CONTRACTS: avoid double map lookup

Author: Remi Delmas

src/goto-instrument/contracts/dynamic-frames/dfcc_swap_and_wrap.cpp

@@ -67,31 +67,35 @@ void dfcc_swap_and_wrapt::swap_and_wrap(
   std::set<irep_idt> &function_pointer_contracts,
   bool allow_recursive_calls)
 {
-  auto found = cache.find(function_id);
-  if(found != cache.end())
-  {
-    auto &pair = found->second;
+  auto pair = cache.insert({function_id, {contract_id, contract_mode}});
+  auto inserted = pair.second;
 
+  if(!inserted)
+  {
+    auto old_contract_id = pair.first->second.first;
+    auto old_contract_mode = pair.first->second.second;
+
+    // different swapp already performed, abort
+    if(old_contract_id != contract_id || old_contract_mode != contract_mode)
+    {
+      auto mode1 = (old_contract_mode == dfcc_contract_modet::REPLACE)
+                     ? "REPLACE"
+                     : "CHECK";
+      auto mode2 =
+        (contract_mode == dfcc_contract_modet::REPLACE) ? "REPLACE" : "CHECK)";
+
+      std::ostringstream err_msg;
+      err_msg << "DFCC: multiple attempts to swap and wrap function '"
+              << function_id << "':\n";
+      err_msg << "- with '" << old_contract_id << "' in mode " << mode1 << "\n";
+      err_msg << "- with '" << contract_id << "' in mode " << mode2 << "\n";
+      throw invalid_input_exceptiont(err_msg.str());
+    }
     // same swap already performed
-    if(pair.first == contract_id && pair.second == contract_mode)
-      return;
-
-    // already swapped with something else, abort
-    auto mode1 =
-      (pair.second == dfcc_contract_modet::REPLACE) ? "REPLACE" : "CHECK";
-    auto mode2 =
-      (contract_mode == dfcc_contract_modet::REPLACE) ? "REPLACE" : "CHECK)";
-
-    std::ostringstream err_msg;
-    err_msg << "DFCC: multiple attempts to swap and wrap function '"
-            << function_id << "':\n";
-    err_msg << "- with '" << pair.first << "' in mode " << mode1 << "\n";
-    err_msg << "- with '" << contract_id << "' in mode " << mode2 << "\n";
-    throw invalid_input_exceptiont(err_msg.str());
+    return;
   }
 
-  cache.insert({function_id, {contract_id, contract_mode}});
-
+  // actually perform the translation
   switch(contract_mode)
   {
   case dfcc_contract_modet::CHECK: