SPI Software Process & Infrastructure QA http://spi.cern.ch/qa - - PowerPoint PPT Presentation

SPI Software Process & Infrastructure

QA

http://spi.cern.ch/qa

Gcov presentation - 03 June 2005

Johanne BENARD johanne.benard@cern.ch

J.Benard SPI - Software Process & Infrastructure 2

GCOV presentation What is Gcov ?

• Code Analysis principle
• Coverage tool
• Other utilities

Application on ROOT

• Compilation
• Test running
• Result

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Code analysis principle

• Aim at showing what percentage of an application has

been executed by the test process.

• Two different principles in gcov:

Statement coverage analysis which breaks the code down into basic blocs. Then by construction, if a line is executed a given number of times, every instruction line within the basic block would have been executed the same number of times. Branch coverage analysis which rather than focusing on a basic blocks, will look at possible paths a conditional can take and how often each path through the conditional is taken. Then knowledge of how many times each line of code was executed can be derived by knowing how many times each conditional was evaluated for each possible outcome.

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Coverage tool

• Code instrumentation during compilation:
• GCC must be used to compile the program with the flags
• fprofile-arcs -ftest-coverage
• GCC generates two output files for each Sourcefile.c compiled:
• Sourcefile.bb: list of source files and functions within those files and

line numbers corresponding to basic blocks in the source file )

• Sourcefile.bbg: list of the program flow arcs for each function
• Data collection during code execution:
• Counter vector entries are incremented every time an

instrumented basic block is entered

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Coverage tool

• Data extraction at program exit time:
• Creates a file sourcefile.da and populates the file with the size of

the vector and the counters of the vector itself

• Coverage analysis and presentation:
• GCOV utility integrates and relates the information of the "*.bbg",

"*.bb" and the "*.da" to produce the "*.gcov" files containing per line coverage output

Runtime Compilation time

File.c File.bb File.bbg File.da

Coverage analysis

File.gcov

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Other utilities

• Genhtml:
• Creates an HTML view from coverage data found in INFOFILE
• Geninfo:
• Converts .da files into .info files
• Genpgn:
• Creates an overview image for a given source code file of either

plain text or .gcov file format

• Gendesc:
• Converts a test case description file into a format as understood

by genhtml INPUTFILE

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Application to ROOT

• Compilation:
• Edition of MyConfig.mk in $ROOTSYS
• Link the shared libraries with libgcc.a
• Test running:
• In $ROOTSYS/test
• In roottest
• Results:

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ROOT test coverage report

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ROOT test coverage report

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More information

• Please visit our web site: http://spi.cern.ch/qa/gcov
• Proposed next actions:
• Publication of test coverage for ROOT
• at a given frequency?
• Addressed to a QA person?
• Run it on CVS tagged or HEAD source
• Add a section on SPI/QA web site dedicated to test coverage for

ROOT

• Produce automatically a list of files that have less than 80% test

coverage

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Conclusion

Thank you for your attention! Question?