LLVMLITE Hello World Example Produces Wrong Output - llvmlite

Question

The problem I am faced with regards to llvmlite is producing a simple hello world example.
I am unable to display the string global variable value in the function I created.
It appears to always print out the number one.
I have already tried to return the stringtype which produced a error.
from llvmlite import ir
i64 = ir.IntType(64)
i8 = ir.IntType(16)
hellostr = 'hello, world!'
stringtype = ir.ArrayType(i64, len(hellostr))
module = ir.Module( name="m_hello_example" )
hello = ir.GlobalVariable(module, stringtype, '.str4')
fn_int_to_int_type = ir.FunctionType(i64, [stringtype.as_pointer()] )
fn_hel = ir.Function( module, fn_int_to_int_type, name="fn_hel" )
fn_hel_block = fn_hel.append_basic_block( name="fn_hel_entry" )
builder = ir.IRBuilder(fn_hel_block )
# zero = builder.constant(i64, 0)
# const_1 = ir.Constant(stringtype,1);
# builder.ret(const_1)
const_1 = ir.Constant(i64,1);
# print(const_1)
builder.ret(const_1)
print( module )
I was expecting the output to print out the string 'hello, world!'.
Any help would be much appreciated.
Thanks.

Answer 1

It ended up that I was able to solve my problem with the following code:
import llvmlite.ir as ir
import llvmlite.binding as llvm
from ctypes import CFUNCTYPE
def main():
m = ir.Module()
func_ty = ir.FunctionType(ir.VoidType(), []) #defining printer function as type void
func = ir.Function(m, func_ty, name="printer") #define function as printer
builder = ir.IRBuilder(func.append_basic_block('entry')) #defining the entry point of the function printer
fmt = "%s\n\0" #in function printf allows for inserting arg in, next global_fmt statements allow for creating #"fstr" assignment
c_fmt = ir.Constant(ir.ArrayType(ir.IntType(8), len(fmt)),
bytearray(fmt.encode("utf8")))
global_fmt = ir.GlobalVariable(m, c_fmt.type, name="fstr")
global_fmt.linkage = 'internal'
global_fmt.global_constant = True
global_fmt.initializer = c_fmt
arg = "Hello, World!\0" #args will be passed into printf function.
c_str_val = ir.Constant(ir.ArrayType(ir.IntType(8), len(arg)),
bytearray(arg.encode("utf8"))) #creates the c_str_value as a constant
printf_ty = ir.FunctionType(ir.IntType(32), [], var_arg=True) #creation of the printf function begins here and specifies the passing of a argument
printf = ir.Function(m, printf_ty, name="printf")
c_str = builder.alloca(c_str_val.type) #creation of the allocation of the %".2" variable
builder.store(c_str_val, c_str) #store as defined on the next line below %".2"
voidptr_ty = ir.IntType(8).as_pointer()
fmt_arg = builder.bitcast(global_fmt, voidptr_ty) #creates the %".4" variable with the point pointing to the fstr
builder.call(printf, [fmt_arg, c_str]) #We are calling the prinf function with the fmt and arg and returning the value as defiend on the next line
builder.ret_void()
#Next lines are for calling llvm and returning the assembly.
llvm.initialize()
llvm.initialize_native_target()
llvm.initialize_native_asmprinter()
print(str(m)) #PRINTING OUT THE ASSEMBLY
llvm_module = llvm.parse_assembly(str(m)) #Parsing teh assembly
tm = llvm.Target.from_default_triple().create_target_machine() #creating the target machine
with llvm.create_mcjit_compiler(llvm_module, tm) as ee:
ee.finalize_object() #Making sure all modules owned by the execution engine are fully processed and usable for execution
fptr = ee.get_function_address("printer") #fptr will reference the printer function
py_func = CFUNCTYPE(None)(fptr)
py_func() #run the function printer
if __name__ == "__main__":
main()
It appears that I didn't correctly assign the variable and hence why I wasn't returning anything.