long double as having
the same format as double. In earlier versions of GCC,
they used the 68881 long double format instead.m68k-uclinux target now uses the same
calling conventions as m68k-linux-gnu. You can
select the original calling conventions by configuring for
m68k-uclinuxoldabi instead. Note that
m68k-uclinuxoldabi also retains the original
80-bit long double on ColdFire targets.-fforce-mem option has been removed
because it has had no effect in the last few GCC releases.-msvr3-shlib option has been removed
since it is no longer used.Fastcall for i386 has been changed not to pass
aggregate arguments in registers, following Microsoft compilers.arm-semi-aof
and armel-semi-aof, which are no longer recognized.
We removed these targets without a deprecation period because we
discovered that they have been unusable since GCC 4.0.0.c4x-* and tic4x-*) has been removed.
This support had been deprecated since GCC 4.0.0.Support for a number of older systems and recently unmaintained or untested target ports of GCC has been declared obsolete in GCC 4.3. Unless there is activity to revive them, the next release of GCC will have their sources permanently removed.
All GCC ports for the following processor architectures have been declared obsolete:
crx-*)mt-*)The following aliases for processor architectures have been
declared obsolete. Users should use the indicated generic target
names instead, with compile-time options such as
-mcpu or configure-time options such as
--with-cpu to control the configuration more
precisely.
strongarm*-*-*, ep9312*-*-*,
xscale*-*-* (use arm*-*-*
instead).parisc*-*-* (use hppa*-*-*
instead).m680[012]0-*-* (use m68k-*-*
instead).All GCC ports for the following operating systems have been declared obsolete:
*-*-beos*)*-*-kaos*)*-*-linux*aout*)*-*-linux*libc1*)*-*-solaris2.[0-6],
*-*-solaris2.[0-6].*)*-*-sysv*)*-*-windiss*)Also, those for some individual systems on particular architectures have been obsoleted:
alpha*-*-unicosmk*)cris-*-aout)hppa1.1-*-bsd*)hppa1.1-*-osf*)hppa1.1-*-pro*)i[34567]86-sequent-ptx4*,
i[34567]86-sequent-sysv4*)i[34567]86-*-sco3.2v5*)i[34567]86-*-uwin*) (support for
UWIN as a host was previously removed
in 2001, leaving only the support for UWIN as a target now
being deprecated)powerpc-*-chorusos*)vax-*-bsd*, vax-*-sysv*,
vax-*-ultrix*)-Wconversion option has been modified. Its purpose now
is to warn for implicit conversions that may alter a value. This
new behavior is available for both C and C++. Warnings about
conversions between signed and unsigned integers can be disabled
by using -Wno-sign-conversion. In C++, they are
disabled by default unless -Wsign-conversion is
explicitly requested. The old behavior of
-Wconversion, that is, warn for prototypes causing a
type conversion that is different from what would happen to the
same argument in the absence of a prototype, has been moved to a
new option -Wtraditional-conversion, which is only
available for C.-m386, -m486, -mpentium and
-mpentiumpro tuning options have been removed because
they were deprecated for more than 3 GCC major releases. Use
-mtune=i386, -mtune=i486,
-mtune=pentium or -mtune=pentiumpro as a
replacement.-funsafe-math-optimizations option now automatically
turns on -fno-trapping-math in addition to
-fno-signed-zeros, as it enables reassociation and thus
may introduce or remove traps.acos, acosh,
asin, asinh, atan2,
atan, atanh, cbrt,
cos, cosh, drem,
erf, erfc, exp10,
exp2, exp, expm1,
fdim, fma, fmax,
fmin, gamma_r, hypot,
j0, j1, jn,
lgamma_r, log10, log1p,
log2, log, pow10,
pow, remainder, remquo,
sin, sincos, sinh,
tan, tanh, tgamma,
y0, y1 and yn. The
float and long double variants of these
functions (e.g. sinf and sinl) are also
handled. The sqrt and cabs functions
with constant arguments were already optimized in prior GCC
releases. Now they also use MPFR. -frecord-gcc-switches has been
added to GCC, although it is only enabled for some targets. The switch
causes the command line that was used to invoke the compiler to be recorded
into the object file that is being created. The exact format of this
recording is target and binary file format dependent, but it usually takes
the form of a note section containing ASCII text. The switch is related to
the -fverbose-asm switch, but that one only records the
information in the assembler output file as comments, so the information
never reaches the object file.
--param large-stack-frame
and --param large-stack-frame-growth
can be used to limit stack frame size growth caused by inlining.memcpy, memset and bzero
functions operate on is discovered and for cases of commonly used small
sizes, specialized inline code is generated.__builtin_expect no longer requires its argument to be
a compile time constant.-finstrument-functions-exclude-function-list and
-finstrument-functions-exclude-file-list. They provide
more control over which functions are annotated
by the -finstrument-functions option.int may not be implicitly converted to a vector
type with element type unsigned int.)
This restriction, which is in line with specifications for SIMD
architectures such as AltiVec, may be relaxed using the
flag -flax-vector-conversions.
This flag is intended only as a compatibility measure and should not
be used for new code.
-Warray-bounds has been added and is now enabled by
default for -Wall . It produces warnings for array
subscripts that can be determined at compile time to be always
out of bounds. -Wno-array-bounds will disable the
warning.
constructor and destructor function
attributes now accept optional priority arguments which control
the order in which the constructor and destructor functions are
run.
-Wtype-limits,
-Wold-style-declaration,
-Wmissing-parameter-type, -Wempty-body,
-Wclobbered and -Wignored-qualifiers
have been added for finer control of the diverse warnings enabled by
-Wextra.
alloc_size has been added to
mark up malloc style functions. For constant sized
allocations this can be used to find out the size of the returned
pointer using the __builtin_object_size() function
for buffer overflow checking and similar.
This supplements the already built-in malloc and
calloc constant size handling.
0b or
0B, followed by a sequence of 0 and 1 digits.
__COUNTER__ has been added.
It expands to sequential integral values starting from 0. In
conjunction with the ## operator, this provides a
convenient means to generate unique identifiers.
-fdirectives-only has been
added. It enables a special preprocessing mode which improves the
performance of applications like distcc and ccache.
-Wc++0x-compat has been added and is now enabled by
default for -Wall. It produces warnings for constructs
whose meaning differs between ISO C++ 1998 and C++0x.-Wparentheses option now works for C++ as it
does for C. It warns if parentheses are omitted when operators with
confusing precedence are nested. It also warns about ambiguous else
statements. Since -Wparentheses is enabled by
-Wall, this may cause additional warnings with existing
C++ code which uses -Wall. These new warnings may be
disabled by using -Wall -Wno-parentheses.-Wmissing-declarations now works for C++ as it
does for C.-fvisibility-ms-compat flag was added, to make it
easier to port larger projects using shared libraries from Microsoft's
Visual Studio to ELF and Mach-O systems.__attribute__((aligned(T))); works for C++ types.what implementations give more elaborate
exception strings for bad_cast,
bad_typeid, bad_exception, and
bad_alloc. std::accumulate, std::for_each,
std::transform, or std::sort, to give
but four examples. These algorithms can be substituted for the normal
(sequential) libstdc++ algorithms on a piecemeal basis, or
all existing algorithms can be transformed via the
-D_GLIBCXX_PARALLEL macro.
