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This file contains information about GCC releases which has been generated
automatically from the online release notes. It covers releases of GCC
(and the former EGCS project) since EGCS 1.0, on the line of development
that led to GCC 3. For information on GCC 2.8.1 and older releases of GCC 2,
see ONEWS.
======================================================================
http://gcc.gnu.org/gcc-4.7/index.html
GCC 4.7 Release Series
June 14, 2012
The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.7.1.
This release is a bug-fix release, containing fixes for regressions in
GCC 4.7.0 relative to previous releases of GCC.
Release History
GCC 4.7.1
June 14, 2012 ([2]changes)
GCC 4.7.0
March 22, 2012 ([3]changes)
References and Acknowledgements
GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.
A list of [4]successful builds is updated as new information becomes
available.
The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [5]amazing group of volunteers is
what makes GCC successful.
For additional information about GCC please refer to the [6]GCC project
web site or contact the [7]GCC development mailing list.
To obtain GCC please use [8]our mirror sites or [9]our SVN server.
For questions related to the use of GCC, please consult these web
pages and the [10]GCC manuals. If that fails, the
[11][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [12][email protected]. All of [13]our lists have public
archives.
Copyright (C) [14]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.
These pages are [15]maintained by the GCC team. Last modified
2012-06-14[16].
References
1. http://www.gnu.org/
2. http://gcc.gnu.org/gcc-4.7/changes.html
3. http://gcc.gnu.org/gcc-4.7/changes.html
4. http://gcc.gnu.org/gcc-4.7/buildstat.html
5. http://gcc.gnu.org/onlinedocs/gcc/Contributors.html
6. http://gcc.gnu.org/index.html
7. mailto:[email protected]
8. http://gcc.gnu.org/mirrors.html
9. http://gcc.gnu.org/svn.html
10. http://gcc.gnu.org/onlinedocs/
11. mailto:[email protected]
12. mailto:[email protected]
13. http://gcc.gnu.org/lists.html
14. http://www.fsf.org/
15. http://gcc.gnu.org/about.html
16. http://validator.w3.org/check/referer
======================================================================
http://gcc.gnu.org/gcc-4.7/changes.html
GCC 4.7 Release Series
Changes, New Features, and Fixes
Caveats
* The -fconserve-space flag has been deprecated. The flag had no
effect for most targets: only targets without a global .bss section
and without support for switchable sections. Furthermore, the flag
only had an effect for G++, where it could result in wrong
semantics (please refer to the GCC manual for further details). The
flag will be removed in GCC 4.8
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 4.7.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
The following ports for individual systems on particular
architectures have been obsoleted:
+ IRIX 6.5 (mips-sgi-irix6.5)
+ MIPS OpenBSD (mips*-*-openbsd*)
+ Solaris 8 (*-*-solaris2.8). Details can be found in the
[1]announcement.
+ Tru64 UNIX V5.1 (alpha*-dec-osf5.1*)
* Support on ARM for the legacy floating-point accelerator (FPA) and
the mixed-endian floating-point format that it used has been
obsoleted. The ports that still use this format have been obsoleted
as well. Many legacy ARM ports already provide an alternative that
uses the VFP floating-point format. The obsolete ports will be
deleted in the next release.
The obsolete ports with alternatives are:
+ arm*-*-rtems (use arm*-*-rtemseabi)
+ arm*-*-linux-gnu (use arm*-*-linux-gnueabi)
+ arm*-*-elf (use arm*-*-eabi)
+ arm*-*-uclinux* (use arm*-*-uclinux*eabi)
Note, however, that these alternatives are not binary compatible
with their legacy counterparts (although some can support running
legacy applications).
The obsolete ports that currently lack a modern alternative are:
+ arm*-*-ecos-elf
+ arm*-*-freebsd
+ arm*-wince-pe*
New ports that support more recent versions of the architecture are
welcome.
* Support for the Maverick co-processor on ARM has been obsoleted.
Code to support it will be deleted in the next release.
* Support has been removed for Unix International threads on Solaris
2, so the --enable-threads=solaris configure option and the
-threads compiler option don't work any longer.
