Compilers: Intel Compilers for C++ and Fortran, Version 9.1
for IA32/EM64T-based applications in Linux_x64
Operating system: 64-bit SUSE Linux 10 Enterprise Edition
Last updated: 07-Mar-2007 PS
The text for many of the descriptions below was taken
from the documentation of the Intel Compilers.
This documentation is copyright © 2006 Intel Corporation. All Rights Reserved.
The original documentation is distributed with the Intel compilers.
Selecting one of the following will take you directly to that section:
HEADER for OPTIMIZATION
Optimizes for speed. Enables high-level optimization. This level does not guarantee higher performance. Using this option may increase the compilation time. Impact on performance is application dependent, some applications may not see a performance improvement.
The optimizations include:
Enables[disables] improved precision of floating-point divides. Disabling may slightly improve speed. Default Enabled.
-xprocessor This option directs the compiler to generate specialized and optimized code for the Intel processor that executes your program. It lets you target your program to run on a specific Intel processor.
processor Is the processor
for which you want to target your program.
Here: P Code is optimized for Intel Core Duo processors,
Intel Core Solo processors, Intel Pentium 4 processors with Steaming SIMD
Extensions 3, and compatible Intel processors with Streaming SIMD Extensions 3.
The resulting code may contain unconditional use of features
that are not supported on other processors.
This option also enables new optimizations in addition to Intel
processor-specific optimizations including advanced data layout and code
restructuring optimizations to improve memory accesses for Intel processors.
Programs compiled with -xP will display a fatal run-time error if they are executed on unsupported processors.
On Intel EM64T systems, W, and P, are the only valid processor values.
-ipo[n]
This option enables interprocedural optimizations between files. This is also called multifile interprocedural optimization (multifile IPO) or Whole Program Optimization (WPO).
When you specify this option, the compiler performs inline function expansion for calls to functions defined in separate files.
You cannot specify the names for the object files that are created.
n Is an optional integer that specifies
the number of object files the compiler should create.
The integer must be greater than or equal to 0.
If you do not specify n, the default is 0.
If n is 0, the compiler decides whether to create one or more object files based on an estimate of the size of the application. It generates one object file for small applications, and two or more object files for large applications.
If n is greater than 0, the compiler generates n object files, unless n exceeds the number of source files (m), in which case the compiler generates only m object files.
-static prevents linking with shared libraries.
Optimizes for speed.
The -O2 option includes the following options:
This options defaults to ON.
This option also enables:
This option instruments a program for profiling as first step in Profile Guided Optimization.
Profile Guided Optimization (PGO) consists of 3 phases:
Phase 1: Compile and generate instrumented code in preparation
to gather profiling information (compiler flag -prof_gen).
Phase 2: Execute the instrumented code and gather profiling information.
Phase 3: Recompile the code and use the profiling information
for improved optimization (compiler flag -prof_use).
The option -prof_gen instruments a program for profiling to get the execution count of each basic block. It also creates a new static profile information file (.spi). This flag is used in phase 1 of the Profile Guided Optimizer (PGO) to instruct the compiler to produce code in your object files in preparation for instrumented execution.
The instrumented code
This option enables the use of profiling information during optimization as final step in Profile Guided Optimization.
Profile Guided Optimization (PGO) consists of 3 phases:
Phase 1: Compile and generate instrumented code in preparation
to gather profiling information (compiler flag -prof_gen).
Phase 2: Execute the instrumented code and gather profiling information.
Phase 3: Recompile the code and use the profiling information
for improved optimization (compiler flag -prof_use).
The option -prof_use instructs the compiler to use the profiling information from phase 2 of PGO in order to produce a profile-optimized executable (phase 3 of PGO).
It also enables function splitting (option -Qfnsplit) and function grouping during optimization.
Note that there is no way to turn off function grouping if you enable it using this option.
The recompilation with -prof_use
Enables function splitting.
This option enables function splitting if -prof-use is also specified. Otherwise, this option has no effect.
It is enabled automatically if you specify -prof-use. If you do not specify one of those options, the default is -fnsplit-, which disables function splitting but leaves function grouping enabled.
To disable function splitting when you use -prof-use, specify -fnsplit-.
Enables global optimizations.
