ACCEL Flag Description
Intel Intel Xeon SandyBridge EN/EP processor (8 core, 2.00 GHz, Intel Xeon CPU E5-2650)

Test sponsored by RWTH Aachen

This result has been formatted using multiple flags files. The "default header section" from each of them appears next.

Default header section from Intel-ic16.0-linux64

SPEC OMP2012 Flag Description for the Intel(R) C/C++ Compiler for IA32 and Intel 64 applications and Intel(R) Fortran Compiler for IA32 and Intel 64 applications

Copyright © 2012 Intel Corporation. All Rights Reserved.

Default header section from flags.workaround.flags

Workaround for Flags Bug (-I.) in 503.postencil and 514.pomriq

This is the set of approved mandatory flags for 503.postencil and 514.pomriq.

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.

• • -GF
  • 

  • This option enables read only string-pooling optimization.

• • -Gf
  • 

  • This option enables read/write string-pooling optimization.

• • -Ob_n
  • 

  • Specifies the level of inline function expansion.

    Ob0 - Disables inlining of user-defined functions. Note that statement functions are always inlined.

    Ob1 - Enables inlining when an inline keyword or an inline attribute is specified. Also enables inlining according to the C++ language.

    Ob2 - Enables inlining of any function at the compiler's discretion.

• • -O2
  • 

  • Enables optimizations for speed. This is the generally recommended optimization level. This option also enables:
    - Inlining of intrinsics
    - Intra-file interprocedural optimizations, which include:
    - inlining
    - constant propagation
    - forward substitution
    - routine attribute propagation
    - variable address-taken analysis
    - dead static function elimination
    - removal of unreferenced variables
    - The following capabilities for performance gain:
    - constant propagation
    - copy propagation
    - dead-code elimination
    - global register allocation
    - global instruction scheduling and control speculation
    - loop unrolling
    - optimized code selection
    - partial redundancy elimination
    - strength reduction/induction variable simplification
    - variable renaming
    - exception handling optimizations
    - tail recursions
    - peephole optimizations
    - structure assignment lowering and optimizations
    - dead store elimination
    

    On IA-32 Windows platforms, -O2 sets the following:

    /Og, /Oi-, /Os, /Oy, /Ob2, /GF (/Qvc7 and above), /Gf (/Qvc6 and below), /Gs, and /Gy.

  • Includes:
    • -Oi-
    • -Gs
    • -Oy
    • -Gy
    • -Os
    • -GF
    • -Gf
    • -Ob_n
    • -Og
    • -O1
      • -unroll_n
      • -Oi-
      • -Op-
      • -Oy
      • -Gy
      • -Os
      • -GF
      • -Gf
      • -Ob_n
      • -Og
• • -Oi-
  • 

  • Disables inline expansion of all intrinsic functions.

• • -Gs
  • 

  • This option disables stack-checking for routines with 4096 bytes of local variables and compiler temporaries.

• • -Oy
  • 

  • Allows use of EBP as a general-purpose register in optimizations.

• • -Gy
  • 

  • This option tells the compiler to separate functions into COMDATs for the linker.

• • -Os
  • 

  • This option enables most speed optimizations, but disables some that increase code size for a small speed benefit.

• • -Og
  • 

  • This option enables global optimizations.

• • -O1
  • 

  • Enables optimizations for speed and disables some optimizations that
    increase code size and affect speed.
    To limit code size, this option:
    - Enables global optimization; this includes data-flow analysis, code motion, strength reduction and test replacement, split-lifetime analysis, and instruction scheduling.
    - Disables intrinsic recognition and intrinsics inlining.
    The O1 option may improve performance for applications with very large code size, many branches, and execution time not dominated by code within loops.
    On IA-32 Windows platforms, -O1 sets the following:

    /Qunroll0, /Oi-, /Op-, /Oy, /Gy, /Os, /GF (/Qvc7 and above), /Gf (/Qvc6 and below), /Ob2, and /Og

  • Includes:
    • -unroll_n
    • -Oi-
    • -Op-
    • -Oy
    • -Gy
    • -Os
    • -GF
    • -Gf
    • -Ob_n
    • -Og
• • -unroll_n
  • 

  • Tells the compiler the maximum number of times to unroll loops.

• • -Op-
  • 

  • Disables conformance to the ANSI C and IEEE 754 standards for floating-point arithmetic.

Shell, Environment, and Other Software Settings

KMP_STACKSIZE

Specify stack size to be allocated for each thread.

KMP_AFFINITY

The value for the environment variable KMP_AFFINITY affects how the threads from an auto-parallelized program are scheduled across processors.
Specifying disabled completely disables the thread affinity interfaces. This forces the OpenMP run-time library to behave as if the affinity interface was not supported by the operating system. This includes the low-level API interfaces such as kmp_set_affinity and kmp_get_affinity, which have no effect and will return a nonzero error code.

KMP_SCHEDULE

For loops running with OpenMP schedule "static", this results in (#iterations/#threads) iterations--rounded to the next lower integer--being allocated to most threads, with at most one additional iteration being allocated to some threads. Although the largest number of iterations assigned to any thread remains the same, this results in a more even sharing of iterations between threads, which may sometimes lead to a performance improvement relative to the default static thread distribution.

OMP_DYNAMIC

OMP_DYNAMIC=[ 1 | 0 ] Enables (1) or disables (0) the dynamic adjustment of the number of threads.

OMP_NESTED

Enables (TRUE) or disables (FALSE) nested parallelism.

KMP_BLOCKTIME

Sets the time, in milliseconds, that a thread should wait, after completing the execution of a parallel region, before sleeping.

KMP_LIBRARY

Selects the OpenMP run-time library.

Set stack size to unlimited

The command "ulimit -s unlimited" is used to set the stack size limit to unlimited.

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 2015-2017 Standard Performance Evaluation Corporation
Tested with SPEC ACCEL v75.
Report generated on Wed Jun 21 17:15:31 2017 by SPEC ACCEL flags formatter v1290.