* Support has been removed for the Solaris BSD Compatibility Package,
which lives in /usr/ucbinclude and /usr/ucblib. It has been removed
from Solaris 11, and was only intended as a migration aid from
SunOS 4 to SunOS 5. The -compat-bsd compiler option is not
recognized any longer.
* The AVR port's libgcc has been improved and its multilib structure
has been enhanced. As a result, all objects contributing to an
application must either be compiled with GCC versions up to 4.6.x
or with GCC versions 4.7.0 or later.
* The ARM port's -mwords-little-endian option has been deprecated. It
will be removed in a future release.
* Support has been removed for the NetWare x86 configuration
obsoleted in GCC 4.6.
* It is no longer possible to use the "l" constraint in MIPS16 asm
statements.
* More information on porting to GCC 4.7 from previous versions of
GCC can be found in the [2]porting guide for this release.
General Optimizer Improvements
* Support for a new parameter --param case-values-threshold=n was
added to allow users to control the cutoff between doing switch
statements as a series of if statements and using a jump table.
* Link-time optimization (LTO) improvements:
+ Improved scalability and reduced memory usage. Link time
optimization of Firefox now requires 3GB of RAM on a 64-bit
system, while over 8GB was needed previously. Linking time has
been improved, too. The serial stage of linking Firefox has
been sped up by about a factor of 10.
+ Reduced size of object files and temporary storage used during
linking.
+ Streaming performance (both outbound and inbound) has been
improved.
+ ld -r is now supported with LTO.
+ Several bug fixes, especially in symbol table handling and
merging.
* Interprocedural optimization improvements:
+ Heuristics now take into account that after inlining code will
be optimized out because of known values (or properties) of
function parameters. For example:
void foo(int a)
{
if (a > 10)
... huge code ...
}
void bar (void)
{
foo (0);
}
The call of foo will be inlined into bar even when optimizing
for code size. Constructs based on __builtin_constant_p are
now understood by the inliner and code size estimates are
evaluated a lot more realistically.
+ The representation of C++ virtual thunks and aliases (both
implicit and defined via the alias attribute) has been
re-engineered. Aliases no longer pose optimization barriers
and calls to an alias can be inlined and otherwise optimized.
+ The inter-procedural constant propagation pass has been
rewritten. It now performs generic function specialization.
For example when compiling the following:
void foo(bool flag)
{
if (flag)
... do something ...
else
... do something else ...
}
void bar (void)
{
foo (false);
foo (true);
foo (false);
foo (true);
foo (false);
foo (true);
}
GCC will now produce two copies of foo. One with flag being
true, while other with flag being false. This leads to
performance improvements previously possible only by inlining
all calls. Cloning causes a lot less code size growth.
* A string length optimization pass has been added. It attempts to
track string lengths and optimize various standard C string
functions like strlen, strchr, strcpy, strcat, stpcpy and their
_FORTIFY_SOURCE counterparts into faster alternatives. This pass is
enabled by default at -O2 or above, unless optimizing for size, and
can be disabled by the -fno-optimize-strlen option. The pass can
e.g. optimize
char *bar (const char *a)
{
size_t l = strlen (a) + 2;
char *p = malloc (l); if (p == NULL) return p;
strcpy (p, a); strcat (p, "/"); return p;
}
into:
char *bar (const char *a)
{
size_t tmp = strlen (a);
char *p = malloc (tmp + 2); if (p == NULL) return p;
memcpy (p, a, tmp); memcpy (p + tmp, "/", 2); return p;
}
or for hosted compilations where stpcpy is available in the runtime
and headers provide its prototype, e.g.
void foo (char *a, const char *b, const char *c, const char *d)
{
strcpy (a, b); strcat (a, c); strcat (a, d);
}
can be optimized into:
void foo (char *a, const char *b, const char *c, const char *d)
{
strcpy (stpcpy (stpcpy (a, b), c), d);
}
New Languages and Language specific improvements
* Version 3.1 of the [3]OpenMP specification is now supported for the
C, C++, and Fortran compilers.
Ada
* The command-line option -feliminate-unused-debug-types has been
re-enabled by default, as it is for the other languages, leading to
a reduction in debug info size of 12.5% and more for relevant
cases, as well as to a small compilation speedup.
