- The use of a label's Name.Defn to point at the named for/select/switch
means that any rewrite of the for/select/switch must overwrite the original
or else the pointer will dangle. Remove that pointer by adding the label
name directly to the for/select/switch representation instead.
- The only uses of a label's Sym.Label were ephemeral values during
markbreak and escape analysis. Use a map for each. Although in general
we are not going to replace all computed fields with maps (too slow),
the one in markbreak is only for labeled for/select/switch, and the one
in escape is for all labels, but even so, labels are fairly rare.
In theory this cleanup should make it easy to allow labeled for/select/switch
in inlined bodies, but this CL does not attempt that. It's only concerned
with cleanup to enable a new Node representation.
Passes buildall w/ toolstash -cmp.
Change-Id: I7e36ee98d2ea40dbae94e6722d585f007b7afcfa
Reviewed-on: https://go-review.googlesource.com/c/go/+/274086
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>