CTools:ICI:Projects:GSOC09:Fine grain tuning

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Revision as of 03:09, 11 August 2009

Google Summer of Code 2009: fine-grain optimizations.

Yuanjie Huang (ICT, China)

This project aims to provide fine-grain optimization selection and tuning abilities in GCC, and thus enable GCC to tune default optimization heuristic of the compiler or fine optimizations for a given program on a given architecture entirely automatically using statistical and machine learning techniques from the MILEPOST project.

• GSOC'09 project description
• SVN repository
• cTuning development mailing list

ICI Fine-grain tuning work flow

Coming soon...

Compilation recording information to XML

Compilation reusing information from XML

ICI Events

ICI events added to the framework for fine-grain tuning are documented here.

ICI Features

New Features

ICI features added to the framework for fine-grain tuning are documented here.

Known Issue on Current ICI Features

• "function_filename" can be empty for functions generated by IPCP optimization (cp pass).

ICI Parameters

ICI parameters now come with a type which should be declared when registering parameters in ICI, currently only a few basic C types are supported: void, char, unsigned char, int, unsigned int, long and unsigned long. A special type named EP_SILENT is introduced to pass parameters that is only used to pass status information to plugin; it's actually int, and is planned to be replaced by a elegant solution. The parameter type is defined in gcc/highlev-plugin-internal.h and gcc/highlev-plugin.h:

/* Datatype of event parameter pointer  */
typedef enum
{
  EP_SILENT,
  EP_VOID,
  EP_CHAR,
  EP_UNSIGNED_CHAR,
  EP_INT;
  EP_UNSIGNED_INT,
  EP_LONG,
  EP_UNSIGNED_LONG
} event_parameter_type;

The representation of parameters is defined in file gcc/events.c:

/* Parameter structure.  */
struct event_parameter
{
  const char *name;            /* Name for the parameter */
  const void *value;           /* Pointer to data */
  event_parameter_type type;   /* Type enumeration of value */
};

ICI API

register_event_parameter: register a new ICI parameter

get_event_parameter_type: get the type of an ICI event parameter

run_pass: run a pass

run_ipa_pass: run an IPA pass

initialize_ici_pass_list: initialize a list of passes for ICI batch execution

insert_ici_pass_list: insert a pass into ICI pass list

run_ici_pass_list: execute an ICI pass list on current function

Adapt Plugin

Description

Adapt plugin provides support for GCC pass sequence record/substitution, function-specific optimization tuning, function clone and instrumentation. Plugins developed for fine-grain tuning are documented here. These plugins are developed to work with ICI-2.0 interface.

HOWTO

Adapt plugin is depends on Mini-XML library, which provides XML reading and writing ability.

This plugin behaves differently depending on the ICI_ADAPT_CONTROL environmental variable, which can be either set to 1 to record information of current compilation into XML files or to 2 to reuse passes from XML files to perform passes substitution, function clone and other functionalities.

To use adapt plugin with ICI, ICI_PLUGIN environment variable should be set to the path to the plugin library (.so), and gcc should be called with with either -fici flag or ICI_USE environment parameter.

Known Issue

none