Specifications

Chapter 3 Performance-Centric Compiler Switches 31
Compiler Usage Guidelines for AMD64 Platforms
32035 Rev. 3.22 November 2007
Table 4, “Profile Guided Optimization for 64-Bit GCC Compilers for Linux
®
,” on page 24 identifies
the recommended optional compilers by their package names. The distribution media include the
RPMs. The package gcc-ssa is installed in /usr/bin by default, while gcc-33 is installed in /opt/gcc33/.
In addition to the supplied compilers, the user can also experiment with the latest GCC compilers
(versions 4.2.0) from the Free Software Foundation (FSF). Users probably cannot expect, however,
the same level of support for FSF GCC compilers as they can expect for supplied compilers.
3.8.2 Invocation Commands
The following commands invoke specific compilers:
• gcc invokes the C compilers for 4.0, 3.4.1, 3.4, 3.3.4 and gcc 3.3.3.
• gcc-ssa invokes the gcc-ssa C compiler.
• gfortran invokes the Fortran 95 compiler for 4.0.
• g++ invokes the C++ compilers for 4.0, 3.4.1, 3.4, 3.3.4 and gcc 3.3.3.
• g++-ssa invokes the gcc-ssa C++ compiler.
• g77 invokes the Fortran 77 compiler for 3.4.1, 3.4, 3.3.4 and gcc 3.3.3.
• g77-ssa invokes the gcc-ssa Fortran 77 compiler.
The user may have to specify the full path of the invocation command for using the optional GCC
compilers. For example, /opt/gcc33/bin/gcc invokes the optional SLES8 GCC compiler.
3.8.3 Generic Performance Switches
Different optimization switches are recommended for 32-bit SuSE GCC 3.3.3, Red Hat gcc-ssa and
3.4 compiler versions. Table 6 shows the recommended optimization switches for the listed
compilers.
Red Hat Enterprise Linux 4 3.4.1 No optional compiler available with the
distribution. The default compiler is the
recommended compiler.
SuSE Linux 10.1 4.1.1 4.2.0
SuSE Linux Enterprise
Server 10
4.1.0 4.2.0
Table 6. Recommended Option Switches for 32-Bit GCC Compilers for Linux
®
Compiler Version Recommended Optimization Switches
Table 5. GCC Versions Included with Linux
®
Distributions