OMP2012 Flag Description
HP HP Proliant DL580 G7 Server Series, Intel Xeon L7555, 1.87 GHz

Base Optimization Flags

C benchmarks

• • -O3
  • 
  • COPTIMIZE

  • 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) or with options /Qax or /Qx (Windows), 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. On IA-32 Windows platforms, -O3 sets the following:

    /GF (/Qvc7 and above), /Gf (/Qvc6 and below), and /Ob2

  • Includes:
    • -GF
    • -Gf
    • -Ob_n
    • -O2
      • -Oi-
      • -Gs
      • -Oy
      • -Gy
      • -Os
      • -GF
      • -Gf
      • -Ob_n
      • -Og
      • -O1
        • -unroll_n
        • -Oi-
        • -Op-
        • -Oy
        • -Gy
        • -Os
        • -GF
        • -Gf
        • -Ob_n
        • -Og
• • -xSSE4.2
  • 
  • COPTIMIZE

  • Code is optimized for Intel(R) processors with support for SSE 4.2 instructions. 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.

    Do not use this option if you are executing a program on a processor that is not an Intel processor. If you use this option on a non-compatible processor to compile the main program (in Fortran) or the function main() in C/C++, the program will display a fatal run-time error if they are executed on unsupported processors.

• • -ansi-alias
  • 
  • COPTIMIZE

  • Enable/disable(DEFAULT) use of ANSI aliasing rules in optimizations; user asserts that the program adheres to these rules.

• • -no-prec-div
  • 
  • COPTIMIZE
  • (disable/enable[default] -[no-]prec-div)

    -prec-div improves precision of floating-point divides. It has a slight impact on speed. -no-prec-div disables this option and enables optimizations that give slightly less precise results than full IEEE division.

• • -openmp
  • 
  • COPTIMIZE

  • Enable the compiler to generate multi-threaded code based on the OpenMP* directives

• • -shared-intel
  • 
  • COPTIMIZE

  • Link Intel provided libraries dynamically

• • -mcmodel=medium
  • 
  • COPTIMIZE

  • -mcmodel= use a specific memory model to generate code and store data small - Restricts code and data to the first 2GB of address space (DEFAULT) medium - Restricts code to the first 2GB; it places no memory restriction on data large - Places no memory restriction on code or data

• • -ipo
  • 
  • COPTIMIZE

  • Multi-file ip optimizations that includes:
    - inline function expansion
    - interprocedural constant propogation
    - dead code elimination
    - propagation of function characteristics
    - passing arguments in registers
    - loop-invariant code motion

C++ benchmarks

• • -O3
  • 
  • CXXOPTIMIZE

  • 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) or with options /Qax or /Qx (Windows), 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. On IA-32 Windows platforms, -O3 sets the following:

    /GF (/Qvc7 and above), /Gf (/Qvc6 and below), and /Ob2

  • Includes:
    • -GF
    • -Gf
    • -Ob_n
    • -O2
      • -Oi-
      • -Gs
      • -Oy
      • -Gy
      • -Os
      • -GF
      • -Gf
      • -Ob_n
      • -Og
      • -O1
        • -unroll_n
        • -Oi-
        • -Op-
        • -Oy
        • -Gy
        • -Os
        • -GF
        • -Gf
        • -Ob_n
        • -Og
• • -xSSE4.2
  • 
  • CXXOPTIMIZE

  • Code is optimized for Intel(R) processors with support for SSE 4.2 instructions. 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.

    Do not use this option if you are executing a program on a processor that is not an Intel processor. If you use this option on a non-compatible processor to compile the main program (in Fortran) or the function main() in C/C++, the program will display a fatal run-time error if they are executed on unsupported processors.

• • -ansi-alias
  • 
  • CXXOPTIMIZE

  • Enable/disable(DEFAULT) use of ANSI aliasing rules in optimizations; user asserts that the program adheres to these rules.

• • -no-prec-div
  • 
  • CXXOPTIMIZE
  • (disable/enable[default] -[no-]prec-div)

    -prec-div improves precision of floating-point divides. It has a slight impact on speed. -no-prec-div disables this option and enables optimizations that give slightly less precise results than full IEEE division.

• • -openmp
  • 
  • CXXOPTIMIZE

  • Enable the compiler to generate multi-threaded code based on the OpenMP* directives

• • -shared-intel
  • 
  • CXXOPTIMIZE

  • Link Intel provided libraries dynamically

• • -mcmodel=medium
  • 
  • CXXOPTIMIZE

  • -mcmodel= use a specific memory model to generate code and store data small - Restricts code and data to the first 2GB of address space (DEFAULT) medium - Restricts code to the first 2GB; it places no memory restriction on data large - Places no memory restriction on code or data

• • -ipo
  • 
  • CXXOPTIMIZE

  • Multi-file ip optimizations that includes:
    - inline function expansion
    - interprocedural constant propogation
    - dead code elimination
    - propagation of function characteristics
    - passing arguments in registers
    - loop-invariant code motion

Fortran benchmarks

• • -O3
  • 
  • FOPTIMIZE

  • 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) or with options /Qax or /Qx (Windows), 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. On IA-32 Windows platforms, -O3 sets the following:

    /GF (/Qvc7 and above), /Gf (/Qvc6 and below), and /Ob2

  • Includes:
    • -GF
    • -Gf
    • -Ob_n
    • -O2
      • -Oi-
      • -Gs
      • -Oy
      • -Gy
      • -Os
      • -GF
      • -Gf
      • -Ob_n
      • -Og
      • -O1
        • -unroll_n
        • -Oi-
        • -Op-
        • -Oy
        • -Gy
        • -Os
        • -GF
        • -Gf
        • -Ob_n
        • -Og
• • -xSSE4.2
  • 
  • FOPTIMIZE

  • Code is optimized for Intel(R) processors with support for SSE 4.2 instructions. 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.

    Do not use this option if you are executing a program on a processor that is not an Intel processor. If you use this option on a non-compatible processor to compile the main program (in Fortran) or the function main() in C/C++, the program will display a fatal run-time error if they are executed on unsupported processors.

• • -no-prec-div
  • 
  • FOPTIMIZE
  • (disable/enable[default] -[no-]prec-div)

    -prec-div improves precision of floating-point divides. It has a slight impact on speed. -no-prec-div disables this option and enables optimizations that give slightly less precise results than full IEEE division.

• • -openmp
  • 
  • FOPTIMIZE

  • Enable the compiler to generate multi-threaded code based on the OpenMP* directives

• • -shared-intel
  • 
  • FOPTIMIZE

  • Link Intel provided libraries dynamically

• • -mcmodel=medium
  • 
  • FOPTIMIZE

  • -mcmodel= use a specific memory model to generate code and store data small - Restricts code and data to the first 2GB of address space (DEFAULT) medium - Restricts code to the first 2GB; it places no memory restriction on data large - Places no memory restriction on code or data

• • -ipo
  • 
  • FOPTIMIZE

  • Multi-file ip optimizations that includes:
    - inline function expansion
    - interprocedural constant propogation
    - dead code elimination
    - propagation of function characteristics
    - passing arguments in registers
    - loop-invariant code motion