Base Compiler Invocation
C benchmarks
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- pgcc
![[user]](http://www.spec.org/auto/cpu2006/flags/user.png)
- CC, LD
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The PGI C compiler for Linux.
C++ benchmarks
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- pgcpp
- CXX, LD
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The PGI C++ compiler for Linux.
Fortran benchmarks
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- pgf95
- FC, LD
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The PGI Fortran 95 compiler for Linux.
This result has been formatted using multiple flags files. The "default header section" from each of them appears next.
The PGI C compiler for Linux.
The PGI C++ compiler for Linux.
The PGI Fortran 95 compiler for Linux.
The PGI C compiler for Linux.
Invoke the Open64 C++ compiler.
Also used to invoke linker for C++ programs.
The PGI C++ compiler for Linux.
Invoke the Open64 Fortran 77, 90 and 95 compilers.
Also used to invoke linker for Fortran programs and
for mixed C / Fortran. openf90 and openf95 are synonymous.
The PGI Fortran 95 compiler for Linux.
The PGI Fortran 95 compiler for Linux.
The PGI Fortran 95 compiler for Linux.
![[suite]](http://www.spec.org/auto/cpu2006/flags/suite.png)
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
Don't include Fortran main program object module.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
Don't include Fortran main program object module.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
Don't include Fortran main program object module.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
![[benchmark]](http://www.spec.org/auto/cpu2006/flags/benchmark.png)
This macro indicates that Fortran functions called from C should have their names lower-cased.
This macro indicates that the benchmark is being compiled on a Linux system.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
Don't include Fortran main program object module.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
Don't include Fortran main program object module.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This macro indicates that Fortran functions called from C should have their names lower-cased.
This macro indicates that the benchmark is being compiled on a Linux system.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Generate zero-overhead C++ exception handlers.
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Enables generation of packed SSE instructions for short vector operations that arise from scalar code outside of loops or within the body of a loop iteration.
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Enables generation of packed SSE instructions for short vector operations that arise from scalar code outside of loops or within the body of a loop iteration.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Use the prefetcht0 instruction.
Aligns or does not align innermost loops on 32 byte boundaries with -tp barcelona. Small loops on barcelona systems may run fast if aligned on 32-byte boundaries; however, in practice, most assemblers do not yet implement efficient padding causing some programs to run more slowly with this as default. Use -Mloop32 on systems with an assembler tuned for barcleona. The default is -Mnoloop32.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Generate profile-feedback instrumentation (PFI); this includes extra code to collect run-time statistics and dump them to a trace file for use in a subsequent compilation. PFI gathers information about a program's execution and data values but does not gather information from hardware performance counters. PFI does gather data for optimizations which are unique to profile-feedback optimization.
The indirect sub-option enables collection of indirect function call targets, which can be used for indirect function call inlining.
Enable profile-feedback optimizations including indirect function call inlining. This option requires a pgfi.out file generated from a binary built with -Mpfi=indirect.
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Adds a call to the routine "mallopt" in the main routine. This option can have a dramatic impact on the performance of programs that dynamically allocate memory, especially for those which have a few large mallocs. To be effective, this switch must be specified when compiling the file containing the Fortran, C, or C++ main routine.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Generate profile-feedback instrumentation (PFI); this includes extra code to collect run-time statistics and dump them to a trace file for use in a subsequent compilation. PFI gathers information about a program's execution and data values but does not gather information from hardware performance counters. PFI does gather data for optimizations which are unique to profile-feedback optimization.
Enable profile-feedback optimizations.
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
"-Munroll=n:n" instructs the compiler to unroll loops 4 times where 4 is a supplied constant value. If no constant value is given, then a default of 4 is used.
"-Munroll=m:n" instructs the compiler to unroll loops with multiple blocks 8 times where 8 is a supplied constant value. If no constant value is given, then a default of 4 is used.
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Don't check dependence relations for vector or parallel code.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Generate zero-overhead C++ exception handlers.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Compiler will generate instructions and schedule them appropriately for the selected processor type. The default value, auto, means to optimize for the platform on which the compiler is running, as determined by reading /proc/cpuinfo. anyx86 means a generic 32-bit x86 processor without SSE2 support.
Uses a selection of optimizations in order to maximize performance.
Specifying "-Ofast" is equivalent to -O3 -ipa -OPT:Ofast -fno-math-errno -ffast-math.
These optimization options are generally safe. Floating-point accuracy may
be affected due to the transformation of the computational code. Note the
interprocedural analysis option, -ipa, specifies limitations on how libraries
and object files (.o files) are built.
-static
On systems that support dynamic linking, this prevents linking with shared
libraries. On other systems, this option has no effect.
-INLINE:aggressive=(on|off|0|1): Instructs the compiler to be very aggressive when performing inlining. The default is "-INLINE:aggressive=OFF".
This option group commands the compiler loop nest optimizer to perform nested loop analysis and transformations. Note an optimization level of "-O3" or higher must be specified in order to enable the "-LNO:" options. To verify the LNO options that were invoked during compilation use the option "-LIST:all_options=ON".
-LNO:opt=(0|1) : Instructs the compiler at which level to perform loop nest optimizations.
The flag can be set to:
0 The compiler is restricted to suppress nearly all loop nest optimizations.
1 The compiler performs full loop nest optimizations.
The default is "-LNO:opt=1"
(For C++ only) -fexceptions enables exception handling and thus generates extra code needed to propagate exceptions. -fno-exceptions disables exception handling. Exception handling is enabled by default.
