cmd/compile: modify debug-hash to support match exclusion
The goal here is to enable a search that will locate all the instances
of a failure, not just the first one. This helps with searches for
loopvar-change breakage, FP differences from fused-multiply-add, and
allows certain semantics queries that can be implemented as compiler
changes (for example, where does integer overflow routinely occur?)
Change-Id: Ic28f1695d47e421c2089d1f3f7c4b40c56db970f
Reviewed-on: https://go-review.googlesource.com/c/go/+/481195
Run-TryBot: David Chase <drchase@google.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>