C family
* A new built-in, __builtin_assume_aligned, has been added, through
which the compiler can be hinted about pointer alignment and can
use it to improve generated code.
* A new -Wunused-local-typedefs warning was added for C, C++,
Objective-C and Objective-C++. This warning diagnoses typedefs
locally defined in a function, and otherwise not used.
* A new experimental -ftrack-macro-expansion option was added for C,
C++, Objective-C, Objective-C++ and Fortran. It allows the compiler
to emit diagnostic about the current macro expansion stack when a
compilation error occurs in a macro expansion.
* Experimental support for transactional memory has been added. It
includes support in the compiler, as well as a supporting runtime
library called libitm. To compile code with transactional memory
constructs, use the -fgnu-tm option.
Support is currently available for Alpha, ARM, PowerPC, SH, SPARC,
and 32-bit/64-bit x86 platforms.
For more details on transactional memory see [4]the GCC WiKi.
* Support for atomic operations specifying the C++11/C11 memory model
has been added. These new __atomic routines replace the existing
__sync built-in routines.
Atomic support is also available for memory blocks. Lock-free
instructions will be used if a memory block is the same size and
alignment as a supported integer type. Atomic operations which do
not have lock-free support are left as function calls. A set of
library functions is available on the GCC atomic wiki in the
"External Atomics Library" section.
For more details on the memory models and features, see the
[5]atomic wiki.
* When a binary operation is performed on vector types and one of the
operands is a uniform vector, it is possible to replace the vector
with the generating element. For example:
typedef int v4si __attribute__ ((vector_size (16)));
v4si res, a = {1,2,3,4};
int x;
res = 2 + a; /* means {2,2,2,2} + a */
res = a - x; /* means a - {x,x,x,x} */
C
* There is support for some more features from the C11 revision of
the ISO C standard. GCC now accepts the options -std=c11 and
-std=gnu11, in addition to the previous -std=c1x and -std=gnu1x.
+ Unicode strings (previously supported only with options such
as -std=gnu11, now supported with -std=c11), and the
predefined macros __STDC_UTF_16__ and __STDC_UTF_32__.
+ Nonreturning functions (_Noreturn and <stdnoreturn.h>).
+ Alignment support (_Alignas, _Alignof, max_align_t,
<stdalign.h>).
+ A built-in function __builtin_complex is provided to support C
library implementation of the CMPLX family of macros.
C++
* G++ now accepts the -std=c++11, -std=gnu++11, and -Wc++11-compat
options, which are equivalent to -std=c++0x, -std=gnu++0x, and
-Wc++0x-compat, respectively.
* G++ now implements [6]C++11 extended friend syntax:
template<class W>
class Q
{
static const int I = 2;
public:
friend W;
};
struct B
{
int ar[Q<B>::I];
};
* Thanks to Ville Voutilainen, G++ now implements [7]C++11 explicit
override control.
struct B {
virtual void f() const final;
virtual void f(int);
};
struct D : B {
void f() const; // error: D::f attempts to override final B::f
void f(long) override; // error: doesn't override anything
void f(int) override; // ok
};
struct E final { };
struct F: E { }; // error: deriving from final class
* G++ now implements [8]C++11 non-static data member initializers.
struct A {
int i = 42;
} a; // initializes a.i to 42
* Thanks to Ed Smith-Rowland, G++ now implements [9]C++11
user-defined literals.
// Not actually a good approximation. :)
constexpr long double operator"" _degrees (long double d) { return d * 0.0175; }
long double pi = 180.0_degrees;
* G++ now implements [10]C++11 alias-declarations.
template <class T> using Ptr = T*;
Ptr<int> ip; // decltype(ip) is int*
* Thanks to Ville Voutilainen and Pedro Lamarao, G++ now implements
[11]C++11 delegating constructors.
struct A {
A(int);
A(): A(42) { } // delegate to the A(int) constructor
};
* G++ now fully implements C++11 atomic classes rather than just
integer derived classes.
class POD {
int a;
int b;
};
std::atomic<POD> my_atomic_POD;
* G++ now sets the predefined macro __cplusplus to the correct value,
199711L for C++98/03, and 201103L for C++11.
