Exit early if there's no validator slashing

beacon-chain/core/epoch/precompute/slashing.go

@@ -1,6 +1,8 @@
 package precompute
 
 import (
+	"errors"
+
 	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	stateTrie "github.com/prysmaticlabs/prysm/beacon-chain/state"
@@ -23,6 +25,25 @@ func ProcessSlashingsPrecompute(state *stateTrie.BeaconState, pBal *Balance) err
 
 	minSlashing := mathutil.Min(totalSlashing*params.BeaconConfig().ProportionalSlashingMultiplier, pBal.ActiveCurrentEpoch)
 	epochToWithdraw := currentEpoch + exitLength/2
+
+	vs := state.ValidatorsReadOnly()
+	var hasSlashing bool
+	// Iterate through validator list in state, stop until a validator satisfies slashing condition of current epoch.
+	for _, v := range vs {
+		if v == nil {
+			return errors.New("nil validator in state")
+		}
+		correctEpoch := epochToWithdraw == v.WithdrawableEpoch()
+		if v.Slashed() && correctEpoch {
+			hasSlashing = true
+			break
+		}
+	}
+	// Exit early if there's no meaningful slashing to process.
+	if !hasSlashing {
+		return nil
+	}
+
 	increment := params.BeaconConfig().EffectiveBalanceIncrement
 	validatorFunc := func(idx int, val *ethpb.Validator) (bool, error) {
 		correctEpoch := epochToWithdraw == val.WithdrawableEpoch

beacon-chain/core/epoch/precompute/slashing_test.go

@@ -13,7 +13,7 @@ import (
 	"github.com/prysmaticlabs/prysm/shared/testutil/require"
 )
 
-func TestProcessSlashingsPrecompute_NotSlashed(t *testing.T) {
+func TestProcessSlashingsPrecompute_NotSlashedWithSlashedTrue(t *testing.T) {
 	s, err := beaconstate.InitializeFromProto(&pb.BeaconState{
 		Slot:       0,
 		Validators: []*ethpb.Validator{{Slashed: true}},
@@ -28,6 +28,21 @@ func TestProcessSlashingsPrecompute_NotSlashed(t *testing.T) {
 	assert.Equal(t, wanted, s.Balances()[0], "Unexpected slashed balance")
 }
 
+func TestProcessSlashingsPrecompute_NotSlashedWithSlashedFalse(t *testing.T) {
+	s, err := beaconstate.InitializeFromProto(&pb.BeaconState{
+		Slot:       0,
+		Validators: []*ethpb.Validator{{}},
+		Balances:   []uint64{params.BeaconConfig().MaxEffectiveBalance},
+		Slashings:  []uint64{0, 1e9},
+	})
+	require.NoError(t, err)
+	pBal := &precompute.Balance{ActiveCurrentEpoch: params.BeaconConfig().MaxEffectiveBalance}
+	require.NoError(t, precompute.ProcessSlashingsPrecompute(s, pBal))
+
+	wanted := params.BeaconConfig().MaxEffectiveBalance
+	assert.Equal(t, wanted, s.Balances()[0], "Unexpected slashed balance")
+}
+
 func TestProcessSlashingsPrecompute_SlashedLess(t *testing.T) {
 	tests := []struct {
 		state *pb.BeaconState