It adds necessary "" around ${CFLAGS} variable. Without them, the value of that variable (a set of flags) is inserted in that place and only a first flag is consumed by -CFLAGS argument of Verilator. The others are just handled as parameters of Verilator.
It adds necessary
""
around${CFLAGS}
variable. Without them, the value of that variable (a set of flags) is inserted in that place and only a first flag is consumed by-CFLAGS
argument of Verilator. The others are just handled as parameters of Verilator.