runtime: add some more preemption checks

In particular this lets BenchmarkPingPongHog in runtime/proc_test.go
    complete.
    
    Reviewed-on: https://go-review.googlesource.com/94735

From-SVN: r257743

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-5d5ea2fd05dbf369ccc53c93d4846623cdea0c47
+cef3934fbc63f5e121abb8f88d3799961ac95b59
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/runtime/chan.go

@@ -148,6 +148,11 @@ func chansend1(c *hchan, elem unsafe.Pointer) {
  * the operation; we'll see that it's now closed.
  */
 func chansend(c *hchan, ep unsafe.Pointer, block bool, callerpc uintptr) bool {
+	// Check preemption, since unlike gc we don't check on every call.
+	if getg().preempt {
+		checkPreempt()
+	}
+
 	if c == nil {
 		if !block {
 			return false
@@ -430,6 +435,11 @@ func chanrecv(c *hchan, ep unsafe.Pointer, block bool) (selected, received bool)
 		print("chanrecv: chan=", c, "\n")
 	}
 
+	// Check preemption, since unlike gc we don't check on every call.
+	if getg().preempt {
+		checkPreempt()
+	}
+
 	if c == nil {
 		if !block {
 			return

libgo/go/runtime/hashmap.go

@@ -356,6 +356,11 @@ func makemap(t *maptype, hint int, h *hmap) *hmap {
 // NOTE: The returned pointer may keep the whole map live, so don't
 // hold onto it for very long.
 func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
+	// Check preemption, since unlike gc we don't check on every call.
+	if getg().preempt {
+		checkPreempt()
+	}
+
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
 		pc := funcPC(mapaccess1)
@@ -409,6 +414,11 @@ func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
 }
 
 func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
+	// Check preemption, since unlike gc we don't check on every call.
+	if getg().preempt {
+		checkPreempt()
+	}
+
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
 		pc := funcPC(mapaccess2)
@@ -463,6 +473,11 @@ func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool)
 
 // returns both key and value. Used by map iterator
 func mapaccessK(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, unsafe.Pointer) {
+	// Check preemption, since unlike gc we don't check on every call.
+	if getg().preempt {
+		checkPreempt()
+	}
+
 	if h == nil || h.count == 0 {
 		return nil, nil
 	}
@@ -521,6 +536,11 @@ func mapaccess2_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) (unsafe.Point
 
 // Like mapaccess, but allocates a slot for the key if it is not present in the map.
 func mapassign(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
+	// Check preemption, since unlike gc we don't check on every call.
+	if getg().preempt {
+		checkPreempt()
+	}
+
 	if h == nil {
 		panic(plainError("assignment to entry in nil map"))
 	}
@@ -772,6 +792,11 @@ func mapiterinit(t *maptype, h *hmap, it *hiter) {
 }
 
 func mapiternext(it *hiter) {
+	// Check preemption, since unlike gc we don't check on every call.
+	if getg().preempt {
+		checkPreempt()
+	}
+
 	h := it.h
 	if raceenabled {
 		callerpc := getcallerpc()

libgo/go/runtime/malloc.go

@@ -826,6 +826,7 @@ func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
 		}
 	}
 
+	// Check preemption, since unlike gc we don't check on every call.
 	if getg().preempt {
 		checkPreempt()
 	}

libgo/go/runtime/proc.go

@@ -4084,8 +4084,9 @@ func preemptone(_p_ *p) bool {
 	// setting a global variable and figuring out a way to efficiently
 	// check that global variable.
 	//
-	// For now we check gp.preempt in schedule and mallocgc,
+	// For now we check gp.preempt in schedule, mallocgc, selectgo,
-	// which is at least better than doing nothing at all.
+	// and a few other places, which is at least better than doing
+	// nothing at all.
 
 	return true
 }

libgo/go/runtime/select.go

@@ -584,6 +584,13 @@ retc:
 	if cas.releasetime > 0 {
 		blockevent(cas.releasetime-t0, 1)
 	}
+
+	// Check preemption, since unlike gc we don't check on every call.
+	// A test case for this one is BenchmarkPingPongHog in proc_test.go.
+	if dfl != nil && getg().preempt {
+		checkPreempt()
+	}
+
 	return casi
 
 sclose: