4 files changed, 26 insertions, 29 deletions
diff --git a/src/cmd/compile/internal/base/hashdebug.go b/src/cmd/compile/internal/base/hashdebug.go
index 0d0b3f3123..5492d9cda2 100644
--- a/src/cmd/compile/internal/base/hashdebug.go
+++ b/src/cmd/compile/internal/base/hashdebug.go
@@ -351,24 +351,24 @@ func (d *HashDebug) debugHashMatchPos(ctxt *obj.Link, pos src.XPos) bool {
 // bytesForPos renders a position, including inlining, into d.bytesTmp
 // and returns the byte array.  d.mu must be locked.
 func (d *HashDebug) bytesForPos(ctxt *obj.Link, pos src.XPos) []byte {
-	d.posTmp = ctxt.AllPos(pos, d.posTmp)
-	// Reverse posTmp to put outermost first.
 	b := &d.bytesTmp
 	b.Reset()
-	start := len(d.posTmp) - 1
-	if d.inlineSuffixOnly {
-		start = 0
-	}
-	for i := start; i >= 0; i-- {
-		p := &d.posTmp[i]
+	format := func(p src.Pos) {
 		f := p.Filename()
 		if d.fileSuffixOnly {
 			f = filepath.Base(f)
 		}
 		fmt.Fprintf(b, "%s:%d:%d", f, p.Line(), p.Col())
-		if i != 0 {
-			b.WriteByte(';')
-		}
+	}
+	if d.inlineSuffixOnly {
+		format(ctxt.InnermostPos(pos))
+	} else {
+		ctxt.AllPos(pos, func(p src.Pos) {
+			if b.Len() > 0 {
+				b.WriteByte(';')
+			}
+			format(p)
+		})
 	}
 	return b.Bytes()
 }
diff --git a/src/cmd/compile/internal/ir/fmt.go b/src/cmd/compile/internal/ir/fmt.go
index dcb8988b66..a9cf716dff 100644
--- a/src/cmd/compile/internal/ir/fmt.go
+++ b/src/cmd/compile/internal/ir/fmt.go
@@ -1085,15 +1085,15 @@ func dumpNodeHeader(w io.Writer, n Node) {
 		case src.PosIsStmt:
 			fmt.Fprint(w, "+")
 		}
-		for i, pos := range base.Ctxt.AllPos(n.Pos(), nil) {
-			if i > 0 {
-				fmt.Fprint(w, ",")
-			}
+		sep := ""
+		base.Ctxt.AllPos(n.Pos(), func(pos src.Pos) {
+			fmt.Fprint(w, sep)
+			sep = " "
 			// TODO(mdempsky): Print line pragma details too.
 			file := filepath.Base(pos.Filename())
 			// Note: this output will be parsed by ssa/html.go:(*HTMLWriter).WriteAST. Keep in sync.
 			fmt.Fprintf(w, "%s:%d:%d", file, pos.Line(), pos.Col())
-		}
+		})
 	}
 }
 
diff --git a/src/cmd/compile/internal/logopt/log_opts.go b/src/cmd/compile/internal/logopt/log_opts.go
index f74be6a63c..b731e55938 100644
--- a/src/cmd/compile/internal/logopt/log_opts.go
+++ b/src/cmd/compile/internal/logopt/log_opts.go
@@ -532,12 +532,9 @@ func appendInlinedPos(posTmp, lastTmp []src.Pos, diagnostic *Diagnostic) {
 // parsePos expands a src.XPos into a slice of src.Pos, with the outermost first.
 // It returns the slice, and the outermost.
 func parsePos(ctxt *obj.Link, pos src.XPos, posTmp []src.Pos) ([]src.Pos, src.Pos) {
-	posTmp = ctxt.AllPos(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
+	posTmp = posTmp[:0]
+	ctxt.AllPos(pos, func(p src.Pos) {
+		posTmp = append(posTmp, p)
+	})
+	return posTmp, posTmp[0]
 }
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 37b5a26d5c..a037b7494d 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -7331,7 +7331,7 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
 		fi := f.DumpFileForPhase("genssa")
 		if fi != nil {
 
-			// inliningDiffers if any filename changes or if any line number except the innermost (index 0) changes.
+			// inliningDiffers if any filename changes or if any line number except the innermost (last index) changes.
 			inliningDiffers := func(a, b []src.Pos) bool {
 				if len(a) != len(b) {
 					return true
@@ -7340,7 +7340,7 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
 					if a[i].Filename() != b[i].Filename() {
 						return true
 					}
-					if i > 0 && a[i].Line() != b[i].Line() {
+					if i != len(a)-1 && a[i].Line() != b[i].Line() {
 						return true
 					}
 				}
@@ -7352,10 +7352,10 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
 
 			for p := pp.Text; p != nil; p = p.Link {
 				if p.Pos.IsKnown() {
-					allPos = p.AllPos(allPos)
+					allPos = allPos[:0]
+					p.Ctxt.AllPos(p.Pos, func(pos src.Pos) { allPos = append(allPos, pos) })
 					if inliningDiffers(allPos, allPosOld) {
-						for i := len(allPos) - 1; i >= 0; i-- {
-							pos := allPos[i]
+						for _, pos := range allPos {
 							fmt.Fprintf(fi, "# %s:%d\n", pos.Filename(), pos.Line())
 						}
 						allPos, allPosOld = allPosOld, allPos // swap, not copy, so that they do not share slice storage.