diff --git a/src/cmd/compile/internal/gc/gsubr.go b/src/cmd/compile/internal/gc/gsubr.go
index 55b16792f9..70b5cd3366 100644
--- a/src/cmd/compile/internal/gc/gsubr.go
+++ b/src/cmd/compile/internal/gc/gsubr.go
@@ -49,6 +49,9 @@ type Progs struct {
 	curfn     *Node      // fn these Progs are for
 	progcache []obj.Prog // local progcache
 	cacheidx  int        // first free element of progcache
+
+	nextLive LivenessIndex // liveness index for the next Prog
+	prevLive LivenessIndex // last emitted liveness index
 }
 
 // newProgs returns a new Progs for fn.
@@ -67,6 +70,8 @@ func newProgs(fn *Node, worker int) *Progs {
 
 	pp.pos = fn.Pos
 	pp.settext(fn)
+	pp.nextLive = LivenessInvalid
+	pp.prevLive = LivenessInvalid
 	return pp
 }
 
@@ -103,6 +108,15 @@ func (pp *Progs) Free() {
 
 // Prog adds a Prog with instruction As to pp.
 func (pp *Progs) Prog(as obj.As) *obj.Prog {
+	if pp.nextLive.stackMapIndex != pp.prevLive.stackMapIndex {
+		// Emit stack map index change.
+		idx := pp.nextLive.stackMapIndex
+		pp.prevLive.stackMapIndex = idx
+		p := pp.Prog(obj.APCDATA)
+		Addrconst(&p.From, objabi.PCDATA_StackMapIndex)
+		Addrconst(&p.To, int64(idx))
+	}
+
 	p := pp.next
 	pp.next = pp.NewProg()
 	pp.clearp(pp.next)
diff --git a/src/cmd/compile/internal/gc/plive.go b/src/cmd/compile/internal/gc/plive.go
index 456a2f7652..7a953546dc 100644
--- a/src/cmd/compile/internal/gc/plive.go
+++ b/src/cmd/compile/internal/gc/plive.go
@@ -153,7 +153,13 @@ type LivenessIndex struct {
 }
 
 // LivenessInvalid indicates an unsafe point.
-var LivenessInvalid = LivenessIndex{-1}
+//
+// We use index -2 because PCDATA tables conventionally start at -1,
+// so -1 is used to mean the entry liveness map (which is actually at
+// index 0; sigh). TODO(austin): Maybe we should use PCDATA+1 as the
+// index into the liveness map so -1 uniquely refers to the entry
+// liveness map.
+var LivenessInvalid = LivenessIndex{-2}
 
 func (idx LivenessIndex) Valid() bool {
 	return idx.stackMapIndex >= 0
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 09d12cba1e..b280fb7397 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -15,7 +15,6 @@ import (
 	"cmd/compile/internal/ssa"
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
-	"cmd/internal/objabi"
 	"cmd/internal/src"
 	"cmd/internal/sys"
 )
@@ -4818,12 +4817,17 @@ func genssa(f *ssa.Func, pp *Progs) {
 	// Emit basic blocks
 	for i, b := range f.Blocks {
 		s.bstart[b.ID] = s.pp.next
+		s.pp.nextLive = LivenessInvalid
 		s.lineRunStart = nil
+
 		// Emit values in block
 		thearch.SSAMarkMoves(&s, b)
 		for _, v := range b.Values {
 			x := s.pp.next
 			s.DebugFriendlySetPosFrom(v)
+			// Attach this safe point to the next
+			// instruction.
+			s.pp.nextLive = s.livenessMap.Get(v)
 			switch v.Op {
 			case ssa.OpInitMem:
 				// memory arg needs no code
@@ -5279,9 +5283,6 @@ func (s *SSAGenState) PrepareCall(v *ssa.Value) {
 			Fatalf("missing stack map index for %v", v.LongString())
 		}
 	}
-	p := s.Prog(obj.APCDATA)
-	Addrconst(&p.From, objabi.PCDATA_StackMapIndex)
-	Addrconst(&p.To, int64(idx.stackMapIndex))
 
 	if sym, _ := v.Aux.(*obj.LSym); sym == Deferreturn {
 		// Deferred calls will appear to be returning to