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Cint : C++ interpreter

Cint : C++ interpreter. Frequently Asked Questions Digest 14 Oct 2002 at CERN Masaharu Goto. On going progress, bug fix. Many activities since ROOT2001 Change ID 1550 to 1723. ???. Frequently Asked Questions. STL (dictionary generation) Optimization (bytecode) problems

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Cint : C++ interpreter

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  1. Cint : C++ interpreter Frequently Asked Questions Digest 14 Oct 2002 at CERN Masaharu Goto

  2. On going progress, bug fix • Many activities since ROOT2001 • Change ID 1550 to 1723 ???

  3. Frequently Asked Questions • STL (dictionary generation) • Optimization (bytecode) problems • Multi-platform issues • Variable arguments • ‘long long’ and ‘long double’ • Basics of Cint (from non ROOT users) ???

  4. How STL is implemented in CINT #include <vector> cint stl lib demo prec_stl dll_stl makecint stl vector list deuqe map set algorithm . _vector.h _list.h _deuqe.h _map.h _set.h algo.h . vector.dll list.dll deuqe.dll map.dll set.dll . vector list deuqe map set algorithm . stl cintdlls are generated under this directory and moved to cint/stl/*.dll cintdlls Top level Interpretation Dictionary generation

  5. Interpreting STL containers • cint/stl/_[container].h are used • Derived from 1994 HP implementation • No default arguments template<class T> class vector { }; • Cint can only interpret simple examples of vector and list

  6. STL dictionary generation • Files under cint/lib/prec_stl are used • Derived from 1997 ANSI/ISO C++ draft • All kinds of STL containers can be compiled with makecint/rootcint • vector,list,deque,map,multimap,set,multiset,queue,stack,valarray • Many compilers have subtle deviation from the standard → #ifdef

  7. STL progress • Support new compilers (versions) • gcc 3.0 , 3.1/3.2 , RedHat 7.2 gcc 2.95 • Borland C++ compiler 5.5 • Intel C++ compiler • More ANSI/ISO conformity • Along with new compiler support

  8. STL suggestion • Use compiled STL containers • With ROOT, install cintdlls • Generic algorithms are interpreted • cint/stl/algo.h • Report STL dictionary generation problems • Or, you could debug cint/lib/prec_stl/* by yourself

  9. Optimization (bytecode) problems • Class object instantiated in a loop for(int I=0;I<5;I++) { TXxxx a; } • Especially when if() statement is false in the 1st iteration for(int I=0;I<5;I++) { if(I) TXxxx a; } • On going bug fix • Bug fix in cint 5.15.59

  10. Optimization suggestion • Use –O0 (optimization off) if speed is not critical • Use script compiler if performance is important : Thanks to Philippe Canal • Use new/delete for class object if possible

  11. Multi-platform issues • There are not many multi-platform issues • Because Cint is made platform independent • Few exceptions are • Variable arguments • ‘long long’ , ‘long double’ • STL (as explained previously) • 64bit issues may be sometimes overlooked

  12. Variable arguments • Implementation of variable arguments in dictionary is highly platform dependent • Progress • va_arg for HP-UX is supported • This was the most difficult one • Need to debug each platform in face • But, this is not easy Patience, patience, patience …

  13. ‘long long’, ‘long double’ • Supported by wrapper class • class G__longlong, G__longdouble • Supported as an optional DLL component • include/long.dll ← compiled in lib/longlong dir • Why not supporting this as basic component of Cint? • Still seeing multi-platform issues. • Investigation needed

  14. Thank you • Send your message to cint@root.cern.ch • Please include following information • Cint version 5.15.xx (different from ROOT version) • CPU, OS, compiler, compiler version

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