Generate code for a 32-bit environment. The 32-bit environment sets int, long and pointer to 32 bits and generates code that runs on any i386 system. The compiler generates x86 or IA32 32-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target platform specified is 64-bit, otherwise the default is 32-bit.
-OPT:unroll_times_max=N
Instructs the compiler to limit the unrolling of inner loops to the
value specified by N. The default is "-OPT:unroll_times_max=4".
-OPT:unroll_size=N
Instructs the compiler to limit the number of instructions produced
when unrolling inner loops. When N=0 the ceiling is disregarded.
Note by specifying "-O3" sets "-OPT:unroll_size=128". The default
is "-OPT:unroll_size=40".
-OPT:unroll_level=(1|2)
Controls the level at which
the compiler will perform unrolling optimizations. When "-OPT:unroll_level=2"
the compiler is instructed to aggressively unroll loops in the
presence of control flow. The default is "-OPT:unroll_level=1".
Instructs the compiler to use 2MB hugepages for bss, data and text segments (i.e. bdt), and/or for heap allocation. Mixed usage of huge and small pages is not supported for bdt, but is supported for heap allocation. The limit option specifies a combined limit on the number of hugepages that may be used by the compiled program. If no limit is set, the number of hugepages that can be used by the program is effectively limited by the system configuration.
-GRA:unspill=(on|off|0|1)
Instructs the compiler's Global Register Allocator (GRA) to aggressively
remove redundant register spills that occur in the boundary region between
GRA and LRA (Local Register Allocator). The default is "-GRA:unspill=off".
-CG:cmp_peep=(on|off|0|1): Instructs the compiler to perform aggressive load execution peeps on compare operations. Note for 32-bit environments the default is "-CG:cmp_peep=ON". The default is "CG:cmp_peep=OFF".
These -TENV: options control the target environment assumed and/or produced by the compiler.
-TENV:frame_pointer=(on|off)
Setting this option to ON tells the compiler to use the frame pointer
register to address local variables in the function stack frame. Generally,
if the compiler determines that the stack pointer is fixed it
will use the stack pointer to address local variables throughout the
function invocation in place of the frame pointer. This frees up the
frame pointer for other purposes.
The default is ON for C/C++ and OFF for Fortran. This flag defaults
to ON for C/C++ because the exception handling mechanism
relies on the frame pointer register being used to address local variables.
This flag can be turned OFF for C/C++ programs that do
not generate exceptions.
Compiler will generate instructions and schedule them appropriately for the selected processor type. The default value, auto, means to optimize for the platform on which the compiler is running, as determined by reading /proc/cpuinfo. anyx86 means a generic 32-bit x86 processor without SSE2 support.
-fb_create <path>
Instructs the compiler to generate an instrumented executable program from
the source code under development. The instrumented executable produces
feedback data files at runtime using an example dataset. filename specifies the
name of the feedback data file generated by the instrumented executable.
opencc -O2 -ipa -fb_create fbdata -o foo foo.c
"fbdata" will contain the instrumented feedback data from the instrumented
executable "foo". The default is "-fb_create" is disabled.
When feedback directed optimization (FDO) is used, an instrumented executable is used for a training run that produces information regarding execution paths and data values. Hardware performance counters are not used. This information is then provided to the optimizer during a second compilation pass to produce an optimized executable. FDO enables the optimizer to perform some optimizations which are not available without feedback data. The safety level of optimizations is unchanged with FDO, i.e. the safety level is the same as determined by the other (non-FDO) optimization flags specified on the compile and link lines.
-fb_opt <prefix for feedback data files>
Instructs the compiler to perform a feedback directed compilation using the
instrumented feedback data produced by the -fb_create option.
opencc -O2 -ipa -fb-opt fbdata -o foo foo.c
The new executable, foo, will be optimized to execute faster, and will not
include any instrumentation library calls. Note the same optimization flags
specified when creating the instrumented data file with the -fb_create must
be specified when invoking the compiler with the -fb_opt option. Otherwise,
the compiler will emit checksum errors. The default is "-fb_opt" disabled.
Perform all the optimizations at the -O2 level as well as many more aggressive optimizations. Examples of such aggressive optimizations are loop nest optimizations and generation of prefetch instructions. Although these more aggressive optimizations can significantly speed up the run time execution of the compiled program, in rare cases they may not be profitable and may instead lead to a slow down. Also, some of these more aggressive optimizations may affect the accuracy of some floating point computations.
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective. Level 2 is assumed if no value is specified (i.e. "-O". The default is "-O2".
-INLINE:aggressive=(on|off|0|1): Instructs the compiler to be very aggressive when performing inlining. The default is "-INLINE:aggressive=OFF".
-OPT:IEEE_arithmetic,IEEE_arith,IEEE_a=(1|2|3)
This flag regulates the level of conformance to ANSI/IEEE 754-
1985 floating point roundoff and overflow. The levels of conformance:
1 Adhere to IEEE 754 accuracy. Specifying "-O0", "-O1",
and "-O2" will set "-OPT:IEEE_arithmetic=1".
2 Inexact results that do not conform to IEEE 754 may be calculated.
Specifying "-O3" will set "-OPT:IEEE_arithmetic=2".
3 All mathematically valid transformations (possibly non-IEEE standard ones) are allowed.
-OPT:IEEE_NaN_Inf=(on|off|0|1)
-OPT:IEEE_NaN_inf=ON instructs the compiler to conform to ANSI/IEEE 754-1985 for all
operations which produce a NaN or infinity result. Note NaN and
infinity are typically handled as special cases in floating-point representations
of real numbers and are defined by the IEEE 754 Standards for Binary Floating-point
Arithmetic. The default is "-OPT:IEEE_NaN_Inf=ON".
