llvmpy/docs/source/doc/examples/JITTutorial2.md

layout	title
page	JIT Tutorial 2

{% highlight python %} #!/usr/bin/env python

from llvm.core import *

create a module

module = Module.new ("tut2")

create a function type taking 2 integers, return a 32-bit integer

ty_int = Type.int (32) func_type = Type.function (ty_int, (ty_int, ty_int))

create a function of that type

gcd = Function.new (module, func_type, "gcd")

name function args

x = gcd.args[0]; x.name = "x" y = gcd.args[1]; y.name = "y"

implement the function

blocks...

entry = gcd.append_basic_block ("entry") ret = gcd.append_basic_block ("return") cond_false = gcd.append_basic_block ("cond_false") cond_true = gcd.append_basic_block ("cond_true") cond_false_2 = gcd.append_basic_block ("cond_false_2")

create a llvm::IRBuilder

bldr = Builder.new (entry) x_eq_y = bldr.icmp (IPRED_EQ, x, y, "tmp") bldr.cbranch (x_eq_y, ret, cond_false)

bldr.position_at_end (ret) bldr.ret(x)

bldr.position_at_end (cond_false) x_lt_y = bldr.icmp (IPRED_ULT, x, y, "tmp") bldr.cbranch (x_lt_y, cond_true, cond_false_2)

bldr.position_at_end (cond_true) y_sub_x = bldr.sub (y, x, "tmp") recur_1 = bldr.call (gcd, (x, y_sub_x,), "tmp") bldr.ret (recur_1)

bldr.position_at_end (cond_false_2) x_sub_y = bldr.sub (x, y, "x_sub_y") recur_2 = bldr.call (gcd, (x_sub_y, y,), "tmp") bldr.ret (recur_2)

print(module) {% endhighlight %}