#include <ext/hash_set>
__gnu_cxx::hash_set<int> s;
Can be transformed (in order of preference) to:
#include <tr1/unordered_set>
std::tr1::unordered_set<int> s;
or
#include <backward/hash_set>
__gnu_cxx::hash_set<int> s;
Similar transformations apply to __gnu_cxx::hash_map,
__gnu_cxx::hash_multimap,
__gnu_cxx::hash_set,
__gnu_cxx::hash_multiset.
-fexternal-blas option has been added, which
generates calls to BLAS routines for intrinsic matrix operations such
as matmul rather than using the built-in algorithms.-fbacktrace
or environment variable GFORTRAN_ERROR_BACKTRACE; on glibc
systems only) or a core dump (-fdump-core,
GFORTRAN_ERROR_DUMPCORE) when a run-time error occured.__GFORTRAN__ when it runs the C
preprocessor (CPP).-finit-local-zero, -finit-real,
-finit-integer, -finit-character, and
-finit-logical options have been added, which can be
used to initialize local variables.GAMMA
and LGAMMA
have been added, which calculate the Gamma function and
its logarithm. Use EXTERNAL gamma if you want to use your
own gamma function.-fbackslash GNU Fortran interprets backslashes as
C-style escape characters.ISO_ENV_FORTRANjv-scan tool has been removed. This
tool never really worked properly. There is no replacement.
gcjh has been rewritten. Some of its more
obscure options no longer work, but are still recognized in an
attempt at compatibility. gjavah is a new program
with similar functionality but different command-line options.
grmic and grmiregistry have been
rewritten. grmid has been added. gjar replaces the old fastjar. gjarsigner (used for signing jars),
gkeytool (used for key management),
gorbd (for CORBA), gserialver (computes
serialization UIDs), and gtnameserv (also for CORBA)
are now installed. gc-analyze tool. They may
be generated on out-of-memory conditions or on demand and are
controlled by the new run time class
gnu.gcj.util.GCInfo. java.util.TimeZone can now read files from
/usr/share/zoneinfo to provide correct, updated,
timezone information. This means that packagers no longer have
to update libgcj when a time zone change is published. -mtune=core2 and -march=core2.-mtune=geode and -march=geode.memcpy) and block set
(memset) was rewritten. GCC can now pick the best
algorithm (loop, unrolled loop, instruction with rep
prefix or a library call) based on the size of the block being
copied and the CPU being optimized for. A new option
-minline-stringops-dynamically has been added. With
this option string operations of unknown size are expanded such
that small blocks are copied by in-line code, while for
large blocks a library call is used. This results in faster code than
-minline-all-stringops when the library implementation is
capable of using cache hierarchy hints. The heuristic choosing
the particular algorithm can be overwritten via
-mstringop-strategy. Newly also memset of
values different from 0 is inlined.cld instruction before string
operations. Both i386 and x86-64 ABI documents mandate the direction
flag to be clear at the entry of a function. It is now invalid to
set the flag in asm statement without reseting it
afterward.-mssse3.-msse4.1.-msse4.2.-msse4.-mpc32, -mpc64
and -mpc80 have been added to allow explicit control
of x87 floating point precision.__float128 (TFmode) IEEE quad type and
corresponding TCmode IEEE complex quad type is available
via the soft-fp library on x86_64 targets.
This includes basic arithmetic operations (addition, subtraction,
negation, multiplication and division) on __float128
real and TCmode complex values, the full set of IEEE comparisons
between __float128 values, conversions to and from
float, double and long double
floating point types, as well as conversions to and from
signed or unsigned integer,
signed or unsigned long integer and
signed or unsigned quad (TImode) integer
types. Additionally, all operations generate the full set of IEEE
exceptions and support the full set of IEEE rounding modes.-mveclibabi=acml
is specified and you link to an ACML ABI compatible library.cris-*-elf target now includes support for
CRIS v32, including libraries, through the
-march=v32 option.crisv32-*-elf target defaults to generate
code for CRIS v32.crisv32-*-linux* target defaults to generate
code for CRIS v32.cris-*-aout target has been obsoleted.lz and
swapwbr instructions to implement the
__builtin_clz, __builtin_ctz and
__builtin_ffs family of functions.__builtin_bswap32 is now implemented using the
swapwb instruction, when available.-mcpu
option.m68k-uclinux targets have improved support for
C++ constructors and destructors, and for shared libraries.mov3q
instruction.__builtin_clz is now implemented using the
ff1 ColdFire instruction, when available.-m68010 option. 68010 code
now uses clr rather than move to
zero volatile memory.symbol(index.size*scale) addresses for
indexed array accesses. Earlier compilers would always
load the symbol into a base register first.--with-cpu.--with-arch configuration option has been added.
