IBM-XL
IBM XL Compiler Flags and Common Unix Commands and Environment Settings
Compilers: IBM XL C/C++ Enterprise Edition Version 8.0 for AIX
Compilers: IBM XL Fortran Enterprise Edition Version 10.1 for AIX
Compilers: IBM XL C/C++ Enterprise Edition Version 9.0 for AIX
Compilers: IBM XL Fortran Enterprise Edition Version 11.1 for AIX
Compilers: IBM XL C/C++ Version 10.1 for AIX
Compilers: IBM XL Fortran Version 12.1 for AIX
Compilers: IBM XL C/C++ Version 11.1 for AIX
Compilers: IBM XL Fortran Version 13.1 for AIX
Compilers: IBM XL C/C++ Version 12.1 for AIX
Compilers: IBM XL Fortran Version 14.1 for AIX
Last updated: 15-Jul-2013
]]>
xlc,
xlc_r
Invoke the IBM XL C compiler. 32-bit binaries are produced by default.
]]>
xlC,
xlC_r
Invoke the IBM XL C++ compiler. 32-bit binaries are produced by default.
]]>
xlf95,
xlf95_r
Invoke the IBM XL Fortran compiler. 32-bit binaries are produced by default.
]]>
-O5
Perform optimizations for maximum performance. This includes maximum
interprocedural analysis on all of the objects presented on the "link"
step. This level of optimization will increase the compiler's memory
usage and compile time requirements. -O5 Provides all of the functionality
of the -O4 option, but also provides the functionality of the
-qipa=level=2 option.
-O5 is equivalent to the following flags
]]>
-O4
Perform optimizations for maximum performance. This includes
interprocedural analysis on all of the objects presented on the "link"
step.
-O4 is equivalent to the following flags
- -O3
- -qipa=level=1
- -qarch=auto
- -qtune=auto
]]>
-O3
In-depth memory access analysis
Better loop scheduling
High-order loop analysis and transformations (-qhot=level=0)
Inlining of small procedures within a compilation unit by default
Eliminating implicit compile-time memory usage limits
Widening, which merges adjacent load/stores and other operations
Pointer aliasing improvements to enhance other optimizations
-O3 is equivalent to the following flags
]]>
-O2
Eliminates redundant code
Basic loop optimization
Can structure code to take advantage of -qarch and -qtune settings
]]>
-O
-qarch
Produces object code containing instructions that will run on the
specified processors. "auto" selects the processor the compile
is being done on. "pwr5x" is the POWER5+ processor.
Supported values for this flag are
- auto - Use the processor on which the program is compiled.
- pwr7 - The POWER7 processor based systems.
- pwr6e - The POWER6 processor in "Enhanced" mode based systems.
- pwr6 - The POWER6 processor based systems.
- pwr5x - The POWER5+ processor based systems.
- pwr5 - The POWER5 processor based systems.
- pwr4 - The POWER4 processor based systems.
- ppc970 - The PPC970 processor based systems.
]]>
-qtune
Specifies the system architecture for which the executable program
is optimized. This includes instruction scheduling and cache setting.
The supported values for suboption are
- auto - Use the processor on which the program is compiled.
- pwr7 - The POWER7 processor based systems.
- pwr6e - The POWER6 processor in "Enhanced" mode based systems.
- pwr6 - The POWER6 processor based systems.
- pwr5x - The POWER5+ processor based systems.
- pwr5 - The POWER5 processor based systems.
- pwr4 - The POWER4 processor based systems.
- ppc970 - The PPC970 processor based systems.
]]>
This option specifies that no functions are to be inlined.
This option inlines glue code that optimizes external
function calls when compiling.
-qhot,
-qhot=level=1,
-qhot=simd
Performs high-order transformations on loops during optimization.
The supported values for suboption are:
- arraypad - The compiler will pad any arrays where it infers that there may be a benefit.
- level=0 - The compiler performs a limited set of high-order loop transformations.
- level=1 - The compiler performs its full set of high-order loop transformations.
- simd - Replaces certain instruction sequences with vector instructions.
- vector - Replaces certain instruction sequences with calls to the MASS library.
Specifying -qhot without suboptions implies -qhot=nosimd, -qhot=noarraypad, -qhot=vector and
-qhot=level=1. The -qhot option is also implied by -O4, and -O5.
]]>
-qipa=level
Enhances optimization by doing detailed analysis across procedures
(interprocedural analysis or IPA).
The level determines the amount of interprocedural analysis
and optimization that is performed.
level=0 Does only minimal interprocedural analysis and optimization
level=1 turns on inlining , limited alias analysis, and limited
call-site tailoring
level=2 turns on full interprocedural data flow and alias analysis
]]>
Suppresses interprocedural analysis (IPA), which is enabled by default
at optimization levels -O4 and -O5.
]]>
The option used in the first pass of a profile directed feedback compile
that causes pdf information to be generated.
The profile directed feedback optimization gathers data on both execution
path and data values. It does not use hardware counters, nor gather any
data other than path and data values for PDF specific optimizations.
The option used in the second pass of a profile directed feedback compile
that causes PDF information to be utilized during optimization.
The compiler generates additional symbol information for use by the AIX "fdpr"
binary optimization tool.
-qxlf90=nosignedzero
-qxlf90=<suboption>
Determines whether the compiler provides the
Fortran 90 or the Fortran 95 level of support for
certain aspects of the language. <suboption> can be
one of the following:
signedzero | nosignedzero
Determines how the SIGN(A,B) function handles
signed real 0.0. In addition, determines
whether negative internal values will be
prefixed with a minus when formatted output
would produce a negative sign zero.
autodealloc | noautodealloc
Determines whether the compiler deallocates
allocatable arrays that are declared locally
without either the SAVE or the STATIC
attribute and have a status of currently
allocated when the subprogram terminates.
oldpad | nooldpad
When the PAD=specifier is present in the
INQUIRE statement, specifying -qxlf90=nooldpad
returns UNDEFINED when there is no connection,
or when the connection is for unformatted I/O.
This behavior conforms with the Fortran 95
standard and above. Specifying -qxlf90=oldpad
preserves the Fortran 90 behavior.
Default:
o signedzero, autodealloc and nooldpad for the
xlf95, xlf95_r, xlf95_r7 and f95 invocation
commands.
o nosignedzero, noautodealloc and oldpad for
all other invocation commands.
]]>
-q64
Generates 64 bit ABI binaries. The default is to generate 32 bit ABI binaries.
Indicates that a program, designed to execute in a
large page memory environment, can take advantage
of large 16 MB pages provided on POWER4 and higher
based systems.
Indicates that the compiler understands how to do alloca().
Causes the Fortran compiler to allocate dynamic arrays on the heap instead
of the stack
Specifies that all local variables be treated as STATIC.
-qsimd
-qnosimd
Enables the generation of vector instructions for processors
that support them.
-qenablevmx
-qnoenablevmx
Enables the generation of vector instructions for processors
that support them.
Specifies whether to use volatile or non-volatile vector
registers. Volatile vector registers are registers whose
value is not preserved across function calls so the
compiler will not depend on values in them across function
calls.
Link the mathematical acceleration subsystem libraries (MASS),
which contain libraries of tuned mathematical intrinsic
functions.
Link the Engineering and Scientific Subroutine Library (ESSL).
Specifies that, if either -lessl or -lesslsmp are also
specified, then Engineering and Scientific Subroutine Library
(ESSL) routines should be used in place of some Fortran 90
intrinsic procedures when there is a safe opportunity to do so.
Cause the C++ compiler to generate Run Time Type Identification code
Causes the compiler to treat "char" variables as signed instead of the
default of unsigned.
Indicates that the input fortran source program is in fixed form.
Adds an underscore to global entities to match the C compiler ABI
-qcpluscmt
Permits the usage of "//" to introduce a comment
that lasts until the end of the current source
line, as in C++.
]]>
-qalias=noansi,
-qalias=nostd
qalias=ansi | noansi
If ansi is specified, type-based aliasing is
used during optimization, which restricts the
lvalues that can be safely used to access a
data object. The default is ansi for the xlc,
xlC, and c89 commands. This option has no
effect unless you also specify the -O option.
qalias=std |nostd
Indicates whether the compilation units contain
any non-standard aliasing (see Compiler Reference
for more information). If so, specify nostd.
]]>
-qalign=natural
Specifies what aggregate alignment rules the
compiler uses for file compilation, where the
alignment options are:
bit_packed
The compiler uses the bit_packed alignment
rules.
full
The compiler uses the RISC System/6000
alignment rules. This is the same as power.
mac68k
The compiler uses the Macintosh alignment
rules. This suboption is valid only for 32-
bit compilations.
natural
The compiler maps structure members to their
natural boundaries.
packed
The compiler uses the packed alignment rules.
power
The compiler uses the RISC System/6000
alignment rules.
twobyte
The compiler uses the Macintosh alignment
rules. This suboption is valid only for 32-
bit compilations. The mac68k option is the
same as twobyte.
The default is -qalign=full.
]]>
-qassert=refalign
qassert=refalign | norefalign
Specifies that all pointers inside the compilation
unit only point to data that is naturally aligned
according to the length of the pointer types.
]]>
-qprefetch=aggressive
qprefetch=aggressive
Aggressively prefetch data
]]>
-qprefetch=dscr=42
The prefetch=dscr option causes the
Data Streams Control Register to be set to the value
specified when executing this program.
]]>
-qrestrict
qrestrict
TBD
]]>
Causes the compiler to automatically generate parallel code using
OMP controls when possible.
Tell the compiler that OMP controls are used to identify parallel code.
-qstrict,
-qnostrict
Ensures that optimizations done by default at
optimization levels -O3 and higher, and, optionally
at -O2, do not alter the semantics of a program.
The -qstrict=all, -qstrict=precision,
-qstrict=exceptions, -qstrict=ieeefp, and
-qstrict=order suboptions and their negative forms
are group suboptions that affect multiple,
individual suboptions. Group suboptions act as if
either the positive or the no form of every
suboption of the group is specified.
Default:
o Always -qstrict or -qstrict=all when the
-qnoopt or -O0 optimization level is in effect
o -qstrict or -qstrict=all is the default when
the -O2 or -O optimization level is in effect
o -qnostrict or -qstrict=none is the default
when -O3 or a higher optimization level is in
effect
<suboptions_list> is a colon-separated list of one
or more of the following:
all | none
all disables all semantics-changing
transformations, including those controlled by
the ieeefp, order, library, precision, and
exceptions suboptions. none enables these
transformations.
precision | noprecision
precision disables all transformations that
are likely to affect floating-point precision,
including those controlled by the subnormals,
operationprecision, association,
reductionorder, and library suboptions.
noprecision enables these transformations.
exceptions | noexceptions
exceptions disables all transformations likely
to affect exceptions or be affected by them,
including those controlled by the nans,
infinities, subnormals, guards, and library
suboptions. noexceptions enables these
transformations.
ieeefp | noieeefp
ieeefp disables transformations that affect
IEEE floating-point compliance, including
those controlled by the nans, infinities,
subnormals, zerosigns, and operationprecision
suboptions. noieeefp enables these
transformations.
nans | nonans
nans disables transformations that may produce
incorrect results in the presence of, or that
may incorrectly produce IEEE floating-point
signaling NaN (not-a-number) values. nonans
enables these transformations.
infinities | noinfinities
infinities disables transformations that may
produce incorrect results in the presence of,
or that may incorrectly produce floating-point
infinities. noinfinities enables these
transformations.
subnormals | nosubnormals
subnormals disables transformations that may
produce incorrect results in the presence of,
or that may incorrectly produce IEEE
floating-point subnormals (formerly known as
denorms). nosubnormals enables these
transformations.
zerosigns | nozerosigns
zerosigns disables transformations that may
affect or be affected by whether the sign of a
floating-point zero is correct. nozerosigns
enables these transformations.
operationprecision | nooperationprecision
operationprecision disables transformations
that produce approximate results for
individual floating-point operations.
nooperationprecision enables these
transformations.
order | noorder
order disables all code reordering between
multiple operations that may affect results or
exceptions, including those controlled by the
association, reductionorder, and guards
suboptions. noorder enables code reordering.
association | noassociation
association disables reordering operations
within an expression. noassociation enables
reordering operations.
reductionorder | noreductionorder
reductionorder disables parallelizing
floating-point reductions. noreductionorder
enables these reductions.
guards | noguards
guards disables moving operations past guards
or calls which control whether the operation
should be executed or not. enables these
moving operations.
library | nolibrary
library disables transformations that affect
floating-point library functions. nolibrary
enables these transformations.
]]>
Allows most any c dialect.
-qipa=inline=limit=1000
-qipa=inline=threshold=100
The inline suboption specifies the threshold and
limit of inlined functions
]]>
-qipa=noobject
Specifies whether to include standard object code in the object files.
The noobject suboption can substantially reduce overall
compilation time, by not generating object code during the first IPA phase.
This option does not affect the code in the final binary created.
]]>
-qipa=partition=large
The partition suboption specifies the size of the program
sections that are analysed together. Larger partitons may produce
better analysis but require more storage. Default is medium.
]]>
-qipa=threads
The threads suboption allows the IPA optimizer to run portions
of the optimization process in parallel threads, which can speed up the
compilation process on multi-processor systems. All the available
threads, or the number specified by N, may be used. N must be a positive
integer. Specifying nothreads does not run any parallel threads;
this is equivalent to running one serial thread.
This option does not affect the code in the final binary created.
]]>
-qspillsize=512,
-qspillsize=32648
Specifies the size of the compiler's internal program storage areas, in bytes.
]]>
Causes the compiler to output a traceback if it abends.
-qsuppress=msg1:msg2
-qsuppress=1500-036,
-qsuppress=cmpmsg
Suppresses the message with the message number specified.
Suppresses informational, language-level, and warning messages. This option sets
-qflag=e:e.