Fix a crash when returning void.

src/d/llvm/backend.d

@@ -248,6 +248,9 @@ public:
 			}
 		}
 
+		import d.llvm.global;
+		GlobalGen(pass).checkModule();
+
 		runLLVMPasses();
 
 		// Now that we generated the IR, we run the unittests.

src/d/llvm/statement.d

@@ -131,8 +131,17 @@ struct StatementGen {
 				break;
 
 			case Return:
+				LLVMValueRef ret;
 				if (bb.value) {
-					auto ret = genExpression(bb.value);
+					auto v = genExpression(bb.value);
+
+					// LLVM IR does not support void return.
+					if (LLVMGetTypeKind(LLVMTypeOf(v)) != LLVMTypeKind.Void) {
+						ret = v;
+					}
+				}
+
+				if (ret) {
 					LLVMBuildRet(builder, ret);
 				} else {
 					LLVMBuildRetVoid(builder);

test/unit/dg.d

@@ -0,0 +1,16 @@
+unittest voiddg {
+	uint a = 0;
+	void increment() {
+		a++;
+	}
+
+	increment();
+	assert(a == 1);
+
+	void forward(void delegate() dg) {
+		return dg();
+	}
+
+	forward(increment);
+	assert(a == 2);
+}