-OPT:IEEE_NaN_inf=OFF instructs the compiler to calculate various operations that do not
produce IEEE-754 results. For example, x/x is set to the value 1
without performing a divide operation and x=x is set to TRUE with
out executing a test operation. "-OPT:IEEE_NaN_inf=OFF"
specifies multiple optimizations that increase performance.
-OPT:fold_unsigned_relops=(on|off|0|1)
Instructs the compiler to fold relational operators involving
unsigned integers that may be simplified at compile time, which
may cause fewer overflows to be seen at run time. The default is
"-OPT:fold_unsigned_relops=ON".
-OPT:malloc_algorithm,malloc_alg=(0|1)
To improve runtime speed the compiler will select an optimal malloc
algorithm. To enable the selected algorithm, setup code is included
in the C/C++ and Fortran main function.
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:
-CG:load_exe=N : The parameter N must be a non-negative integer which specifies the threshold for the compiler to consider folding a memory load operation directly into its subsequent use in an arithmetic instruction (thereby eliminating the memory load operation). If N=0 this folding optimization is not performed (in other words, the optimization is turned off). If the number of times the result of the memory load is used exceeds the value of N, then the folding optimization is not performed. For example, if N=1 this optimization is performed only when the result of the memory load has only one use. The default value of N varies with target processor and source language.
(For C++ only) -fexceptions enables exception handling and thus generates extra code needed to propagate exceptions. -fno-exceptions disables exception handling. Exception handling is enabled by default.
Generate code for a 32-bit environment. The 32-bit environment sets int, long and pointer to 32 bits and generates code that runs on any i386 system. The compiler generates x86 or IA32 32-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target platform specified is 64-bit, otherwise the default is 32-bit.
Instructs the compiler to use 2MB hugepages for bss, data and text segments (i.e. bdt), and/or for heap allocation. Mixed usage of huge and small pages is not supported for bdt, but is supported for heap allocation. The limit option specifies a combined limit on the number of hugepages that may be used by the compiled program. If no limit is set, the number of hugepages that can be used by the program is effectively limited by the system configuration.
Compiler will generate instructions and schedule them appropriately for the selected processor type. The default value, auto, means to optimize for the platform on which the compiler is running, as determined by reading /proc/cpuinfo. anyx86 means a generic 32-bit x86 processor without SSE2 support.
-fb_create <path>
Instructs the compiler to generate an instrumented executable program from
the source code under development. The instrumented executable produces
feedback data files at runtime using an example dataset. filename specifies the
name of the feedback data file generated by the instrumented executable.
opencc -O2 -ipa -fb_create fbdata -o foo foo.c
"fbdata" will contain the instrumented feedback data from the instrumented
executable "foo". The default is "-fb_create" is disabled.
When feedback directed optimization (FDO) is used, an instrumented executable is used for a training run that produces information regarding execution paths and data values. Hardware performance counters are not used. This information is then provided to the optimizer during a second compilation pass to produce an optimized executable. FDO enables the optimizer to perform some optimizations which are not available without feedback data. The safety level of optimizations is unchanged with FDO, i.e. the safety level is the same as determined by the other (non-FDO) optimization flags specified on the compile and link lines.
-fb_opt <prefix for feedback data files>
Instructs the compiler to perform a feedback directed compilation using the
instrumented feedback data produced by the -fb_create option.
opencc -O2 -ipa -fb-opt fbdata -o foo foo.c
The new executable, foo, will be optimized to execute faster, and will not
include any instrumentation library calls. Note the same optimization flags
specified when creating the instrumented data file with the -fb_create must
be specified when invoking the compiler with the -fb_opt option. Otherwise,
the compiler will emit checksum errors. The default is "-fb_opt" disabled.
Uses a selection of optimizations in order to maximize performance.
Specifying "-Ofast" is equivalent to -O3 -ipa -OPT:Ofast -fno-math-errno -ffast-math.
These optimization options are generally safe. Floating-point accuracy may
be affected due to the transformation of the computational code. Note the
interprocedural analysis option, -ipa, specifies limitations on how libraries
and object files (.o files) are built.
-INLINE:aggressive=(on|off|0|1): Instructs the compiler to be very aggressive when performing inlining. The default is "-INLINE:aggressive=OFF".
Instructs the compiler to use 2MB hugepages for bss, data and text segments (i.e. bdt), and/or for heap allocation. Mixed usage of huge and small pages is not supported for bdt, but is supported for heap allocation. The limit option specifies a combined limit on the number of hugepages that may be used by the compiled program. If no limit is set, the number of hugepages that can be used by the program is effectively limited by the system configuration.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Adds a call to the routine "mallopt" in the main routine. This option can have a dramatic impact on the performance of programs that dynamically allocate memory, especially for those which have a few large mallocs. To be effective, this switch must be specified when compiling the file containing the Fortran, C, or C++ main routine.
Use the prefetchnta instruction.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Compiler will generate instructions and schedule them appropriately for the selected processor type. The default value, auto, means to optimize for the platform on which the compiler is running, as determined by reading /proc/cpuinfo. anyx86 means a generic 32-bit x86 processor without SSE2 support.
-fb_create <path>
Instructs the compiler to generate an instrumented executable program from
the source code under development. The instrumented executable produces
feedback data files at runtime using an example dataset. filename specifies the
name of the feedback data file generated by the instrumented executable.
opencc -O2 -ipa -fb_create fbdata -o foo foo.c
"fbdata" will contain the instrumented feedback data from the instrumented
executable "foo". The default is "-fb_create" is disabled.
When feedback directed optimization (FDO) is used, an instrumented executable is used for a training run that produces information regarding execution paths and data values. Hardware performance counters are not used. This information is then provided to the optimizer during a second compilation pass to produce an optimized executable. FDO enables the optimizer to perform some optimizations which are not available without feedback data. The safety level of optimizations is unchanged with FDO, i.e. the safety level is the same as determined by the other (non-FDO) optimization flags specified on the compile and link lines.
-fb_opt <prefix for feedback data files>
Instructs the compiler to perform a feedback directed compilation using the
instrumented feedback data produced by the -fb_create option.
opencc -O2 -ipa -fb-opt fbdata -o foo foo.c
The new executable, foo, will be optimized to execute faster, and will not
include any instrumentation library calls. Note the same optimization flags
specified when creating the instrumented data file with the -fb_create must
be specified when invoking the compiler with the -fb_opt option. Otherwise,
the compiler will emit checksum errors. The default is "-fb_opt" disabled.
Perform extensive global optimizations. Examples of such optimizations are control flow optimizations, partial redundancy elimination, and strength reduction. These optimizations can very often reduce the execution time of the compiled program significantly, but they may do so at the expense of increased compilation time. This is the default level of optimization.
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective. Level 2 is assumed if no value is specified (i.e. "-O". The default is "-O2".
-OPT:Ofast
Maximizes performance for a given platform using the selected optimizations.
"-OPT:Ofast" specifies four optimizations; "-OPT:ro=2",
"-OPT:Olimit=0", "-OPT:div_split=ON", and "-OPT:alias=typed".
Note the specified optimizations are ordinarily safe but floating
point accuracy due to transformations may be diminished.
-OPT:roundoff,ro=(0|1|2|3)
"-OPT:roundoff" specifies acceptable levels of divergence for both
accuracy and overflow/underflow behavior of floating-point results
relative to the source language rules. The roundoff value is
in the range 0-3 with each value described as follows:
0 Do no transformations which could affect floating-point
results. The default for optimization levels "-O0", "-O1",
and "-O2".
1 Allow all transformations which have a limited affect
on floating-point results. For roundoff, limited is defined
as only the last bit or two of the mantissa is affected.
For overflow or underflow, limited is defined as
intermediate results of the transformed calculation may
overflow or underflow within a factor of two of where
the original expression may have overflowed or underflowed.
Note that effects may be less limited when
compounded by multiple transformations. This is the
default when "-O3" is specified.
2 Specifies transformations with extensive effects on
floating-point results. For example, allow associative
rearrangement (i.e. even across loop iterations) and the
distribution of multiplication over addition or
subtraction. Do not specify transformations known to
cause: a. cumulative roundoff errors, or b. overflow/underflow
of operands in a large range of valid floating-point values.
This is the default when specifying "-OPT:Ofast".
3 Specify any mathematically valid transformation of
floating-point expressions. For example, floating point
induction variables in loops are permitted (even if
known to cause cumulative roundoff errors). Also
permitted are fast algorithms for complex absolute
value and divide (which will overflow/underflow for
operands beyond the square root of the representable extremes).
-OPT:unroll_size=N
Instructs the compiler to limit the number of instructions produced
when unrolling inner loops. When N=0 the ceiling is disregarded.
Note by specifying "-O3" sets "-OPT:unroll_size=128". The default
is "-OPT:unroll_size=40".
Instructs the compiler to use 2MB hugepages for bss, data and text segments (i.e. bdt), and/or for heap allocation. Mixed usage of huge and small pages is not supported for bdt, but is supported for heap allocation. The limit option specifies a combined limit on the number of hugepages that may be used by the compiled program. If no limit is set, the number of hugepages that can be used by the program is effectively limited by the system configuration.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Set the fetch-ahead distance for prefetch instructions to 8 cache lines
Use the prefetcht0 instruction.
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Link with the huge page runtime library. Use huge pages for an executable's .BSS section.
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Generate profile-feedback instrumentation (PFI); this includes extra code to collect run-time statistics and dump them to a trace file for use in a subsequent compilation. PFI gathers information about a program's execution and data values but does not gather information from hardware performance counters. PFI does gather data for optimizations which are unique to profile-feedback optimization.
The indirect sub-option enables collection of indirect function call targets, which can be used for indirect function call inlining.
Enable profile-feedback optimizations including indirect function call inlining. This option requires a pgfi.out file generated from a binary built with -Mpfi=indirect.
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Instructs the vectorizer to enable loop fusion.
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Set the fetch-ahead distance for prefetch instructions to 8 cache lines
Use the prefetcht0 instruction.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Compiler will generate instructions and schedule them appropriately for the selected processor type. The default value, auto, means to optimize for the platform on which the compiler is running, as determined by reading /proc/cpuinfo. anyx86 means a generic 32-bit x86 processor without SSE2 support.
Uses a selection of optimizations in order to maximize performance.
Specifying "-Ofast" is equivalent to -O3 -ipa -OPT:Ofast -fno-math-errno -ffast-math.
These optimization options are generally safe. Floating-point accuracy may
be affected due to the transformation of the computational code. Note the
interprocedural analysis option, -ipa, specifies limitations on how libraries
and object files (.o files) are built.
