Alphabetical Quick Reference Guide

Option

Description

Default

-1

Executes at least one iteration of DO loops (same as the -onetrip option). This option has the same effect as -f66.

OFF

-66

Enforces FORTRAN-66 semantics (same as the -f66 option).

-nof66

-72, -80, -132

Treats the statement field of each fixed-form source line as ending in column 72, 80, or 132. Option -132 is the same as the -extend_source option.

-72

-align keyword

Tells the compiler how to align data items. 
keyword: all, none,
[no]commons,
[no]dcommons,
[no]records,
recnbyte,
[no]sequence
For details on these keywords, see your user's guide or the ifort man page.

-align nocommons
-align nodcommons
-align records
-align nosequence

-ansi_alias-

Tells the compiler to assume the program does not adhere to the Fortran 95 Standard type aliasability rules.

-ansi_alias

-arch keyword 
(i32 only)

Determines the version of the architecture for which the compiler generates instructions.
keyword:
pn1 - Optimizes for the Intel® Pentium® processor.
pn2 - Optimizes for the Intel® Pentium® Pro, Intel® Pentium® II, and Intel® Pentium® III processors.
pn3 - This is the same as specifying the -arch pn2 option.
pn4 - Optimizes for the Intel® Pentium® 4 processor.
SSE - Optimizes for Intel Pentium 4 processors with Streaming SIMD Extensions (SSE).
SSE2 - Optimizes for Intel Pentium 4 processors with Streaming SIMD Extensions 2 (SSE2).

-arch pn4

-assume keyword

Specifies assumptions made by the compiler.
keyword: none, [no]bscc, [no]buffered_io,
[no]byterecl,
[no]cc_omp,
[no]dummy_aliases,
[no]minus0,
[no]protect_constants,
[no]source_include,
[no]underscore
If -openmp is specified, it sets -assume cc_omp.
For details on these keywords, see your user's guide or the ifort man page.

OFF
(-assume none)

-auto

Places variables, except those declared as SAVE, on the run-time stack (same as -automatic or -nosave).
If you specify -recursive or -openmp, the default is -auto.

-auto_scalar

-auto_ilp32
(i32em, i64)

Specifies that the application cannot exceed a 32-bit address space, which allows the compiler to use 32-bit pointers whenever possible. To use this option, you must also specify -ipo.

On Intel® EM64T systems, this option has no effect unless you also specify -xP or -axP.

If you use the -auto_ilp32 option on programs that can exceed 32-bit address space (2**32), unpredictable results may occur during program execution.

OFF

-auto_scalar

Makes AUTOMATIC all scalar local variables of intrinsic type INTEGER, REAL, COMPLEX, or LOGICAL. You cannot specify -save, -auto, or -automatic with this option.

ON unless
-recursive or
-openmp is specified.

-autodouble

Defines real variables to be REAL(KIND=8). This option is the same as specifying -r8.

OFF

-automatic

Places variables, except those declared as SAVE, on the run-time stack (same as the -auto or -nosave options).
If you specify -recursive or -openmp, the default is -auto.

-auto_scalar

-ax{K|W|N|B|P}
(i32, i32em)

Generates processor-specific code if there is a performance benefit. The processor type is indicated by one of the following values:

K - Intel® Pentium® III processors and compatible Intel processors.

W - Intel® Pentium® 4 processors and compatible Intel processors.

N - Intel® Pentium® 4 processors and compatible Intel processors.

B - Intel® Pentium® M and compatible Intel processors

P - Intel® Pentium® 4 processor with Streaming SIMD Extensions 3 (SSE3) instruction support

The only options available on Intel® EM64T systems are -axP and -axW.

For more details, see your user's guide or the ifort man page.

OFF

-Bdynamic

Enables dynamic linking of libraries at run time. Smaller executables are created than with static linking.

OFF

-Bstatic

Enables static linking of a user's library.

OFF

-c

Causes the compiler to compile to an object (.o) file only and not link.

OFF

-CB

Performs run-time checks on whether array subscript and substring references are within declared bounds. Same as the -check bounds option.

OFF

-ccdefault keyword

Specifies the type of carriage control used for units 6 and *.
keyword: default, fortran, list, or none.
The default setting can be affected by the -vms option.
For details on these keywords, see your user's guide or the ifort man page.

-ccdefault default

-check keyword

Checks several run-time conditions.
keyword: all, none, [no]arg_temp_created, [no]bounds, [no]format, [no]output_conversion.
For details on these keywords, see your user's guide or the ifort man page.

OFF
(-nocheck or
-check none)

-cm

Suppresses all messages about questionable programming practices (same as the -warn nousage option).

OFF (-nocm)

-common_args

Tells the compiler that dummy (formal) arguments to procedures share memory locations with other dummy arguments or with  variables shared through use association, host association, or common block use. This is the same as specifying
-assume dummy_aliases.

OFF (-no
common_args)

-complex_limited_
range[-] 

Enables the use of basic algebraic expansions of some arithmetic operations involving data of type COMPLEX. This can cause some performance improvements in programs that use a lot of COMPLEX arithmetic, but values at the extremes of the exponent range may not compute correctly.

OFF
(-complex_
limited_
range-)

-convert keyword

Specifies the format of unformatted files containing numeric data.
keyword: big_endian, cray, fdx, fgx, ibm, little_endian, native, vaxd, vaxg.

-convert native

-cpp

Runs the Fortran preprocessor on source files prior to compilation (same as the -fpp option).

OFF (-nocpp)

-Dname
-Dname[=value]

Defines the name as a definition to use with conditional compilation directives or the Fortran preprocessor (-fpp). The value can be an integer or it can be a character string delimited by double quotes; for example,
-Dname="string". If no definition is given, name is defined as "1".

OFF

-d_lines

Compiles debug statements indicated by the letter D in column 1 of the source code; this is the same as specifying -DD.

OFF (-nod_lines)

-DD

Compiles debug statements indicated by the letter D in column 1 of the source code; this is the same as specifying -d_lines.

OFF

-debug keyword (*new)

Specifies settings that enhance debugging. To use these options, you must also specify -g.
keyword: variable_locations
For details on this keyword, see your user's guide or the ifort man page.

OFF

-double_size size

Defines the SIZE of DOUBLE PRECISION and DOUBLE COMPLEX declarations, constants, functions, and intrinsics.  
size can be 64 or 128.

-double_size 64

-dryrun

Specifies that driver tool commands should be shown but not executed.

OFF (-nodryrun)

-dynamic-linkerfile

Specifies a dynamic linker in file other than the default.

OFF

-dyncom "a,b,c"

Enables dynamic allocation of the specified COMMON blocks at run time. The quotes are required.

OFF

-E

Causes the Fortran preprocessor to send output to stdout.

OFF

-e90

Causes the compiler to issue errors instead of warnings for nonstandard Fortran 90.

OFF

-e95

Causes the compiler to issue errors instead of warnings for nonstandard Fortran 95.

OFF

-EP

Causes the Fortran preprocessor to send output to stdout, omitting #line directives.

OFF

-[no]error_limit n

Specifies the maximum number of error-level or fatal-level compiler errors allowed for a file specified on the command line. If you specify -noerror_limit, there is no limit to the number of errors that are allowed.

-error_limit 30

-extend_source [size]

Specifies the column number to use to end the statement field in fixed-form source files.  
size can be 72, 80, or 132.  
Specifying -noextend_source implies column 72. If you specify -extend_source with no size, it's the same as specifying -extend_source 132.

OFF (-no
extend_source)

-F

Causes the Fortran preprocessor to send output to a file (same as the
-preprocess_only and -P options). To use this option, you must also specify -fpp.

OFF

-f66

Tells the compiler to apply FORTRAN-66 semantics; the default is to apply Fortran 95 semantics.
For more details, see your user's guide or the ifort man page.

OFF (-nof66)

-f77rtl

Tells the compiler to use the run-time behavior of FORTRAN 77 instead of Intel® Fortran.
For more details, see your user's guide or the ifort man page.

OFF
(-nof77rtl)

-fast

Maximizes speed across the entire program.

On Itanium®-based systems, this option sets options -O3, -ipo, and -static. On IA-32 and Intel® EM64T systems, this option sets options -O3, -ipo, -static, and -xP.

Note that on IA-32 systems, programs compiled with the -xP option will detect non-compatible processors and generate an error message during execution.

OFF (-nofast)

-fcode_asm

Produces an assembly file with optional code annotations. To use this option, you must also specify -S.

OFF

-FI

Specifies source files are in fixed format (same as the -fixed option).

OFF

-fixed

Specifies source files are in fixed format (same as the -FI option). By default, source file format is determined by the file suffix.

OFF

-fltconsistency

Enables improved floating-point consistency. The default setting provides better accuracy and run-time performance at the expense of less consistent floating-point results.
For more details, see your user's guide or the ifort man page.

OFF (-no
fltconsistency)

-fminshared

Specifies that a compilation unit is a component of a main program and will not be linked as part of a shareable object.

OFF

-fno-alias

Specifies that aliasing should not be assumed in the program.

-falias

-fno-fnalias

Specifies that aliasing should not be assumed within functions, but should be assumed across calls.

-ffnalias

-fnsplit
(i64 only)

Enables function splitting if -prof_use is also specified. Otherwise, the default value disables the splitting within a routine but leaves function grouping enabled.

OFF (-fnsplit-)

-fp
(i32, i32em)

Disables using EBP as a general purpose register so it can be used as a stack frame printer.

OFF (-fp-)

-fp_port
(i32 only)

Rounds floating-point results after floating-point operations, so rounding to user-declared precision happens at assignments and type conversions; this has some impact on speed.
The default is to keep results of floating-point operations in higher precision; this provides better performance but less consistent floating-point results.

OFF

-fpconstant

Tells the compiler to extend the precision to double precision for single-precision constants assigned to double-precision variables.

OFF
(-nofpconstant)

-fpen

Specifies floating-point exception handling at run time for the main program. n=0, 1, 3.
0 - floating underflow results in zero; all other floating-point exceptions abort execution
1 - floating underflow results in zero; all other floating-point exceptions produce exceptional values (signed Infinities or NaNs) and execution continues
3 - all floating-point exceptions produce exceptional values (signed infinities, denormals, or NaNs) and execution continues; also see -ftz.

-fpe3

-fpic

Generates position-independent code. Can also be specified as -fPIC.
On Itanium-based systems, this option must be used when building shared objects.

OFF

-fpp

Runs the Fortran preprocessor on source files prior to compilation.

OFF

-fpscomp [keyword]

Specifies the level of compatibility with Microsoft* Fortran PowerStation or Intel® Fortran. 
keyword: all, none, [no]filesfromcmd, [no]general, [no]ioformat, [no]libs, [no]ldio_spacing, [no]logicals.
For details on these keywords, see your user's guide or the ifort man page.

For all and nolibs:
-fpscomp libs

For the rest:
-fpscomp none

-fpstkchk 
(i32 only)

Generates extra code after every function call to ensure that the FP (floating-point) stack is in the expected state. By default, there is no checking.
For more details, see your user's guide or the ifort man page.

OFF

-FR

Specifies source files are in free format (same as the -free option).

Based on source file extension

-fr32
(i64 only)

Disables use of high floating-point registers. Uses only the lower 32 floating-point registers.

OFF

-free

Specifies source files are in free format (same as the -FR option). By default, source file format is determined by the file suffix.

OFF

-fsource_asm

Produces an assembly file with optional code annotations. To use this option, you must also specify -S.

OFF

-ftz

Enables floating underflow results set to zero.
On Itanium-based systems, option -O3 sets the -ftz option.

OFF
(-ftz-)

-fverbose-asm

Produces an assembly file with compiler comments, including options and version information. To use this option, you must also specify -S, which sets -fverbose-asm. If you do not want this default when you specify -S, specify -fnoverbose-asm.

OFF
(-fnoverbose-asm)

-fvisibility=keyword 
-fvisibility-keyword
=file

The first form specifies the default visibility for global symbols.

The second form specifies the visibility for symbols that are in a file (this form overrides the first form).
file is the pathname of a file containing the list of symbols whose visibility you want to set; the symbols are separated by whitespace (spaces, tabs, or newlines).

keyword: external, default, protected, hidden, and internal.
For details on these keywords, see your user's guide or the ifort man page.

OFF

-g

Produces symbolic debug information in the object file. The compiler does not support the generation of debugging information in assemblable files. If you specify the -g option, the resulting object file will contain debugging information, but the assemblable file will not.

On IA-32 systems, specifying the -g or -O0 option automatically enables the
-fp option. For more information, see "Optimizations and Debugging" in Volume II of your user's guide.

OFF

-help

Displays the list of compiler options.

OFF

-Idir

Specifies a directory to add to the include path, which is used to search for module files (USE statement) and include files (INCLUDE statement).

OFF

-i_dynamic

Links Intel-provided libraries dynamically.

OFF

-i{2|4|8}

Specifies the default size of integer and logical variables to be 2, 4, or 8 bytes (same as -integer_size {16|32|64}).

-integer_size 32

-implicitnone

Sets the default type of a variable to undefined (IMPLICIT NONE). Same as the -u option.

OFF

-inline_debug_info

Produces enhanced source position information for inlined code. It also provides enhanced debug information useful for function call traceback. To use this option for debugging, you must also specify -g.

OFF

-intconstant

Tells the compiler to use Fortran 77 semantics, rather than Fortran 95/90 semantics, to determine the KIND for integer constants.

OFF
(-no
intconstant)

-integer_size size

Specifies the default size of integer and logical variables. size can be 16, 32, or 64.

-integer_size 32

-ip

Enables single-file interprocedural optimizations. If you specify this option, the compiler performs inline function expansion for calls to functions defined within the current source file.

OFF

-ip_no_inlining

Disables full and partial inlining enabled by -ip. To use this option, you must specify -ip or -ipo.

OFF

-ip_no_pinlining

Disables partial inlining. To use this option, you must specify -ip or -ipo.

OFF

-IPF_fltacc
(i64 only)

Disables optimizations that affect floating-point accuracy. If the default setting is used, the compiler may apply optimizations that reduce floating-point accuracy. You can use -IPF_fltacc or -mp to improve floating-point accuracy, but at the cost of disabling some optimizations.

OFF
(-IPF_fltacc-)

-IPF_flt_eval_
method0
(i64 only)

Tells the compiler to evaluate the expressions involving floating-point operands in the precision indicated by the variable types declared in the program. By default, intermediate floating-point expressions are maintained in higher precision.

OFF

-IPF_fma
(i64 only)

Enables the combining of floating-point multiplies and add/subtract operations. Also enables the contraction of floating-point multiply and add/subtract operations into a single operation. The compiler contracts these operations whenever possible. However, if -mp is specified, these contractions are disabled.

OFF
(-IPF_fma-)

-IPF_fp_relaxed (*new)
(i64 only)

Enables use of faster but slightly less accurate code sequences for math functions, such as divide and sqrt. When compared to strict IEEE* precision, this option slightly reduces the accuracy of floating-point calculations performed by these functions, usually limited to the least significant digit.

OFF
(-IPF_fp_relaxed-)

-IPF_fp_speculation
mode
(i64 only)

Tells the compiler to speculate on floating-point (FP) operations in one of the following modes: 
fast: speculate on floating-point operations 
safe: speculate on floating-point operations only when safe
strict: same as specifying off
off: disables speculation of floating-point operations

-IPF_fp_
speculation
fast

-ipo[n]

Enables multifile interprocedural (IP) optimizations (between files). When you specify this option, the compiler performs inline function expansion for calls to functions defined in separate files.

n is an optional integer that specifies the number of object files the compiler should create. Any integer greater than or equal to 0 is valid.

If n is 0, the compiler decides whether to create one or more object files based on an estimate of the size of the object file. It generates one object file for small applications, and two or more object files for large applications.

If n is greater than 0, the compiler generates n object files, unless n exceeds the number of source files (m), in which case the compiler generates only m object files.

If you do not specify n, the default is 1.

OFF

-ipo_c

Generates a multifile object file (ipo_out.o) that can be used in further link steps.

OFF

-ipo_obj

Forces the generation of real object files. To use this option, you must specify -ipo.

OFF (-ipo_obj-)

-ipo_S

Generates a multifile assembly file (ipo_out.s) that can be used in further link steps.

OFF

-ipo_separate (*new)

Tells the compiler to generate one object file per source file. This option overrides any -ipon specification.

OFF

-ivdep_parallel
(i64 only)

Tells the compiler that there is no loop-carried memory dependency in any loop following an IVDEP directive.

OFF

-Kpic

This is a deprecated option; it can also be specified as -KPIC. Use -fpic instead.

OFF

-Ldir

Tells the linker to search for libraries in dir before searching the standard directories.

OFF

-lowercase

Causes the compiler to ignore case differences in identifiers and to convert external names to lowercase (same as the -names lowercase option).

ON

-logo

Displays the compiler version information.

OFF (-nologo)

-mixed_str_len_arg

Tells the compiler that the hidden length passed for a character argument is to be placed immediately after its corresponding character argument in the argument list. The default places the hidden lengths in sequential order at the end of the argument list.

OFF
(-no
mixed_str_len_arg)

-module dir

Specifies the directory dir where module (.mod) files should be placed when created and where they should be searched for (USE statement).

OFF

-mp

Maintains floating-point precision (while disabling some optimizations). Restricts optimization to maintain declared precision and to ensure that floating-point arithmetic conforms more closely to the ANSI* and IEEE standards.

For most programs, specifying this option adversely affects performance. If you are not sure whether your application needs this option, try compiling and running your program both with and without it to evaluate the effects on both performance and precision.

OFF

-mp1

Improves floating-point precision. This option disables fewer optimizations and has less impact on performance than -mp.

OFF

-names keyword

Specifies how source code identifiers and external names are interpreted.
keyword: as_is, lowercase, uppercase.
For details on these keywords, see your user's guide or the ifort man page.

-names lowercase

-nbs

Tells the compiler to treat a backslash (\) as a normal character, not an escape character (same as the -assume nobscc option).

ON

-no_cpprt

Prevents linking of the C++ run-time libraries.

OFF

-noalign

Prevents the alignment of data items. This is the same as specifying -align none.

OFF (-align)

-noaltparam

Specifies that the alternate form of parameter constant declarations should not be recognized.

OFF (-altparam)

-nobss_init

Places any variables that are explicitly initialized with zeros in the DATA section. By default, variables explicitly initialized with zeros are placed in the BSS section.

OFF

-nodefaultlibs

Prevents the compiler from using standard libraries when linking.

OFF

-nodefine

Specifies that all preprocessor definitions apply only to -fpp and not to Intel Fortran conditional compilation directives.

OFF

-nodps

Specifies that the alternate form of parameter constant declarations (without parentheses) should not be recognized (same as the -noaltparam option).

OFF (-dps)

-nofor_main

Specifies the main program is not written in Fortran, and prevents the compiler from linking for_main.o into applications.

OFF (-for_main)

-noinclude

Prevents the compiler from searching in /usr/include for files specified in an INCLUDE statement. You can specify the -Idir option along with this option. This option does not affect cpp(1) behavior, and is not related to the Fortran 95/90 USE statement.

OFF

-nolib_inline

Disables inline expansion of intrinsic functions.

OFF

-nostartfiles

Prevents the compiler from using standard startup files when linking.

OFF

-nostdinc

Removes standard directories from the include file search path (same as the -X option).

OFF

-nostdlib

Prevents the compiler from using standard libraries and startup files when linking.

OFF

-nus

Prevents the compiler from appending an underscore character to external user-defined names.
This option is the same as the -assume nounderscore option, and is the opposite of -us.

ON

-oname

Specifies the name for an output file as follows:
If -c is specified, -o specifies the name of an object file.
If -S is specified, -o specifies the name of an assembly listing file.
Otherwise, -o specifies the name of the executable file.

OFF

-O0

Disables -On optimizations. On IA-32 and Intel® EM64T systems, this option sets the -fp option.

OFF

-O1

On IA-32 and Intel® EM64T systems, enables optimizations for speed. Also disables intrinsic recognition and the -fp option. This option is the same as the -O2 option.

On Itanium-based systems, enables optimizations for server applications (straight-line and branch-like code with flat profile). Enables optimizations for speed, while being aware of code size. For example, this option disables software pipelining and loop unrolling.

OFF

-O2 or -O

This option is the default for optimizations. However, if -g is specified, the default is -O0.

On IA-32 and Intel® EM64T systems, this option is the same as the -O1 option.

On Itanium-based systems, the -O2 option enables optimizations for speed, including global code scheduling, software pipelining, predication, and speculation.

On these systems, it enables inlining of intrinsics. It also enables 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, and dead store elimination.

ON

-O3

Enables -O2 optimizations plus more aggressive optimizations, such as prefetching, scalar replacement, and loop transformations. Enables optimizations for maximum speed, but does not guarantee higher performance unless loop and memory access transformation take place.

On IA-32 and Intel® EM64T systems, when the -O3 option is used with the -ax and -x options, it causes the compiler to perform more aggressive data dependency analysis than for -O2, which may result in longer compilation times.

On Itanium-based systems, the -O3 option enables optimizations for technical computing applications (loop-intensive code): loop optimizations and data prefetch.

OFF

-onetrip

Executes at least one iteration of DO loops (same as the -1 option). This option has the same effect as -f66.

OFF

-openmp

Enables the parallelizer to generate multithreaded code based on OpenMP* directives. The code can be executed in parallel on both uniprocessor and multiprocessor systems.
The -openmp option works with both -O0 (no optimization) and any optimization level of -On.
Specifying -O0 with -openmp helps to debug OpenMP applications.

OFF

-openmp_profile (*new)

Enables analysis of OpenMP* applications.  
To use this option, you must have Thread Profiler installed, which is one of the Intel® Threading Tools. If this threading tool is not installed, this option has no effect.

OFF

-openmp_
report[n]

Controls the OpenMP parallelizer's level of diagnostic messages. n=0, 1, 2.
0 - Displays no diagnostic information.
1 - Displays diagnostics indicating loops, regions, and sections successfully parallelized.
2 - Displays the diagnostics specified by -openmp_report1 plus diagnostics indicating successful handling of MASTER constructs, SINGLE constructs, CRITICAL constructs, ORDERED constructs, ATOMIC directives, etc..

-openmp
_report1

-openmp_stubs

Tells the compiler to generate sequential code. The OpenMP directives are ignored and a stub OpenMP library is linked.

OFF

-opt_report

Tells the compiler to generate an optimization report to stderr.

OFF

-opt_report_file
file

Tells the compiler to generate an optimization report and name it file.

OFF

-opt_report_help

Lists the logical names of optimizers available for report generation (for -opt_report_phase).

OFF

-opt_report_level
level

Specifies the detail level of the optimization report.
level can be min, med, or max.

-opt_report_
levelmin

-opt_report
_phasephase

Specifies the optimizer phase to generate reports for. The compiler generates reports for the optimizer you specify in phase. This option can be used multiple times on the same command line to generate reports for multiple optimizers. Currently, the following optimizer reports are supported:

ipo − Interprocedural Optimizer
hlo − High Level Optimizer
ilo − Intermediate Language Scalar Optimizer
ecg − Code Generator
omp − Open MP
all − All phases

When one of the above logical names for optimizers is specified for phase, all reports from that optimizer are generated.

OFF

-opt_report_routine 
[substring]

Generates a report on the routines containing the specified substring. If substring is not specified, reports from all routines are generated.

OFF

-p

Compiles and links for function profiling with gprof(1). This is the same as specifying -pg or -qp.

OFF

-P

Causes the Fortran preprocessor to send output to a file (same as the -preprocess_only and -F options). To use this option, you must also specify -fpp.

OFF

-pad

Enables the changing of the variable and array memory layout.

OFF (-nopad)

-pad_source

Specifies that fixed-form source records shorter than the statement field width are to be padded with spaces (on the right) to the end of the statement field. This affects the interpretation of character and Hollerith literals that are continued across source records.

OFF (-no
pad_source)

-par_report[n]

Controls the auto-parallelizer's level of diagnostic messages. n=0, 1, 2, 3.

0 - Displays no diagnostic information.
1 - Displays diagnostics indicating loops successfully auto-parallelized. Issues a "LOOP AUTO-PARALLELIZED" message for parallel loops.
2 - Displays diagnostics indicating loops successfully auto-parallelized, as well as unsuccessful loops.
3 - Displays the diagnostics specified by -par_report2 plus additional information about any proven or assumed dependencies inhibiting auto-parallelization (reasons for not parallelizing).

-par_report1

-par_thresholdn

Sets a threshold for the auto-parallelization of loops based on the probability of profitable execution of the loop in parallel. This option is used for loops whose computation work volume cannot be determined at compile-time. The threshold is usually relevant when the loop trip count is unknown at compile-time.
n=0 to 100.
The compiler applies a heuristic that tries to balance the overhead of creating multiple threads versus the amount of work available to be shared amongst the threads.

-par_threshold100

-parallel

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 -O2 or -O3.

OFF

-pcn
(i32, i32em)

Enables control of floating-point significand precision. Some floating-point algorithms are sensitive to the accuracy of the significand, or fractional part of the floating-point value. For example, iterative operations like division and finding the square root can run faster if you lower the precision with the -pcn option. 
n=32, 64, 80.

32 - Rounds the significand to 24 bits
64 - Rounds the significand to 53 bits
80 - Rounds the significand to 64 bits

-pc64

-pg

Compiles and links for function profiling with gprof(1). This is the same as specifying -p or -qp.

OFF

-prec_div
(i32, i32em)

Improves precision of floating-point divides; it has some speed impact. With some optimizations, such as -xN and -xB, the compiler may change floating-point division computations into multiplication by the reciprocal of the denominator. For example, A/B is computed as A * (1/B) to improve the speed of the computation. However, for values of B greater than 2126, the value of 1/B is "flushed" (changed) to 0.

When it is important to maintain the value of 1/B, use -prec_div to disable the floating-point division-to-multiplication optimization. The result of -prec_div is more accurate, with some loss of performance.

OFF

-prefetch-
(i32 only)

Disables prefetch insertion optimization.  To use this option, you must also specify -O3.

OFF (-prefetch)

-preprocess_only

Causes the Fortran preprocessor to send output to a file (same as the -F and -P options). To use this option, you must also specify -fpp.

OFF

-prof_dirdir

Specifies a directory (dir) for profiling output files *.dyn and *dpi.

OFF

-prof_filefile

Specifies a file name (file) for the profiling summary file.

OFF

-prof_format_32
(i32, i64)

Produces profile data with 32-bit counters; allows compatibility with earlier compilers. The default is to produce profile data with 64-bit counters to handle large numbers of events.

OFF

-prof_gen

Instruments a program for profiling.

OFF

-prof_use

Enables use of profiling information during optimization.

OFF

-Qinstalldir

Sets dir as a root directory for compiler installation.

OFF

-Qlocation,str,dir

Sets dir as the location of the tools specified by str.

OFF

-Qoption,str,opts

Passes options (opts) to the tools specified by str, which can be fpp, f, c, link, asm (on IA-32 systems), or ias (on Itanium-based systems).

OFF

-qp

Compiles and links for function profiling with gprof(1). This is the same as specifying -p or -pg.

OFF

-r8

Defines REAL declarations, constants, functions, and intrinsics as DOUBLE PRECISION REAL*8, and defines COMPLEX declarations, constants, functions, and intrinsics as DOUBLE COMPLEX (COMPLEX*16). This option is the same as specifying -real_size 64 or -autodouble.

OFF

-r16

Defines REAL and DOUBLE PRECISION declarations, constants, functions, and intrinsics as REAL*16, and defines COMPLEX and DOUBLE COMPLEX declarations, constants, functions, and intrinsics as COMPLEX*32. This option is the same as specifying -real_size 128.

OFF

-rcd
(i32 only)

Enables fast float-to-integer conversions.
Disables the change to truncation of the rounding mode for all floating-point calculations, including floating point-to-integer conversions. This option can improve performance, but floating-point conversions to integer will not conform to Fortran semantics.
For more details, see your user's guide or the ifort man page.

OFF

-real_size size  

Defines the size of REAL and COMPLEX declarations, constants, functions, and intrinsics. size can be 32, 64, or 128.

-real_size 32

-recursive

Specifies that all routines should be compiled for possible recursive execution. This option sets the -auto option.

OFF
(-norecursive)

-reentrancy keyword

Specifies that the compiler should generate reentrant code that supports a multithreaded application.
keyword: none, threaded, async.
For details on these keywords, see your user's guide or the ifort man page.

OFF
(-reentrancy
none)

-S

Causes the compiler to compile to an assembly file (.s) only and not link.

OFF

-safe_cray_ptr

Specifies that CRAY* pointers do not alias other variables.

OFF

-save

Places variables, except those declared as AUTOMATIC, in static memory (same as -noauto or -noautomatic).
If you specify -recursive or -openmp, the default is -auto.

OFF
(-auto_scalar)

-scalar_rep
(i32 only)

Enables scalar replacement performed during loop transformation. To use this option, you must also specify -03.

OFF
(-scalar_rep-)

-shared

Instructs the compiler to build a Dynamic Shared Object (DSO) instead of an executable.
On Itanium-based systems, you must specify -fpic for the compilation of each object file you want to include in the shared library.

OFF

-shared-libcxa

Links the Intel libcxa C++ library dynamically, overriding the default behavior when -static is used.
This option is the opposite of -static-libcxa.

ON

-sox[-]
(i32, i32em)

Tells the compiler to save the compiler options and version in the executable.

OFF (-sox-)

-stand [keyword]

Causes the compiler to issue compile-time messages for nonstandard language elements. keyword: f90, f95, none.
For details on these keywords, see your user's guide or the ifort man page.

OFF (-stand
none)

-static

Prevents linking with shared libraries. Causes the executable to link all libraries statically.

OFF

-static-libcxa

Links the Intel libcxa C++ library statically.
This option is the opposite of -shared-libcxa.

OFF

-std90

Causes the compiler to issue messages for language elements that are not standard in Fortran 90 (same as the -stand f90 option).

OFF

-std95 or -std

Causes the compiler to issue messages for language elements that are not standard in Fortran 95 (same as the -stand f95 option). This option is set if you specify -warn stderrors.

OFF

-syntax_only

Specifies that the source file should be checked only for correct syntax (same as the -syntax and -y options). No code is generated, no object file is produced, and some error checking done by the optimizer is bypassed. This option lets you do a quick syntax check of your source file.

OFF (-no
syntax_only)

-T file  

Tells the linker to read link commands from the specified file.

OFF

-tcheck (*new)

Enables analysis of threaded applications.  
To use this option, you must have Intel® Thread Checker installed, which is one of the Intel® Threading Tools. If this threading tool is not installed, this option has no effect.

OFF

-Tffile

Specifies that file should be compiled as a Fortran source file. This option is useful when you have a file with a nonstandard filename suffix.

OFF

-threads

Specifies that multithreaded libraries should be linked. This option sets the
-reentrancy threaded option.

OFF (-nothreads)

-tpp{1|2}
(i64 only)

-tpp1 - Optimizes for the Intel® Itanium® processor.
-tpp2 - Optimizes for the Intel® Itanium® 2 processor.

-tpp2

-tpp{5|6|7}
(i32, i32em)

-tpp5 - Optimizes for the Intel Pentium® processor.
-tpp6 - Optimizes for the Intel Pentium Pro, Pentium II, and Pentium III processors.
-tpp7 - Optimizes for the Intel® Pentium® 4 processors, Intel® Xeon(TM) processors, Intel® Pentium® M processors, and Intel® Pentium® 4 processor with Streaming SIMD Extensions 3 (SSE3) instruction support.

The only option available on Intel® EM64T systems is -tpp7.

-tpp7

-traceback

Tells the compiler to generate extra information in the object file to allow the display of source file traceback information at run time when a severe error occurs.

OFF
(-notraceback)

-tune keyword
(i32 only)

Determines the version of the architecture for which the compiler generates instructions. Indicated by keyword:
pn1 - Optimizes for the Intel® Pentium® processor.
pn2 - Optimizes for the Intel® Pentium® Pro, Intel® Pentium® II, and Intel® Pentium® III processors.
pn3 - Optimizes for the Intel® Pentium® Pro, Intel® Pentium® II, and Intel® Pentium® III processors. This is the same as specifying the -tune pn2 option.
pn4 - Optimizes for the Intel® Pentium® 4 processor.

-tune pn4

-u

Sets the default type of a variable to undefined (IMPLICIT NONE).  This is the same as specifying the -implicitnone option.

ON

-Uname

Removes the predefined macro name.

OFF

-unroll[n]

Sets the maximum number of times to unroll loops.
n=0 (-unroll0) disables loop unrolling.
If you omit n, the compiler uses default heuristics.
On Itanium-based systems, the compiler currently recognizes only n=0; any other value is ignored.

-unroll

-uppercase

Causes the compiler to ignore case differences in identifiers and to convert external names to uppercase (same as the -names uppercase option).

OFF
(-lowercase or
-names lowercase)

-us

Tells the compiler to append an underscore character to external user-defined names.
This option is the same as the -assume underscore option, and is the opposite of -nus.

OFF

-use_asm

Tells the compiler to produce objects through the assembler.

OFF

-V

Displays the compiler version information.

OFF

-v

Tells the driver that tool commands should be shown and executed.

OFF

-vec_report[n]
(i32, i32em)

Controls amount of vectorizer diagnostic information. n=1, 2, 3, 4, or 5:
0 - Produces no information
1 - Indicates vectorized loops
2 - Indicates vectorized and non-vectorized loops
3 - Indicates vectorized and non-vectorized loops and prohibiting data dependence information
4 - Indicates non-vectorized loops
5 - Indicates non-vectorized loops and prohibiting data dependence information.

-vec_report1

-vms

Causes the run-time system to behave like HP* Fortran for OpenVMS Alpha systems and VAX systems (VAX FORTRAN*) in certain ways.
For details on the affect of this option, see your user's guide or the ifort man page.

OFF

-w

Disables all warning messages (same as the -nowarn and -warn nogeneral options).

OFF

-Wn

Disables warnings (n =0) or enables warnings (n =1).
-W1 is the same as specifying -warn general.
-W0 is the same as specifying -warn nogeneral, -nowarn, or -w.

-W1

-w90 or
-w95

Suppresses warning messages about Fortran features that are deprecated or obsolescent in Fortran 95.

OFF

-warn keyword

Specifies the level of warning messages issued by the compiler.
keyword: all, none, [no]alignments, [no]declarations, [no]errors, [no]general, [no]ignore_loc, [no]stderrors, [no]truncated_source, [no]uncalled, [no]unused, [no]usage.
For details on these keywords, see your user's guide or the ifort man page.

OFF
(-warn none or
-nowarn)

-what

Displays the version strings of the Fortran command and the compiler.

OFF

-Wl o1 [, o2,...]

Passes options -o1, -o2, etc. to the linker for processing.

OFF

-Wp o1 [, o2,...]

Passes options -o1, -o2, etc. to the preprocessor.

OFF

-X

Removes standard directories from the include file search path (same as the -nostdinc option).
You can use the -X option with the -I option to prevent the compiler from searching the default path for include files and direct it to use an alternate path.

OFF

-x{K|W|N|B|P}
(i32, i32em)

Generates specialized and optimized code for the processor that executes your program. The processor type is indicated by one of the following values:

K - Intel® Pentium® III processors and compatible Intel processors.

W - Intel® Pentium® 4 processors and compatible Intel processors.

N - Intel® Pentium® 4 processors and compatible Intel processors

B - Intel® Pentium® M and compatible Intel processors

P - Intel® Pentium® 4 processor with Streaming SIMD Extensions 3 (SSE3) instruction support.

When the main program is compiled with the -xN, -xB, or -xP option, it will detect non-compatible processors and generate a fatal error message during execution.
These options also enable new optimizations in addition to Intel processor-specific optimizations.

The only options available on Intel® EM64T systems are -xP and -xW.

For more details, see your user's guide or the ifort man page.

OFF

-Xlinker value

Passes value directly to the linker for processing.

OFF

-y

Specifies that the source file should be checked only for correct syntax (same as the -syntax_only and
-syntax options).

OFF

-zero

Initializes to zero all local scalar variables of intrinsic type INTEGER, REAL, COMPLEX, or LOGICAL that are saved but not yet initialized.
Use -save on the command line to make all local variables specifically marked as SAVE.

OFF (-zero-)

-Zp[n]

Aligns fields of records and components of derived types on the smaller of the size boundary specified or the boundary that will naturally align them (same as the -align recnbyte option).
n can be:1, 2, 4, 8, or 16.
If you do not specify n, you get -Zp16.

-Zp16