Compaq C for Linux Alpha Systems

 Munich 22 Oct 99 Compaq offers a C compiler for Linux Alpha systems with performance improvements in floating point operations of a factor of two and more and integer of 15% to 30%. It is compatible with gcc and includes most features and options of the newest C compiler for Tru64 Unix.

A Beta test of Compaq C for Linux Alpha Systems provides the same code optimization technology used in Compaq Fortran for Linux Alpha Systems, which is current with the very latest compilers for Compaq's Tru64 UNIX. It can provide significant performance improvements in applications previously built for Linux Alpha. A factor of two or more has been gained in some floating-point intensive applications, more modest improvements in the range of 15% to 30% has been seen for integer codes.

The compiler supports most language features and options provided by the newest C compilers for Tru64 UNIX. Actual exceptions are OpenMP, 128-bit long double, feedback-based optimization, -[x]taso and pointer_size pragmas, and structured exception handling. These features rely on underlying support in Tru64 UNIX that is not currently available on Linux Alpha.

The compiler also contains some enhancements that are not yet available in the Tru64 UNIX compiler. These are primarily features to ease compilation of code that has become somewhat dependent on gcc features, including language extensions like inline extern functions, pointer arithmetic on pointers to void, and the #include_next preprocessor directive. There are also diagnostic message controls to make the compiler's "pickiness" more similar to gcc's default mode. Finally, the command line options processor attempts to accept either Tru64 UNIX command line options or gcc command line options, or a mixture of the two.

The intent is to minimize the makefile editing required to build a program originally developed on either Tru64 UNIX or on Linux Alpha. The compiler and associated software has been tested primarily under the Red Hat 5.2 distribution. It also installs cleanly and basically works under Red Hat 6.0, although there have been some problems reported with segfaults under 6.0 that do not happen under 5.2 and are as yet undiagnosed. Other distributions have not been tested at all yet.

 

Uwe Harms

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