CPU2006 Flag Description
Itautec Servidor Itautec MX221 (Intel Xeon X5450)

Base Optimization Flags

C benchmarks

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -inline-calloc
  • 
  • COPTIMIZE

  • Directs the compiler to inline calloc() calls as malloc()/memset()

• • -opt-malloc-options=3
  • 
  • COPTIMIZE

  • The compiler adds setup code in the C/C++/Fortran main function to enable optimal malloc algorithms:

    • n=0: Default, no changes to the malloc options. No call to mallopt() is made.
    • n=1: M_MMAP_MAX=2 and M_TRIM_THRESHOLD=0x10000000. Call mallopt with the two settings.
    • n=2: M_MMAP_MAX=2 and M_TRIM_THRESHOLD=0x40000000. Call mallopt with these two settings.
    • n=3: M_MMAP_MAX=0 and M_TRIM_THRESHOLD=-1. Call mallopt with these two settings. This will cause use of sbrk() calls instead of mmap() calls to get memory from the system.

    The two parameters, M_MMAP_MAX and M_TRIM_THRESHOLD, are described below

    Function: int mallopt (int param, int value) When calling mallopt, the param argument specifies the parameter to be set, and value the new value to be set. Possible choices for param, as defined in malloc.h, are:

    • M_TRIM_THRESHOLD This is the minimum size (in bytes) of the top-most, releasable chunk that will cause sbrk to be called with a negative argument in order to return memory to the system.
    • M_TOP_PAD This parameter determines the amount of extra memory to obtain from the system when a call to sbrk is required. It also specifies the number of bytes to retain when shrinking the heap by calling sbrk with a negative argument. This provides the necessary hysteresis in heap size such that excessive amounts of system calls can be avoided.
    • M_MMAP_THRESHOLD All chunks larger than this value are allocated outside the normal heap, using the mmap system call. This way it is guaranteed that the memory for these chunks can be returned to the system on free. Note that requests smaller than this threshold might still be allocated via mmap.
    • M_MMAP_MAX The maximum number of chunks to allocate with mmap. Setting this to zero disables all use of mmap.

C++ benchmarks

• • -xT
  • 
  • CXXOPTIMIZE

  • Code is optimized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3. 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.

• • -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

• • -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.
  • Includes:
    • -O2
      • -O1
        • -funroll-loops
        • -fno-builtin
        • -mno-ieee-fp
        • -fomit-framepointer
        • -ffunction-sections
        • -ftz
• • -no-prec-div
  • 
  • CXXOPTIMIZE
  • (disable/enable[default] -prec-div)

    -no-prec-div enables optimizations that give slightly less precise results than full IEEE division.

    When you specify -no-prec-div along 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, do not use -no-prec-div. This will enable the default -prec-div and the result will be more accurate, with some loss of performance.

• • -Wl,-z,muldefs
  • 
  • EXTRA_LDFLAGS

  • Enable SmartHeap and/or other library usage by forcing the linker to ignore multiple definitions if present

• • -L/opt/sh/SmartHeap_8.1/lib -lsmartheap
  • 
  • EXTRA_LIBS

  • MicroQuill SmartHeap Library V8.1 available from http://www.microquill.com/

Peak Optimization Flags

C benchmarks

400.perlbench

• • -prof-gen
  • 
  • PASS1_CFLAGS, PASS1_LDFLAGS

  • Instrument program for profiling for the first phase of two-phase profile guided otimization. This instrumentation gathers information about a program's execution paths and data values but does not gather information from hardware performance counters. The profile instrumentation also gathers data for optimizations which are unique to profile-feedback optimization.

• • -prof-use
  • 
  • PASS2_CFLAGS, PASS2_LDFLAGS

  • Instructs the compiler to produce a profile-optimized executable and merges available dynamic information (.dyn) files into a pgopti.dpi file. If you perform multiple executions of the instrumented program, -prof-use merges the dynamic information files again and overwrites the previous pgopti.dpi file.
    Without any other options, the current directory is searched for .dyn files

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -ansi-alias
  • 
  • COPTIMIZE

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

• • -prefetch
  • 
  • COPTIMIZE

  • Enable/disable(DEFAULT) the compiler to generate prefetch instructions to prefetch data.

