"I have an output which is 32-bit, but the io-ports have only 38 ports in which the bottom 8"
32 + 8 = 40, where another two pins came from?
"So i am not able to map my output to io.when i do i am getting index out of range error"
I do not see such error in the log.
"How should i relove this issue?"
YOu mean the warning about 32 bit being extended to 38 bits? Just extend the verilog literal that is being assigned as you need.