cmd/compile: add debug log prior to export data lookup

If there is a crash in LookupFunc (which has occurred a few times now),
this ensures that we log the offending symbol before crashing.

For #67016.

Change-Id: I0119597de2be3d1b97c41a9361273d1feb90ec11
Reviewed-on: https://go-review.googlesource.com/c/go/+/581437
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/cmd/compile/internal/pgoir/irgraph.go b/src/cmd/compile/internal/pgoir/irgraph.go
index cb4333e6d7c675fd4b943a6f4d069348e0e44982..f1c8d13dec046725545403a66693b3660488450d 100644 (file)
--- a/src/cmd/compile/internal/pgoir/irgraph.go
+++ b/src/cmd/compile/internal/pgoir/irgraph.go
@@ -333,6 +333,9 @@ func addIndirectEdges(g *IRGraph, namedEdgeMap pgo.NamedEdgeMap) {
                        // devirtualization. Instantiation of generic functions
                        // will likely need to be done at the devirtualization
                        // site, if at all.
+                       if base.Debug.PGODebug >= 3 {
+                               fmt.Printf("addIndirectEdges: %s attempting export data lookup\n", key.CalleeName)
+                       }
                        fn, err := LookupFunc(key.CalleeName)
                        if err == nil {
                                if base.Debug.PGODebug >= 3 {