runtime: minor clarifications of markroot
This puts the _Root* indexes in a more friendly order and tweaks
markrootSpans to use a for-range loop instead of its own indexing.
Change-Id: I2c18d55c9a673ea396b6424d51ef4997a1a74825
Reviewed-on: https://go-review.googlesource.com/14548
Reviewed-by: Rick Hudson <rlh@golang.org>
diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index 128a163..c8f8a66 100644
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -121,8 +121,7 @@
sg := mheap_.sweepgen
startSpan := shard * len(work.spans) / _RootSpansShards
endSpan := (shard + 1) * len(work.spans) / _RootSpansShards
- for spanidx := startSpan; spanidx < endSpan; spanidx++ {
- s := work.spans[spanidx]
+ for _, s := range work.spans[startSpan:endSpan] {
if s.state != mSpanInUse {
continue
}
