View source for Open64

{{more citations needed|date=September 2010}}
{{Infobox software
| name                   = Open64
| screenshot             =
| caption                =
| developer              = [[Silicon Graphics]], Inc., Institute of Computing Technology, [[Chinese Academy of Sciences]], [[Hewlett-Packard]], [[University of Delaware]]
| released               = {{Start date and age|2002}}
|discontinued = yes
| latest release version = 5.0
| latest release date    = {{Start date and age|2011|11|10}}
| operating system       = [[Cross-platform]], [[Linux]]
| genre                  = [[Compiler]]
| license                = [[GNU General Public License]]
| website                = {{URL|sourceforge.net/projects/open64/}}
}}

'''Open64''' is a [[free software|free]], [[open-source software|open-source]], optimizing [[compiler]] for the [[Itanium]] and [[x86-64]] [[microprocessor]] architectures. It derives from the [[Silicon Graphics|SGI]] compilers for SGI's [[MIPS architecture|MIPS]] processors, called ''MIPSPro''.<ref>{{Cite web |title=MIPSPro - TechPubs Wiki |url=https://tech-pubs.net/wiki/index.php/MIPSPro |access-date=2025-10-30 |website=tech-pubs.net}}</ref> It was initially released in 2000 as [[GNU GPL]] software under the name Pro64. The following year, University of Delaware adopted the project and renamed the compiler to Open64. It now mostly serves as a research platform for compiler and [[computer architecture]] research groups. Open64 supports [[Fortran]] 77/95 and [[C (programming language)|C]]/[[C++]], as well as the [[Shared memory (interprocess communication)|shared memory]] programming model [[OpenMP]]. It can conduct high-quality [[interprocedural optimization|interprocedural analysis]], [[data-flow analysis]], data [[dependence analysis]], and array region analysis.  Development has ceased, although other projects can use the project's source.

== The infrastructure ==
Its major components are the [[front end processor (program)|frontend]] for C/C++ (using [[GNU Compiler Collection|GCC]]) and Fortran 77/90 (using the CraySoft front-end and libraries), [[interprocedural optimization|Interprocedural analysis]] (IPA), loop nest optimizer (LNO), global optimizer (WOPT), and [[code generation (compiler)|code generator]] (CG). Despite being initially written for a single computer architecture, Open64 has proven that it can generate efficient code for [[complex instruction set computer|CISC]], [[reduced instruction set computer|RISC]], and [[very long instruction word|VLIW]] architectures, including [[MIPS architecture|MIPS]], [[x86]], [[Itanium|IA-64]], [[ARM architecture|ARM]], and others.

== Intermediate representation ==
A hierarchical [[intermediate representation]] (IR) with five main levels is used in this compiler to serve as the common interface among all the [[frontend and backend]] components.  This IR is named WHIRL.

== Versions ==
The original version of Open64 that was released in 2002 was missing its very advanced [[software pipelining]] code generator, and had only a rudimentary code generator for Itanium.  The [http://portal.acm.org/citation.cfm?id=231385 Showdown Paper] documents the code generator that was not included in Open64.  The very advanced compiler from Tilera, for its 64-core TILE64 chip, is based on Blackbird.

Open64 exists in many [[fork (software development)|forks]], each of which has different features and limitations. The "classic" Open64 branch is the Open Research Compiler (ORC), which produces code only for the Itanium (IA-64), and was funded by [[Intel]]. The ORC effort ended in 2003, and the current official branch (which originated from the Intel ORC project) is managed by [[Hewlett-Packard]] and the [[University of Delaware]]'s Computer Architecture and Parallel Systems Laboratory (CAPSL).

Other important branches include the compilers from [[Tensilica]] and the [[AMD]] x86 Open64 Compiler Suite.<ref>{{ cite web | title = x86 Open64 Compiler Suite | publisher = [[AMD]] | url = http://developer.amd.com/tools-and-sdks/cpu-development/x86-open64-compiler-suite/ | access-date = 12 November 2013 | url-status = dead | archive-url = https://web.archive.org/web/20131113100944/http://developer.amd.com/tools-and-sdks/cpu-development/x86-open64-compiler-suite/ | archive-date = 13 November 2013 }}</ref>

[[Nvidia]] is also using an Open64 fork to optimize code in its [[CUDA]] toolchain.<ref>[https://www.capsl.udel.edu/conferences/open64/2008/Papers/101.doc NVIDIA’s Experience with Open64]</ref>

Open64 is used as the backend for the [[NonStop (server computers)|HPE NonStop OS]] compilers on the x86-64 platform.<ref>{{cite web|url=http://blog.ecubesystems.com/john-reagan-interview-on-llvm-part-2/|title=John Reagan Interview on LLVM, part 2|date=2019-05-01|access-date=2020-12-21|website=ecubesystems.com|archive-date=2020-11-25|archive-url=https://web.archive.org/web/20201125080221/http://blog.ecubesystems.com/john-reagan-interview-on-llvm-part-2/|url-status=dead}}</ref>

