cmd/compile: clean up the switch statements in (*genInst).node()
There were two main outer switch statements in node() that can just be
combined. Also, for simplicity, changed an IsCmp() conditional into just
another case in the switch statement.
Also, the inner OCALL switch statement had a bunch of fairly duplicate
cases. Combined the cases that all had no special semantics, into a
single default case calling transformCall().
In the OCALL case in dictPass(), got rid of a check for OFUNCINST (which
will always have been removed by this point). Also, eliminated an assert
that could cause unneded failures. transformCall() should always be
called if the node op is still OCALL, so no need to assert on the ops of
call.X.
Added an extra test in issue47078.go, to explicitly check for case where
the X argument of a call is a DOTTYPE.
Change-Id: Ifb3f812ce12820a4ce08afe2887f00f7fc00cd2f
Reviewed-on: https://go-review.googlesource.com/c/go/+/358596
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>