Specifications

Chapter 3 Performance-Centric Compiler Switches 27
Compiler Usage Guidelines for AMD64 Platforms
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uses these routines, using ACML in place generic C/Fortran implementation may greatly improve the
performance. Use the GNU64 libraries of ACML for the 64-bit PathScale compiler. For additional
details on how to install this library and use it, see
http://developer.amd.com/assets/acml_userguide.pdf.
Refer to the PathScale EKOPath Compiler Suite User Guide, Version 2.1, for more options and
suggestions for tuning your application performance.
3.5 Intel Compilers (64-Bit) for Microsoft
®
Windows
®
Intel provides C, C++ and Fortran compilers for EM64T and compatible architecture-based systems
running 64-bit Microsoft
®
Windows
®
operating systems. The current version (as of August 2007) is
10.0. All options described here apply to this version.
3.5.1 Invocation Commands
The following commands invoke specific compilers:
• icl invokes the Intel C and C++ compiler.
• ifort invokes the Intel Fortran compiler.
3.5.2 Generic Performance Switches
The switches -QxW -Qipo -O3 are generally recommended.
3.5.3 Other Switches
In addition to the generic performance switches above, it is worth experimenting with the following
switches.
Profile Guided Optimization. Intel compilers allow profile guided optimization. Use the
following steps for profile guided optimization with Intel compilers.
1. Compile the program with the -Qprof_gen switch. The -Qipo or -Qip switch is ignored by the
compiler if used with -Qprof_gen.
2. Run the executable produced in Step 1. Running this executable generates several files with
profile information (*.dyn and *.dpi).
3. Recompile the program with the -Qprof_use switch. It is recommended to also use -Qipo in this
stage.
-Qansi-alias. Try this switch if the program strictly conforms to the ISO C99 standard. If the
program adheres to the standard, this switch allows the compiler to perform more aggressive
optimizations.