401.bzip2

• • -prof-gen
  • 
  • PASS1_CFLAGS, PASS1_LDFLAGS

  • Instrument program for profiling for the first phase of two-phase profile guided otimization. This instrumentation gathers information about a program's execution paths and data values but does not gather information from hardware performance counters. The profile instrumentation also gathers data for optimizations which are unique to profile-feedback optimization.

• • -prof-use
  • 
  • PASS2_CFLAGS, PASS2_LDFLAGS

  • Instructs the compiler to produce a profile-optimized executable and merges available dynamic information (.dyn) files into a pgopti.dpi file. If you perform multiple executions of the instrumented program, -prof-use merges the dynamic information files again and overwrites the previous pgopti.dpi file.
    Without any other options, the current directory is searched for .dyn files

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -prefetch
  • 
  • COPTIMIZE

  • Enable/disable(DEFAULT) the compiler to generate prefetch instructions to prefetch data.

403.gcc

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -inline-calloc
  • 
  • COPTIMIZE

  • Directs the compiler to inline calloc() calls as malloc()/memset()

• • -opt-malloc-options=3
  • 
  • COPTIMIZE

  • The compiler adds setup code in the C/C++/Fortran main function to enable optimal malloc algorithms:

    • n=0: Default, no changes to the malloc options. No call to mallopt() is made.
    • n=1: M_MMAP_MAX=2 and M_TRIM_THRESHOLD=0x10000000. Call mallopt with the two settings.
    • n=2: M_MMAP_MAX=2 and M_TRIM_THRESHOLD=0x40000000. Call mallopt with these two settings.
    • n=3: M_MMAP_MAX=0 and M_TRIM_THRESHOLD=-1. Call mallopt with these two settings. This will cause use of sbrk() calls instead of mmap() calls to get memory from the system.

    The two parameters, M_MMAP_MAX and M_TRIM_THRESHOLD, are described below

    Function: int mallopt (int param, int value) When calling mallopt, the param argument specifies the parameter to be set, and value the new value to be set. Possible choices for param, as defined in malloc.h, are:

    • M_TRIM_THRESHOLD This is the minimum size (in bytes) of the top-most, releasable chunk that will cause sbrk to be called with a negative argument in order to return memory to the system.
    • M_TOP_PAD This parameter determines the amount of extra memory to obtain from the system when a call to sbrk is required. It also specifies the number of bytes to retain when shrinking the heap by calling sbrk with a negative argument. This provides the necessary hysteresis in heap size such that excessive amounts of system calls can be avoided.
    • M_MMAP_THRESHOLD All chunks larger than this value are allocated outside the normal heap, using the mmap system call. This way it is guaranteed that the memory for these chunks can be returned to the system on free. Note that requests smaller than this threshold might still be allocated via mmap.
    • M_MMAP_MAX The maximum number of chunks to allocate with mmap. Setting this to zero disables all use of mmap.

429.mcf

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -prefetch
  • 
  • COPTIMIZE

  • Enable/disable(DEFAULT) the compiler to generate prefetch instructions to prefetch data.

445.gobmk

• • -prof-gen
  • 
  • PASS1_CFLAGS, PASS1_LDFLAGS

  • Instrument program for profiling for the first phase of two-phase profile guided otimization. This instrumentation gathers information about a program's execution paths and data values but does not gather information from hardware performance counters. The profile instrumentation also gathers data for optimizations which are unique to profile-feedback optimization.

• • -prof-use
  • 
  • PASS2_CFLAGS, PASS2_LDFLAGS

  • Instructs the compiler to produce a profile-optimized executable and merges available dynamic information (.dyn) files into a pgopti.dpi file. If you perform multiple executions of the instrumented program, -prof-use merges the dynamic information files again and overwrites the previous pgopti.dpi file.
    Without any other options, the current directory is searched for .dyn files

• • -xT
  • 
  • COPTIMIZE

  • Code is optimized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3. 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.

