diff --git a/artiq/devices/corecom_dummy.py b/artiq/devices/corecom_dummy.py
index 4d3cb5aef..61a40a929 100644
--- a/artiq/devices/corecom_dummy.py
+++ b/artiq/devices/corecom_dummy.py
@@ -9,7 +9,7 @@ class _RuntimeEnvironment(LinkInterface):
         self.ref_period = ref_period
 
     def emit_object(self):
-        return str(self.module)
+        return str(self.llvm_module)
 
 
 class CoreCom:
diff --git a/artiq/devices/runtime.py b/artiq/devices/runtime.py
index 2554fced9..1c8d88275 100644
--- a/artiq/devices/runtime.py
+++ b/artiq/devices/runtime.py
@@ -46,13 +46,13 @@ def _str_to_functype(s):
 
 class LinkInterface:
     def init_module(self, module):
-        self.module = module
+        self.llvm_module = module.llvm_module
         self.var_arg_fixcount = dict()
         for func_name, func_type_str in _syscalls.items():
             var_arg_fixcount, func_type = _str_to_functype(func_type_str)
             if var_arg_fixcount is not None:
                 self.var_arg_fixcount[func_name] = var_arg_fixcount
-            self.module.add_function(func_type, "__syscall_"+func_name)
+            self.llvm_module.add_function(func_type, "__syscall_"+func_name)
 
     def syscall(self, syscall_name, args, builder):
         r = _chr_to_value[_syscalls[syscall_name][-1]]()
@@ -63,7 +63,7 @@ class LinkInterface:
                 args = args[:fixcount] \
                     + [lc.Constant.int(lc.Type.int(), len(args) - fixcount)] \
                     + args[fixcount:]
-            llvm_function = self.module.get_function_named(
+            llvm_function = self.llvm_module.get_function_named(
                 "__syscall_" + syscall_name)
             r.set_ssa_value(builder, builder.call(llvm_function, args))
         return r
@@ -76,5 +76,5 @@ class Environment(LinkInterface):
 
     def emit_object(self):
         tm = lt.TargetMachine.new(triple="or1k", cpu="generic")
-        obj = tm.emit_object(self.module)
+        obj = tm.emit_object(self.llvm_module)
         return obj
diff --git a/artiq/py2llvm/fractions.py b/artiq/py2llvm/fractions.py
index ff46e90ae..3544d7275 100644
--- a/artiq/py2llvm/fractions.py
+++ b/artiq/py2llvm/fractions.py
@@ -1,21 +1,29 @@
+import inspect
+import ast
+
 from llvm import core as lc
 
 from artiq.py2llvm.values import VGeneric
 from artiq.py2llvm.base_types import VBool, VInt
 
 
-def _gcd64(builder, a, b):
-    gcd_f = builder.basic_block.function.module.get_function_named("__gcd64")
-    return builder.call(gcd_f, [a, b])
+def _gcd(a, b):
+    while a:
+        c = a
+        a = b % a
+        b = c
+    return b
 
 def init_module(module):
-    func_type = lc.Type.function(
-        lc.Type.int(64), [lc.Type.int(64), lc.Type.int(64)])
-    module.add_function(func_type, "__gcd64")
+    funcdef = ast.parse(inspect.getsource(_gcd)).body[0]
+    module.compile_function(funcdef, {"a": VInt(64), "b": VInt(64)})
 
+def _call_gcd(builder, a, b):
+    gcd_f = builder.basic_block.function.module.get_function_named("_gcd")
+    return builder.call(gcd_f, [a, b])
 
 def _frac_normalize(builder, numerator, denominator):
-    gcd = _gcd64(builder, numerator, denominator)
+    gcd = _call_gcd(builder, numerator, denominator)
     numerator = builder.sdiv(numerator, gcd)
     denominator = builder.sdiv(denominator, gcd)
     return numerator, denominator
@@ -135,12 +143,12 @@ class VFraction(VGeneric):
                 numerator, denominator = self._nd(builder, invert)
                 i = other.get_ssa_value(builder)
                 if div:
-                    gcd = _gcd64(i, numerator)
+                    gcd = _call_gcd(builder, i, numerator)
                     i = builder.sdiv(i, gcd)
                     numerator = builder.sdiv(numerator, gcd)
                     denominator = builder.mul(denominator, i)
                 else:
-                    gcd = _gcd64(i, denominator)
+                    gcd = _call_gcd(builder, i, denominator)
                     i = builder.sdiv(i, gcd)
                     denominator = builder.sdiv(denominator, gcd)
                     numerator = builder.mul(numerator, i)
diff --git a/artiq/py2llvm/module.py b/artiq/py2llvm/module.py
index 4dfd646ba..43c9bd418 100644
--- a/artiq/py2llvm/module.py
+++ b/artiq/py2llvm/module.py
@@ -11,8 +11,8 @@ class Module:
         self.env = env
 
         if self.env is not None:
-            self.env.init_module(self.llvm_module)
-        fractions.init_module(self.llvm_module)
+            self.env.init_module(self)
+        fractions.init_module(self)
 
     def finalize(self):
         pass_manager = lp.PassManager.new()
diff --git a/soc/runtime/symbols.c b/soc/runtime/symbols.c
index 224c98941..5f04ce347 100644
--- a/soc/runtime/symbols.c
+++ b/soc/runtime/symbols.c
@@ -16,18 +16,6 @@ static const struct symbol syscalls[] = {
     {NULL, NULL}
 };
 
