how to deal with these compilation warnings ?

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I get several warnings after full compilation as below: 

 Warning (332174): Ignored filter at qsta_default_script.tcl(1028): *ws_dgrp|dffpipe_se9:dffpipe16|dffe17a* could not be matched with a clock or keeper or register or port or pin or cell or partition  Warning (332049): Ignored set_false_path at qsta_default_script.tcl(1028): Argument <to> is not an object ID  Info (332050): read_sdc  Warning (332174): Ignored filter at LTE.sdc(8): \ could not be matched with a clock  Warning (287001): Assertion warning: Number of metastability protection registers is not specified. Based on the parameter value CLOCKS_ARE_SYNCHRONIZED=FALSE, the synchronization register chain length between read and write clock domains will be 2  Warning (169064): Following 4 pins have no output enable or a GND or VCC output enable - later changes to this connectivity may change fitting results  Info (169065): Pin UPP_D[8] has a permanently enabled output enable  Info (169065): Pin UPP_D[9] has a permanently enabled output enable  Info (169065): Pin UPP_D[10] has a permanently enabled output enable  Info (169065): Pin UPP_D[11] has a permanently enabled output enable  I have no idea what problems these warnings will lead to. Can someone make a detail and clear explanation of the meaning of these warnings? So I can deal with them. My sdc file is post below:  set_time_format -unit ns -decimal_places 3   create_clock -name F20M -period 50 [get_ports {F20M}] create_clock -name SDWE -period 10 [get_ports {SDWE}] create_clock -name BS_clk -period 32.552 [get_ports {BS_clko1}] derive_pll_clocks derive_clock_uncertainty set_clock_groups -asynchronous   -group {F20M}   -group {SDWE}   -group {BS_clk   PLL1_inst|altpll_component|auto_generated|pll1|clk[0]   PLL1_inst|altpll_component|auto_generated|pll1|clk[1] \   PLL1_inst|altpll_component|auto_generated|pll1|clk[3] \   }   -group {   PLL1_inst|altpll_component|auto_generated|pll1|clk[2]   }      Thanks!  Tigre