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

lenovo-omp2012-oneAPI-20210211.xml SPEC OMP2012 Flag Description for the Intel(R) C/C++ Compiler for IA32 and Intel 64 applications and Intel(R) Fortran Compiler for IA32 and Intel 64 applications Open MP Tuning Flags

KMP_AFFINITY

The KMP_AFFINITY environment variable uses the following general syntax:

Syntax
KMP_AFFINITY=[<modifier>,...]<type>[,<permute>][,<offset>]

For example, to list a machine topology map, specify KMP_AFFINITY=verbose,none to use a modifier of verbose and a type of none.

The following table describes the supported specific arguments.

Argument	Default	Description
modifier	noverbose respect granularity=core	Optional. String consisting of keyword and specifier. granularity=<specifier> takes the following specifiers: fine, thread, and core norespect noverbose nowarnings proclist={<proc-list>} respect verbose warnings
type	none	Required string. Indicates the thread affinity to use. compact disabled explicit none scatter logical (deprecated; instead use compact, but omit any permute value) physical (deprecated; instead use scatter, possibly with an offset value) The logical and physical types are deprecated but supported for backward compatibility.
permute	0	Optional. Positive integer value. Not valid with type values of explicit, none, or disabled.
offset	0	Optional. Positive integer value. Not valid with type values of explicit, none, or disabled.

Affinity Types

Type is the only required argument.

type = none (default)

Does not bind OpenMP threads to particular thread contexts; however, if the operating system supports affinity, the compiler still uses the OpenMP thread affinity interface to determine machine topology. Specify KMP_AFFINITY=verbose,none to list a machine topology map.

type = compact

Specifying compact assigns the OpenMP thread <n>+1 to a free thread context as close as possible to the thread context where the <n> OpenMP thread was placed. For example, in a topology map, the nearer a node is to the root, the more significance the node has when sorting the threads.

type = disabled

Specifying disabled completely disables the thread affinity interfaces. This forces the OpenMP run-time library to behave as if the affinity interface was not supported by the operating system. This includes the low-level API interfaces such as kmp_set_affinity and kmp_get_affinity, which have no effect and will return a nonzero error code.

type = explicit

Specifying explicit assigns OpenMP threads to a list of OS proc IDs that have been explicitly specified by using the proclist= modifier, which is required for this affinity type.

type = scatter

Specifying scatter distributes the threads as evenly as possible across the entire system. scatter is the opposite of compact; so the leaves of the node are most significant when sorting through the machine topology map.

Deprecated Types: logical and physical

Types logical and physical are deprecated and may become unsupported in a future release. Both are supported for backward compatibility.

For logical and physical affinity types, a single trailing integer is interpreted as an offset specifier instead of a permute specifier. In contrast, with compact and scatter types, a single trailing integer is interpreted as a permute specifier.

Specifying logical assigns OpenMP threads to consecutive logical processors, which are also called hardware thread contexts. The type is equivalent to compact, except that the permute specifier is not allowed. Thus, KMP_AFFINITY=logical,n is equivalent to KMP_AFFINITY=compact,0,n (this equivalence is true regardless of the whether or not a granularity=fine modifier is present).

Permute and offset combinations

For both compact and scatter, permute and offset are allowed; however, if you specify only one integer, the compiler interprets the value as a permute specifier. Both permute and offset default to 0.

The permute specifier controls which levels are most significant when sorting the machine topology map. A value for permute forces the mappings to make the specified number of most significant levels of the sort the least significant, and it inverts the order of significance. The root node of the tree is not considered a separate level for the sort operations.

The offset specifier indicates the starting position for thread assignment.

Modifier Values for Affinity Types

Modifiers are optional arguments that precede type. If you do not specify a modifier, the noverbose, respect, and granularity=core modifiers are used automatically.

Modifiers are interpreted in order from left to right, and can negate each other. For example, specifying KMP_AFFINITY=verbose,noverbose,scatter is therefore equivalent to setting KMP_AFFINITY=noverbose,scatter, or just KMP_AFFINITY=scatter.

modifier = noverbose (default)

Does not print verbose messages.

modifier = verbose

Prints messages concerning the supported affinity. The messages include information about the number of packages, number of cores in each package, number of thread contexts for each core, and OpenMP thread bindings to physical thread contexts.

Information about binding OpenMP threads to physical thread contexts is indirectly shown in the form of the mappings between hardware thread contexts and the operating system (OS) processor (proc) IDs. The affinity mask for each OpenMP thread is printed as a set of OS processor IDs.

KMP_LIBRARY

KMP_LIBRARY = { throughput | turnaround | serial }, Selects the OpenMP run-time library execution mode. The options for the variable value are throughput, turnaround, and serial.

Execution modes

The compiler with OpenMP enables you to run an application under different execution modes that can be specified at run time. The libraries support the serial, turnaround, and throughput modes.

Serial

The serial mode forces parallel applications to run on a single processor.

Turnaround

In a dedicated (batch or single user) parallel environment where all processors are exclusively allocated to the program for its entire run, it is most important to effectively utilize all of the processors all of the time. The turnaround mode is designed to keep active all of the processors involved in the parallel computation in order to minimize the execution time of a single job. In this mode, the worker threads actively wait for more parallel work, without yielding to other threads.

Avoid over-allocating system resources. This occurs if either too many threads have been specified, or if too few processors are available at run time. If system resources are over-allocated, this mode will cause poor performance. The throughput mode should be used instead if this occurs.

Throughput

In a multi-user environment where the load on the parallel machine is not constant or where the job stream is not predictable, it may be better to design and tune for throughput. This minimizes the total time to run multiple jobs simultaneously. In this mode, the worker threads will yield to other threads while waiting for more parallel work.

The throughput mode is designed to make the program aware of its environment (that is, the system load) and to adjust its resource usage to produce efficient execution in a dynamic environment. This mode is the default.

KMP_BLOCKTIME

KMP_BLOCKTIME = value. Sets the time, in milliseconds, that a thread should wait, after completing the execution of a parallel region, before sleeping.Use the optional character suffixes: s (seconds), m (minutes), h (hours), or d (days) to specify the units.Specify infinite for an unlimited wait time.

KMP_STACKSIZE

KMP_STACKSIZE = value. Sets the number of bytes to allocate for each OpenMP* thread to use as the private stack for the thread. Recommended size is 16m. Use the optional suffixes: b (bytes), k (kilobytes), m (megabytes), g (gigabytes), or t (terabytes) to specify the units. This variable does not affect the native operating system threads created by the user program nor the thread executing the sequential part of an OpenMP* program or parallel programs created using -parallel.

OMP_NUM_THREADS

Sets the maximum number of threads to use for OpenMP* parallel regions if no other value is specified in the application. This environment variable applies to both -openmp and -parallel. Example syntax on a Linux system with 8 cores: export OMP_NUM_THREADS=8

OMP_DYNAMIC

OMP_DYNAMIC={ 1 | 0 } Enables (1, true) or disables (0,false) the dynamic adjustment of the number of threads.

OMP_SCHEDULE

OMP_SCHEDULE={ type,[chunk size]} Controls the scheduling of the for-loop work-sharing construct. type can be either of static,dynamic,guided,runtime chunk size should be positive integer

OMP_NESTED

OMP_NESTED={ 1 | 0 } Enables creation of new teams in case of nested parallel regions (1,true) or serializes (0,false) all nested parallel regions. Default is 0.

]]>

Invoke the Intel C/C++ compiler for Intel 64 applications

]]> Invoke the Intel C/C++ compiler for 32-bit applications

]]> Invoke the Intel C compiler for IA32 applications.

You need binutils 2.16.91.0.7 or later with this compiler to support new instructions on Intel Core 2 processors

]]> Invoke the Intel C++ compiler for IA32 and Intel 64 applications.

You need binutils 2.16.91.0.7 or later with this compiler to support new instructions on Intel Core 2 processors

]]> Invoke the Intel Fortran compiler Classic for IA32 and Intel 64 applications.

You need binutils 2.16.91.0.7 or later with this compiler to support new instructions on Intel Core 2 processors

]]> Invoke the Intel oneAPI DPC++/C++ compiler and runtime environment.

The Intel® oneAPI DPC++/C++ Compiler can be found in the Intel® oneAPI Base Toolkit, Intel® oneAPI HPC Toolkit, Intel® oneAPI IoT Toolkit, or as a standalone compiler. More information and specifications can be found on the Intel® oneAPI DPC++/C++ Compiler main page.

]]> Invoke the Intel oneAPI DPC++/C++ compiler and runtime environment.