=== Open64 releases ===
{| class=wikitable
!Version !! Release date
|-
|5.0
|2011-11-11
|-
|4.2.4
|2011-04-12
|-
|4.2.3
|2010-04-09
|-
|4.2.1
|2008-12-08
|-
|4.2
|2008-10-01
|-
|4.1
|2007-12-03
|-
|4.0
|2007-06-15
|-
|3.1
|2007-04-13
|-
|3.0
|2006-11-22
|-
|2.0
|2006-10-02
|-
|1.0
|2006-09-22
|-
|0.16
|2003-07-07
|-
|0.15
|2002-11-30
|-
|0.14
|2002-03-04
|-
|0.13
|2002-01-10
|}

=== AMD x86 Open64 releases ===
{| class=wikitable
!Version !! Release date
|-
|4.5.2.1
|2013-03-28
|-
|4.5.2
|2012-08-08
|-
|4.5.1
|2011-12-19
|-
|4.2.4
|2010-06-29
|-
|4.2.3.2
|2010-05-17
|-
|4.2.3.1
|2010-01-29
|-
|4.2.3
|2009-12-11
|-
|4.2.2.3
|2009-11-23
|-
|4.2.2.2
|2009-08-31
|-
|4.2.2.1
|2009-06-03
|-
|4.2.2
|2009-04-24
|}

== Current development projects ==
Open64 is also used in a number of research projects, such as the [[Unified Parallel C]] (UPC) and [[speculative multithreading]] work at various universities.  The 2010 Open64 Developers Forum describes projects done at [[Absoft Fortran Compilers|Absoft]], [[AMD]], [[Chinese Academy of Sciences]], [[Fudan University]], [[Hewlett-Packard|HP]], [[National Tsing Hua University]], [[Nvidia]], [[Tensilica]], [[Tsinghua University]], and [[University of Houston]].<ref>{{Cite web |url=http://dynopt.ece.udel.edu/open64/program.shtml |title=2010 Open64 Developers Forum, August 25, 2010 |access-date=September 6, 2010 |archive-date=June 12, 2010 |archive-url=https://web.archive.org/web/20100612125720/http://dynopt.ece.udel.edu/open64/program.shtml |url-status=dead }}</ref>  The [[Chinese Academy of Sciences]] ported Open64 to the [[Loongson]] II platform.<ref>[https://www.capsl.udel.edu/conferences/open64/2009/Papers/102-Open64onMIPS2.pdf Open64 on MIPS: porting and enhancing Open64 for Loongson II]</ref>

[[AMD]] has extended and productized Open64 with optimizations designed for x86 multi-core processor advancements and multi-threaded code development.<ref>{{cite web|url=http://blogs.amd.com/nigel-dessau/2009/06/22/sweet-suite/|archive-url=https://web.archive.org/web/20100906085610/http://blogs.amd.com/nigel-dessau/2009/06/22/sweet-suite/|url-status=dead|title= Sweet Suite, blog posting |author= Nigel Dessau, AMD CMO|date=June 22, 2009|archive-date=2010-09-06}}</ref>  AMD supports Open64 as a complementary compiler to [[GNU Compiler Collection|GCC]].<ref>{{Cite web |url=http://developer.amd.com/tools/cpu-development/x86-open64-compiler-suite/ |title=AMD Open64 download page |access-date=2012-11-13 |archive-url=https://web.archive.org/web/20130313225744/http://developer.amd.com/tools/cpu-development/x86-open64-compiler-suite/ |archive-date=2013-03-13 |url-status=dead }}</ref>

The University of Houston's OpenUH project, which is based on Open64, released a new version of its compiler suite in November 2015.<ref>{{Cite web |url=http://web.cs.uh.edu/~openuh/download/ |title=OpenUH downloads page |access-date=2016-08-31 |archive-date=2016-10-28 |archive-url=https://web.archive.org/web/20161028010507/http://web.cs.uh.edu/~openuh/download/ |url-status=dead }}</ref>

== See also ==
{{Portal|Free and open-source software}}
* [[GNU Compiler Collection]]
* [[List of compilers]]
* [[GPGPU]]

== References ==
{{Reflist}}

== External links ==
* {{Official website}}
* [https://developer.amd.com/x86-open64-compiler-suite/ AMD Open64 page]
* [https://upc.nersc.gov/ The Berkeley UPC-to-C translator]
* [https://web.archive.org/web/20130515024142/http://www2.cs.uh.edu/~openuh/ OpenUH project at University of Houston]

{{FOSS}}
{{Software in the Public Interest}}

[[Category:C (programming language) compilers]]
[[Category:C++ compilers]]
[[Category:Compilers]]
[[Category:Fortran compilers]]
[[Category:Free and open source compilers]]
[[Category:2002 software]]