shader: keep pixel helper lanes out of the EXEC and VCC words

src/graphics/shader/recompiler/backend/spirv/spirvEmitterFlow.cpp

@@ -819,6 +819,13 @@ uint32_t EmitBallot(ValueEmitContext& ctx, IR::Value predicate) {
 	return ctx.Ballot(predicate);
 }
 
+uint32_t EmitLiveMask(EmitterState& state) {
+	const auto helper =
+	    EmitNative<spv::OpLoad, IR::Type::U1>(state, state.helper_invocation_variable);
+	return EmitNative<spv::OpGroupNonUniformBallot, IR::Type::U32x4>(
+	    state, ConstantU32(state, spv::ScopeSubgroup), EmitLogicalNotBool(state, helper));
+}
+
 uint32_t EmitReadFirstLane(ValueEmitContext& ctx, const IR::Inst& inst) {
 	const auto ballot = ctx.Ballot(inst.Arg(1));
 	const auto lane   = ctx.FirstLane(ballot);