firstname lastname cern ph-sft ch-1211 geneva 23 sftweb.cern.ch root.cern.ch cling – past, present...

Firstname LastnameCERN PH-SFT

CH-1211 Geneva 23sftweb.cern.ch

root.cern.ch

Cling – Past, Present and FutureCling – Past, Present and Future

V. Vassilev, P. Canal, A. Naumann, P. RussoV. Vassilev, P. Canal, A. Naumann, P. Russo

CERN, PH-SFT & FermiLabCERN, PH-SFT & FermiLab

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Role of C++ Interpreter in ROOT

o Load/Store C++ objectsoRuntime Dynamism

• TFile::Open(“http://...”)• gDirectory->Get(“hist”)• python runReco.py

o Fast Prototyping

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Limited C++ language support for reflection and type introspection.

ROOT

CINT

Reflection

TPluginManager

IO

...

PyR

OO

T

Type Info

TClass

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

LLVM Toolchain As an Alternative

o LLVM Core “The LLVM Project is a collection of modular and reusable compiler and toolchain technologies...”

• More than 120 active contributorsApple, ARM, Google, Qualcomm, QuIC, NVidia, AMD and more

• ~250 commits/weekoClang

“The goal of the Clang project is to create a new C, C++, Objective C and Objective C++ front-end for the LLVM compiler.“

• More than 100 active contributorsApple, ARM, AMD and more

• ~150 commits/week

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

In The Meanwhile: LLVM

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LLVM and Clang “The LLVM Project is a collection of modular and reusable compiler and

toolchain technologies...”

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Cling's Dual Personality

oAn interpreter – looks like an interpreter and behaves like an interpreterCling follows the read-evaluate-print-loop (repl) concept.

oMore than interpreter – built on top of compiler libraries (Clang and LLVM)Contains interpreter parts and compiler parts. More of an interactive compiler or an interactive compiler interface for clang.

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No need to compile Cling/ROOT with Clang/LLVM or having clang installed on the OS

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Cling Is Better Than CINT

o Full C++ support incl. C++11o Stable and informative intermediate representations of the

sourceoBeing developed with the vision to be used in multithreaded

environment (an interpreter object per thread)

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March 2013

Full C++ Support

o Templates and STL are not an issue

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Full C++ Support

oNatural path to the new standards C++11/C++*

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March 2013

Full C++ Support

oNatural path to the new standards C++11/C++*

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March 2013

Full C++ Support

o Boost is not a dream

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March 2013

Diagnostics

oColumn numbers and caret diagnosticsCaretDiagnostics.C:4:13: warning: '.*' specified field precision is missing a matching 'int' argumentprintf("%.*d"); ~~^~

oRange highlightingRangeHighlight.C:14:39: error: invalid operands to binary expression ('int' and 'A')return y + func(y ? ((SomeA.X + 40) + SomeA) / 42 + SomeA.X : SomeA.X); ~~~~~~~~~~~~ ^ ~~~~~~

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Diagnostics

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o Pointer vs Referencesinput_line_410:2:6: error: member reference type 'TNamed' is not a pointernRef->GetName();~~~~^

input_line_413:2:7: error: member reference type 'TNamed *' is a pointer; maybe you meant to use '->’?nPtr1.GetName();~~~~^ ->

o Fix-it hintsFixItHints.C:7:27: warning: use of GNU old-style field designator extensionstruct point origin = { x: 0.0, y: 0.0 }; ^~ .x = FixItHints.C:12:3: error: use of undeclared identifier 'floot'; did you mean 'float’? floot p; ^~~~ float

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Diagnostics

o AmbiguitiesAmbiguities.C:20:30: error: return type of virtual function 'Clone' is not covariant with the return type of the function it overrides (ambiguous conversion from derived class 'TeachingAssistant' to base class 'Person': class TeachingAssistant -> class Student -> class Person class TeachingAssistant -> class Teacher -> class Person)virtual TeachingAssistant* Clone() const; ^Ambiguities.C:7:19: note: overridden virtual function is herevirtual Person* Clone() const; ^

o Templatesinput_line_401:2:2:error: use of class template LorentzVector requires template arguments LorentzVector v; ^Math/GenVector/LorentzVectorfwd.h:28:39: note: template is declared here template<class CoordSystem> class LorentzVector; ~~~~~~~~~~~~~~~~~~~~~~~~ ^

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Personvirtual void

Clone()

Personvirtual void

Clone()

TeachingAssistantvirtual void Clone()TeachingAssistantvirtual void Clone()

StudentStudent TeacherTeacher

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Diagnostics

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o Macro expansionsMacroExpansionInformation.C:14:7: error: invalid operands to binary expression ('int' and 'A’) X = MAX(X, *SomeA); ^~~~~~~~~~~~~~MacroExpansionInformation.C:5:24: note: expanded from macro 'MAX’#define MAX(A, B) ((A) > (B) ? (A) : (B)) ~~~ ^ ~~~

o Template instantiationsinput_line_395:2:18: error: no matching constructor for initialization of 'PtEtaPhiEVector' (aka 'LorentzVector<PtEtaPhiE4D<double> >’)PtEtaPhiEVector v2( "v1.Rho()", v1.Eta(), v1.Phi(), v1.E() ); ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~Math/GenVector/LorentzVector.h:77:8: note: candidate constructor not viable: no known conversion from 'const char [9]' to 'const Scalar’ (aka 'const double') for 1st argumentLorentzVector(const Scalar & a,^Math/GenVector/LorentzVector.h:88:17: note: candidate constructor template not viable: requires single argument 'v', but 4 arguments were provided explicit LorentzVector(const LorentzVector<Coords> & v ) : ^

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 201316

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Data Flow

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Machine Code (x86, Alpha, ...)

