cmd/compile: ensure ops have the expected argument widths

The generic SSA representation uses explicit extension and
truncation operations to change widths of values. The map
intrinsics were playing somewhat fast and loose with this
requirement. Fix that, and add a check to make sure we
don't regress.

I don't think there is a triggerable bug here, but I ran into
this with some prove pass modifications, where
cmd/compile/internal/ssa/prove.go:isCleanExt (and/or its uses)
is actually wrong when this invariant is not maintained.

Change-Id: Idb7be6e691e2dbf6d7af6584641c3227c5c64bf5
Reviewed-on: https://go-review.googlesource.com/c/go/+/731300
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>

0 files changed, 0 insertions, 0 deletions