* G++ now correctly implements the two-phase lookup rules such that
an unqualified name used in a template must have an appropriate
declaration found either in scope at the point of definition of the
template or by argument-dependent lookup at the point of
instantiation. As a result, code that relies on a second
unqualified lookup at the point of instantiation to find functions
declared after the template or in dependent bases will be rejected.
The compiler will suggest ways to fix affected code, and using the
-fpermissive compiler flag will allow the code to compile with a
warning.
template <class T>
void f() { g(T()); } // error, g(int) not found by argument-dependent lookup
void g(int) { } // fix by moving this declaration before the declaration of f
template <class T>
struct A: T {
// error, B::g(B) not found by argument-dependent lookup
void f() { g(T()); } // fix by using this->g or A::g
};
struct B { void g(B); };
int main()
{
f<int>();
A<B>().f();
}
* G++ now properly re-uses stack space allocated for temporary
objects when their lifetime ends, which can significantly lower
stack consumption for some C++ functions. As a result of this, some
code with undefined behavior will now break:
const int &f(const int &i) { return i; }
....
const int &x = f(1);
const int &y = f(2);
Here, x refers to the temporary allocated to hold the 1 argument,
which only lives until the end of the initialization; it
immediately becomes a dangling reference. So the next statement
re-uses the stack slot to hold the 2 argument, and users of x get
that value instead.
Note that this should not cause any change of behavior for
temporaries of types with non-trivial destructors, as they are
already destroyed at end of full-expression; the change is that now
the storage is released as well.
* A new command-line option -Wdelete-non-virtual-dtor has been added
to warn when delete is used to destroy an instance of a class which
has virtual functions and non-virtual destructor. It is unsafe to
delete an instance of a derived class through a pointer to a base
class if the base class does not have a virtual destructor. This
warning is enabled by -Wall.
* A new command-line option -Wzero-as-null-pointer-constant has been
added to warn when a literal '0' is used as null pointer constant.
It can be useful to facilitate the conversion to nullptr in C++11.
* As per C++98, access-declarations are now deprecated by G++.
Using-declarations are to be used instead. Furthermore, some
efforts have been made to improve the support of class scope
using-declarations. In particular, using-declarations referring to
a dependent type now work as expected ([12]bug c++/14258).
* The ELF symbol visibility of a template instantiation is now
properly constrained by the visibility of its template arguments
([13]bug c++/35688).
Runtime Library (libstdc++)
* [14]Improved experimental support for the new ISO C++ standard,
C++11, including:
+ using noexcept in most of the library;
+ implementations of pointer_traits, allocator_traits and
scoped_allocator_adaptor;
+ uses-allocator construction for tuple;
+ vector meets the allocator-aware container requirements;
+ replacing monotonic_clock with steady_clock;
+ enabling the thread support library on most POSIX targets;
+ many small improvements to conform to the FDIS.
* Added --enable-clocale=newlib configure option.
* Debug Mode iterators for unordered associative containers.
* Avoid polluting the global namespace and do not include <unistd.h>.
Fortran
* The compile flag [15]-fstack-arrays has been added, which causes
all local arrays to be put on stack memory. For some programs this
will improve the performance significantly. If your program uses
very large local arrays, it is possible that you will have to
extend your runtime limits for stack memory.
* The [16]-Ofast flag now also implies [17]-fno-protect-parens and
[18]-fstack-arrays.
* Front-end optimizations can now be selected by the
[19]-ffrontend-optimize option and deselected by the
-fno-frontend-optimize option.
* When front-end optimization removes a function call,
[20]-Wfunction-elimination warns about that.
* When performing front-end-optimization, the
[21]-faggressive-function-elimination option allows the removal of
duplicate function calls even for impure functions.
* The flag [22]-Wreal-q-constant has been added, which warns if
floating-point literals have been specified using q (such as
1.0q0); the q marker is now supported as a vendor extension to
denote quad precision (REAL(16) or, if not available, REAL(10)).
