Merge pull request #1171 from kmod/undef_assert

Fix usage of undef variables

src/codegen/compvars.cpp

@@ -2782,10 +2782,6 @@ public:
         return rtn;
     }
     ConcreteCompilerVariable* makeConverted(IREmitter& emitter, VAR* var, ConcreteCompilerType* other_type) override {
-        if (other_type == other_type->getBoxType()) {
-            assert(other_type == UNKNOWN);
-            return emitter.getNone()->makeConverted(emitter, other_type);
-        }
         llvm::Value* v = llvm::UndefValue::get(other_type->llvmType());
         return new ConcreteCompilerVariable(other_type, v);
     }

src/codegen/irgen/irgenerator.cpp

@@ -922,7 +922,7 @@ private:
                     // trigger an exception, but the irgenerator will know that definitely-defined
                     // local symbols will not throw.
                     emitter.getBuilder()->CreateUnreachable();
-                    exc_type = exc_value = exc_tb = emitter.getNone();
+                    exc_type = exc_value = exc_tb = undefVariable();
                     // endBlock(DEAD);
                 }
 

src/codegen/irgen/refcounts.cpp

@@ -76,6 +76,9 @@ bool RefcountTracker::isNullable(llvm::Value* v) {
 }
 
 void RefcountTracker::refConsumed(llvm::Value* v, llvm::Instruction* inst) {
+    if (llvm::isa<UndefValue>(v))
+        return;
+
     assert(this->vars[v].reftype != RefType::UNKNOWN);
 
     this->refs_consumed[inst].push_back(v);
@@ -632,6 +635,9 @@ void RefcountTracker::addRefcounts(IRGenState* irstate) {
         if (rt->vars.count(v))
             return;
 
+        if (llvm::isa<UndefValue>(v))
+            return;
+
         auto t = v->getType();
         auto p = llvm::dyn_cast<llvm::PointerType>(t);
         if (!p) {

test/tests/undef_join.py

+# Regression test: promoting an UNDEF to a known type
+
+def f():
+    match = None # This could be a function that usually returns None but sometimes returns a string
+    if 0:
+        s = match.foo() or ""
+        print s
+for i in xrange(10000):
+    f()