801f63e487c35a928cf5a0b6d3cc48674
Reviewed-on: https://go-review.googlesource.com/c/go/+/206658
Run-TryBot: David Chase <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Cherry Zhang <[email protected]>
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@dr2chase
dr2chase committed Apr 11, 2020
1 parent fced302 commit 06314b6
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Showing 3 changed files with 139 additions and 41 deletions.
78 changes: 60 additions & 18 deletions src/cmd/compile/internal/gc/escape.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ package gc
import (
"cmd/compile/internal/logopt"
"cmd/compile/internal/types"
"cmd/internal/src"
"fmt"
"math"
"strings"
Expand Down Expand Up @@ -945,7 +946,7 @@ func (k EscHole) note(where *Node, why string) EscHole {
if where == nil || why == "" {
Fatalf("note: missing where/why")
}
if Debug['m'] >= 2 {
if Debug['m'] >= 2 || logopt.Enabled() {
k.notes = &EscNote{
next: k.notes,
where: where,
Expand Down Expand Up @@ -1092,10 +1093,16 @@ func (e *Escape) flow(k EscHole, src *EscLocation) {
return
}
if dst.escapes && k.derefs < 0 { // dst = &src
if Debug['m'] >= 2 {
if Debug['m'] >= 2 || logopt.Enabled() {
pos := linestr(src.n.Pos)
fmt.Printf("%s: %v escapes to heap:\n", pos, src.n)
e.explainFlow(pos, dst, src, k.derefs, k.notes)
if Debug['m'] >= 2 {
fmt.Printf("%s: %v escapes to heap:\n", pos, src.n)
}
explanation := e.explainFlow(pos, dst, src, k.derefs, k.notes, []*logopt.LoggedOpt{})
if logopt.Enabled() {
logopt.LogOpt(src.n.Pos, "escapes", "escape", e.curfn.funcname(), fmt.Sprintf("%v escapes to heap", src.n), explanation)
}

}
src.escapes = true
return
Expand Down Expand Up @@ -1187,9 +1194,15 @@ func (e *Escape) walkOne(root *EscLocation, walkgen uint32, enqueue func(*EscLoc
// that value flow for tagging the function
// later.
if l.isName(PPARAM) {
if Debug['m'] >= 2 && !l.escapes {
fmt.Printf("%s: parameter %v leaks to %s with derefs=%d:\n", linestr(l.n.Pos), l.n, e.explainLoc(root), base)
e.explainPath(root, l)
if (logopt.Enabled() || Debug['m'] >= 2) && !l.escapes {
if Debug['m'] >= 2 {
fmt.Printf("%s: parameter %v leaks to %s with derefs=%d:\n", linestr(l.n.Pos), l.n, e.explainLoc(root), base)
}
explanation := e.explainPath(root, l)
if logopt.Enabled() {
logopt.LogOpt(l.n.Pos, "leak", "escape", e.curfn.funcname(),
fmt.Sprintf("parameter %v leaks to %s with derefs=%d", l.n, e.explainLoc(root), base), explanation)
}
}
l.leakTo(root, base)
}
Expand All @@ -1198,9 +1211,14 @@ func (e *Escape) walkOne(root *EscLocation, walkgen uint32, enqueue func(*EscLoc
// outlives it, then l needs to be heap
// allocated.
if addressOf && !l.escapes {
if Debug['m'] >= 2 {
fmt.Printf("%s: %v escapes to heap:\n", linestr(l.n.Pos), l.n)
e.explainPath(root, l)
if logopt.Enabled() || Debug['m'] >= 2 {
if Debug['m'] >= 2 {
fmt.Printf("%s: %v escapes to heap:\n", linestr(l.n.Pos), l.n)
}
explanation := e.explainPath(root, l)
if logopt.Enabled() {
logopt.LogOpt(l.n.Pos, "escape", "escape", e.curfn.funcname(), fmt.Sprintf("%v escapes to heap", l.n), explanation)
}
}
l.escapes = true
enqueue(l)
Expand All @@ -1225,43 +1243,67 @@ func (e *Escape) walkOne(root *EscLocation, walkgen uint32, enqueue func(*EscLoc
}

// explainPath prints an explanation of how src flows to the walk root.
func (e *Escape) explainPath(root, src *EscLocation) {
func (e *Escape) explainPath(root, src *EscLocation) []*logopt.LoggedOpt {
visited := make(map[*EscLocation]bool)

pos := linestr(src.n.Pos)
var explanation []*logopt.LoggedOpt
for {
// Prevent infinite loop.
if visited[src] {
fmt.Printf("%s: warning: truncated explanation due to assignment cycle; see golang.org/issue/35518\n", pos)
if Debug['m'] >= 2 {
fmt.Printf("%s: warning: truncated explanation due to assignment cycle; see golang.org/issue/35518\n", pos)
}
break
}
visited[src] = true

dst := src.dst
edge := &dst.edges[src.dstEdgeIdx]
if edge.src != src {
Fatalf("path inconsistency: %v != %v", edge.src, src)
}

e.explainFlow(pos, dst, src, edge.derefs, edge.notes)
explanation = e.explainFlow(pos, dst, src, edge.derefs, edge.notes, explanation)

if dst == root {
break
}
src = dst
}

return explanation
}

func (e *Escape) explainFlow(pos string, dst, src *EscLocation, derefs int, notes *EscNote) {
func (e *Escape) explainFlow(pos string, dst, srcloc *EscLocation, derefs int, notes *EscNote, explanation []*logopt.LoggedOpt) []*logopt.LoggedOpt {
ops := "&"
if derefs >= 0 {
ops = strings.Repeat("*", derefs)
}
print := Debug['m'] >= 2

flow := fmt.Sprintf(" flow: %s = %s%v:", e.explainLoc(dst), ops, e.explainLoc(srcloc))
if print {
fmt.Printf("%s:%s\n", pos, flow)
}
if logopt.Enabled() {
var epos src.XPos
if notes != nil {
epos = notes.where.Pos
} else if srcloc != nil && srcloc.n != nil {
epos = srcloc.n.Pos
}
explanation = append(explanation, logopt.NewLoggedOpt(epos, "escflow", "escape", e.curfn.funcname(), flow))
}

fmt.Printf("%s: flow: %s = %s%v:\n", pos, e.explainLoc(dst), ops, e.explainLoc(src))
for note := notes; note != nil; note = note.next {
fmt.Printf("%s: from %v (%v) at %s\n", pos, note.where, note.why, linestr(note.where.Pos))
if print {
fmt.Printf("%s: from %v (%v) at %s\n", pos, note.where, note.why, linestr(note.where.Pos))
}
if logopt.Enabled() {
explanation = append(explanation, logopt.NewLoggedOpt(note.where.Pos, "escflow", "escape", e.curfn.funcname(),
fmt.Sprintf(" from %v (%v)", note.where, note.why)))
}
}
return explanation
}

func (e *Escape) explainLoc(l *EscLocation) string {
Expand Down
80 changes: 60 additions & 20 deletions src/cmd/compile/internal/logopt/log_opts.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -294,18 +294,23 @@ func checkLogPath(flag, destination string) {
dest = destination
}

var loggedOpts []LoggedOpt
var loggedOpts []*LoggedOpt
var mu = sync.Mutex{} // mu protects loggedOpts.

func NewLoggedOpt(pos src.XPos, what, pass, fname string, args ...interface{}) *LoggedOpt {
pass = strings.Replace(pass, " ", "_", -1)
return &LoggedOpt{pos, pass, fname, what, args}
}

func LogOpt(pos src.XPos, what, pass, fname string, args ...interface{}) {
if Format == None {
return
}
pass = strings.Replace(pass, " ", "_", -1)
lo := NewLoggedOpt(pos, what, pass, fname, args...)
mu.Lock()
defer mu.Unlock()
// Because of concurrent calls from back end, no telling what the order will be, but is stable-sorted by outer Pos before use.
loggedOpts = append(loggedOpts, LoggedOpt{pos, pass, fname, what, args})
loggedOpts = append(loggedOpts, lo)
}

func Enabled() bool {
Expand All @@ -321,7 +326,7 @@ func Enabled() bool {
// byPos sorts diagnostics by source position.
type byPos struct {
ctxt *obj.Link
a []LoggedOpt
a []*LoggedOpt
}

func (x byPos) Len() int { return len(x.a) }
Expand Down Expand Up @@ -402,15 +407,9 @@ func FlushLoggedOpts(ctxt *obj.Link, slashPkgPath string) {
// For LSP, make a subdirectory for the package, and for each file foo.go, create foo.json in that subdirectory.
currentFile := ""
for _, x := range loggedOpts {
posTmp = ctxt.AllPos(x.pos, posTmp)
// Reverse posTmp to put outermost first.
l := len(posTmp)
for i := 0; i < l/2; i++ {
posTmp[i], posTmp[l-i-1] = posTmp[l-i-1], posTmp[i]
}

p0 := posTmp[0]
posTmp, p0 := x.parsePos(ctxt, posTmp)
p0f := uprootedPath(p0.Filename())

if currentFile != p0f {
if w != nil {
w.Close()
Expand All @@ -429,16 +428,27 @@ func FlushLoggedOpts(ctxt *obj.Link, slashPkgPath string) {

diagnostic.Code = x.what
diagnostic.Message = target
diagnostic.Range = Range{Start: Position{p0.Line(), p0.Col()},
End: Position{p0.Line(), p0.Col()}}
diagnostic.Range = newPointRange(p0)
diagnostic.RelatedInformation = diagnostic.RelatedInformation[:0]

for i := 1; i < l; i++ {
p := posTmp[i]
loc := Location{URI: uriIfy(uprootedPath(p.Filename())),
Range: Range{Start: Position{p.Line(), p.Col()},
End: Position{p.Line(), p.Col()}}}
diagnostic.RelatedInformation = append(diagnostic.RelatedInformation, DiagnosticRelatedInformation{Location: loc, Message: "inlineLoc"})
appendInlinedPos(posTmp, &diagnostic)