①

⑦

Compilation Engine (clang)

Compilation Engine (clang)

Transformation Engine

Transformation Engine

⑤②③④⑥ClingCling

⑧①, ② –Text③, ④, ⑤, ⑥ – Abstract Syntax Tree⑦ - LLVM Bit Code⑧ -Target Machine Code

LLVM Execution

Engine

LLVM Execution

Engine

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Compilation Engine

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Clang ParserClang Parser

Clang Code Generator

Clang Code Generator

LLVM Execution

Engine

LLVM Execution

Engine

Transformation Engine

Transformation Engine

ClingCling

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Transformation Engine

o TransactionCling represents the incremental input as a set of AST nodes.

o Transaction TransformersCling enables each transaction to be further customized by other clients by implementing a transaction transformer.

o Interpreter CallbacksImplements callbacks for the “interesting” events.

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ClingCling Transformation Engine

Transformation Engine

Transaction

TransactionTransaction

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 201320

LLVM EE-s have complete target info Thus calling into compiled libraries is not an issue.

No boundary interpreted/compiled world Possible to derive from compiled classes, proper calculation of offsets and so on.

Machine Code (x86, Alpha, ...)

Compiled libs(.so)

��

LLILLI LLVMJIT

LLVMJIT MCJITMCJIT

Execution Engine

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Challenges

o Incompatible concepts like compilation and interpretationMany tasks that are trivial for an interpreter become a nightmare for a compiler.

oMake C++ usable at the promptIncorporate the experience we have with CINT. First step: adopt the successful usability extensions from CINT.

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Extending C++ Language

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[root]$ sin(12);void wrapper() { sin(12);}

[root]$ [root]$

int i = 12;sin(i);

void wrapper1() { int i = 12;}

void wrapper2() { sin(i);} ?

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Extending C++ Language

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[root]$ [root]$

void wrapper1() { int i = 12; printf("%d\n",i);}

void wrapper2() { printf("%f\n", sin(i));}

int i = 12;

int i = 12; printf("%d\n",i);printf("%f\n",sin(i));

oWrap the inputo Look for declarationso Extract the declarations one level up, as global declarations

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Streaming Execution Results

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[root]$ [root]$

int i = 12(int) 12sin(i)(double) -5.365729e-01

[root]$

[root]$

std::string s = “Hello”(std::string) @0x7fff65ae783cc_str: “Hello”enum e { e1 = 12, e2 = 13, e3 = 13}; e1(enum e) (e::e1) : (int) 12

[root]$ HelloWorld(void (void)) Function @0x108880030 at /tmp/HelloWorld.h:2:void HelloWorld() { printf("HelloWorld!\n");}

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Error Recovery

o Filled input-by-input (aka Transaction)o Incorrect inputs must be discarded as a whole

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Implicit auto keyword

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i = 5; f = new TNamed(“a”, ”b”)

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Late Binding

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if (cond) {

TFile* F = 0;

if (is_day_of_month_even())

F = TFile::Open("even.root");

else

F = TFile::Open("odd.root");

hist->Draw();

}

hist->Draw();

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Late Binding

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if (cond) {

TFile* F = 0;

if (is_day_of_month_even())

F = TFile::Open("even.root");

else

F = TFile::Open("odd.root");

gCling->EvaluateT<void>("hist->Draw()", ...);

}

hist->Draw();

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Code Unloading

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[root]$ [root]$ [root]$ [root]$ [root]$ [root]$ [root]$ [root]$

.L Calculator.hCalculator calc;calc.Add(3, 1)(int) 2 //WTF!?*.L Calculator.hCalculator calc;calc.Add(3, 1)(int) 4 //

// Calculator.hclass Calculator { int Add(int a, int b) { return a + b; }...};

// Calculator.hclass Calculator { int Add(int a, int b) { return a - b; }...};

* What's That Function

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Future Plans

oMigrate to MCJIT• Object file emitted to memory• Runtime dynamic linker

oWindows 64 Supporto Tools

• Automatic Differentiation

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

o See Tomas Gahr’s demo later at the workshop

Thank you!

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Backup slides

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March 2013

Pre-Compiled Headers/Modules

Carefully crafted data structures designed to improve translator's performance:oReduce lexical, syntax and semantic analysisoLoaded “lazily” on demand

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

Pre-Compiled Headers/Modules

Design advantages:oLoading is significantly faster than re-parsingoMinimize the cost of readingoRead times don't depend on sizeoCost of generating isn't large

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sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 201335

PCH PCM

sftweb.cern.chroot.cern.ch vvassilev/ROOT Users Workshop 11-14

March 2013

PCH vs PCM

oWhere we should get it from? Who knows more about types than the translator?

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CINT

Reflection

Type Info

Not very descriptive

GCCXML

Reflex