CPU2006 Flag Description
Apple Computer, Inc. iMac 20-inch 2.0GHz Intel Core Duo

Last updated: 17-Jul-2006

This flags disclosure file describes the compiler flags associated with the following Intel compilers:

• Intel C++ Compiler for Mac OSX v9.1
• Intel Fortran Compiler for Mac OSX v9.1

Implicitly Included Flags

This section contains descriptions of flags that were included implicitly by other flags, but which do not have a permanent home at SPEC.

• • -O3
  • 

  • Enables O2 optimizations plus more aggressive optimizations, such as prefetching, scalar replacement, and loop and memory access transformations.

    Enables optimizations for maximum speed, such as:

    • Loop unrolling, including instruction scheduling
    • Code replication to eliminate branches
    • Padding the size of certain power-of-two arrays to allow more efficient cache use

    On IA-32 and Intel EM64T processors, when O3 is used with options -ax or -x (Linux/Mac OSX), the compiler performs more aggressive data dependency analysis than for O2, which may result in longer compilation times.

    The O3 optimizations may not cause higher performance unless loop and memory access transformations take place. The optimizations may slow down code in some cases compared to O2 optimizations.

    The O3 option is recommended for applications that have loops that heavily use floating-point calculations and process large data sets.

• • -ipo
  • 

  • This option enables multi-file interprocedural optimizations that includes:

    • inline function expansion
    • interprocedural constant propogation
    • dead code elimination
    • propagation of function characteristics
    • passing arguments in registers
    • loop-invariant code motion

    When you specify this option, the compiler performs inline function expansion for calls to functions defined in separate files.

• • -no-prec-div
  • 

  • This option improves precision of floating-point divides. It has a slight impact on speed.

    With some optimizations, such as -xN and -xB (Linux) or /QxN and /QxB (Windows), the compiler may change floating-point division computations into multiplication by the reciprocal of the denominator. For example, A/B is computed as A * (1/B) to improve the speed of the computation.

    However, sometimes the value produced by this transformation is not as accurate as full IEEE division. When it is important to have fully precise IEEE division, use this option to disable the floating-point division-to-multiplication optimization. The result is more accurate, with some loss of performance.

    If you specify -no-prec-div (Linux and Mac OSX), it enables optimizations that give slightly less precise results than full IEEE division. The default is -prec-div.

• • -mdynamic-no-pic
  • 

  • Code is not relocatable, but external references are relocatable.

System and Other Tuning Information

The system under test is deemed reasonably quiet by turning off the following from the System Preferences panel:

• Automatic Software Updates (turned ON by default)
• Screen Savers (turned ON by default)
• Unused wireless and bluetooth connectivity (turned ON by default)
• Network time syncrhonization (turned ON by default)

Flag description origin markings:

	Indicates that the flag description came from the user flags file.
	Indicates that the flag description came from the suite-wide flags file.
	Indicates that the flag description came from a per-benchmark flags file.

For questions about the meanings of these flags, please contact the tester.
For other inquiries, please contact webmaster@spec.org
Copyright 2006-2014 Standard Performance Evaluation Corporation
Tested with SPEC CPU2006 v90.
Report generated on Tue Jul 22 10:00:13 2014 by SPEC CPU2006 flags formatter v6906.