• • -O2
  • 
  • COPTIMIZE

  • 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
    

  • Includes:
    • -O1
      • -funroll-loops
      • -fno-builtin
      • -mno-ieee-fp
      • -fomit-framepointer
      • -ffunction-sections
      • -ftz
• • -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

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

    -no-prec-div enables optimizations that give slightly less precise results than full IEEE division.

    When you specify -no-prec-div along 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, do not use -no-prec-div. This will enable the default -prec-div and the result will be more accurate, with some loss of performance.

• • -ansi-alias
  • 
  • COPTIMIZE

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

456.hmmer

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -unroll2
  • 
  • COPTIMIZE

  • Tells the compiler the maximum number of times to unroll loops. For example -unroll2 would unroll a maximum of 2 times.

• • -ansi-alias
  • 
  • COPTIMIZE

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

• • -opt-multi-version-aggressive
  • 
  • COPTIMIZE

  • Multi-versioning is used for generating different versions of the loop based on run time dependence testing, alignment and checking for short/long trip counts. If this option is turned on, it will trigger more versioning at the expense of creating more overhead to check for pointer aliasing and scalar replacement.

458.sjeng

• • -prof-gen
  • 
  • PASS1_CFLAGS, PASS1_LDFLAGS

  • Instrument program for profiling for the first phase of two-phase profile guided otimization. This instrumentation gathers information about a program's execution paths and data values but does not gather information from hardware performance counters. The profile instrumentation also gathers data for optimizations which are unique to profile-feedback optimization.

• • -prof-use
  • 
  • PASS2_CFLAGS, PASS2_LDFLAGS

  • Instructs the compiler to produce a profile-optimized executable and merges available dynamic information (.dyn) files into a pgopti.dpi file. If you perform multiple executions of the instrumented program, -prof-use merges the dynamic information files again and overwrites the previous pgopti.dpi file.
    Without any other options, the current directory is searched for .dyn files

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -unroll4
  • 
  • COPTIMIZE

  • Tells the compiler the maximum number of times to unroll loops. For example -unroll2 would unroll a maximum of 2 times.

462.libquantum

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -unroll4
  • 
  • COPTIMIZE

  • Tells the compiler the maximum number of times to unroll loops. For example -unroll2 would unroll a maximum of 2 times.

• • -Ob0
  • 
  • COPTIMIZE

  • 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.

• • -prefetch
  • 
  • COPTIMIZE

  • Enable/disable(DEFAULT) the compiler to generate prefetch instructions to prefetch data.

• • -opt-streaming-stores always
  • 
  • COPTIMIZE

  • Specifies whether streaming stores are generated:

    always - enables generation of streaming stores under the assumption that the application is memory bound

    auto - compiler decides when streaming stores are used (DEFAULT)

    never - disables generation of streaming stores

• • -vec-guard-write
  • 
  • COPTIMIZE

  • Enables cache/bandwidth optimization for stores under conditionals (within vector loops) This option tells the compiler to perform a conditional check in a vectorized loop. This checking avoids unnecessary stores and may improve performance by conserving bandwidth.

• • -opt-malloc-options=3
  • 
  • COPTIMIZE

  • The compiler adds setup code in the C/C++/Fortran main function to enable optimal malloc algorithms:

    • n=0: Default, no changes to the malloc options. No call to mallopt() is made.
    • n=1: M_MMAP_MAX=2 and M_TRIM_THRESHOLD=0x10000000. Call mallopt with the two settings.
    • n=2: M_MMAP_MAX=2 and M_TRIM_THRESHOLD=0x40000000. Call mallopt with these two settings.
    • n=3: M_MMAP_MAX=0 and M_TRIM_THRESHOLD=-1. Call mallopt with these two settings. This will cause use of sbrk() calls instead of mmap() calls to get memory from the system.