This option group commands the compiler loop nest optimizer to perform nested loop analysis and transformations. Note an optimization level of "-O3" or higher must be specified in order to enable the "-LNO:" options. To verify the LNO options that were invoked during compilation use the option "-LIST:all_options=ON".
-LNO:fission=N : Instsructs the compiler to perform loop fission. This option can be
set to:
0 Suppress loop fission.
1 The compiler performs normal loop fission as necessary.
2 The compiler performs loop fission prior to loop fusion.
Note loop fusion is usually applied before loop fission, therefore
if "-LNO:fission=ON" and "-LNO:fusion=ON" when the compiler is
invoked a reverse effect may be induced. To counter this effect
specify "-LNO:fission=2" to instruct the compiler to perform loop
fission prior to loop fusion. The default is "-LNO:fission=0".
This option group commands the compiler loop nest optimizer to perform nested loop analysis and transformations. Note an optimization level of "-O3" or higher must be specified in order to enable the "-LNO:" options. To verify the LNO options that were invoked during compilation use the option "-LIST:all_options=ON".
-LNO:simd=(0|1|2) : The compiler is instructed to use single instruction multiple data
(SIMD) instructions, supported by the target processor, when vectorizing
the inner loop. The flag can be set to:
0 The compiler is instructed to suppress vectorization.
1 The compiler is instructed to vectorize only if there is
no performance degradation due to sub-optimal alignment
and does not induce floating-point operation inaccuracies.
2 Instructs the compiler to aggressively vectorize with no
constraints in place.
The default is "LNO:simd=1".
This option group commands the compiler loop nest optimizer to perform nested loop analysis and transformations. Note an optimization level of "-O3" or higher must be specified in order to enable the "-LNO:" options. To verify the LNO options that were invoked during compilation use the option "-LIST:all_options=ON".
-LNO:prefetch_ahead=N : The compiler is instructed to prefetch ahead N cache line(s). The default is "-LNO:prefetch_ahead=2".
-CG:load_exe=N : The parameter N must be a non-negative integer which specifies the threshold for the compiler to consider folding a memory load operation directly into its subsequent use in an arithmetic instruction (thereby eliminating the memory load operation). If N=0 this folding optimization is not performed (in other words, the optimization is turned off). If the number of times the result of the memory load is used exceeds the value of N, then the folding optimization is not performed. For example, if N=1 this optimization is performed only when the result of the memory load has only one use. The default value of N varies with target processor and source language.
Instructs the compiler to use 2MB hugepages for bss, data and text segments (i.e. bdt), and/or for heap allocation. Mixed usage of huge and small pages is not supported for bdt, but is supported for heap allocation. The limit option specifies a combined limit on the number of hugepages that may be used by the compiled program. If no limit is set, the number of hugepages that can be used by the program is effectively limited by the system configuration.
Compiler will generate instructions and schedule them appropriately for the selected processor type. The default value, auto, means to optimize for the platform on which the compiler is running, as determined by reading /proc/cpuinfo. anyx86 means a generic 32-bit x86 processor without SSE2 support.
Uses a selection of optimizations in order to maximize performance.
Specifying "-Ofast" is equivalent to -O3 -ipa -OPT:Ofast -fno-math-errno -ffast-math.
These optimization options are generally safe. Floating-point accuracy may
be affected due to the transformation of the computational code. Note the
interprocedural analysis option, -ipa, specifies limitations on how libraries
and object files (.o files) are built.
The "-OPT:" option group controls various optimizations. The "-OPT:" options supersede the defaults that are based on the main optimization level.
-OPT:alias=<model>
Identify which pointer aliasing model to use. The compiler will
make assumptions during compilation when one or more of the
following <model> is specified:
typed
Assumes that two pointers of different types will not
point to the same location in memory (i.e. the code
adheres to the ANSI/ISO C standards). Note when
specifying "-OPT:Ofast" turns this option ON.
restrict
Assumes that distinct pointers are pointing to distinct
non-overlapping objects. The default is that this optimization
is disabled.
disjoint
Assumes that any two pointer expressions are pointing
to distinct non-overlapping objects. This default is that this
optimization is disabled.
no_f90_pointer_alias
Assumes that any two different Fortran 90 pointers are
pointing to distinct non-overlapping objects. The default
is that this optimization is disabled.
This option group commands the compiler loop nest optimizer to perform nested loop analysis and transformations. Note an optimization level of "-O3" or higher must be specified in order to enable the "-LNO:" options. To verify the LNO options that were invoked during compilation use the option "-LIST:all_options=ON".
-LNO:blocking=(on|off|0|1): Instructs the compiler to perform cache blocking transformation. The default is "-LNO:blocking=ON".
-CG:load_exe=N : The parameter N must be a non-negative integer which specifies the threshold for the compiler to consider folding a memory load operation directly into its subsequent use in an arithmetic instruction (thereby eliminating the memory load operation). If N=0 this folding optimization is not performed (in other words, the optimization is turned off). If the number of times the result of the memory load is used exceeds the value of N, then the folding optimization is not performed. For example, if N=1 this optimization is performed only when the result of the memory load has only one use. The default value of N varies with target processor and source language.
-IPA:plimit=N : The compiler is instructed to halt inlining within a program once the intermediate representation indicates that the code size of the program has surpassed the limit set by N. The default is "-IPA:plimit=2500".
Instructs the compiler to use 2MB hugepages for bss, data and text segments (i.e. bdt), and/or for heap allocation. Mixed usage of huge and small pages is not supported for bdt, but is supported for heap allocation. The limit option specifies a combined limit on the number of hugepages that may be used by the compiled program. If no limit is set, the number of hugepages that can be used by the program is effectively limited by the system configuration.
