[RF] JIT all generated code in one gInterpreter call

This speeds up RooFit codegen by about 20 %.

Author: guitargeek

roofit/roofitcore/inc/RooFit/CodegenContext.h

@@ -117,6 +117,7 @@ class CodegenContext {
    std::vector<double> const &xlArr() { return _xlArr; }
 
    void collectFunction(std::string const &name);
+   std::string const &collectedCode() { return _collectedCode; }
    std::vector<std::string> const &collectedFunctions() { return _collectedFunctions; }
 
    std::string
@@ -207,6 +208,7 @@ class CodegenContext {
    std::unordered_map<RooFit::UniqueId<RooAbsCollection>::Value_t, std::string> _listNames;
    std::vector<double> _xlArr;
    std::vector<std::string> _collectedFunctions;
+   std::string _collectedCode;
 };
 
 template <>

roofit/roofitcore/src/RooEvaluatorWrapper.cxx

@@ -258,12 +258,28 @@ RooFuncWrapper::RooFuncWrapper(RooAbsReal &obj, const RooAbsData *data, RooSimul
       }
    }
 
-   gInterpreter->Declare("#pragma cling optimize(2)");
-
    // Declare the function and create its derivative.
    auto print = [](std::string const &msg) { oocoutI(nullptr, Fitting) << msg << std::endl; };
    ROOT::Math::Util::TimingScope timingScope(print, "Function JIT time:");
    _funcName = ctx.buildFunction(obj, nodeOutputSizes);
+
+   // Make sure the codegen implementations are known to the interpreter
+   gInterpreter->Declare("#include <RooFit/CodegenImpl.h>\n");
+
+   if (!gInterpreter->Declare(ctx.collectedCode().c_str())) {
+      std::stringstream errorMsg;
+      std::string debugFileName = "_codegen_" + _funcName + ".cxx";
+      errorMsg << "Function " << _funcName << " could not be compiled. See above for details. Full code dumped to file "
+               << debugFileName << "for debugging";
+      {
+         std::ofstream outFile;
+         outFile.open(debugFileName.c_str());
+         outFile << ctx.collectedCode();
+      }
+      oocoutE(nullptr, InputArguments) << errorMsg.str() << std::endl;
+      throw std::runtime_error(errorMsg.str().c_str());
+   }
+
    _func = reinterpret_cast<Func>(gInterpreter->ProcessLine((_funcName + ";").c_str()));
 
    _xlArr = ctx.xlArr();
@@ -385,7 +401,6 @@ void RooFuncWrapper::writeDebugMacro(std::string const &filename) const
 #include <RooFit/Detail/MathFuncs.h>
 #include <Math/CladDerivator.h>
 
-#pragma cling optimize(2)
 )" << allCode.str()
            << R"(
 #pragma clad ON

roofit/roofitcore/src/RooFit/CodegenContext.cxx

@@ -341,13 +341,11 @@ CodegenContext::buildFunction(RooAbsArg const &arg, std::map<RooFit::Detail::Dat
    }
    ctx._xlArr = _xlArr;
    ctx._collectedFunctions = _collectedFunctions;
+   ctx._collectedCode = _collectedCode;
 
    static int iCodegen = 0;
    auto funcName = "roo_codegen_" + std::to_string(iCodegen++);
 
-   // Make sure the codegen implementations are known to the interpreter
-   gInterpreter->Declare("#include <RooFit/CodegenImpl.h>\n");
-
    ctx.pushScope();
    std::string funcBody = ctx.getResult(arg);
    ctx.popScope();
@@ -357,24 +355,13 @@ CodegenContext::buildFunction(RooAbsArg const &arg, std::map<RooFit::Detail::Dat
    std::stringstream bodyWithSigStrm;
    bodyWithSigStrm << "double " << funcName << "(double* params, double const* obs, double const* xlArr) {\n"
                    << "constexpr double inf = std::numeric_limits<double>::infinity();\n"
-                   << funcBody << "\n}";
+                   << funcBody << "\n}\n\n";
    ctx._collectedFunctions.emplace_back(funcName);
-   if (!gInterpreter->Declare(bodyWithSigStrm.str().c_str())) {
-      std::stringstream errorMsg;
-      std::string debugFileName = "_codegen_" + funcName + ".cxx";
-      errorMsg << "Function " << funcName << " could not be compiled. See above for details. Full code dumped to file "
-               << debugFileName << "for debugging";
-      {
-         std::ofstream outFile;
-         outFile.open(debugFileName.c_str());
-         outFile << bodyWithSigStrm.str();
-      }
-      oocoutE(nullptr, InputArguments) << errorMsg.str() << std::endl;
-      throw std::runtime_error(errorMsg.str().c_str());
-   }
+   ctx._collectedCode += bodyWithSigStrm.str();
 
    _xlArr = ctx._xlArr;
    _collectedFunctions = ctx._collectedFunctions;
+   _collectedCode = ctx._collectedCode;
 
    return funcName;
 }