Consider using a kind parameter (such as in 1.0_qp) instead, which
can be obtained via [23]SELECTED_REAL_KIND.
* The GFORTRAN_USE_STDERR environment variable has been removed. GNU
Fortran now always prints error messages to standard error. If you
wish to redirect standard error, please consult the manual for your
OS, shell, batch environment etc. as appropriate.
* The -fdump-core option and GFORTRAN_ERROR_DUMPCORE environment
variable have been removed. When encountering a serious error,
gfortran will now always abort the program. Whether a core dump is
generated depends on the user environment settings; see the ulimit
-c setting for POSIX shells, limit coredumpsize for C shells, and
the [24]WER user-mode dumps settings on Windows.
* The [25]-fbacktrace option is now enabled by default. When
encountering a fatal error, gfortran will attempt to print a
backtrace to standard error before aborting. It can be disabled
with -fno-backtrace. Note: On POSIX targets with the addr2line
utility from GNU binutils, GNU Fortran can print a backtrace with
function name, file name, line number information in addition to
the addresses; otherwise only the addresses are printed.
* [26]Fortran 2003:
+ Generic interface names which have the same name as derived
types are now supported, which allows to write constructor
functions. Note that Fortran does not support static
constructor functions; only default initialization or an
explicit structure-constructor initialization are available.
+ [27]Polymorphic (class) arrays are now supported.
* [28]Fortran 2008:
+ Support for the DO CONCURRENT construct has been added, which
allows the user to specify that individual loop iterations
have no interdependencies.
+ [29]Coarrays: Full single-image support except for polymorphic
coarrays. Additionally, preliminary support for multiple
images via an MPI-based [30]coarray communication library has
been added. Note: The library version is not yet usable as
remote coarray access is not yet possible.
* [31]TS 29113:
+ New flag [32]-std=f2008ts permits programs that are expected
to conform to the Fortran 2008 standard and the draft
Technical Specification (TS) 29113 on Further Interoperability
of Fortran with C.
+ The OPTIONAL attribute is now allowed for dummy arguments of
BIND(C) procedures.
+ The RANK intrinsic has been added.
+ The implementation of the ASYNCHRONOUS attribute in GCC is
compatible with the candidate draft of TS 29113 (since GCC
4.6).
Go
* GCC 4.7 implements the [33]Go 1 language standard. The library
support in 4.7.0 is not quite complete, due to release timing.
Release 4.7.1 is expected to include complete support.
* Go has been tested on GNU/Linux and Solaris platforms. It may work
on other platforms as well.
New Targets and Target Specific Improvements
ARM
* GCC now supports the Cortex-A7 processor implementing the v7-a
version of the architecture using the option -mcpu=cortex-a7.
* The default vector size in auto-vectorization for NEON is now 128
bits. If vectorization fails thusly, the vectorizer tries again
with 64-bit vectors.
* A new option -mvectorize-with-neon-double was added to allow users
to change the vector size to 64 bits.
AVR
* GCC now supports the XMEGA architecture. This requires GNU binutils
2.22 or later.
* Support for the [34]named address spaces __flash, __flash1, ...,
__flash5 and __memx has been added. These address spaces locate
read-only data in flash memory and allow reading from flash memory
by means of ordinary C code, i.e. without the need of (inline)
assembler code:
const __flash int values[] = { 42, 31 };
int add_values (const __flash int *p, int i)
{
return values[i] + *p;
}
* Support for AVR-specific [35]built-in functions has been added.
* Support has been added for the signed and unsigned 24-bit scalar
integer types __int24 and __uint24.
* New command-line options -maccumulate-args, -mbranch-cost=cost and
-mstrict-X were added to allow better fine-tuning of code
optimization.
* The command option -fdata-sections now also takes affect on the
section names of variables with the progmem attribute.
* A new inline assembler print modifier %i to print a RAM address as
I/O address has been added:
#include <avr/io.h> /* Port Definitions from AVR-LibC */
void set_portb (uint8_t value)
{
asm volatile ("out %0, %i1" :: "r" (value), "n" (&PORTB) : "memory");
}
The offset between an I/O address and the RAM address for that I/O
location is device-specific. This offset is taken into account when
printing a RAM address with the %i modifier so that the address is
suitable to be used as operand in an I/O command. The address must
be a constant integer known at compile time.
