This section provides links to a few tutorials, targeted from beginners to advanced users. Before performing one or more of theses tutorials, be sure that you have installed GeCoS. At the beginning of each tutorial, a section named Feature requirement show which features you need to have installed before running each tutorial.

*Disclaimer* As GeCoS is a rapidly changing software, some tutorials may contains bugs or have inconsistencies. You may also find the tutorial unclear or just simply wrong. In that case please report the problems that you encountered either on the gecos-user mailing lists or report a bug on the bug tracking page

• Create and run a new GeCoS project
• Generate Gecos IR from C source code
• Generate C source code from Gecos IR
• Generate the application call graph
• Convert instruction trees to instruction DAGs representation
• Convert instruction DAGs to instruction trees representation

• Loop unrolling
• Function inlining
• Applying transformation on a Stereo Vision algorithm
• Transform Instructions Into MIR Format
• Local Common Sub-Expressions Elimination
• Global Common Sub-Expression Elimination
• Variable range profiling

The GeCoS module “ModuleTester” provides a simple and quick way to test transformations used inside a GeCoS script. In short, given a list of GecosProjects, it can performs the following steps, depending on the specified options:

• Generate C code version for each of the projects.
• Compile the generated C codes for all versions.
• Link each version to generate an executable (the project must have a “main” Procedure!).
• Execute all versions.
• Compare their outputs.

The “ModuleTester” is part of GeCoS testing framework. Thus, in order to use it you should get the following plugin from the GeCoS svn repository:

• /trunk/gecos/test-utils/fr.irisa.cairn.gecos.tests.framework

This module currently issues bash commands. The following commands are required:

• bash
• gcc
• timeout

The “ModuleTester” can be invoked in a GeCoS scirpt as following:

TesterModule(projects, String testMode, String compareMode, Boolean compareCode, String codegenDir) with:

• projects: List of GecosProjects to be tested.
• testMode: String specifying the Test mode. It can be one of the following:
  • “CODEGEN”: generate code only for all projects.
  • “COMPILE”: “CODEGEN” + compile all projects.
  • “EXECUTE”: “COMPILE” + link and execute all projects. (NOTE: this require the projects to have a “main” procedure!)
  • [“AUTO”] : “EXECUTE” if a “main” procedure is available in both versions, otherwise “COMPILE”.
• compareMode: String specifying the Comparison mode when “EXECUTE”. Supported values are:
  • [“EXIT”] : Check the exit code of the “EXECUTE” commands: if non-zero the test is considered a failure.
  • “STDOUT” : “EXIT” + compare outputs on stdout.
• compareCode: if true the source code files of both versions are compared.
• codegenDir: the path of directory to used for placing the generated files.

Here is an example of how the “ModuleTester” can be used to test the loop unrolling transformation:

# Create a GecosProject and Parse it
project = CreateGecosProject("Unroll Project");
AddSourceToGecosProject(project,"test.c");
CDTFrontend(project);
 
# save project before applying the transformation
SaveGecosProject(project, "project_orig.gecosproject");
 
# Perform loop unrolling
ModelForUnroll(project);
 
### Testing the transformation:
# - origProj: is the GeCosProject before applying loop unrolling
# - project: is the project after loop unrolling
origProj = LoadGecosProject"project_orig.gecosproject");
modProj = project;
 
# This will do the following:
# - generate c code for both projects in "./test"
# - compile, link and execute code from both projects
# - Assert that the exit code is zero for both executables and finally 
# compares the output on the 
TesterModule({origProj, modProj}, "EXECUTE", "STDOUT", false, "./test");

• What is an Eclipse plug-in and why GeCoS need it
• Create a GeCoS module

• Understand the GeCoS IR
• Query information on GeCoS IR
• Using GeCoS factories
• GeCoS IR manipulation

• Extend the GeCoS IR
• Extend the CGenerator

• SSA representation in GeCoS

• GeCoS Polyhedral Framework

• Hierarchical Tasks Graph in GeCoS
• HTG issues and limitations

• Using the IGraph adapter framework

• GeCoS features/plug-in description
• GeCoS script information