Function codegen_program_riscv 

pub fn codegen_program_riscv(
    program: &CompiledProgram,
    policies: &PolicyRegistry,
    interner: &Interner,
) -> Result<String, RiscVLowerError>

Emit program as RV64GC assembly text. Returns RiscVLowerError::Unsupported if the program uses any op/shape outside the currently-lowered fragment.