Compiler will generate instructions and schedule them appropriately for the selected processor type. The default value, auto, means to optimize for the platform on which the compiler is running, as determined by reading /proc/cpuinfo. anyx86 means a generic 32-bit x86 processor without SSE2 support.
Uses a selection of optimizations in order to maximize performance.
Specifying "-Ofast" is equivalent to -O3 -ipa -OPT:Ofast -fno-math-errno -ffast-math.
These optimization options are generally safe. Floating-point accuracy may
be affected due to the transformation of the computational code. Note the
interprocedural analysis option, -ipa, specifies limitations on how libraries
and object files (.o files) are built.
-OPT:rsqrt=(0|1|2)
Instructs the compiler to use the reciprocal square root instruction
when calculating the square root. This transformation may vary
the accuracy slightly.
0 Restrain from using the reciprocal square root instruction.
1 Use the reciprocal square root instruction followed by
operations that will improve the accuracy of the results.
2 Use the reciprocal square root instruction without improving
the result accuracy.
Note "-OPT:rsqrt=1" if "-OPT:roudoff=2" or "-OPT:roundoff=3".
The default is "-OPT:rsqrt=0".
Instructs the compiler to use 2MB hugepages for bss, data and text segments (i.e. bdt), and/or for heap allocation. Mixed usage of huge and small pages is not supported for bdt, but is supported for heap allocation. The limit option specifies a combined limit on the number of hugepages that may be used by the compiled program. If no limit is set, the number of hugepages that can be used by the program is effectively limited by the system configuration.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Instructs the compiler to enable auto-concurrentization of loops. If -Mconcur is specified, multiple processors will be used to execute loops that the compiler determines to be parallelizable.
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Generate profile-feedback instrumentation (PFI); this includes extra code to collect run-time statistics and dump them to a trace file for use in a subsequent compilation. PFI gathers information about a program's execution and data values but does not gather information from hardware performance counters. PFI does gather data for optimizations which are unique to profile-feedback optimization.
The indirect sub-option enables collection of indirect function call targets, which can be used for indirect function call inlining.
Enable profile-feedback optimizations including indirect function call inlining. This option requires a pgfi.out file generated from a binary built with -Mpfi=indirect.
Instructs the compiler to perform interprocedural analysis. Equivalant to -Mipa=align,arg,const,f90ptr,shape,globals,libc,localarg,ptr,pure.
Interprocedural Analysis option: Automatically determine which functions to inline, limit to 2 levels (default). IPA-based function inlining is performed from leaf routines upward.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Enables generation of packed SSE instructions for short vector operations that arise from scalar code outside of loops or within the body of a loop iteration.
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Use the prefetcht0 instruction.
Enable partial redundancy elimination.
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Chooses generally optimal flags for the target platform. As of the PGI 7.0 release, the flags "-fast" and "-fastsse" are equivalent for 64-bit compilations. For 32-bit compilations "-fast" does not include "-Mscalarsse", "-Mcache_align", or "-Mvect=sse".
Disables alternate code generation for vectorized loops.
Link with the huge page runtime library. The maximum number of huge pages the application can use is limited by the number of huge pages the operating system has available or the value of the environment variable PGI_HUGE_PAGES.
Set the fetch-ahead distance for prefetch instructions to 8 cache lines
Instructs the compiler to use relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The default on an AMD system is "-Mfprelaxed=sqrt,rsqrt,order". The default on an Intel system is "-Mfprelaxed=rsqrt,sqrt,div,order"
Specify the type of the target processor as AMD64 Shanghai Processor 64-bit mode.
Statically link with the PGI runtime libraries. System libraries may still be dynamically linked.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
Interprocedural Analysis option: Specifies the number of concurrent IPA second pass compilation process that may be performed. This option speeds-up the compilation time on multi-core systems but does not perform any optimizations.
This section contains descriptions of flags that were included implicitly by other flags, but which do not have a permanent home at SPEC.
Level-two optimization (-O2 or -O) specifies global optimization. The -fast option generally will specify global optimization; however, the -fast switch will vary from release to release depending on a reasonable selection of switches for any one particular release. The -O or -O2 level performs all level-one local optimizations as well as global optimizations. Control flow analysis is applied and global registers are allocated for all functions and subroutines. Loop regions are given special consideration. This optimization level is a good choice when the program contains loops, the loops are short, and the structure of the code is regular.
The PGI compilers perform many different types of global optimizations, including but not limited to:
Level-one optimization specifies local optimization (-O1). The compiler performs scheduling of basic blocks as well as register allocation. This optimization level is a good choice when the code is very irregular; that is it contains many short statements containing IF statements and the program does not contain loops (DO or DO WHILE statements). For certain types of code, this optimization level may perform better than level-two (-O2) although this case rarely occurs.
The PGI compilers perform many different types of local optimizations, including but not limited to:
Instructs the compiler to completely unroll loops with a constant loop count of less than or equal to 1 where 1 is a supplied constant value. If no constant value is given, then a default of 4 is used. A value of 1 inhibits the complete unrolling of loops with constant loop counts.
Invokes the loop unroller.
Inline functions declared with the inline keyword.
Enable an optional post-pass instruction scheduling.
Enables loop-carried redundancy elimination, an optimization that can reduce the number of arithmetic operations and memory references in loops.
Eliminates operations that set up a true stack frame pointer for every function. With this option enabled, you cannot perform a traceback on the generated code and you cannot access local variables.
