[dev.typeparams] cmd/compile/internal/ir: more position details in dump

When dumping node positions, include column position and the full
inlining tree. These details are helpful for diagnosing "toolstash
-cmp" failures due to subtly changing positions.

Change-Id: I953292d6c01899fd98e2f315bafaa123c4d98ffd
Reviewed-on: https://go-review.googlesource.com/c/go/+/321089
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>

1 files changed, 11 insertions, 6 deletions

diff --git a/src/cmd/compile/internal/ir/fmt.go b/src/cmd/compile/internal/ir/fmt.go
index f2ae0f7606..4ac5f3fea2 100644
--- a/src/cmd/compile/internal/ir/fmt.go
+++ b/src/cmd/compile/internal/ir/fmt.go
@@ -1114,16 +1114,21 @@ func dumpNodeHeader(w io.Writer, n Node) {
 	}
 
 	if n.Pos().IsKnown() {
-		pfx := ""
+		fmt.Fprint(w, " # ")
 		switch n.Pos().IsStmt() {
 		case src.PosNotStmt:
-			pfx = "_" // "-" would be confusing
+			fmt.Fprint(w, "_") // "-" would be confusing
 		case src.PosIsStmt:
-			pfx = "+"
+			fmt.Fprint(w, "+")
+		}
+		for i, pos := range base.Ctxt.AllPos(n.Pos(), nil) {
+			if i > 0 {
+				fmt.Fprint(w, ",")
+			}
+			// TODO(mdempsky): Print line pragma details too.
+			file := filepath.Base(pos.Filename())
+			fmt.Fprintf(w, "%s:%d:%d", file, pos.Line(), pos.Col())
 		}
-		pos := base.Ctxt.PosTable.Pos(n.Pos())
-		file := filepath.Base(pos.Filename())
-		fmt.Fprintf(w, " # %s%s:%d", pfx, file, pos.Line())
 	}
 }