]]> Invoke the Intel Fortran Compiler (Beta), it a new compiler based on the Intel Fortran Compiler Classic (ifort) frontend and runtime libraries, using LLVM backend technology.

ifx does not support 32-bit target.

The Intel® Fortran Compiler (Beta) (ifx) can be found in the Intel® oneAPI Base Toolkit, Intel® oneAPI HPC Toolkit, Intel® oneAPI IoT Toolkit, or as a standalone compiler. For more information, see Introducing the Intel® Fortran Compiler Classic and Intel® Fortran Compiler (Beta).

]]> Compiler option to set the path for include files. Used in some integer peak benchmarks which were built using the Intel 64-bit C++ compiler. Compiler option to set the path for library files. Used in some integer peak benchmarks which were built using the Intel 64-bit C++ compiler. Compiler option to set the path for include files. Used in some peak benchmarks which were built using the Intel 32-bit C++ compiler. Compiler option to set the path for library files. Used in some integer peak benchmarks which were built using the Intel 32-bit C++ compiler. Compiler option to set the path for include files. Used in some peak benchmarks which were built using the Intel 32-bit Fortran compiler. Compiler option to set the path for library files. Used in some integer peak benchmarks which were built using the Intel 32-bit Fortran compiler. Define the MPICH_IGNORE_CXX_SEEK macro at compilation stage to catastrophic error: "SEEK_SET is #defined but must not be for the C++ binding of MPI" when compiling C++ MPI application.

]]> For mixed-language benchmarks, tell the compiler to convert routine names to lowercase for compatibility

]]> For mixed-language benchmarks, tell the compiler to assume that routine names end with an underscore

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

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

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

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

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

]]> Enables O2 optimizations plus more aggressive optimizations, such as prefetching, scalar replacement, and loop and memory access transformations. Enables optimizations for maximum speed, such as:
- Loop unrolling, including instruction scheduling
- Code replication to eliminate branches
- Padding the size of certain power-of-two arrays to allow more efficient cache use.
On IA-32 and Intel EM64T processors, when O3 is used with options -ax or -x (Linux) or with options /Qax or /Qx (Windows), the compiler performs more aggressive data dependency analysis than for O2, which may result in longer compilation times.
The O3 optimizations may not cause higher performance unless loop and memory access transformations take place. The optimizations may slow down code in some cases compared to O2 optimizations.
The O3 option is recommended for applications that have loops that heavily use floating-point calculations and process large data sets. On IA-32 Windows platforms, -O3 sets the following:

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

]]> Sets certain aggressive options to improve the speed of your application.

]]> Disables inline expansion of all intrinsic functions. Disables conformance to the ANSI C and IEEE 754 standards for floating-point arithmetic.

]]> Allows use of EBP as a general-purpose register in optimizations. This option enables most speed optimizations, but disables some that increase code size for a small speed benefit.

]]> This option enables global optimizations. 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.

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

]]> This option enables read only string-pooling optimization. This option enables read/write string-pooling optimization. This option disables stack-checking for routines with 4096 bytes of local variables and compiler temporaries.

]]> Tells the compiler the maximum number of times to unroll loops. specify source files are in free format. Same as -FR. -nofree indicates fixed format specify source files are in fixed format. Same as -FI. -nofixed indicates free format This option enables additional interprocedural optimizations for single file compilation. These optimizations are a subset of full intra-file interprocedural optimizations. One of these optimizations enables the compiler to perform inline function expansion for calls to functions defined within the current source file. Enables interprocedural optimization between files. Arguments: n Is an optional integer that specifies the number of object files the compiler should create. The integer must be greater than or equal to 0. -ipo[n]
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
(n - number of multi-file objects)

]]> This option instructs the compiler to analyze and transform the program so that 64-bit pointers are shrunk to 32-bit pointers, and 64-bit longs (on Linux) are shrunk into 32-bit longs wherever it is legal and safe to do so. In order for this option to be effective the compiler must be able to optimize using the -ipo/-Qipo option and must be able to analyze all library/external calls the program makes.

This option requires that the size of the program executable never exceeds 2^32 bytes and all data values can be represented within 32 bits. If the program can run correctly in a 32-bit system, these requirements are implicitly satisfied. If the program violates these size restrictions, unpredictable behavior might occur.

]]> This option specifies that the main program is not written in Fortran. It is a link-time option that prevents the compiler from linking for_main.o into applications.