-static long long int gcd64(long long int a, long long int b)
-{
-    long long int c;
-
-    while(a) {
-        c = a;
-        a = b % a;
-        b = c;
-    }
-    return b;
-}
-
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wimplicit-int"
 extern __divsi3, __modsi3, __ledf2, __gedf2, __unorddf2, __negsf2, __negdf2,
@@ -38,49 +26,51 @@ extern __divsi3, __modsi3, __ledf2, __gedf2, __unorddf2, __negsf2, __negdf2,
     __udivdi3, __umoddi3, __moddi3;
 #pragma GCC diagnostic pop
 
-static const struct symbol arithmetic[] = {
-    {"__divsi3", &__divsi3},
-    {"__modsi3", &__modsi3},
-    {"__ledf2", &__ledf2},
-    {"__gedf2", &__gedf2},
-    {"__unorddf2", &__gedf2},
-    {"__negsf2", &__negsf2},
-    {"__negdf2", &__negdf2},
-    {"__addsf3", &__addsf3},
-    {"__subsf3", &__subsf3},
-    {"__mulsf3", &__mulsf3},
-    {"__divsf3", &__divsf3},
-    {"__lshrdi3", &__lshrdi3},
-    {"__muldi3", &__muldi3},
-    {"__divdi3", &__divdi3},
-    {"__ashldi3", &__ashldi3},
-    {"__ashrdi3", &__ashrdi3},
-    {"__udivmoddi4", &__udivmoddi4},
-    {"__floatsisf", &__floatsisf},
-    {"__floatunsisf", &__floatunsisf},
-    {"__fixsfsi", &__fixsfsi},
-    {"__fixunssfsi", &__fixunssfsi},
-    {"__adddf3", &__adddf3},
-    {"__subdf3", &__subdf3},
-    {"__muldf3", &__muldf3},
-    {"__divdf3", &__divdf3},
-    {"__floatsidf", &__floatsidf},
-    {"__floatunsidf", &__floatunsidf},
-    {"__floatdidf", &__floatdidf},
-    {"__fixdfsi", &__fixdfsi},
-    {"__fixunsdfsi", &__fixunsdfsi},
-    {"__clzsi2", &__clzsi2},
-    {"__ctzsi2", &__ctzsi2},
-    {"__udivdi3", &__udivdi3},
-    {"__umoddi3", &__umoddi3},
-    {"__moddi3", &__moddi3},
-    {"__gcd64", gcd64},
+static const struct symbol compiler_rt[] = {
+    {"divsi3", &__divsi3},
+    {"modsi3", &__modsi3},
+    {"ledf2", &__ledf2},
+    {"gedf2", &__gedf2},
+    {"unorddf2", &__gedf2},
+    {"negsf2", &__negsf2},
+    {"negdf2", &__negdf2},
+    {"addsf3", &__addsf3},
+    {"subsf3", &__subsf3},
+    {"mulsf3", &__mulsf3},
+    {"divsf3", &__divsf3},
+    {"lshrdi3", &__lshrdi3},
+    {"muldi3", &__muldi3},
+    {"divdi3", &__divdi3},
+    {"ashldi3", &__ashldi3},
+    {"ashrdi3", &__ashrdi3},
+    {"udivmoddi4", &__udivmoddi4},
+    {"floatsisf", &__floatsisf},
+    {"floatunsisf", &__floatunsisf},
+    {"fixsfsi", &__fixsfsi},
+    {"fixunssfsi", &__fixunssfsi},
+    {"adddf3", &__adddf3},
+    {"subdf3", &__subdf3},
+    {"muldf3", &__muldf3},
+    {"divdf3", &__divdf3},
+    {"floatsidf", &__floatsidf},
+    {"floatunsidf", &__floatunsidf},
+    {"floatdidf", &__floatdidf},
+    {"fixdfsi", &__fixdfsi},
+    {"fixunsdfsi", &__fixunsdfsi},
+    {"clzsi2", &__clzsi2},
+    {"ctzsi2", &__ctzsi2},
+    {"udivdi3", &__udivdi3},
+    {"umoddi3", &__umoddi3},
+    {"moddi3", &__moddi3},
     {NULL, NULL}
 };
 
 void *resolve_symbol(const char *name)
 {
-    if(strncmp(name, "__syscall_", 10) == 0)
-        return find_symbol(syscalls, name + 10);
-    return find_symbol(arithmetic, name);
+    if(strncmp(name, "__", 2) != 0)
+        return NULL;
+    name += 2;
+    if(strncmp(name, "syscall_", 8) == 0)
+        return find_symbol(syscalls, name + 8);
+    return find_symbol(compiler_rt, name);
 }