tree 93c5e3055ee8cd4ee9084fc27df683a981f5bfe1
parent 03a686069191e3515c7f27f6d90b66d272e0e3a2
author Cherry Zhang <cherryyz@google.com> 1599792089 -0400
committer Cherry Zhang <cherryyz@google.com> 1599832383 +0000

cmd/link: record only the first occurance in Reachparent graph

In the deadcode pass, a type symbol may be marked twice, one
without UsedInIface, one with. For the second time, don't
update the Reachparent graph, so it only records the path of
the first time the symbol is reached. This ensures the
Reachparent graph is acyclic.

TODO: add a test. (This only affects GOEXPERIMENT=fieldtrack)

Change-Id: I68e8a1a69c3830bc8aee5df946151dc22dcb2b29
Reviewed-on: https://go-review.googlesource.com/c/go/+/254297
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>