[FRONTEND] Added support for element-wise function defined in external LLVM bitcode (e.g., libdevice) (#562)

lib/ir/instructions.cc

@@ -988,6 +988,28 @@ globaltimer_inst* globaltimer_inst::create(context &ctx, const std::string &name
   return new globaltimer_inst(ctx, name, next);
 }
 
+// extern elementwise
+extern_elementwise_inst::extern_elementwise_inst(
+    context &ctx, const std::vector<value *> &args, type *ret_ty,
+    const std::string &lib_name, const std::string &lib_path,
+    const std::string &symbol_name, instruction *next)
+    : instruction(ret_ty, INST_EXTERN_ELEMENTWISE, args.size(), symbol_name,
+                  next),
+      lib_name_(lib_name),
+      lib_path_(lib_path) {
+  for (size_t i = 0; i < args.size(); i++) {
+    set_operand(i, args[i]);
+  }
+}
+
+extern_elementwise_inst *extern_elementwise_inst::create(
+    context &ctx, const std::vector<value *> &args, type *ret_ty,
+    const std::string &lib_name, const std::string &lib_path,
+    const std::string &symbol_name, instruction *next) {
+  return new extern_elementwise_inst(ctx, args, ret_ty, lib_name, lib_path,
+                                     symbol_name, next);
+}
+
 // clock
 clock_inst::clock_inst(context &ctx, const std::string &name, instruction *next)
   : instruction(type::get_int64_ty(ctx), INST_CLOCK, 0, name, next) { }