Enables/disables inline expansion of intrinsic functions.
Default enabled
This option enables most speed optimizations, but disables some that increase code size for a small speed benefit.
Default enabled
Enables [disables] the use of the EBP register in optimizations. When you disable with -Oy-, the EBP register is used as frame pointer. -Oy has the effect of reducing the number of general-purpose registers by 1, and can produce slightly less efficient code.
Default enabled
n = 0
Disables inlining of user-defined functions.
However, statement functions are always inlined
n = 1
Enables inlining of functions declared with the __inline keyword.
Also enables inlining according to the C++ language
n = 2
Enables inlining of any function.
However, the compiler decides which functions are inlined.
This option enables interprocedural optimizations and has the same
effect as specifying option ip.
Default enabled with n = 2
Disables stack-checking for routines with n or more bytes of local variables and compiler temporaries.
Default enabled with n = 4096.
Assume [not assume] no aliasing
Default disabled
Enables all speed optimizations.
Overrides -Os
Assume[not assume] no cross function aliasing.
Enables string-pooling optimization.
Packages functions to enable linker optimization.
Default enabled
Generates specialized code for processor specific codes W, P while also generating generic IA-32 code.
HEADER for PORTABILITY
-DSPEC_CPU_LP64 compiles using LP64 programming model.
Compile for an I386 system running Linux.
-DSPEC_CPU_LINUX compiles for a system running Linux.
For mixed-language benchmarks, tell the compiler that the main program is not written in Fortran.
This macro indicates that Fortran functions called from C should have their names lower-cased.
HEADER for COMPILER
/opt/intel/fc/9.1.041/bin/ifort invokes the 32-bit Intel Fortran compiler.
Also used to invoke linker for 32-bit programs
in Fortran and C/Fortran mixtures.
Invoke the 64-bit Intel Fortran compiler.
Also used to invoke linker for 64-bit programs
in Fortran and C/Fortran mixtures.
/opt/intel/cc/9.1.046/bin/icc invokes the 32-bit Intel C compiler.
Also used to invoke linker for 32-bit C programs.
/opt/intel/cc/9.1.046/bin/icpc invokes the 32-bit Intel C++ compiler.
Also used to invoke linker for 32-bit C++ programs.
Invoke the 64-bit Intel C compiler.
Also used to invoke linker for 64-bit C programs.
Invoke the 64-bit Intel C++ compiler.
Also used to invoke linker for 64-bit C++ programs.
-I/opt/intel/cc/9.1.046/include is the include path of 32-bit Intel C/C++ compiler
-L/opt/intel/cc/9.1.046/lib is the library path of 32-bit Intel C/C++ compiler
-I/opt/intel/fc/9.1.041/include is the include path of 32-bit Intel Fortran compiler
-L/opt/intel/fc/9.1.041/lib is the library path of 32-bit Intel Fortran compiler
Platform settings
One or more of the following settings may have been set. If so, the "General Notes" section of the report will say so; and you can read below to find out more about what these settings mean.
Hardware Prefetch:
This BIOS option allows the enabling/disabling of a processor mechanism to prefetch data into the cache according to a pattern-recognition algorithm.
In some cases, setting this option to Disabled may improve performance. Users should only disable this option after performing application benchmarking to verify improved performance in their environment.
Adjacent Sector Prefetch:
This BIOS option allows the enabling/disabling of a processor mechanism to fetch the adjacent cache line within an 128-byte sector that contains the data needed due to a cache line miss.
In some cases, setting this option to Disabled may improve performance. Users should only disable this option after performing application benchmarking to verify improved performance in their environment.
-I
Compiler option to set the path for include files.
Used in some peak benchmarks which were build using the Intel 32-bit compiler.
-L
Compiler option to set the path for library files.
Used in some peak benchmarks which were build using the Intel 32-bit compiler.
ulimit -s
Sets the stack size to n kbytes, or unlimited to allow the stack size to grow without limit.
submit= MYMASK=`printf '0x%x' \$((1<<\$SPECCOPYNUM))`; /usr/bin/taskset \$MYMASK $command
When running multiple copies of benchmarks, the SPEC config file feature submit is sometimes used to cause individual jobs to be bound to specific processors. This specific submit command is used for Linux. The description of the elements of the command are: