FLAG DESCRIPTIONS
SUN C, C++ AND FORTRAN
Forte[tm] Developer 6 updates 1 and 2
6/28/01
-D Set definition for preprocessor.
-dalign Assume double-type data is double
aligned.
-dn Specify static binding.
-e Accept extended (132 character) input
source lines (FORTRAN).
-fast This is a convenience option for
selecting a set of optimizations for
performance, and it chooses:
o The -native best machine
characteristics option (-xarch=native,
-xchip=native, -xcache=native)
o Optimization level: -xO5
o A set of inline expansion templates
(-libmil)
o The -fsimple=2 option
o The -dalign option
o The -xalias_level=basic option (C
only)
o The -xlibmopt option
o The -xdepend option (FORTRAN only)
o The -xprefetch option (FORTRAN only)
o Options to turn off all trapping (-fns
-ftrap=%none)
-fixed Accept fixed-format input source files
(FORTRAN).
-fns Select non-standard floating point mode.
This flag causes the nonstandard
floating point mode to be enabled when a
program begins execution. By default,
the nonstandard floating point mode will
not be enabled automatically.
On some SPARC systems, the nonstandard
floating point mode disables "gradual
underflow", causing tiny results to be
flushed to zero rather than producing
subnormal numbers. It also causes
subnormal operands to be silently
replaced by zero. On those SPARC systems
that do not support gradual underflow
and subnormal numbers in hardware, use
of this option can significantly improve
the performance of some programs.
Warning: When nonstandard mode is
enabled, floating point arithmetic may
produce results that do not con- form to
the requirements of the IEEE 754
standard. See the Numerical Computation
Guide for more information.
-fsimple=0 Permits no simplifying assumptions.
Preserves strict IEEE 754 conformance.
-fsimple=1 With -fsimple=1, the optimizer can
assume the following:
o The IEEE 754 default rounding/trapping
modes do not change after process
initialization.
o Computations producing no visible
result other than potential
floating-point exceptions may be
deleted.
o Computations with Infinity or NaNs as
operands need not propagate NaNs to
their results. For example, x*0 may be
replaced by 0.
o Computations do not depend on sign of
zero.
-fsimple=2 Permits aggressive floating point
optimizations that may cause programs to
produce different numeric results due to
changes in rounding. Even with
-fsimple=2, the optimizer still is not
permitted to introduce a floating point
exception in a program that otherwise
produces none.
-fsimple[=n] Allows the compiler to make simplifying
assumptions concerning floating-point
arithmetic.
-ftrap=t Sets the IEEE 754 trapping mode in
effect at startup.
t is a comma-separated list that
consists of one or more of the
following: %all, %none, common,
[no%]invalid, [no%]overflow,
[no%]underflow, [no%]division,
[no%]inexact.
The default is -ftrap=%none.
This option sets the IEEE 754 trapping
modes that are established at program
initialization. Processing is
left-to-right. The common exceptions, by
definition, are invalid, division by
zero, and overflow.
o %none, the default, turns off all
trapping modes.
Do not use this option for programs that
depend on IEEE standard exception
handling; you can get different
numerical results, premature program
termination, or unexpected SIGFPE
signals.
-inline=%auto Enables automatic inlining
-libmil Use inline expansion templates for libm.
-library=iostream Use "classic" (pre 1998 C++ standard)
iostream library
Prior to the C++ standard (1998), there
was one iostream library, what is now
often called "classic" iostreams. The
C++ standard defines a different, but
similar, iostream library, which we call
"standard" iostreams. To get classic
iostreams in standard (default) mode,
you use the option "-library=iostream".
-library=iostream,no%Cstd Same as -library=iostream plus
-library=no%Cstd
You can combine two options into one:
-library=iostream,no%Cstd
-library=no%Cstd Do not find the standard library headers
or the runtime library itself, in order
to avoid mixing the standard library
with classic iostreams.
Some of the remainder of the C++
standard library (in particular, the
standard string class) relies on using
standard iostreams. If you attempt to
use those library features with classic
iostreams, the code will not work. To
ensure that you don't attempt to mix the
standard library with classic iostreams,
you can use the option -library=no%Cstd.
With that option, the compiler does not
find the standard library headers or the
runtime library itself.
-lm Link with math library
-lmopt This chooses the math library that is
optimized for speed
-native Select native machine characteristics
for optimization.
-Qoption <phase> <flags> Pass flags along to compiler phase:
f90comp Fortran first pass
iropt Global optimizer
cg Code generator
-Qoption cg <flags> See -Wc,<flags> below.
-Qoption cg -Qgsched-T4 See -Wc,-Qgsched-T4
-Qoption cg -Qgsched-trace_late=1 See -Wc,-Qgsched-trace_late=1
-Qoption iropt -Mt<n> See -W2,-Mt<n>
-Qoption iropt -restrict See -W2,-O4+restrict
-Qoption iropt -restrict_g See -W2,-O4+restrict_g
-Qoption f90comp
-array_pad_rows,<n> Enable padding of f90 arrays by n.
-Qoption f90comp -expansion Enable f90 array expansion.
-Qoption iropt +ansi_alias assume (more restrictive) ANSI C
semantics for pointer aliasing
-Qoption iropt <flags> See -W2,<flags> below.
