19. OPcacheの最適化内容 substitute persistent constants (true, false, null, etc) perform compile-time evaluation of constant binary and unary operations optimize series of ADD_STRING and/or ADD_CHAR convert CAST(IS_BOOL,x) into BOOL(x) convert INTI_FCALL_BY_NAME + DO_FCALL_BY_NAME into DO_FCALL convert non-numeric constants to numeric constants in numeric operators optimize constant conditional JMPs opt