This option allows you to restrict a target to ColdFire or
non-ColdFire processors.__mcfv*__ macro is now defined for all ColdFire
targets. (Earlier versions of GCC only defined
__mcfv4e__.)__mcf_cpu_*, __mcf_family_* and
__mcffpu__ macros have been added.__mc68010 and
__mc68010__ when generating 68010 code.-march, -mcpu,
-mtune and -mhard-float have been added.
These options apply to both m68k and ColdFire targets.-mno-short, -mno-bitfield and
-mno-rtd are now accepted as negative versions
of -mshort, etc.-fforce-addr has been removed. It is now ignored
by the compiler.m68k-uclinux targets now try to avoid
situations that lead to the load-time error:
BINFMT_FLAT: reloc outside program.libffi and libjava now support all
three GNU/Linux ABIs: o32, n32 and n64. Every GNU/Linux
configuration now builds these libraries by default.-mno-shared
code unless overridden by -fpic,
-fPIC, -fpie or
-fPIE.mipsisa32*-linux-gnu configurations now generate
hard-float code by default, just like other mipsisa32*
and mips*-linux-gnu configurations. You can
build a soft-float version of any mips*-linux-gnu
configuration by passing --with-float=soft to
configure.mips-wrs-vxworks now supports run-time processes
(RTPs).-march and -mtune options no
longer accept 24k as a processor name. Please
use 24kc, 24kf2_1 or
24kf1_1 instead.-march and -mtune options now
accept 24kf2_1, 24kef2_1 and
34kf2_1 as synonyms for 24kf,
24kef and 34kf respectively.
The options also accept 24kf1_1,
24kef1_1 and 34kf1_1 as synonyms for
24kx, 24kex and 34kx.GCC now supports the following configurations:
mipsisa32r2*-linux-gnu*, which generates MIPS32
revision 2 code by default. Earlier releases also recognized
this configuration, but they treated it in the same way as
mipsisa32*-linux-gnu*. Note that you can
customize any mips*-linux-gnu* configuration
to a particular ISA or processor by passing an appropriate
--with-arch option to configure.mipsisa*-sde-elf*, which provides compatibility
with MIPS Technologies' SDE toolchains. The configuration
uses the SDE libraries by default, but you can use it like
other newlib-based ELF configurations by passing
--with-newlib to configure. It is
the only configuration besides mips64vr*-elf* to
build MIPS16 as well as non-MIPS16 libraries.mipsisa*-elfoabi*, which is similar to the general
mipsisa*-elf* configuration, but uses the o32 and
o64 ABIs instead of the 32-bit and 64-bit forms of the EABI.-msmartmips option.-mdspr2 option. A new preprocessor macro
called __mips_dsp_rev indicates the revision of
the ASE in use.-march and -mtune
options.sync instructions to implement atomic built-in
functions such as __sync_fetch_and_add. The
memory reference must be 4 bytes wide for 32-bit targets and
either 4 or 8 bytes wide for 64-bit targets.clz and dclz
instructions to implement the __builtin_ctz and
__builtin_ffs families of functions.__builtin___clear_cache function
for flushing the instruction cache. GCC expands this function
inline on MIPS32 revision 2 targets, otherwise it calls the
function specified by -mcache-flush-func.mips16 and nomips16, for specifying
which mode a function should use.-minterlink-mips16
makes non-MIPS16 code link-compatible with MIPS16 code.-mhard-float support should now work fairly
reliably.save and
restore instructions.-fsection-anchors now works in MIPS16 mode.
