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Cint : C++ interpreter

Get the latest on CINT interpreter: STL implementation, optimization tips, multi-platform compatibility, and handling variable arguments. Bug fixes and ongoing progress included.

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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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