pub fn llvm(&self) -> WeldResult<String> {
        unsafe {
            let c_str = LLVMPrintModuleToString(self.module);
            let ir = CStr::from_ptr(c_str)
                .to_str()
                .map_err(|e| WeldCompileError::new(e.to_string()))?;
            let ir = ir.to_string();
            LLVMDisposeMessage(c_str);
            Ok(ir)
        }
    }
Dumps the optimized LLVM IR for this module.
weld/src/codegen/llvm2/jit.rs