A More Complicated FunctionΒΆ

#!/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

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