    The two parameters, M_MMAP_MAX and M_TRIM_THRESHOLD, are described below

    Function: int mallopt (int param, int value) When calling mallopt, the param argument specifies the parameter to be set, and value the new value to be set. Possible choices for param, as defined in malloc.h, are:

    • M_TRIM_THRESHOLD This is the minimum size (in bytes) of the top-most, releasable chunk that will cause sbrk to be called with a negative argument in order to return memory to the system.
    • M_TOP_PAD This parameter determines the amount of extra memory to obtain from the system when a call to sbrk is required. It also specifies the number of bytes to retain when shrinking the heap by calling sbrk with a negative argument. This provides the necessary hysteresis in heap size such that excessive amounts of system calls can be avoided.
    • M_MMAP_THRESHOLD All chunks larger than this value are allocated outside the normal heap, using the mmap system call. This way it is guaranteed that the memory for these chunks can be returned to the system on free. Note that requests smaller than this threshold might still be allocated via mmap.
    • M_MMAP_MAX The maximum number of chunks to allocate with mmap. Setting this to zero disables all use of mmap.
• • -parallel
  • 
  • COPTIMIZE

  • Tells the auto-parallelizer to generate multithreaded code for loops that can be safely executed in parallel. To use this option, you must also specify option O2 or O3. The default numbers of threads spawned is equal to the number of processors detected in the system where the binary is compiled. Can be changed by setting the environment variable OMP_NUM_THREADS

• • -par-runtime-control
  • 
  • COPTIMIZE

  • Enable compiler to generate runtime control code for effective automatic parallelization. This option generates code to perform run-time checks for loops that have symbolic loop bounds. If the granularity of a loop is greater than the parallelization threshold, the loop will be executed in parallel. If you do not specify this option, the compiler may not parallelize loops with symbolic loop bounds if the compile-time granularity estimation of a loop can not ensure it is beneficial to parallelize the loop.

464.h264ref

• • -prof-gen
  • 
  • PASS1_CFLAGS, PASS1_LDFLAGS

  • Instrument program for profiling for the first phase of two-phase profile guided otimization. This instrumentation gathers information about a program's execution paths and data values but does not gather information from hardware performance counters. The profile instrumentation also gathers data for optimizations which are unique to profile-feedback optimization.

• • -prof-use
  • 
  • PASS2_CFLAGS, PASS2_LDFLAGS

  • Instructs the compiler to produce a profile-optimized executable and merges available dynamic information (.dyn) files into a pgopti.dpi file. If you perform multiple executions of the instrumented program, -prof-use merges the dynamic information files again and overwrites the previous pgopti.dpi file.
    Without any other options, the current directory is searched for .dyn files

• • -fast
  • 
  • COPTIMIZE

  • The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

    -O3   (maximum speed and high-level optimizations)

    -ipo (enables interprocedural optimizations across files)

    -xT  (generate code specialized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3)

    -static  Statically link in libraries at link time

    -no-prec-div (disable -prec-div) where -prec-div improves precision of FP divides (some speed impact)

    To override one of the options set by /fast, specify that option after the -fast option on the command line. The exception is the xT or QxT option which can't be overridden. The options set by /fast may change from release to release.

  • Includes:
    • -O3
      • -O2
        • -O1
          • -funroll-loops
          • -fno-builtin
          • -mno-ieee-fp
          • -fomit-framepointer
          • -ffunction-sections
          • -ftz
    • -ipo
    • -xT
    • -static
    • -no-prec-div
• • -unroll2
  • 
  • COPTIMIZE

  • Tells the compiler the maximum number of times to unroll loops. For example -unroll2 would unroll a maximum of 2 times.

• • -ansi-alias
  • 
  • COPTIMIZE

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

C++ benchmarks

471.omnetpp

• • -prof-gen
  • 
  • PASS1_CXXFLAGS, PASS1_LDFLAGS

  • Instrument program for profiling for the first phase of two-phase profile guided otimization. This instrumentation gathers information about a program's execution paths and data values but does not gather information from hardware performance counters. The profile instrumentation also gathers data for optimizations which are unique to profile-feedback optimization.

