Eliminate undefined operator

src/dead_code_elimination.cpp

@@ -41,8 +41,8 @@ void dead_code_elimination::apply(program& p) const
         // Skip the last instruction
         if(i == last)
             break;
-        // Skip instruction with empty shape as output unless its a builtin
-        if(i->get_shape().elements() == 0 and not(i->name().front() == '@'))
+        // Skip instruction with empty shape as output unless its a builtin or undefined
+        if(i->get_shape().elements() == 0 and not(i->name().front() == '@') and not(i->name() == "undefined"))
             continue;
         assert(bidistance(p, i, last) > 0);
         fix([&](auto self, auto leaf) {

test/dead_code_elimination_test.cpp

 #include <migraphx/dead_code_elimination.hpp>
 #include <basic_ops.hpp>
+#include <migraphx/operators.hpp>
 #include <test.hpp>
 
 struct dce_target
@@ -111,4 +112,21 @@ TEST_CASE(depth_test)
     EXPECT(result != migraphx::literal{4});
 }
 
+TEST_CASE(undefined_test)
+{
+    migraphx::program p;
+
+    auto one = p.add_literal(1);
+    auto two = p.add_literal(2);
+    auto undef = p.add_instruction(migraphx::op::undefined{});
+    p.add_instruction(sum_op{}, one, two);
+    auto count = std::distance(p.begin(), p.end());
+    p.compile(dce_target{});
+    EXPECT(std::distance(p.begin(), p.end()) == count - 1);
+    EXPECT(not p.has_instruction(undef));
+    auto result = p.eval({});
+    EXPECT(result == migraphx::literal{3});
+    EXPECT(result != migraphx::literal{4});
+}
+
 int main(int argc, const char* argv[]) { test::run(argc, argv); }