International Compiler Experts Unite to Target Itanium® Processor Performance on GCC

1 January 1970

A group of international compiler experts on Intel® Itanium® processors, including representatives from HP, Intel, Red Hat, Novell®/SUSE®, the Gelato Federation (www.gelato.org), and the GCC community, recently came together to plan Itanium processor-specific improvements to the GNU Compiler Collection (GCC) -- a multi-platform set of compilers for C, C++, Fortran, Objective-C, and the Java™ programming language as well as others. The workshop, hosted by Gelato Member the Institute for System Programming of the Russian Academy of Sciences (ISP-RAS) and sponsored by Intel and HP, was held August 7-8 in Moscow, Russia. The group discussed specific GCC optimizations to improve the performance of compiled code running on Itanium-based systems. See gcc.gelato.org/MoscowMeeting for full details.

Improved GCC Helps Itanium Adoption

Improving GCC performance on Itanium architecture is important in the acceleration of the processor's adoption in the broader computing community beyond high-performance computing. The Itanium-based platform is unique because it relies far more on the compiler in comparison to other platforms, and GCC is the standard compiler on GNU/Linux distributions. Many have dismissed Itanium-based platforms as viable determined only on GCC-compiled application performance. GCC has not been fully tuned specifically for the Itanium processor and its high-performance features. Thus, improving GCC performance on Itanium architecture will mean automatically improving thousands of applications and libraries provided by Linux distributions for Itanium-based systems.

Workshop Targets GCC Improvements

On selecting improvements to address, Diego Novillo, Red Hat Principal Software Engineer, explains, "We discussed several potential improvements to GCC and based our list on a combination of estimated benefit, effort, available resources to implement, and likelihood of acceptance by the GCC community."

The group agreed to concentrate on three strategic areas: alias analysis, instruction scheduling, and data prefetching. Proposed alias analysis work, including modifications to RTL and GIMPLE, will be spearheaded by Novillo, ISP-RAS, and other members of the GCC development community. Instruction scheduling modifications for the Itanium processor have been underway for some time. Superblock work, led by the University of Illinois and sponsored by the Itanium® Solutions Alliance, allows optimizations to be performed over larger blocks of code. ISP-RAS is working on implementing a modified scheduler for GCC to directly improve execution times on Itanium-based platforms. Finally, by enabling prefetching by default for GCC compilations on Itanium architecture, execution performance is expected to be significantly enhanced. Novell/SUSE is taking a lead role in this work. Beyond the boost in performance for Itanium architecture, these modifications are also expected to benefit other platforms. See gcc.gelato.org/MeetingNotes for more specifics.

Mark K. Smith, Managing Director of the Gelato Federation, states, "This meeting was a great success to move the improvement of GCC forward. The face-to-face discussions enabled attendees to quickly pinpoint and prioritize optimizations to implement, to build collaborative relationships, and to develop a strategic plan of action."

The workshop in Russia was a continuation of an effort to focus attention and resources on improving GCC for Itanium architecture. The first meeting of the group was held in Geneva, Switzerland, January 2005 (www.gelato.org/community/workshop/gcc/index.php). Most recently the group met at Gelato ICE 2006 San Jose this past April (www.gelato.org/community/gelato_meeting.php?id=ICE06aprT#pres96).

Continued Coordination Key

Measures are in place to continue promoting coordination between the Linux Itanium project developers and the GCC representatives to insure efforts will be implemented and to pave the way for future work. Close contact is maintained through an active mailing list, conference calls, and a workgroup wiki. Development contributions are planned to be made according to the GCC release cycle schedule, and results will be shared at the Gelato ICE: Itanium® Conference & Expo in San Jose, April 15-18, 2007.

About Gelato

The Gelato Federation is the global technical community dedicated to advancing Linux on the Intel Itanium-based platform through collaboration, education, and leadership. Gelato members are suppliers and users of Linux/Itanium processor technology with a shared goal of producing open-source solutions for academic, government, and industrial high-performance computing users. The Gelato portal (www.gelato.org) serves as the primary channel for Federation business and collaborations. Information about Gelato members' software and solutions are available through the portal, and the community is welcome to participate and contribute.

Intel and Itanium are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries. Linux is a registered trademark of Linus Torvalds in several countries. Sun, Sun Microsystems, the Sun logo, Solaris, Java, and The Network Is The Computer are trademarks or registered trademarks of Sun Microsystems, Inc. All other trademarks mentioned herein are the property of their respective owners.

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