• • -prof-use
  • 
  • PASS2_CXXFLAGS, PASS2_LDFLAGS

  • Instructs the compiler to produce a profile-optimized executable and merges available dynamic information (.dyn) files into a pgopti.dpi file. If you perform multiple executions of the instrumented program, -prof-use merges the dynamic information files again and overwrites the previous pgopti.dpi file.
    Without any other options, the current directory is searched for .dyn files

• • -xT
  • 
  • CXXOPTIMIZE

  • Code is optimized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3. 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.

• • -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.
  • Includes:
    • -O2
      • -O1
        • -funroll-loops
        • -fno-builtin
        • -mno-ieee-fp
        • -fomit-framepointer
        • -ffunction-sections
        • -ftz
• • -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

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

    -no-prec-div enables optimizations that give slightly less precise results than full IEEE division.

    When you specify -no-prec-div along 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, do not use -no-prec-div. This will enable the default -prec-div and the result will be more accurate, with some loss of performance.

• • -ansi-alias
  • 
  • CXXOPTIMIZE

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

• • -opt-ra-region-strategy=block
  • 
  • CXXOPTIMIZE

  • Select the method that the register allocator uses to partition each routine into regions

    • routine - one region per routine
    • block - one region per block
    • trace - one region per trace
    • loop - one region per loop
    • default - compiler selects best option
• • -Wl,-z,muldefs
  • 
  • EXTRA_LDFLAGS

  • Enable SmartHeap and/or other library usage by forcing the linker to ignore multiple definitions if present

• • -L/opt/sh/SmartHeap_8.1/lib -lsmartheap
  • 
  • EXTRA_LIBS

  • MicroQuill SmartHeap Library V8.1 available from http://www.microquill.com/

473.astar

• • -prof-gen
  • 
  • PASS1_CXXFLAGS, PASS1_LDFLAGS

  • Instrument program for profiling for the first phase of two-phase profile guided otimization. This instrumentation gathers information about a program's execution paths and data values but does not gather information from hardware performance counters. The profile instrumentation also gathers data for optimizations which are unique to profile-feedback optimization.

• • -prof-use
  • 
  • PASS2_CXXFLAGS, PASS2_LDFLAGS

  • Instructs the compiler to produce a profile-optimized executable and merges available dynamic information (.dyn) files into a pgopti.dpi file. If you perform multiple executions of the instrumented program, -prof-use merges the dynamic information files again and overwrites the previous pgopti.dpi file.
    Without any other options, the current directory is searched for .dyn files

• • -xT
  • 
  • CXXOPTIMIZE

  • Code is optimized for Intel(R) Core(TM)2 Duo processors, Intel(R) Core(TM)2 Quad processors and Intel(R) Xeon(R) processors with SSSE3. 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.

• • -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.
  • Includes:
    • -O2
      • -O1
        • -funroll-loops
        • -fno-builtin
        • -mno-ieee-fp
        • -fomit-framepointer
        • -ffunction-sections
        • -ftz
• • -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

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

    -no-prec-div enables optimizations that give slightly less precise results than full IEEE division.

    When you specify -no-prec-div along 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, do not use -no-prec-div. This will enable the default -prec-div and the result will be more accurate, with some loss of performance.

• • -ansi-alias
  • 
  • CXXOPTIMIZE

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

• • -opt-ra-region-strategy=routine
  • 
  • CXXOPTIMIZE

  • Select the method that the register allocator uses to partition each routine into regions

    • routine - one region per routine
    • block - one region per block
    • trace - one region per trace
    • loop - one region per loop
    • default - compiler selects best option
• • -Wl,-z,muldefs
  • 
  • EXTRA_LDFLAGS

  • Enable SmartHeap and/or other library usage by forcing the linker to ignore multiple definitions if present

• • -L/opt/sh/SmartHeap_8.1/lib -lsmartheap
  • 
  • EXTRA_LIBS

  • MicroQuill SmartHeap Library V8.1 available from http://www.microquill.com/

483.xalancbmk

• • basepeak = yes