Instructs the vectorizer to search for vectorizable loops and, where possible, make use of SSE, SSE2, and prefetch instructions.
Enable automatic vector pipelining.
Instructs the vectorizer to enable certain associativity conversions that can change the results of a computations due to roundoff error. A typical optimization is to change an arithmetic operation to an arithmetic opteration that is mathmatically correct, but can be computationally different, due to round-off error.
Instructs the vectorizer to generate alternate code for vectorized loops when appropriate. For each vectorized loop the compiler decides whether to generate altcode and what type or types to generate, which may be any or all of:
The compiler also determines suitable loop count and array alignment conditions for executing the altcode.
Align "unconstrained" data objects of size greater than or equal to 16 bytes on cache-line boundaries. An "unconstrained" object is a variable or array that is not a member of an aggregate structure or common block, is not allocatable, and is not an automatic array. On by default on 64-bit Linux systems.
Set SSE to flush-to-zero mode; if a floating-point underflow occurs, the value is set to zero.
Treat denormalized numbers as zero. Included with "-fast" on Intel based systems. For AMD based systems, "-Mdaz" is not included by default with "-fast".
Use SSE/SSE2 instructions to perform scalar floating-point arithmetic on targets where these instructions are supported.
Instructs the compiler to use relaxed precision in the calculation of floating-point reciprocal square root (1/sqrt). Can result in improved performance at the expense of numerical accuracy.
Instructs the compiler to use relaxed precision in the calculation of floating-point square root. Can result in improved performance at the expense of numerical accuracy.
Instructs the compiler to use relaxed precision in the calculation of floating-point division. Can result in improved performance at the expense of numerical accuracy.
Instructs the compiler to allow floating-point expression reordering, including factoring. Can result in improved performance at the expense of numerical accuracy.
Interprocedural Analysis option: Recognize when targets of pointer dummy are aligned.
Interprocedural Analysis option: Remove arguments replaced by -Mipa=ptr,const
Interprocedural Analysis option: Enable pointer disambiguation across procedure calls.
Interprocedural Analysis option: Enable interprocedural constant propagation.
Interprocedural Analysis option: Fortran 90/95 Pointer disambiguation across calls.
Interprocedural Analysis option: Perform Fortran 90 array shape propagation.
Interprocedural Analysis option: Optimize references to global values.
Interprocedural Analysis option: Used to optimize calls to certain functions in the system standard C library, libc.
Interprocedural Analysis option: -Mipa=arg plus externalizes local pointer targets.
Interprocedural Analysis option: Pure function detection.
Enable generation of prefetch instructions on processors where they are supported.
Perform all the optimizations at the -O2 level as well as many more aggressive optimizations. Examples of such aggressive optimizations are loop nest optimizations and generation of prefetch instructions. Although these more aggressive optimizations can significantly speed up the run time execution of the compiled program, in rare cases they may not be profitable and may instead lead to a slow down. Also, some of these more aggressive optimizations may affect the accuracy of some floating point computations.
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective. Level 2 is assumed if no value is specified (i.e. "-O". The default is "-O2".
Perform extensive global optimizations. Examples of such optimizations are control flow optimizations, partial redundancy elimination, and strength reduction. These optimizations can very often reduce the execution time of the compiled program significantly, but they may do so at the expense of increased compilation time. This is the default level of optimization.
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective. Level 2 is assumed if no value is specified (i.e. "-O". The default is "-O2".
Perform minimal local optimizations on sections of straight-line code (basic blocks) only. Examples of such optimizations are instruction scheduling and some peephole optimizations. These optimizations do not usually have any noticeable impact on compilation time.
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective. Level 2 is assumed if no value is specified (i.e. "-O". The default is "-O2".
Instructs the compiler to invoke inter-procedural analysis. Specifying "-ipa" is equivalent to "-IPA" and "-IPA:" with no suboptions, thus the default settings for the individual IPA suboptions are used.
-OPT:Ofast
Maximizes performance for a given platform using the selected optimizations.
"-OPT:Ofast" specifies four optimizations; "-OPT:ro=2",
"-OPT:Olimit=0", "-OPT:div_split=ON", and "-OPT:alias=typed".
Note the specified optimizations are ordinarily safe but floating
point accuracy due to transformations may be diminished.
-OPT:roundoff,ro=(0|1|2|3)
"-OPT:roundoff" specifies acceptable levels of divergence for both
accuracy and overflow/underflow behavior of floating-point results
relative to the source language rules. The roundoff value is
in the range 0-3 with each value described as follows:
0 Do no transformations which could affect floating-point
results. The default for optimization levels "-O0", "-O1",
and "-O2".
1 Allow all transformations which have a limited affect
on floating-point results. For roundoff, limited is defined
as only the last bit or two of the mantissa is affected.
For overflow or underflow, limited is defined as
intermediate results of the transformed calculation may
overflow or underflow within a factor of two of where
the original expression may have overflowed or underflowed.
Note that effects may be less limited when
compounded by multiple transformations. This is the
default when "-O3" is specified.
2 Specifies transformations with extensive effects on
floating-point results. For example, allow associative
rearrangement (i.e. even across loop iterations) and the
distribution of multiplication over addition or
subtraction. Do not specify transformations known to
cause: a. cumulative roundoff errors, or b. overflow/underflow
of operands in a large range of valid floating-point values.
This is the default when specifying "-OPT:Ofast".
3 Specify any mathematically valid transformation of
floating-point expressions. For example, floating point
induction variables in loops are permitted (even if
known to cause cumulative roundoff errors). Also
permitted are fast algorithms for complex absolute
value and divide (which will overflow/underflow for
operands beyond the square root of the representable extremes).
-OPT:Olimit=N
Controls the size of procedures to be optimized. Procedures above
the specified cutoff limit, N, are not optimized. N=0 means
"infinite Olimit", which causes all procedures to be optimized
with no consideration regarding compilation times. Note if
"-OPT:Ofast" is enabled then "-OPT:Olimit=0" or when "-O3" is
enabled "-OPT:Olimit=9000". The default is "-OPT:Olimit=6000".
-OPT:div_split=(on|off|0|1)
Instruct the compiler to transform x/y into x*(recip(y)). Flags
-OPT:Ofast or -OPT:IEEE_arithmetic=3 will enable this optimization.
Note this transform generates fairly accurate code. The default
is "-OPT:div_split=OFF".
The "-OPT:" option group controls various optimizations. The "-OPT:" options supersede the defaults that are based on the main optimization level.
-OPT:alias=<model>
Identify which pointer aliasing model to use. The compiler will
make assumptions during compilation when one or more of the
following <model> is specified:
typed
Assumes that two pointers of different types will not
point to the same location in memory (i.e. the code
adheres to the ANSI/ISO C standards). Note when
specifying "-OPT:Ofast" turns this option ON.
restrict
Assumes that distinct pointers are pointing to distinct
non-overlapping objects. The default is that this optimization
is disabled.
disjoint
Assumes that any two pointer expressions are pointing
to distinct non-overlapping objects. This default is that this
optimization is disabled.
no_f90_pointer_alias
Assumes that any two different Fortran 90 pointers are
pointing to distinct non-overlapping objects. The default
is that this optimization is disabled.
Do not set ERRNO after calling math functions that are executed with a single instruction, e.g. sqrt. A program that relies on IEEE exceptions for math error handling may want to use this flag for speed while maintaining IEEE arithmetic compatibility. Note specifying "-Ofast" implies "-fno-math-errno". The default is "-fmath-errno".
"-fast-math" instructs the compiler to relax ANSI/ISO or IEEE
rules/specifications for math functions in order to optimize
floating-point computations to improve runtime.
"-fno-fast-math" instructs the compiler to conform to ANSI and
IEEE math rules. This option causes the preprocessor macro
__FAST_MATH__ to be defined.
Note:
"-Ofast" implies "-ffast-math".
"-ffast-math" sets options "-fno-math-errno" and "-OPT:IEEE_arithmetic=2".
"-fno-fast-math" sets options "-fmath-errno" and "-OPT:IEEE arithmetic=1".
Linux Huge Page settings
In order to take full advantage of using PGI's huge page runtime library, your system must be configured to use huge pages. It is safe to run binaries compiled with "-Msmartalloc=huge" on systems not configured to use huge pages, however, you will not benefit from the performance improvements huge pages offer. To configure your system for huge pages perform the following steps:
Note that further information about huge pages may be found in your Linux documentation file: /usr/src/linux/Documentation/vm/hugetlbpage.txt
PGI_HUGE_PAGES
For the PGI compiler, the maximum number of huge pages an application is allowed to use can be set at run time via the environment variable PGI_HUGE_PAGES. If not set, then the process may use all available huge pages when compiled with "-Msmartalloc=huge" or a maximum of n pages where the value of n is set via the compile time flag "-Msmartalloc=huge:n".
HUGETLB_LIMIT
For the x86 Open64 compiler, the maximum number of huge pages an application is allowed to use can be set at run time via the environment variable HUGETLB_LIMIT. If not set, then the process may use all available huge pages when compiled with "-HP (or -HUGEPAGE)" or a maximum of n pages where the value of n is set via the compile time flag "-HP:limit=n".
Using numactl to bind processes and memory to cores
For multi-copy runs or single copy runs on systems with multiple sockets, it is advantageous to bind a process to a particular core. Otherwise, the OS may arbitrarily move your process from one core to another. This can effect performance. To help, SPEC allows the use of a "submit" command where users can specify a utility to use to bind processes. We have found the utility 'numactl' to be the best choice.
numactl runs processes with a specific NUMA scheduling or memory placement policy. The policy is set for a command and inherited by all of its children. The numactl flag "--physcpubind" specifies which core(s) to bind the process. "-l" instructs numactl to keep a process memory on the local node while "-m" specifies which node(s) to place a process memory. For full details on using numactl, please refer to your Linux documentation, 'man numactl'
Note that some versions of numactl, particularly the version found on SLES 10, we have found that the utility incorrectly interprets application arguments as it's own. For example, with the command "numactl --physcpubind=0 -l a.out -m a", numactl will interpret a.out's "-m" option as it's own "-m" option. To work around this problem, a user can put the command to be run in a shell script and then run the shell script using numactl. For example: "echo 'a.out -m a' > run.sh ; numactl --physcpubind=0 bash run.sh"
ulimit -s <n>
Sets the stack size to n kbytes, or unlimited to allow the stack size to grow without limit.
ulimit -l <n>
Sets the maximum size of memory that may be locked into physical memory.
NCPUS
Sets the maximum number of OpenMP parallel threads auto-parallelized (-Mconcur) applications may use.
powersave -f
Makes the powersave daemon set the CPUs to the highest supported frequency.
Flag description origin markings:
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Indicates that the flag description came from the user flags file. |
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Indicates that the flag description came from the suite-wide flags file. |
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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 v1.1.
Report generated on Wed Jul 23 02:41:49 2014 by SPEC CPU2006 flags formatter v6906.