MIPS16 code compiled with -G0
-fsection-anchors is often smaller than code
compiled with -G8. However, please note that you
must usually compile all objects in your application with the
same -G option; see the documentation of
-G for details.-mcode-readable specifies
which instructions are allowed to load from the code segment.
-mcode-readable=yes is the default and says that
any instruction may load from the code segment. The other
alternatives are -mcode-readable=pcrel, which
says that only PC-relative MIPS16 instructions may load from
the code segment, and -mcode-readable=no, which
says that no instruction may do so. Please see the
documentation for more details, including example uses.There are three new options for controlling small data:
-mno-extern-sdata, which disables small-data
accesses for externally-defined variables. Code compiled
with -Gn -mno-extern-sdata will be
link-compatible with any -G setting between
-G0 and -Gn inclusive.-mno-local-sdata, which disables the use of
small-data sections for data that is not externally visible.
This option can be a useful way of reducing small-data usage
in less performance-critical parts of an application.-mno-gpopt, which disables the use of the
$gp register while still honoring the
-G limit when placing externally-visible data.
This option implies -mno-extern-sdata and
-mno-local-sdata and it can be useful in
situations where $gp does not necessarily hold
the expected value.-mbranch-cost
for tweaking the perceived cost of branches..gnu_attribute directive, it will use that
directive to record certain properties of the output code.
.gnu_attribute is new to GAS 2.18.near
and far, for overriding the command-line setting
of -mlong-calls on a function-by-function
basis.-mfp64, which previously required a 64-bit target,
now works with MIPS32 revision 2 targets as well. The
mipsisa*-elfoabi* and mipsisa*-sde-elf*
configurations provide suitable library support.-mdmx and -mmt
options and passes them down to the assembler. It does nothing
else with the options at present.powerpc-*-linux*paired* target
configuration. It is enabled by an associated -mpaired
option and can be accessed using new built-in functions.-march=z9-ec option,
the compiler will generate code making use of instructions
provided by the decimal floating point facility and the
floating point conversion facility (pfpo). Besides the
instructions used to implement decimal floating point
operations these facilities also contain instructions to move
between general purpose and floating point registers and to
modify and copy the sign-bit of floating point values.-march=z9-ec option is used the new
-mhard-dfp/-mno-hard-dfp options can be used to
specify whether the decimal floating point hardware
instructions will be used or not. If none of them is given
the hardware support is enabled by default.-mstack-guard option can now be omitted when
using stack checking via -mstack-size in order to
let GCC choose a sensible stack guard value according to the
frame size of each function.a + b + carry < b.S32C1I instructions.__builtin_ctz and __builtin_clz
functions.The compiler's --help command-line option has
been extended so that it now takes an optional set of arguments.
These arguments restrict the information displayed to specific
classes of command-line options, and possibly only a subset of
those options. It is also now possible to replace the descriptive
text associated with each displayed option with an indication of
its current value, or for binary options, whether it has been
enabled or disabled.
Here are some examples. The following will display all the options controlling warning messages:
--help=warnings
Whereas this will display all the undocumented, target specific options:
--help=target,undocumented
This sequence of commands will display the binary
optimizations that are enabled by -O3:
gcc -c -Q -O3 --help=optimizers > /tmp/O3-opts
gcc -c -Q -O2 --help=optimizers > /tmp/O2-opts
diff /tmp/O2-opts /tmp/O3-opts | grep enabled
--with-pkgversion and
--with-bugurl have been added. These allow
distributors of GCC to include a distributor-specific string in
manuals and --version output and to specify the URL
for reporting bugs in their versions of GCC.Please send FSF & GNU inquiries & questions to gnu@gnu.org. There are also other ways to contact the FSF.
These pages are maintained by the GCC team.
For questions related to the use of GCC, please consult these web pages and the GCC manuals. If that fails, the gcc-help@gcc.gnu.org mailing list might help.Copyright (C) Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA.
Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.
| Last modified 2008-02-28 |
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