libgo: update to final Go1.14 release

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/221158

3 files changed, 27 insertions, 6 deletions

diff --git a/libgo/go/runtime/malloc.go b/libgo/go/runtime/malloc.go
index 35ace7f..266f5eb 100644
--- a/libgo/go/runtime/malloc.go
+++ b/libgo/go/runtime/malloc.go
@@ -62,9 +62,10 @@
 // Allocating and freeing a large object uses the mheap
 // directly, bypassing the mcache and mcentral.
 //
-// Free object slots in an mspan are zeroed only if mspan.needzero is
-// false. If needzero is true, objects are zeroed as they are
-// allocated. There are various benefits to delaying zeroing this way:
+// If mspan.needzero is false, then free object slots in the mspan are
+// already zeroed. Otherwise if needzero is true, objects are zeroed as
+// they are allocated. There are various benefits to delaying zeroing
+// this way:
 //
 //	1. Stack frame allocation can avoid zeroing altogether.
 //
diff --git a/libgo/go/runtime/mkpreempt.go b/libgo/go/runtime/mkpreempt.go
index 64e2207..31b6f5c 100644
--- a/libgo/go/runtime/mkpreempt.go
+++ b/libgo/go/runtime/mkpreempt.go
@@ -244,6 +244,15 @@ func genAMD64() {
 
 	// TODO: MXCSR register?
 
+	// Apparently, the signal handling code path in darwin kernel leaves
+	// the upper bits of Y registers in a dirty state, which causes
+	// many SSE operations (128-bit and narrower) become much slower.
+	// Clear the upper bits to get to a clean state. See issue #37174.
+	// It is safe here as Go code don't use the upper bits of Y registers.
+	p("#ifdef GOOS_darwin")
+	p("VZEROUPPER")
+	p("#endif")
+
 	p("PUSHQ BP")
 	p("MOVQ SP, BP")
 	p("// Save flags before clobbering them")
diff --git a/libgo/go/runtime/netpoll_stub.go b/libgo/go/runtime/netpoll_stub.go
index fe45cfb..f86f2f6 100644
--- a/libgo/go/runtime/netpoll_stub.go
+++ b/libgo/go/runtime/netpoll_stub.go
@@ -13,16 +13,23 @@ var netpollWaiters uint32
 
 var netpollStubLock mutex
 var netpollNote note
-var netpollBroken uint32
+
+// netpollBroken, protected by netpollBrokenLock, avoids a double notewakeup.
+var netpollBrokenLock mutex
+var netpollBroken bool
 
 func netpollGenericInit() {
 	atomic.Store(&netpollInited, 1)
 }
 
 func netpollBreak() {
-	if atomic.Cas(&netpollBroken, 0, 1) {
+	lock(&netpollBrokenLock)
+	broken := netpollBroken
+	netpollBroken = true
+	if !broken {
 		notewakeup(&netpollNote)
 	}
+	unlock(&netpollBrokenLock)
 }
 
 // Polls for ready network connections.
@@ -34,8 +41,12 @@ func netpoll(delay int64) gList {
 		// This lock ensures that only one goroutine tries to use
 		// the note. It should normally be completely uncontended.
 		lock(&netpollStubLock)
+
+		lock(&netpollBrokenLock)
 		noteclear(&netpollNote)
-		atomic.Store(&netpollBroken, 0)
+		netpollBroken = false
+		unlock(&netpollBrokenLock)
+
 		notetsleep(&netpollNote, delay)
 		unlock(&netpollStubLock)
 	}