For example, if the main program is written in C and calls a Fortran subprogram, specify -nofor-main when compiling the program with the ifort command. If you omit this option, the main program must be a Fortran program.

]]> -scalar-rep enables scalar replacement performed during loop transformation. To use this option, you must also specify O3. -scalar-rep- disables this optimization.

]]> This options tells the compiler to assume no aliasing in the program.

]]> enable floating point model variation
[no-]except - enable/disable floating point semantics
fast[=1|2] - enables more aggressive floating point optimizations
precise - allows value-safe optimizations
source - enables intermediates in source precision
strict - enables -fp-model precise -fp-model except, disables
contractions and enables pragma stdc fenv_access
double - rounds intermediates in 53-bit (double) precision
extended - rounds intermediates in 64-bit (extended) precision

]]> specify how data items are aligned
keywords: all (same as -align), none (same as -noalign),
[no]commons, [no]dcommons,
[no]qcommons, [no]zcommons,
rec1byte, rec2byte, rec4byte,
rec8byte, rec16byte, rec32byte,
array8byte, array16byte, array32byte,
array64byte, array128byte, array256byte,
[no]records, [no]sequence

]]> 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 (disable -prec-div) 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.

]]> Compiler option to statically link in libraries at link time Link Intel provided libraries statically Link Intel provided libraries dynamically -mcmodel=<size>
use a specific memory model to generate code and store data
small - Restricts code and data to the first 2GB of address space (DEFAULT)
medium - Restricts code to the first 2GB; it places no memory restriction on data
large - Places no memory restriction on code or data

]]> enable language support for , as described below
c99 enable C99 support for C programs
c++11 enable C++11 experimental support for C++ programs
c++0x same as c++11

]]> Defines a macro Generate instructions for the highest instruction set and processor available on the compilation host machine.

]]> 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.

]]> Code is optimized for Intel(R) processors with support for AVX instructions. The resulting code may contain unconditional use of features that are not supported on other processors. This option also enables new optimizations in addition to Intel processor-specific optimizations including advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

]]> Code is optimized for Intel(R) processors with support for AVX2 instructions. The resulting code may contain unconditional use of features that are not supported on other processors. This option also enables new optimizations in addition to Intel processor-specific optimizations including advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

]]> Code is optimized for Intel(R) processors with support for AVX512 instructions. The resulting code may contain unconditional use of features that are not supported on other processors. This option also enables new optimizations in addition to Intel processor-specific optimizations including advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

]]> May generate Intel(R) Advanced Vector Extensions 512 (Intel(R) AVX-512) Foundation instructions, Intel(R) AVX512 Conflict Detection instructions, as well as the instructions enabled with CORE-AVX2. Optimizes for Intel(R) processors that support Intel(R) AVX-512 instructions.

]]> Code is optimized for Intel(R) processors with support for SSE 4.2 instructions. The resulting code may contain unconditional use of features that are not supported on other processors. This option also enables new optimizations in addition to Intel processor-specific optimizations including advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

]]> Code is optimized for Intel(R) processors with support for SSE 4.1 instructions. The resulting code may contain unconditional use of features that are not supported on other processors. This option also enables new optimizations in addition to Intel processor-specific optimizations including advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

]]> Code is optimized for Intel(R) processors with support for SSSE3 instructions. The resulting code may contain unconditional use of features that are not supported on other processors. This option also enables new optimizations in addition to Intel processor-specific optimizations including advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

]]> Code is optimized for Intel Pentium M and compatible Intel processors. 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.

]]> Code is optimized for Intel Pentium 4 and compatible Intel processors; this is the default for Intel?EM64T systems. The resulting code may contain unconditional use of features that are not supported on other processors.

]]> 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

]]> The use of -Qparallel to generate auto-parallelized code requires spport libraries that are dynamically linked by default. Specifying libguide.lib on the link line, statically links in libguide.lib to allow auto-parallelized binaries to work on systems which do not have the dynamic version of this library installed.

]]> The use of -Qparallel to generate auto-parallelized code requires spport libraries that are dynamically linked by default. Specifying libguide40.lib on the link line, statically links in libguide40.lib to allow auto-parallelized binaries to work on systems which do not have the dynamic version of this library installed.

]]> Optimizes for Intel Pentium 4 and compatible processors with Streaming SIMD Extensions 2 (SSE2). ]]> Enables generation of streaming stores for optimization. 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

Determines whethre the compiler assumes that there are no "large" integers being used or being computed inside loops.

]]> Defines a level of zmm registers usage. -qopt-zmm-usage=keywoard Specifies the level of zmm register usage. You can specify one of the following:

low - Tells the compiler that the compiled program is unlikely to benefit from zmm register usage. It specifies that the compiler should avoid using zmm register unless it can prove the gain from their usage.

high - Tells the compiler to generate zmm code without restrictions

]]> Enables or disables prefetch insertion optimization. Is the level of software prefetching optimization desired. Possible values are:

0 - Disable software prefetching.

1 to 5 - Enable different level of software prefetching. If you do not specify a valune tfor n, default is 2. Use lower values to reduce the amount prefetching.

]]> Specify malloc configuration parameters. Specifying a non-zero value will cause alternate configuration parameters to be set for how malloc allocates and frees memory. OpenMP* SIMD compilation is enabled if option O2 or higher is in effect. OpenMP* SIMD compilation is always disabled at optimization levels of O1 or lower. When option O2 or higher is in effect, OpenMP SIMD compilation can only be disabled by specifying option -qno-openmp-simd or /Qopenmp-simd-. It is not disabled by specifying option -qno-openmp or /Qopenmp-. (disable/enable[default] -[no-]prec-div) -prec-div improves precision of floating-point divides. It has a slight impact on speed. -no-prec-div disables this option and enables optimizations that give slightly less precise results than full IEEE division.

]]> (disable/enable[default] -[no-]prec-div) -prec-sqrt improves precision of floating-point square root. It has a slight impact on speed. -no-prec-sqrt disables this option and enables optimizations that give slightly less precise results than full IEEE division.

]]> 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.

]]> 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

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

]]> Enable SmartHeap library usage by forcing the linker to ignore multiple definitions

]]> set the stack reserve amount specified to the linker Enable/disable(DEFAULT) use of ANSI aliasing rules in optimizations; user asserts that the program adheres to these rules. Enable/disable(DEFAULT) use of ANSI aliasing rules in optimizations; user asserts that the program adheres to these rules. Enable/disable(DEFAULT) the compiler to generate prefetch instructions to prefetch data. Directs the compiler to inline calloc() calls as malloc()/memset() Specify malloc configuration parameters. Specifying a non-zero value will cause alternate configuration parameters to be set for how malloc allocates and frees memory Enable/disable(DEFAULT) calls to fast calloc function Enables cache/bandwidth optimization for stores under conditionals (within vector loops) Enable compiler to generate runtime control code for effective automatic parallelization 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 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 Enables more aggressive multi-versioning Enable the compiler to generate multi-threaded code based on the OpenMP* directives Enable the compiler to generate multi-threaded code based on the OpenMP* directives(New option.) Enables or disables OpenMP* SIMD compilation. You can use this option if you want to enable or disable the SIMD support with no impact on other OpenMP features. In this case, no OpenMP runtime library is needed to link and the compiler does not need to generate OpenMP runtime initialization code. Enables recognition of OpenMP* features and tells the parallelizer to generate multi-threaded code based on OpenMP* directives. Emit OpenMP code only for SIMD-based constructs. Advanced users who prefer to use OpenMP* as it is implemented by the LLVM community can get most of that functionality by using -fopenmp-simd. Enables recognition of OpenMP* features, such as parallel, simd, and offloading directives. This is an alternate option for compiler option [Q or q]openmp. Enables OpenMP* offloading compilation for target pragmas. This option only applies to Intel(R) Graphics Technology. Enabled by default with -qopenmp. Use -qno-openmp-offload to disable. Specify kind to specify the default device for target pragmas host - allow target code to run on host system while still doing the outlining for offload mic - specify Intel(R) MIC Architecture gfx - Specify Intel(R) Graphics Technology Make all local variables AUTOMATIC. Same as -automatic Enables more aggressive unrolling heuristics Lets you select between old or new implementations of parallel loop support. Specifies which implementation to use. Possible values are:

new

Enables the new implementation of parallel-loop support. As a result, parallel C++ range-based loops and collapsing complex loop stacks will not result in compilation errors. This is the default.

old

Enables the old implementation of parallel-loop support. This is the same implementation that was supported in 18.0 and earlier releases.

default>

This is the same as specifying new.

]]> Lets you identify and fix code that may be vulnerable to speculative execution side-channel attacks, which can leak your secure data as a result of bad speculation of a conditional branch direction. Indicates to the compiler what action to take. Possible values are:

keep

Tells the compiler to not attempt any vulnerable code detection or fixing. This is equivalent to not specifying the -mconditional-branch option.

pattern-report

Tells the compiler to perform a search of vulnerable code patterns in the compilation and report all occurrences to stderr.

pattern-fix

Tells the compiler to perform a search of vulnerable code patterns in the compilation and generate code to ensure that the identified data accesses are not executed speculatively. It will also report any fixed patterns to stderr.

This setting does not guarantee total mitigation, it only fixes cases where all components of the vulnerability can be seen or determined by the compiler. The pattern detection will be more complete if advanced optimization options are specified or are in effect, such as option O3 and option -ipo (or /Qipo).

all-fix

Tells the compiler to fix all of the vulnerable code so that it is either not executed speculatively, or there is no observable side-channel created from their speculative execution. Since it is a complete mitigation against Spectre variant 1 attacks, this setting will have the most run-time performance cost.

In contrast to the pattern-fix setting, the compiler will not attempt to identify the exact conditional branches that may have led to the mis-speculated execution.

all-fix-lfence

This is the same as specifying setting all-fix.

all-fix-cmov

Tells the compiler to treat any path where speculative execution of a memory load creates vulnerability (if mispredicted). The compiler automatically adds mitigation code along any vulnerable paths found, but it uses a different method then the one used for all-fix (or all-fix-lfence).

This method uses CMOVcc instruction execution, which constrains speculative execution. Thus, it is used for keeping track of the predicate value, which is updated on each conditional branch.

To prevent Spectre v.1 attack, each memory load that is potentially vulnerable is bitwise ORed with the predicate to mask out the loaded value if the code is on a mispredicted path.

This is analogous to the Clang compiler's option to do Speculative Load Hardening.

This setting is only supported on Intel® 64 architecture-based systems.

]]> Determines whether the compiler optimizes tail recursive calls. This feature is only available for ifort. Determines whether calls to routines are optimized by passing arguments in registers instead of on the stack. This option is deprecated and will be removed in a future release. This feature is only available for ifort. Tells the compiler to generate code for Intel® 64 architecture. Determines whether the compiler generates fused multiply-add (FMA) instructions if such instructions exist on the target processor. Tells the compiler to generate code for processors that support certain features. May generate instructions for processors that support the specified Intel® processor or microarchitecture code name. Keywords knl and silvermont are only available on Linux* systems. This content is specific to C++; it does not apply to DPC++. Keyword icelake is deprecated and may be removed in a future release.

amberlake

broadwell

cannonlake

cascadelake

coffeelake

goldmont

goldmont-plus

haswell

icelake-client (or icelake)

icelake-server

ivybridge

kabylake

knl

knm

sandybridge

silvermont

skylake

skylake-avx512

tremont

whiskeylake

core-avx2 - Generates code for processors that support Intel® Advanced Vector Extensions 2 (Intel® AVX2), Intel® AVX, SSE4.2, SSE4.1, SSE3, SSE2, SSE, and SSSE3 instructions.

core-avx-i - Generates code for processors that support Float-16 conversion instructions and the RDRND instruction, Intel® Advanced Vector Extensions (Intel® AVX), Intel® SSE4.2, SSE4.1, SSE3, SSE2, SSE, and SSSE3 instructions.

corei7-avx - Generates code for processors that support Intel® Advanced Vector Extensions (Intel® AVX), Intel® SSE4.2, SSE4.1, SSE3, SSE2, SSE, and SSSE3 instructions.

corei7 - Generates code for processors that support Intel® SSE4 Efficient Accelerated String and Text Processing instructions. May also generate code for Intel® SSE4 Vectorizing Compiler and Media Accelerator, Intel® SSE3, SSE2, SSE, and SSSE3 instructions.

atom - Generates code for processors that support MOVBE instructions. May also generate code for SSSE3 instructions and Intel® SSE3, SSE2, and SSE instructions.

core2 - Generates code for the Intel® Core™2 processor family.

pentium4m - Generates for Intel® Pentium® 4 processors with MMX technology.

pentium-m - Generates code for Intel® Pentium® processors. Value pentium3 is only available on Linux* systems.

pentium4

pentium3

pentium

]]> Performs optimizations for specific processors but does not cause extended instruction sets to be used (unlike -march).

amberlake

broadwell

cannonlake

cascadelake

coffeelake

goldmont

goldmont-plus

haswell

icelake-client (or icelake)

icelake-server

ivybridge

kabylake

knl

knm

sandybridge

silvermont

skylake

skylake-avx512

tremont

whiskeylake

core-avx2 - Generates code for processors that support Intel® Advanced Vector Extensions 2 (Intel® AVX2), Intel® AVX, SSE4.2, SSE4.1, SSE3, SSE2, SSE, and SSSE3 instructions.

corei7-avx - Generates code for processors that support Intel® Advanced Vector Extensions (Intel® AVX), Intel® SSE4.2, SSE4.1, SSE3, SSE2, SSE, and SSSE3 instructions.

atom - Generates code for processors that support MOVBE instructions. May also generate code for SSSE3 instructions and Intel® SSE3, SSE2, and SSE instructions.

core2 - Generates code for the Intel® Core™2 processor family.

pentium4m - Generates for Intel® Pentium® 4 processors with MMX technology.

pentium-m - Generates code for Intel® Pentium® processors. Value pentium3 is only available on Linux* systems.

pentium4

pentium3

pentium

]]> Enables or disables the optimization for multiple adjacent gather/scatter type vector memory references. This content is specific to C++; it does not apply to DPC++. Allow aggressive, lossy floating-point optimizations. Enable optimizations based on the strict definition of an enum's value range. Enable optimizations based on the strict rules for overwriting polymorphic C++ objects. Enables dead virtual function elimination optimization. Requires -flto=full. Allow optimizations for floating point arithmetic that assume arguments and results are not NaNs or Infinities. Creates multiple processes that can be used to compile large numbers of source files at the same time. n is the maximum number of processes that the compiler should create. compile all procedures for possible recursive execution. Allow optimizations that ignore the sign of floating point zeros Enables or disables vectorization. To disable vectorization, specify -no-vec (Linux* and macOS) or /Qvec- (Windows*). To disable interpretation of SIMD directives, specify -no-simd (Linux* and macOS) or /Qsimd- (Windows*). To disable all compiler vectorization, use the "-no-vec -no-simd" (Linux* and macOS) or "/Qvec- /Qsimd-" (Windows*) compiler options. The option -no-vec (and /Qvec-) disables all auto-vectorization, including vectorization of array notation statements. The option -no-simd (and /Qsimd-) disables vectorization of loops that have SIMD directives. Enables or disables vectorization. To disable vectorization, specify -no-vec (Linux* and macOS) or /Qvec- (Windows*). To disable interpretation of SIMD directives, specify -no-simd (Linux* and macOS) or /Qsimd- (Windows*). To disable all compiler vectorization, use the "-no-vec -no-simd" (Linux* and macOS) or "/Qvec- /Qsimd-" (Windows*) compiler options. The option -no-vec (and /Qvec-) disables all auto-vectorization, including vectorization of array notation statements. The option -no-simd (and /Qsimd-) disables vectorization of loops that have SIMD directives. Enables a program to be compiled as a SYCL* program rather than as plain C++11 program. Enables elimination of DPC++ dead kernel arguments Enables LLVM-related optimizations before SPIR-V* generation. Determines whether EBP is used as a general-purpose register in optimizations. Determines whether EBP is used as a general-purpose register in optimizations. Control the level of memory layout transformations performed by the compiler This option controls the level of memory layout transformations performed by the compiler. This option can improve cache reuse and cache locality.

Is the level of memory layout transformations. Possible values are:

Disables memory layout transformations. This is the same as specifying -qno-opt-mem-layout-trans (Linux* or macOS) or /Qopt-mem-layout-trans- (Windows*).

Enables basic memory layout transformations.

Enables more memory layout transformations. This is the same as specifying [q or Q]opt-mem-layout-trans with no argument.

Enables more memory layout transformations like copy-in/copy-out of structures for a region of code. You should only use this setting if your system has more than 4GB of physical memory per core.

Enables more aggressive memory layout transformations. You should only use this setting if your system has more than 4GB of physical memory per core.

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Syntax

Default

Description

Affinity Types

type = none (default)

type = compact

type = disabled

type = explicit

type = scatter

Deprecated Types: logical and physical

Permute and offset combinations

Modifier Values for Affinity Types

modifier = noverbose (default)

modifier = verbose

Execution modes

Serial

Turnaround

Throughput