global gcc project - rmll2008.rmll.info/img/pdf/ggcc_rmll2008_2.pdfitea 2 - 7 in software-intensive...

Global GCC PROJECT

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ITEA 2 - 2

in Software-intensiveSystems and Services

European Leadership

MotivationImprove software safety, efficiency and quality

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European Leadership

GoalEnhance existing open source gcc

• Give quality feedback to programmer as early as possible

• Enhance existing open source gcc used by hundred of thousands of developers in the world

Implementation Testing MaintenanceDesignRequirements

1

10

100

1000

cost

Time

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European Leadership

GoalExtend open source compiler infrastructure for :

• Coding rule checking

• Static analysis and threat detection

• Improved optimization

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European LeadershipStructure of the project

• WP2 – test and examples• WP3 – infrastructures• WP4 – static checking• WP5 – global optimisation• WP6 – coding rule checking

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European LeadershipStatic checking

• Goal : Detect at compile time coding errors• Mean : Use gcc powerful infrastructure and add directly check

there

• Step 1 : compiler probe• Add a compiler probe allowing to display during the compilation,

the compiler behaviour trough a graphical UI

• Step 2 : gcc infrastructure• Integration of a new garbage collector in gcc for small, dynamic

data structures. Integration of a lisp like dynamic translator in gcc to have a simpler way to express ggcc analysis algorithms

probe cc1

file.c

file.s

requests

replies

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European LeadershipStatic checking

• Step 3 : static rule coding • Coding of rules in lisp for ensuring rules

• Special branch (melt) in gcc tree with all melt advances• generation of ~500 000 code lines

int n=4;double*zone=malloc(n*sizeof(double));sum=0for (int i=0; i <= n; i++) { sum=sum+data[i]; zone[i]=sum;}

int n=4;double*zone=malloc(n*sizeof(double));sum=0for (int i=0; i <= n; i++) { sum=sum+data[i]; zone[i]=sum;}

compilation

Beware writingout of memoryfor zone

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European LeadershipCoding Rule Conformance

• Standard coding rules sets do exist e.g.: – MISRA-C (C language): automotive industry standard– High-Integrity C++ (HICPP): sponsored by a private company– Javacard: addressing specific restrictions of Java Smart Cards

• Some projects and organisations need to adapt standard coding rule sets or write their own rules.

• Rules written in natural language are ambiguous, which undermines any effort to automatically enforce them.

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European LeadershipCoding rule conformance

• Rule formalisation• Based on first order logic and written in a declarative domain

specific language. A prolog engine is used in order to check for compliance.

• A rule is not coded itself but its negation.

::Animal

::Mammal ::WingedAnimal

::Bat

virtual

Rule HICPP 3.3.15:

“Ensure base classes common to more than onederived class are virtual.”

Rule translation :

violate_hicpp_3_3_15(A,B, C, D):-

class(A), class(B), class(C),

class(D), B \= C,

direct_base_of(A, B),

direct_base_of(A, C),

base_of(B, D), base_of(C, D),

\+ virtual_base_of(A, C).

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European LeadershipCoding rule conformance

Coding RuleFormalisation

Coding RuleCompiler

Prolog Repr.of Coding

Rules

Coding RuleChecker

Coding RuleComplianceDiagnosis

GGCC coding rulecompliance architecture

Global Optimizer

StaticAnalysers

Other GGCCtools

Source files :.c, .cpp, .java

GCC Front-End

Gimple, SSA,and other

GCC internalrepr.

GCCBack-end

Object Code

Gnu Compiler Collection (GCC)

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European LeadershipEnabling Interactivity in GCC for Optimizations

• Interface GCC with external research tools.• iterative optimizations• design space exploration• machine learning techniques• feature extraction• fine-grain instrumentation/modification of the compiler-flow

• With clean internals in GCC :• homogeneous data extraction decoupled from internals• central data-management system

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European LeadershipInteractivity in optimisation

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European LeadershipInteractive Compilation Interface

• IC Interface defines the set of functions accessible by the controller

• IC Controller is dynamically linked with GCC. It doesn't depend on GCC internals

• The controller can interact with external tools enabling GCC to be controlled from other applications written in any programming language

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European LeadershipResults

• Melt branch in gcc tree– generation of 500 000 lines from the lisp to C generator allowing the

writing of lisp code to create static analysis with full access to all gcc internal data structures

– will allow the creation of optimisation pass in lisp

• Release of UPM : http://git.infradead.org/gcc.git – dump information about a C++ program in Prolog facts– a Prolog engine is used for codifying coding rules and search the

dumped data for violations of the rules.– Very few rules are implemented right now but, hopefully, some more

rules will be added in the next days/weeks.– At time being, only structural information (classes, inheritance,

methods, variables, types) is dumped, and only the middle-end of the compiler has been modified.

• ICI compiler implemented but still not released.

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European LeadershipConclusion

• GGCC will increase the safety of products

• GGCC will increase the efficiency of development (and save money)

• GGCC is unique among open source

Thank you for your attention

global gcc project - rmll2008.rmll.info/img/pdf/ggcc_rmll2008_2.pdfitea 2 - 7 in software-intensive...

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