* The inline assembler constraint "R" to represent integers in the
range -6 ... 5 has been removed without replacement.
* Many optimizations to:
+ 64-bit integer arithmetic
+ Widening multiplication
+ Integer division by a constant
+ Avoid constant reloading in multi-byte instructions.
+ Micro-optimizations for special instruction sequences.
+ Generic built-in functions like __builtin_ffs*,
__builtin_clz*, etc.
+ If-else decision trees generated by switch instructions
+ Merging of data located in flash memory
+ New libgcc variants for devices with 8-bit wide stack pointer
+ ...
* Better documentation:
+ Handling of EIND and indirect jumps on devices with more than
128 KiB of program memory.
+ Handling of the RAMPD, RAMPX, RAMPY and RAMPZ special function
registers.
+ Function attributes OS_main and OS_task.
+ AVR-specific built-in macros.
C6X
* Support has been added for the Texas Instruments C6X family of
processors.
CR16
* Support has been added for National Semiconductor's CR16
architecture.
Epiphany
* Support has been added for Adapteva's Epiphany architecture.
IA-32/x86-64
* Support for Intel AVX2 intrinsics, built-in functions and code
generation is available via -mavx2.
* Support for Intel BMI2 intrinsics, built-in functions and code
generation is available via -mbmi2.
* Implementation and automatic generation of __builtin_clz* using the
lzcnt instruction is available via -mlzcnt.
* Support for Intel FMA3 intrinsics and code generation is available
via -mfma.
* A new -mfsgsbase command-line option is available that makes GCC
generate new segment register read/write instructions through
dedicated built-ins.
* Support for the new Intel rdrnd instruction is available via
-mrdrnd.
* Two additional AVX vector conversion instructions are available via
-mf16c.
* Support for new Intel processor codename IvyBridge with RDRND,
FSGSBASE and F16C is available through -march=core-avx-i.
* Support for the new Intel processor codename Haswell with AVX2,
FMA, BMI, BMI2, LZCNT is available through -march=core-avx2.
* Support for new AMD family 15h processors (Piledriver core) is now
available through -march=bdver2 and -mtune=bdver2 options.
* Support for [36]the x32 psABI is now available through the -mx32
option.
* Windows mingw targets are using the -mms-bitfields option by
default.
* Windows x86 targets are using the __thiscall calling convention for
C++ class-member functions.
* Support for the configure option --with-threads=posix for Windows
mingw targets.
MIPS
* GCC now supports thread-local storage (TLS) for MIPS16. This
requires GNU binutils 2.22 or later.
* GCC can now generate code specifically for the Cavium Octeon+ and
Octeon2 processors. The associated command-line options are
-march=octeon+ and -march=octeon2 respectively. Both options
require GNU binutils 2.22 or later.
* GCC can now work around certain 24k errata, under the control of
the command-line option -mfix-24k. These workarounds require GNU
binutils 2.20 or later.
* 32-bit MIPS GNU/Linux targets such as mips-linux-gnu can now build
n32 and n64 multilibs. The result is effectively a 64-bit GNU/Linux
toolchain that generates 32-bit code by default. Use the
configure-time option --enable-targets=all to select these extra
multilibs.
* Passing -fno-delayed-branch now also stops the assembler from
automatically filling delay slots.
PowerPC/PowerPC64
* Vectors of type vector long long or vector long are passed and
returned using the same method as other vectors with the VSX
instruction set. Previously GCC did not adhere to the ABI for
128-bit vectors with 64-bit integer base types (PR 48857). This
will also be fixed in the GCC 4.6.1 and 4.5.4 releases.
* A new option -mno-pointers-to-nested-functions was added to allow
AIX 32-bit/64-bit and GNU/Linux 64-bit PowerPC users to specify
that the compiler should not load up the chain register (r11)
before calling a function through a pointer. If you use this
option, you cannot call nested functions through a pointer, or call
other languages that might use the static chain.
