Riscv-nuclei-elf-as: unrecognized option `-x'

Hi everyone,
I am new to this forum and new to RISC v and seeed product longan nano. I tried to compile an assembly file with platform IO . I am getting the following error message in the platform IO terminal. "riscv-nuclei-elf-as: unrecognized option `-x’ " . I copied an asm file to blink led from bronzebeard assembler examples and pasted into the source folder inside project of the platform io. On building the project i get a .O file in the build folder but no .hex file. The platform IO is throwing the above message. Requesting help to convert the .O file to .hex. Is there a way to build assembly files in platform IO?