-Qoption iropt -Adata_access enable optimizations based on data
access patterns
-Qoption iropt -Amemopt See -W2,-Amemopt
-Qoption iropt bmerge enable branch merge optimizations
-Qoption iropt -Ma<n> See -W2,-Ma<n>
-Qoption iropt -Mm<n> See -W2,-Mm<n>
-Qoption iropt -Mr<n> See -W2,-Mr<n>
-Qoption iropt -O4+algassoc enable floating point reassociation
-Qoption iropt -O4+bcopy allows replacing copy and memset loops
with library calls
-Qoption iropt -O4+scalarrep disable scalar replacement optimization
-Qoption iropt -whole See -W2,-whole
-stackvar Allocate routine local variables on
stack (FORTRAN).
-W<phase>,<flags> Pass flags along to compiler phase:
2 global optimizer
c code generator
-W2,-Abopt Enable aggressive optimizations of all
branches.
-W2,-Adata_access Enable optimizations based on data
access patterns.
-W2,-Aheap Allows the compiler to recognize
malloc-like memory allocation functions.
-W2,-Amemopt Memory access optimization
-W2,-Aunroll Enables outer-loop unrolling.
-W2,-crit Enable optimization of critical control
paths
-W2,-Ma<n> Enable inlining of routines with frame
size up to n.
-W2,-Mm<n> Maximum module increase limit for
inlining.
-W2,-Mp<n> Procedures with entry counts equal or
greater than n become candidates for
inlining.
-W2,-Mr<n> Maximum code increase due to inlining is
limited to n triples.
-W2,-Ms<n> Maximum level of recursive inlining.
-W2,-Mt<n> The maximum size of a routine body
eligible for inlining is limited to n
triples.
-W2,-O4+ansi_alias Assume (more restrictive) ANSI C
semantics for pointer aliasing.
-W2,-O4+restrict This tells the compiler to assume that
different pointer-type formal parameters
point to their own memory locations (C
restricted pointers)
-W2,-O4+restrict_g This tells the compiler to assume that
different global pointer variables point
to their own memory locations.
-W2,-reroll=1 Turns on loop rerolling.
-W2,-whole Do whole program optimizations.
-Wc,-Qdepgraph-early_cross_call=1 Enable early cross-call instruction
scheduling.
-Wc,-Qgsched-T4 Sets the aggressiveness of the trace
formation.
-Wc,-Qgsched-trace_late=1 Turns on the late trace scheduler.
-Wc,-Qgsched-trace_spec_load=1 Turns on the conversion of loads to
non-faulting loads inside the trace.
-Wc,-Qiselect-funcalign=<n> Do function entry alignment at n-byte
boundaries.
-Wc,-Qpeep-Sh0 Disables the max live base registers
algorithm for sethi hoisting.
-Xa Assume ANSI C conformance, allow K & R
extensions. (default mode)
-xalias_level=<a> Allows compiler to perform type-based
alias analysis at the given alias level.
basic assume ISO C9X aliasing rules for
basic types only.
std assume ISO C9X aliasing rules.
strong assume all pointers are type safe
(strongly typed).
-xarch=<a> Limit the set of instructions the
compiler may use.
-Xc Assume strict ANSI C conformance.
-xcache=<c> Defines the cache properties for use by
the optimizer.
c must be one of the following:
o native (set parameters for the host
environment)
o s1/l1/a1
o s1/l1/a1:s2/l2/a2
o s1/l1/a1:s2/l2/a2:s3/l3/a3
The si/li/ai are defined as follows:
si The size of the data cache at level
i, in kilobytes.
li The line size of the data cache at
level i, in bytes.
ai The associativity of the data cache
at level i.
-xchip=<c> Specifies the target processor for use
by the optimizer. c must be one of:
generic, generic64, native, native64,
old, super, super2, micro, micro2,
hyper, hyper2, powerup, ultra, ultra2,
ultra2i, ultra3, 386, 486, pentium,
pentium_pro, 603, 604.
-xcrossfile Enable cross-file inlining.
-xdepend Analyze loops for data dependencies.
-xO1 Does basic local optimization
(peephole).
-xO2 xO1 and more local and global
optimizations.
-xO3 Besides what xO2 does, it optimizes
references or definitions for external
variables. Loop unrolling and software
pipelining are also performed.
-xO4 xO3 plus function inlining.
-xO5 Besides what xO4 does, it enables
speculative code motion.
-xpad=common[:<n>] Pad common block variables, for better
use of cache. n specifies the amount of
padding to apply. If no parameter is
specified then the compiler selects one
automatically.
-xpad=local[:<n>] Pad local variables only, for better use
of cache. n specifies the amount of
padding to apply. If no parameter is
specified then the compiler selects one
automatically.
-xparallel Use parallel processing to improve
performance.
-xprefetch Enable generation of prefetch
instructions.
-xprofile See below
-xprofile=collect Collect profile data for feedback
directed optimizations.
-xprofile=use Use data collected for profile feedback.
-xreduction Parallelize loops containing reductions.
-xregs=syst Allows use of the system reserved
registers %g6 and %g7, and %g5 if not
already allowed by -xarch value.
-xrestrict[=f1,...,f2,%all, Treat pointer-valued function parameters
%none] as restricted pointers. The default is
%none. Specifying -xrestrict is
equivalent to specifying
-xrestrict=%all.
-xsafe=mem Enables the use of non-faulting loads
when used in conjunction with
-xarch=v8plus is set, assumes that no
memory based traps will occur.
-Xt Assume K & R conformance, allow ANSI C.
-xvector Enable vectorization of loops with calls
to math routines.
Kernel Parameters
consistent_coloring
Consistent Coloring controls the
page coloring policy. It can be
set to one of the following:
0: (default) dynamic (uses
various vaddr bits)
1: static (virtual=paddr)
2: bin hopping