* A new option msave-toc-indirect was added to allow AIX
32-bit/64-bit and GNU/Linux 64-bit PowerPC users control whether we
save the TOC in the prologue for indirect calls or generate the
save inline. This can speed up some programs that call through a
function pointer a lot, but it can slow down other functions that
only call through a function pointer in exceptional cases.
* The PowerPC port will now enable machine-specific built-in
functions when the user switches the target machine using the
#pragma GCC target or __attribute__ ((__target__ ("target"))) code
sequences. In additon, the target macros are updated. However, due
to the way the -save-temps switch is implemented, you won't see the
effect of these additional macros being defined in preprocessor
output.
SH
* A new option -msoft-atomic has been added. When it is specified,
GCC will generate GNU/Linux-compatible gUSA atomic sequences for
the new __atomic routines.
* Since it is neither supported by GAS nor officially documented,
code generation for little endian SH2A has been disabled.
Specifying -ml with -m2a* will now result in a compiler error.
* The defunct -mbranch-cost option has been fixed.
* Some improvements to the generated code of:
+ Utilization of the tst #imm,R0 instruction.
+ Dynamic shift instructions on SH2A.
+ Integer absolute value calculations.
SPARC
* The option -mflat has been reinstated. When it is specified, the
compiler will generate code for a single register window model.
This is essentially a new implementation and the corresponding
debugger support has been added to GDB 7.4.
* Support for the options -mtune=native and -mcpu=native has been
added on selected native platforms (GNU/Linux and Solaris).
* Support for the SPARC T3 (Niagara 3) processor has been added.
* VIS:
+ An intrinsics header visintrin.h has been added.
+ Builtin intrinsics for the VIS 1.0 edge handling and pixel
compare instructions have been added.
+ The little-endian version of alignaddr is now supported.
+ When possible, VIS builtins are marked const, which should
increase the compiler's ability to optimize VIS operations.
+ The compiler now properly tracks the %gsr register and how it
behaves as an input for various VIS instructions.
+ Akin to fzero, the compiler can now generate fone instructions
in order to set all of the bits of a floating-point register
to 1.
+ The documentation for the VIS intrinsics in the GCC manual has
been brought up to date and many inaccuracies were fixed.
+ Intrinsics for the VIS 2.0 bmask, bshuffle, and
non-condition-code setting edge instructions have been added.
Their availability is controlled by the new -mvis2 and
-mno-vis2 options. They are enabled by default on
UltraSPARC-III and later CPUs.
* Support for UltraSPARC Fused Multiply-Add floating-point extensions
has been added. These instructions are enabled by default on SPARC
T3 (Niagara 3) and later CPUs.
TILE-Gx/TILEPro
* Support has been added for the Tilera TILE-Gx and TILEPro families
of processors.
Other significant improvements
* A new option (-grecord-gcc-switches) was added that appends
compiler command-line options that might affect code generation to
the DW_AT_producer attribute string in the DWARF debugging
information.
* GCC now supports various new GNU extensions to the DWARF debugging
information format, like [37]entry value and [38]call site
information, [39]typed DWARF stack or [40]a more compact macro
representation. Support for these extensions has been added to GDB
7.4. They can be disabled through the -gstrict-dwarf command-line
option.
GCC 4.7.1
This is the [41]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.7.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).
For questions related to the use of GCC, please consult these web
pages and the [42]GCC manuals. If that fails, the
[43][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [44][email protected]. All of [45]our lists have public
archives.
Copyright (C) [46]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.
These pages are [47]maintained by the GCC team. Last modified
2012-06-14[48].
