Only free options objects in Options::shutdown if safe for FrontEnd

Adds a query to TR_FrontEnd (which defaults to "not safe") to answer
whether Options::shutdown() should free the command-line options
objects. For compilers like JitBuilder and the Test compiler, not
freeing the options represents a memory leak and there is not reason
not to free the options objects, so these compilers arrange for
the objects to be freed.

Other FrontEnds (but notably OpenJ9) by default will not free the
options objects, because e.g. OpenJ9 cannot guarantee that the
options objects will not be later read in one of its many event
handlers that continue to operate throughout the shutdown process.

This change addresses crashes in OpenJ9 that started happening
after we plugged the memory leak represented by the options objects
previously not being freed at shutdown.

Signed-off-by: Mark Stoodley <[email protected]>

Author: mstoodle

compiler/control/OMROptions.cpp

@@ -2994,19 +2994,22 @@ OMR::Options::shutdown(TR_FrontEnd * fe)
          TR::Options::closeLogsForOtherCompilationThreads(fe);
       }
 
-   if (TR::Options::getAOTCmdLineOptions()->_countString)
+   if (fe->isSafeToFreeOptionsOnShutdown())
       {
-      TR::Options::jitPersistentFree(const_cast<void *>(reinterpret_cast<const void *>(TR::Options::getAOTCmdLineOptions()->_countString)));
-      }
-   TR::Options::jitPersistentFree(_aotCmdLineOptions);
-   _aotCmdLineOptions = NULL;
+      if (TR::Options::getAOTCmdLineOptions()->_countString)
+         {
+         TR::Options::jitPersistentFree(const_cast<void *>(reinterpret_cast<const void *>(TR::Options::getAOTCmdLineOptions()->_countString)));
+         }
+      TR::Options::jitPersistentFree(_aotCmdLineOptions);
+      _aotCmdLineOptions = NULL;
 
-   if (TR::Options::getJITCmdLineOptions()->_countString)
-      {
-      TR::Options::jitPersistentFree(const_cast<void *>(reinterpret_cast<const void *>(TR::Options::getJITCmdLineOptions()->_countString)));
+      if (TR::Options::getJITCmdLineOptions()->_countString)
+         {
+         TR::Options::jitPersistentFree(const_cast<void *>(reinterpret_cast<const void *>(TR::Options::getJITCmdLineOptions()->_countString)));
+         }
+      TR::Options::jitPersistentFree(_jitCmdLineOptions);
+      _jitCmdLineOptions = NULL;
       }
-   TR::Options::jitPersistentFree(_jitCmdLineOptions);
-   _jitCmdLineOptions = NULL;
    }
 
 

compiler/env/FrontEnd.cpp

@@ -318,3 +318,15 @@ TR_FrontEnd::methodTrampolineLookup(TR::Compilation *comp, TR::SymbolReference *
    TR_UNIMPLEMENTED();
    return 0;
    }
+
+void
+TR_FrontEnd::setIsSafeToFreeOptionsOnShutdown(bool isSafe)
+   {
+   _isSafeToFreeOptionsOnShutdown = isSafe;
+   }
+
+bool
+TR_FrontEnd::isSafeToFreeOptionsOnShutdown()
+   {
+   return _isSafeToFreeOptionsOnShutdown;
+   }

compiler/env/FrontEnd.hpp

@@ -103,7 +103,9 @@ struct TR_BinaryEncodingData
 class TR_FrontEnd : private TR::Uncopyable
    {
 public:
-   TR_FrontEnd() {}
+   TR_FrontEnd()
+      : _isSafeToFreeOptionsOnShutdown(false)   // most conservative setting, relied upon by OpenJ9
+      {}
 
    // --------------------------------------------------------------------------
    // Method
@@ -222,6 +224,11 @@ class TR_FrontEnd : private TR::Uncopyable
    virtual char *getFormattedName(char *, int32_t, char *, char *, bool);
    virtual void printVerboseLogHeader(TR::Options *cmdLineOptions) {}
 
+   virtual void setIsSafeToFreeOptionsOnShutdown(bool isSafe=true);
+   virtual bool isSafeToFreeOptionsOnShutdown();
+
+private:
+   bool _isSafeToFreeOptionsOnShutdown;
    };
 
 #endif

fvtest/compilertest/control/TestJit.cpp

@@ -166,6 +166,8 @@ initializeTestJit(TR_RuntimeHelper *helperIDs, void **helperAddresses, int32_t n
 
    // --------------------------------------------------------------------------
    static TR::FrontEnd fe;
+   fe.setIsSafeToFreeOptionsOnShutdown(true);
+
    auto jitConfig = fe.jitConfig();
 
    initializeAllHelpers(jitConfig, helperIDs, helperAddresses, numHelpers);

jitbuilder/control/Jit.cpp

@@ -137,6 +137,8 @@ initializeJitBuilder(TR_RuntimeHelper *helperIDs, void **helperAddresses, int32_
 
    // --------------------------------------------------------------------------
    static TR::FrontEnd fe;
+   fe.setIsSafeToFreeOptionsOnShutdown(true);
+
    auto jitConfig = fe.jitConfig();
 
    initializeAllHelpers(jitConfig, helperIDs, helperAddresses, numHelpers);