cmd/compile: copy blank parameter node when substituting function type

When a function type is copied (e.g. for substituting type
parameters), we make copies of its parameter ir.Name nodes, so
they are not shared with the old function type. But currently a
blank (_) identifier is not copied but shared. The parameter
node's frame offset is assigned (in ABI analysis) and then used in
the concurrent backend. Shared node can cause a data race. Make a
new blank parameter node to avoid sharing. (Unified IR does already
not have this problem. This fixes non-unified-IR mode.)

This seems to fix #55357.

Change-Id: Ie27f08e5589ac7d5d3f0d0d5de1a21e4fd2765c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/443158
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@google.com>

0 files changed, 0 insertions, 0 deletions