This CL includes multiple test cases that exercise unique failures
with -G=3 mode that did not affect unified IR mode. Most of these were
found over a period of about 3 hours of manual experimentation.
Thanks to Cuong Manh Le for test cases 11 and 12.
Updates #46704.
Change-Id: Ia2fa619536732b121b6c929329065c85b9384511
Reviewed-on: https://go-review.googlesource.com/c/go/+/326169
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Dan Scales <danscales@google.com>
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>