runtime: remove unused gcTriggerAlways

This was used during the implementation of concurrent runtime.GC() but
now there's nothing that triggers GC unconditionally. Remove this
trigger type and simplify (gcTrigger).test() accordingly.

Change-Id: I17a893c2ed1f661b8146d7783d529f71735c9105
Reviewed-on: https://go-review.googlesource.com/c/go/+/66090
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>

diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index 4d4cdc14ca810660fe7fe740568ad3057de081d0..5b974d466b81f09e4d3fe2812fa92bfe2a83decc 100644 (file)
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -1136,15 +1136,10 @@ type gcTrigger struct {
 type gcTriggerKind int
 
 const (
-       // gcTriggerAlways indicates that a cycle should be started
-       // unconditionally, even if GOGC is off or we're in a cycle
-       // right now. This cannot be consolidated with other cycles.
-       gcTriggerAlways gcTriggerKind = iota
-
        // gcTriggerHeap indicates that a cycle should be started when
        // the heap size reaches the trigger heap size computed by the
        // controller.
-       gcTriggerHeap
+       gcTriggerHeap gcTriggerKind = iota
 
        // gcTriggerTime indicates that a cycle should be started when
        // it's been more than forcegcperiod nanoseconds since the
@@ -1161,13 +1156,7 @@ const (
 // that the exit condition for the _GCoff phase has been met. The exit
 // condition should be tested when allocating.
 func (t gcTrigger) test() bool {
-       if !memstats.enablegc || panicking != 0 {
-               return false
-       }
-       if t.kind == gcTriggerAlways {
-               return true
-       }
-       if gcphase != _GCoff {
+       if !memstats.enablegc || panicking != 0 || gcphase != _GCoff {
                return false
        }
        switch t.kind {
@@ -1233,7 +1222,7 @@ func gcStart(trigger gcTrigger) {
        }
 
        // For stats, check if this GC was forced by the user.
-       work.userForced = trigger.kind == gcTriggerAlways || trigger.kind == gcTriggerCycle
+       work.userForced = trigger.kind == gcTriggerCycle
 
        // In gcstoptheworld debug mode, upgrade the mode accordingly.
        // We do this after re-checking the transition condition so