cmd/compile: handle rematerialized op for incompatible reg constraint
This CL fixes an issue raised by contributor dominikh@.
Cherry-picked from the dev.simd branch. This CL is not
necessarily SIMD specific. Apply early to reduce risk. Test is
SIMD specific so not included for now.
Change-Id: I941b330a6ba6f6c120c69951ddd24933f2f0b3ec
Reviewed-on: https://go-review.googlesource.com/c/go/+/704056
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: David Chase <drchase@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/708861