Open64 5.0

Open64 is an open research compiler.

Open64 is the final result of research contributions from a number of compiler groups around the world. Formerly known as Pro64, Open64 was initially created by SGI and licensed under the Opens external link in new windowGNU Public License (GPL). It was derived from SGI's MIPSPro compiler.

Open64 also derives from work done by Intel Corp, in conjunction with the Chinese Academy of Sciences. They created the Opens external link in new windowOpen Research Compiler (ORC), a specially modified version of Open64 with custom modifications for researchers. These changes were later folded back into the main Open64 source tree in 2005.

Open64 has been retargetted to a number of architectures. Pathscale modified Open64 to create Opens external link in new windowEkoPath, a compiler for the AMD64 architecture. The University of Delaware's Computer Architecture and Parallel Systems Laboratory (CAPSL) modified Open64 to create the Opens external link in new windowKylin Compiler, a compiler for Intel's X-Scale architecture. CAPSL and Hewlet-Packard are currently working on Osprey, a project to replace Open64's front end (derived from GCC 2.95's frontend) with the current GCC front end.

The Open64 compiler suite currently includes compilers for C, C++, and Fortran90/95 compilers for the IA-64 Linux ABI and API standards. Open64 is currently in version 4.0. Professor Guang Gao and CAPSL at the University of Delaware are the current gatekeepers of the project.


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What's New in This Release: [ read full changelog ]

Important bug fixes:

The following bugs listed in the Open64 Bugzilla database were resolved in this release:

· 116 135 361 363 445 450 473 497 518 529 547 584 615 617 670 673 675 682 715 721 723 726 732 738 741 746 747 748 749 750 751 752 753 754 756 758 759 760 761 762 764 765 766 767 768 769 771 775 782 784 786 789 792 793 795 796 799 801 802 813 815 824 826 827 828 830 831 832 833 838 842 847 851 853 855 856 857 861 863 865 867 869 871 872 875 876 877 878 880 882 883 888 893 894 895

· Please refer to https://bugs.open64.net/show_bug.cgi?id=NNN for more details. (Replace NNN with the numbers listed above.)

Frontend/infrastructure/tool changes:

· Added configure options to allow disabling of IPA or shared library support.
· Added support for VCG graphs for procedure CFGs.
· Addressed various C standard compliant problems related to "volatile".
· Improved debugging by allowing the allocation of stack space for unused variables during -g compilation.
· Added triaging support for field sensitive alias analysis.
· Implemented ZDL (Zero-Delay-Loop) feature for DSP.
· Extended intrinsic support for IA64.

New/improved optimizations:

· Enabled more if-conversion.
· Enabled CFLOW optimization within EH regions.
· Avoided creating unnecessary region exit blocks.
· Extended proactive loop optimizations.
· Added inlining support for field sensitive alias analysis.
· Implemented multi-target function pointer inlining.
· Improved -O3 floating point performance.
· Added frame-pointer optimization.
Improved optimization for structures:
· avoided unnecessary structure copies;
· added copy-in/copy-out optimization.
Improved vectorization:
· introduced an object-oriented framework for SIMD expressions;
· more vectoriable operators;
· loops with small trip count;
· reduced vectorization overhead;
· eliminated unnecessary remainder loops;
· if statement vectorization;
· code motion of vectorizable loop to innermost position.
Improved optimization for C++ programs:
· multi-target icall promotion;
· devirtualization with overridden map.

Code generation/architecture support:

· Improved SIB (Scaled-Index-Base) addressing mode code generation.
· Improved support and code generation for SSE 4.x, AVX, and FMA instructions.
· Improved register pressure based scheduling.
· Added interior pointer optimization.
· Improve padding and code alignment of basic blocks.
· Implemented best fit loop unrolling algorithm.
· Added comprehensive support and tuning for the Bulldozer processor.

Special note:

The following two features are now officially deprecated:

· 1. gcc 3.x frontend support
· 2. IRIX support