-
-
Save sulami/5fb47f4a36d70f89df8453f5b4236732 to your computer and use it in GitHub Desktop.
Call c `printf` from llvmlite
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
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(), []) | |
i32_ty = ir.IntType(32) | |
func = ir.Function(m, func_ty, name="printer") | |
voidptr_ty = ir.IntType(8).as_pointer() | |
fmt = "Hello, %s! %i times!\n\0" | |
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 = "World\0" | |
c_str_val = ir.Constant(ir.ArrayType(ir.IntType(8), len(arg)), | |
bytearray(arg.encode("utf8"))) | |
printf_ty = ir.FunctionType(ir.IntType(32), [voidptr_ty], var_arg=True) | |
printf = ir.Function(m, printf_ty, name="printf") | |
builder = ir.IRBuilder(func.append_basic_block('entry')) | |
c_str = builder.alloca(c_str_val.type) | |
builder.store(c_str_val, c_str) | |
# this val can come from anywhere | |
int_val = builder.add(i32_ty(5), i32_ty(3)) | |
fmt_arg = builder.bitcast(global_fmt, voidptr_ty) | |
builder.call(printf, [fmt_arg, c_str, int_val]) | |
builder.ret_void() | |
llvm.initialize() | |
llvm.initialize_native_target() | |
llvm.initialize_native_asmprinter() | |
print(str(m)) | |
llvm_module = llvm.parse_assembly(str(m)) | |
tm = llvm.Target.from_default_triple().create_target_machine() | |
with llvm.create_mcjit_compiler(llvm_module, tm) as ee: | |
ee.finalize_object() | |
fptr = ee.get_function_address("printer") | |
py_func = CFUNCTYPE(None)(fptr) | |
py_func() | |
if __name__ == "__main__": | |
main() |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment