Intel(R) C Compiler Help
Intel(R) C Compiler Help
========================
usage: icc [options] file1 [file2 …]
where options represents zero or more compiler options
fileN is a C/C++ source (.C .c .cc .cpp .cxx .c++ .i .ii),
assembly (.s .S), object (.o), static library (.a), or other
linkable file
Commonly used options may be placed in the icc.cfg file.
Compiler Option List
——————–
Performance
———–
-O1 optimize for maximum speed, but disable some optimizations which
increase code size for a small speed benefit.
-O2 enable optimizations (DEFAULT)
-O3 enable -O2 plus more aggressive optimizations that may not improve
performance for all programs
-O0 disable optimizations
-O same as -O2
-Os enable speed optimizations, but disable some optimizations which
increase code size for small speed benefit
-fast enable -xP -O3 -ipo -no-prec-div -static
-Ob<n> control inline expansion:
n=0 disables inlining
n=1 inline functions declared with __inline, and perform C++ inlining
n=2 inline any function, at the compiler’s discretion (same as -ip)
-falias assume aliasing in program (DEFAULT)
-fno-alias assume no aliasing in program
-ffnalias assume aliasing within functions (DEFAULT)
-fno-fnalias assume no aliasing within functions, but assume aliasing across
calls
-finline-functions
inline any function, at the compiler’s discretion (same as -ip)
-fno-builtin disable inline expansion of intrinsic functions
-mp maintain floating point precision (disables some optimizations)
-mp1 improve floating-point precision (speed impact is less than -mp)
-m[no-]ieee-fp
same as -mp
-ffunction-sections
separate functions for the linker (COMDAT)
-f[no-]exceptions
enable(DEFAULT)/disable exception handling
-fdata-sections
same as -ffunction-sections
-fp disable using EBP as general purpose register
-f[no-]omit-frame-pointer
negative version same as -fp
-[no-]prec-div
improve precision of floating-point divides (some speed impact)
-[no-]prec-sqrt
determine if certain square root optimizations are enabled
-fp-port round fp results at assignments & casts (some speed impact)
-fpstkchk enable fp stack checking after every function/procedure call
-pc32 set internal FPU precision to 24 bit significand
-pc64 set internal FPU precision to 53 bit significand
-pc80 set internal FPU precision to 64 bit significand (DEFAULT)
-rcd rounding mode to enable fast float-to-int conversions
-mcpu=<cpu> optimize for a specific cpu
pentium – optimize for Pentium(R) processor
pentiumpro – optimize for Pentium(R) Pro, Pentium(R) II and Pentium(R)
III processors
pentium4 – optimize for Pentium(R) 4 processor (DEFAULT)
-mtune=<cpu> optimize for a specific cpu
pentium – optimize for Pentium(R) processor
pentiumpro – optimize for Pentium(R) Pro, Pentium(R) II and Pentium(R)
III processors
pentium4 – optimize for Pentium(R) 4 processor (DEFAULT)
-march=<cpu> generate code excusively for a given <cpu>
pentiumpro – Pentium(R) Pro and Pentium(R) II processor instructions
pentiumii – MMX(TM)instructions
pentiumiii – streaming SIMD extensions
pentium4 – Pentium(R) 4 New Instructions
-msse generate code for Intel Pentium III and compatible Intel processors
-msse2 generate code for Intel Pentium 4 and compatible Intel processors
-msse3 generate code for Intel Pentium 4 processors with SSE3 extensions
-ax<codes> generate code specialized for processors specified by <codes>
while also generating generic IA-32 code. <codes> includes
one or more of the following characters:
K Intel Pentium III and compatible Intel processors
W Intel Pentium 4 and compatible Intel processors
N Intel Pentium 4 and compatible Intel processors. Enables new
optimizations in addition to Intel processor-specific optimizations
P Intel Pentium 4 processors with SSE3 extensions
B Intel Pentium M and compatible Intel processors
-x<codes> generate specialized code to run exclusively on processors
indicated by <codes> as described above.
Advanced Performance
——————–
Enable and specify the scope of Interprocedural (IP) Optimizations:
-ip enable single-file IP optimizations (within files)
-ipo[n] enable multi-file IP optimizations (between files)
-ipo-c generate a multi-file object file (ipo_out.o)
-ipo-S generate a multi-file assembly file (ipo_out.s)
Modify the behavior of IP:
-ip-no-inlining disable full and partial inlining (requires -ip or -ipo)
-ip-no-pinlining disable partial inlining (requires -ip or -ipo)
-ipo-separate create one object file for every source file
(overrides -ipo[n])
Other Advanced Performance Options:
-unroll[n] set maximum number of times to unroll loops. Omit n to use
default heuristics. Use n=0 to disable loop unroller.
-unroll [n] set maximum number of times to unroll loops. Omit n to use
default heuristics. Use n=0 to disable loop unroller.
-funroll-loops unroll loops based on default heuristics
-prof-dir <d> specify directory for profiling output files (*.dyn and *.dpi)
-prof-file <f> specify file name for profiling summary file
-prof-gen[x] instrument program for profiling; with the x qualifier, extra
information is gathered
-prof-use enable use of profiling information during optimization
-prof-gen-sampling
prepare code for use with profrun sample gathering tool
-qp compile and link for function profiling with UNIX gprof tool
-p same as -qp
-[no-]prefetch enable(DEFAULT)/disable prefetch insertion
-vec-report[n] control amount of vectorizer diagnostic information:
n=0 no diagnostic information
n=1 indicate vectorized loops (DEFAULT)
n=2 indicate vectorized/non-vectorized loops
n=3 indicate vectorized/non-vectorized loops and prohibiting
data dependence information
n=4 indicate non-vectorized loops
n=5 indicate non-vectorized loops and prohibiting data
dependence information
-opt-report generate an optimization report to stderr
-opt-report-file<file> specify the filename for the generated report
-opt-report-level[level] specify the level of report verbosity (min|med|max)
-opt-report-phase<name> specify the phase that reports are generated against
-opt-report-routine<name> reports on routines containing the given name
-opt-report-help display the optimization phases available for
reporting
-tcheck generate instrumentation to detect multi-threading bugs
(requires Intel(R) Threading Tools; cannot be used with
compiler alone)
-openmp enable the compiler to generate multi-threaded code
based on the OpenMP directives
-openmp-profile link with instrumented OpenMP runtime library to
generate OpenMP profiling information for use with the
OpenMP component of the VTune(TM) Performance Analyzer
-openmp-stubs enables the user to compile OpenMP programs in
sequential mode. The openmp directives are ignored and
a stub OpenMP library is linked (sequential)
-openmp-report{0|1|2} control the OpenMP parallelizer diagnostic level
-parallel enable the auto-parallelizer to generate multi-threaded
code for loops that can be safely executed in parallel
-par-report{0|1|2|3} control the auto-parallelizer diagnostic level
-par-threshold[n] set threshold for the auto-parallelization of loops
where n is an integer from 0 to 100
-[no-]alias-args enable(DEFAULT)/disable C/C++ rule that function
arguments may be aliased; when disabling the rule, the
user asserts that this is safe
-fargument-alias same as -alias-args
-fargument-noalias same as -alias-args-
-fargument-noalias-global
arguments do not alias each other and do not alias
global storage
-[no-]ansi-alias enable/disable(DEFAULT) use of ANSI aliasing rules in
optimizations; user asserts that the program adheres to
these rules
-[no-]complex-limited-range
enable/disable(DEFAULT) the use of the basic
algebraic expansions of some complex arithmetic
operations. This can allow for some performance
improvement in programs which use a lot of complex
arithmetic at the loss of some exponent range.
-ftls-model=<model> change thread-local storage model, where <model> can
be the following: global-dynamic, local-dynamic,
initial-exec or local-exec
-ssp enable software-based speculative pre-computation
-fp-model <name> enable <name> floating point model variation
except[-] – enable/disable floating point semantics
extended – enables intermediates in 80-bit precision
fast – allows value-unsafe optimizations
precise – allows value-safe optimizations
source – enables intermediates in source precision
strict – enables /fp:precise /fp:except and disables floating
point multiply add
Output, Debug, PCH
————-
-c compile to object (.o) only, do not link
-S compile to assembly (.s) only, do not link (*I)
-use-asm produce objects through assembler
-use-msasm Support Microsoft style assembly language insertion using MASM
style syntax
-fcode-asm produce assembly file with optional code annotations (requires -S)
-fsource-asm produce assembly file with optional source annotations
(requires -S)
-f[no]verbose-asm produce assembly file with compiler comments (DEFAULT)
(requires -S)
-o<file> name output file
-g produce symbolic debug information in object file (implies -O0 when
another optimization option is not explicitly set)
-g0 disable generation of symbolic debug information
-debug [keyword]
enable debug information and control output of enhanced
debug information.
keywords: all, full, minimal, none (same as -nodebug),
inline-debug-info, variable-locations,
semantic-stepping, extended, [no]expr-source-pos
-nodebug do not enable debug information
-inline-debug-info preserve the source position of inlined code instead
of assigning the call-site source position to inlined code
-ftrapuv trap uninitialized variables
-pch enable automatic precompiled header file creation/usage
-create-pch <file> create precompiled header file
-use-pch <file> use precompiled header file
-pch-dir <dir> name precompiled header directory
-map-opts enable option mapping tool
-print-multi-lib
print information about libraries being used
C Preprocessor
————–
-A<name>[(val)] create an assertion ‘name’ having value ‘val’
-A- remove all predefined macros
-C don’t strip comments
-D<name>[=<text>] define macro
-E preprocess to stdout
-EP preprocess to stdout omitting #line directives
-P, -F preprocess to file omitting #line directives
-I<dir> add directory to include file search path
-idirafter<dir>
add directory to the second include file search path (after -I)
-isystem<dir>
add directory to the start of the system include path
-iprefix <prefix>
use <prefix> with -iwithprefix as a prefix
-iwithprefix <dir>
append <dir> to the prefix passed in by -iprefix and put it on
the include search path at the end of the include directories
-iwithprefixbefore <dir>
similar to -iwithprefix except the include directory is placed
in the same place as -I command line include directories
-U<name> remove predefined macro
-imacros <file>
treat <file> as an #include file, but throw away all preprocessing
while macros defined remain defined
-X remove standard directories from include file search path
-nostdinc same as -X
-H print include file order
-M generate makefile dependency information
-MM similar to -M, but do not include system header files
-MG similar to -M, but treat missing header files as generated files
-MD preprocess and compile, generating output file containing
dependency information ending with extension .d
-MMD similar to -MD, but do not include system header files
-MF<file> generate makefile dependency information in file (must specify -M
or -MM)
-MP add a phony target for each dependency
-MT<target>
change the default target rule for dependency generation
-MQ<target>
same as -MT, but quotes special Make characters
-dM output macro definitions in effect after preprocessing (use with -E)
-no-gcc do not predefine the __GNUC__, __GNUC_MINOR__, and
__GNUC_PATCHLEVEL__ macros
Component Control
—————–
-Qoption,<str>,<opts> pass options <opts> to tool specified by <str>
-Qlocation,<str>,<dir> set <dir> as the location of tool specified by <str>
-Qinstall <dir> set <dir> as root of compiler installation
Language
——–
-[no]restrict
enable/disable the ‘restrict’ keyword for disambiguating pointers
-export enable the export template feature
-export-dir <dir>
add directory to export template search path
-ansi equivalent to GNU -ansi
-strict-ansi
strict ANSI conformance dialect
-[no-]c99 enable/disable(DEFAULT) C99 support for C programs
-std=c99 enable C99 support for C programs
-Kc++ compile all source or unrecognized file types as C++ source files
-fno-rtti disable RTTI support
-[no]align analyze and reorder memory layout for variables and arrays
-malign-double
same as -align
-Zp[n] specify alignment constraint for structures (n=1,2,4,8,16)
-fshort-enums
allocate as many bytes as needed for enumerated types
-fsyntax-only
perform syntax and semantic checking only (no object file produced)
-funsigned-char
change default char type to unsigned
-funsigned-bitfields
change default bitfield type to unsigned
-fno-implicit-templates
never emit code for non-inline templates which are instantiated
implicitly; only emit code for explicit instantiations
-fno-implicit-inline-templates
do not emit code for implicit instantiations of inline templates
-ftemplate-depth-<n>
control the depth in which recursive templates are expanded
-fno-operator-names
disable support for operator name keywords
-fno-gnu-keywords
do not recognize ‘typeof’ as a keyword
-fpermissive
allow for non-conformant code
Compiler Diagnostics
——————–
-w disable all warnings
-w<n> control diagnostics:
n=0 display errors (same as -w)
n=1 display warnings and errors (DEFAULT)
n=2 display remarks, warnings, and errors
-wn<n> print a maximum of n errors
-wd<L1>[,<L2>,…] disable diagnostics L1 through LN
-we<L1>[,<L2>,…] change severity of diagnostics L1 through LN to error
-ww<L1>[,<L2>,…] change severity of diagnostics L1 through LN to warning
-wr<L1>[,<L2>,…] change severity of diagnostics L1 through LN to remark
-Werror force warnings to be reported as errors
-Wall enable all warnings
-Wbrief print brief one-line diagnostics
-Wcheck enable more strict diagnostics
-W[no-]missing-prototypes
warn for missing prototypes
-W[no-]pointer-arith
warn for questionable pointer arithmetic
-W[no-]uninitialized
warn if a variable is used before being initialized
-Winline enable inline diagnostics
-W[no-]deprecated print warnings related to deprecated features
-W[no-]abi warn if generated code is not C++ ABI compliant (DEFAULT)
-Wcontext-limit=<n>
set maximum number of template instantiation contexts shown
in diagnostic
-W[no-]unused-function
warn if declared function is not used
-W[no-]unknown-pragmas
warn if an unknown #pragma directive is used (DEFAULT)
-W[no-]main warn if return type of main is not expected
-W[no-]comment[s] warn when /* appears in the middle of a /* */ comment
-W[no-]return-type warn when a function uses the default int return type and
warn when a return statement is used in a void function
-Wp64 print diagnostics for 64-bit porting
-[no]traceback specify whether the compiler generates data to allow for
source file traceback information at runtime (only to be
used when linking with Fortran programs)
Miscellaneous
————-
-help print this help message
-V display compiler version information
–version display GCC style version information
-dryrun show driver tool commands but do not execute tools
-v show driver tool commands and execute tools
-x <type> all source files found subsequent to -x <type> will be recognized
as one of the following types:
c – C source file
c++ – C++ source file
c-header – C header file
cpp-output – C pre-processed file
c++-cpp-output – C++ pre-processed file
assembler – assembly file
assembler-with-cpp – assembly file that needs to be preprocessed
none – disable recognition, and revert to file extension
-[no-]sox enable/disable(DEFAULT) saving of compiler options and version
in the executable
-f[no-]pic, -f[no-]PIC
required to build fully preemptable and position independent code
for shared objects (OFF by default)
-fvisibility=[extern|default|protected|hidden|internal]
Global symbols (data and functions) will get the visibility
attribute given by default. Symbol visibility attributes
explicitly set in the source code or using the symbol visibility
attribute file options will override the -fvisibility setting
-fvisibility-extern=<file>
Space separated symbols listed in the <file> argument will get
visibility set to extern
-fvisibility-default=<file>
Space separated symbols listed in the <file> argument will get
visibility set to default
-fvisibility-protected=<file>
Space separated symbols listed in the <file> argument will get
visibility set to protected
-fvisibility-hidden=<file>
Space separated symbols listed in the <file> argument will get
visibility set to hidden
-fvisibility-internal=<file>
Space separated symbols listed in the <file> argument will get
visibility set to internal
-fminshared Compilation is for the main executable. Absolute addressing can
be used and non-position independent code generated for symbols
that are at least protected
-f[no-]common Enables the compiler to treat common variables as if they were
defined. That in turn allows the use of gprel addressing of
common data variables
-fpack-struct pack structure members together
-freg-struct-return
return struct and union values in registers when possible
-fno-builtin-<func>
disable the <func> intrinsic
-f[no-]math-errno
set ERRNO after calling standard math library functions
-fstack-security-check
enable overflow security checks
-long_double enable 80-bit ‘long double’
-nobss-init disable placement of zero-initialized variables in BSS (use DATA)
-[no-]global-hoist
enable(DEFAULT)/disable external globals are load safe
-gcc-name=<name>
name and location of gcc if not where expected
-gcc-version=<version>
specify the <version> of gcc compatibility. Default value
matches gcc version installed
320 – gcc 3.2 compatibility
330 – gcc 3.3 compatibility
340 – gcc 3.4 compatibility
-B<prefix> find libraries, headers and executables in <prefix>
[no-]multibyte-chars
provide support for multi-byte characters
-fabi-version=<val>
directs the compiler to select a specific ABI implementation
0 – most recent ABI implementation
1 – g++ 3.2 compatible ABI implementation
2 – most conformant ABI implementation
Linking/Linker
————–
-L<dir> instruct linker to search <dir> for libraries
-i-dynamic link Intel provided libraries dynamically
-i-static link Intel provided libraries statically
-dynamic-linker<file>
select dynamic linker other than the default
-no-cpprt do not link in C++ runtime libraries
-nodefaultlibs do not use standard libraries when linking
-nostartfiles do not use standard startup files when linking
-nostdlib do not use standard libraries and startup files when linking
-static prevents linking with shared libraries
-shared produce a shared object
-static-libcxa link Intel libcxa C++ library statically
-shared-libcxa link Intel libcxa C++ library dynamically, overrides the default
behavior when -static is used
-cxxlib-<mode> tell the compiler which C++ run-time libraries to use
gcc[=dir] – link using C++ run-time libraries provided with gcc
(default on systems running gcc 3.2 or above)
dir is an optional top-level location for the gcc
binaries and libraries
icc – link using C++ run-time libraries provided by Intel
(default on systems running a gcc version lower
than 3.2)
-u <symbol> pretend the <symbol> is undefined
-T <file> direct linker to read link commands from <file>
-Xlinker <val> pass <val> directly to the linker for processing
-Wa,<o1>[,<o2>,…] pass options o1, o2, etc. to the assembler
-Wl,<o1>[,<o2>,…] pass options o1, o2, etc. to the linker for processing
-Wp,<o1>[,<o2>,…] pass options o1, o2, etc. to the preprocessor
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