From 7e16da4a7783bfea2e866d7a9f023531726b489d Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Tue, 1 Mar 2016 12:26:18 +0000
Subject: [PATCH] transforms.llvm_ir_generator: ignore assignments of None
 (fixes #309).

---
 artiq/compiler/transforms/llvm_ir_generator.py | 5 ++++-
 artiq/test/lit/codegen/assign_none.py          | 6 ++++++
 2 files changed, 10 insertions(+), 1 deletion(-)
 create mode 100644 artiq/test/lit/codegen/assign_none.py

diff --git a/artiq/compiler/transforms/llvm_ir_generator.py b/artiq/compiler/transforms/llvm_ir_generator.py
index 0c0d532cd..c59e16689 100644
--- a/artiq/compiler/transforms/llvm_ir_generator.py
+++ b/artiq/compiler/transforms/llvm_ir_generator.py
@@ -655,8 +655,11 @@ class LLVMIRGenerator:
 
     def process_SetLocal(self, insn):
         env = insn.environment()
-        llptr = self.llptr_to_var(self.map(env), env.type, insn.var_name)
         llvalue = self.map(insn.value())
+        if isinstance(llvalue.type, ll.VoidType):
+            # We store NoneType as {} but return it as void. So, bail out here.
+            return ll.Constant(ll.LiteralStructType([]), [])
+        llptr = self.llptr_to_var(self.map(env), env.type, insn.var_name)
         if isinstance(llvalue, ll.Block):
             llvalue = ll.BlockAddress(self.llfunction, llvalue)
         if llptr.type.pointee != llvalue.type:
diff --git a/artiq/test/lit/codegen/assign_none.py b/artiq/test/lit/codegen/assign_none.py
new file mode 100644
index 000000000..000e87ac7
--- /dev/null
+++ b/artiq/test/lit/codegen/assign_none.py
@@ -0,0 +1,6 @@
+# RUN: %python -m artiq.compiler.testbench.llvmgen %s
+
+def f():
+    pass
+def g():
+    a = f()