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#!/usr/bin/env python
from llvm.core import Module,Type,Builder,ModuleProvider
from llvm.ee import ExecutionEngine
import llvm.core
import ctypes
def test_jit_ctypes():
# This example demonstrates calling an LLVM defined function using
# ctypes. It illustrates the common C pattern of having an output
# variable in the argument list to the function. The function also
# returns an error code upon exit.
# setup llvm types
ty_errcode = Type.int()
ty_float = Type.float()
ty_ptr_float = Type.pointer(Type.float())
ty_func = Type.function(ty_errcode, [ty_float, ty_float, ty_ptr_float])
# setup ctypes types
ct_errcode = ctypes.c_int
ct_float = ctypes.c_float
ct_ptr_float = ctypes.POINTER(ct_float)
ct_argtypes = [ct_float, ct_float, ct_ptr_float]
# generate the function using LLVM
my_module = Module.new('my_module')
mult = my_module.add_function(ty_func, "mult")
mult.args[0].name = "a"
mult.args[1].name = "b"
mult.args[2].name = "out"
mult.args[2].add_attribute(llvm.core.ATTR_NO_CAPTURE) # add nocapture to output arg
mult.does_not_throw = True # add nounwind attribute to function
bb = mult.append_basic_block("entry")
builder = Builder.new(bb)
tmp = builder.mul( mult.args[0], mult.args[1] )
builder.store( tmp, mult.args[2] )
builder.ret(llvm.core.Constant.int(ty_errcode, 0))
if 0:
# print the created module
print my_module
# compile the function
mp = ModuleProvider.new(my_module)
ee = ExecutionEngine.new(mp)
# let ctypes know about the function
func_ptr_int = ee.get_pointer_to_function( mult )
FUNC_TYPE = ctypes.CFUNCTYPE(ct_errcode, *ct_argtypes)
py_mult = FUNC_TYPE(func_ptr_int)
# now run the function, calling via ctypes
output_value = ct_float(123456.0)
errcode = py_mult( 2.0, 3.0, ctypes.byref(output_value) )
if errcode != 0:
raise RuntimeError('unexpected error')
assert output_value.value == 6.0
if __name__=='__main__':
test_jit_ctypes()
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