// Diagnostic explanation is stored in RelatedInformation after inlining info
if len(x.target) > 1 {
switch y := x.target[1].(type) {
case []*LoggedOpt:
for _, z := range y {
posTmp, p0 := z.parsePos(ctxt, posTmp)
loc := newLocation(p0)
msg := z.what
if len(z.target) > 0 {
msg = msg + ": " + fmt.Sprint(z.target[0])
}

diagnostic.RelatedInformation = append(diagnostic.RelatedInformation, DiagnosticRelatedInformation{Location: loc, Message: msg})
appendInlinedPos(posTmp, &diagnostic)
}
}
}

encoder.Encode(diagnostic)
Expand All @@ -448,3 +458,33 @@ func FlushLoggedOpts(ctxt *obj.Link, slashPkgPath string) {
}
}
}

func newPointRange(p src.Pos) Range {
return Range{Start: Position{p.Line(), p.Col()},
End: Position{p.Line(), p.Col()}}
}

func newLocation(p src.Pos) Location {
loc := Location{URI: uriIfy(uprootedPath(p.Filename())), Range: newPointRange(p)}
return loc
}

// appendInlinedPos extracts inlining information from posTmp and append it to diagnostic
func appendInlinedPos(posTmp []src.Pos, diagnostic *Diagnostic) {
for i := 1; i < len(posTmp); i++ {
p := posTmp[i]
loc := newLocation(p)
diagnostic.RelatedInformation = append(diagnostic.RelatedInformation, DiagnosticRelatedInformation{Location: loc, Message: "inlineLoc"})
}
}

func (x *LoggedOpt) parsePos(ctxt *obj.Link, posTmp []src.Pos) ([]src.Pos, src.Pos) {
posTmp = ctxt.AllPos(x.pos, posTmp)
// Reverse posTmp to put outermost first.
l := len(posTmp)
for i := 0; i < l/2; i++ {
posTmp[i], posTmp[l-i-1] = posTmp[l-i-1], posTmp[i]
}
p0 := posTmp[0]
return posTmp, p0
}
22 changes: 19 additions & 3 deletions src/cmd/compile/internal/logopt/logopt_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,11 @@ func n() int {
`

func want(t *testing.T, out string, desired string) {
if !strings.Contains(out, desired) {
t.Errorf("did not see phrase %s in \n%s", desired, out)
// On Windows, Unicode escapes in the JSON output end up "normalized" elsewhere to /u....,
// so "normalize" what we're looking for to match that.
s := strings.ReplaceAll(desired, string(os.PathSeparator), "/")
if !strings.Contains(out, s) {
t.Errorf("did not see phrase %s in \n%s", s, out)
}
}

Expand Down Expand Up @@ -178,7 +181,20 @@ func s15a8(x *[15]int64) [15]int64 {
want(t, slogged, `{"range":{"start":{"line":11,"character":6},"end":{"line":11,"character":6}},"severity":3,"code":"isInBounds","source":"go compiler","message":""}`)
want(t, slogged, `{"range":{"start":{"line":7,"character":6},"end":{"line":7,"character":6}},"severity":3,"code":"canInlineFunction","source":"go compiler","message":"cost: 35"}`)
want(t, slogged, `{"range":{"start":{"line":21,"character":21},"end":{"line":21,"character":21}},"severity":3,"code":"cannotInlineCall","source":"go compiler","message":"foo cannot be inlined (escaping closure variable)"}`)

// escape analysis explanation
want(t, slogged, `{"range":{"start":{"line":7,"character":13},"end":{"line":7,"character":13}},"severity":3,"code":"leak","source":"go compiler","message":"parameter z leaks to ~r2 with derefs=0",`+
`"relatedInformation":[`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow: flow: y = z:"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow: from y = \u003cN\u003e (assign-pair)"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow: flow: ~r1 = y:"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":4,"character":11},"end":{"line":4,"character":11}}},"message":"inlineLoc"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow: from y.b (dot of pointer)"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":4,"character":11},"end":{"line":4,"character":11}}},"message":"inlineLoc"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow: from \u0026y.b (address-of)"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":4,"character":9},"end":{"line":4,"character":9}}},"message":"inlineLoc"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow: from ~r1 = \u003cN\u003e (assign-pair)"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow: flow: ~r2 = ~r1:"},`+
`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow: from return (*int)(~r1) (return)"}]}`)
})
}

Expand Down

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