References
1. http://gcc.gnu.org/ml/gcc-patches/2011-03/msg01263.html
2. http://gcc.gnu.org/gcc-4.7/porting_to.html
3. http://openmp.org/wp/openmp-specifications/
4. http://gcc.gnu.org/wiki/TransactionalMemory
5. http://gcc.gnu.org/wiki/Atomic/GCCMM
6. http://gcc.gnu.org/gcc-4.7/cxx0x_status.html
7. http://gcc.gnu.org/gcc-4.7/cxx0x_status.html
8. http://gcc.gnu.org/gcc-4.7/cxx0x_status.html
9. http://gcc.gnu.org/gcc-4.7/cxx0x_status.html
10. http://gcc.gnu.org/gcc-4.7/cxx0x_status.html
11. http://gcc.gnu.org/gcc-4.7/cxx0x_status.html
12. http://gcc.gnu.org/PR14258
13. http://gcc.gnu.org/PR35688
14. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/libstdc++/manual/manual/status.html#status.iso.2011
15. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfstack-arrays_007d-254
16. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Optimize-Options.html#index-Ofast-689
17. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfno-protect-parens_007d-270
18. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfstack-arrays_007d-254
19. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfrontend-optimize_007d-275
20. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Error-and-Warning-Options.html#index-g_t_0040code_007bWfunction-elimination_007d-170
21. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfaggressive-function-elimination_007d-270
22. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Error-and-Warning-Options.html#index-g_t_0040code_007bWreal-q-constant_007d-149
23. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/SELECTED_005fREAL_005fKIND.html
24. http://msdn.microsoft.com/en-us/library/bb787181%28v=vs.85%29.aspx
25. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Debugging-Options.html#index-g_t_0040code_007bfno-backtrace_007d-183
26. http://gcc.gnu.org/wiki/Fortran2003Status
27. http://gcc.gnu.org/wiki/OOP
28. http://gcc.gnu.org/wiki/Fortran2008Status
29. http://gcc.gnu.org/wiki/Coarray
30. http://gcc.gnu.org/wiki/CoarrayLib
31. http://gcc.gnu.org/wiki/TS29113Status
32. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gfortran/Fortran-Dialect-Options.html#index-g_t_0040code_007bstd_003d_007d_0040var_007bstd_007d-option-53
33. http://weekly.golang.org/doc/go1.html
34. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Named-Address-Spaces.html
35. http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/AVR-Built%5f002din-Functions.html
36. http://sites.google.com/site/x32abi/
37. http://www.dwarfstd.org/ShowIssue.php?issue=100909.1
38. http://www.dwarfstd.org/ShowIssue.php?issue=100909.2
39. http://www.dwarfstd.org/doc/040408.1.html
40. http://www.dwarfstd.org/ShowIssue.php?issue=110722.1
41. http://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.7.1
42. http://gcc.gnu.org/onlinedocs/
43. mailto:[email protected]
44. mailto:[email protected]
45. http://gcc.gnu.org/lists.html
46. http://www.fsf.org/
47. http://gcc.gnu.org/about.html
48. http://validator.w3.org/check/referer
======================================================================
http://gcc.gnu.org/gcc-4.6/index.html
GCC 4.6 Release Series
March 1, 2012
The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.6.3.
This release is a bug-fix release, containing fixes for regressions in
GCC 4.6.2 relative to previous releases of GCC.
Release History
GCC 4.6.3
March 1, 2012 ([2]changes)
GCC 4.6.2
October 26, 2011 ([3]changes)
GCC 4.6.1
June 27, 2011 ([4]changes)
GCC 4.6.0
March 25, 2011 ([5]changes)
References and Acknowledgements
GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.
A list of [6]successful builds is updated as new information becomes
available.
The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [7]amazing group of volunteers is
what makes GCC successful.
For additional information about GCC please refer to the [8]GCC project
web site or contact the [9]GCC development mailing list.
To obtain GCC please use [10]our mirror sites or [11]our SVN server.
For questions related to the use of GCC, please consult these web
pages and the [12]GCC manuals. If that fails, the
[13][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [14][email protected]. All of [15]our lists have public
archives.
Copyright (C) [16]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.
These pages are [17]maintained by the GCC team. Last modified
2012-03-01[18].
References
1. http://www.gnu.org/
2. http://gcc.gnu.org/gcc-4.6/changes.html
3. http://gcc.gnu.org/gcc-4.6/changes.html
4. http://gcc.gnu.org/gcc-4.6/changes.html
5. http://gcc.gnu.org/gcc-4.6/changes.html
6. http://gcc.gnu.org/gcc-4.6/buildstat.html
7. http://gcc.gnu.org/onlinedocs/gcc/Contributors.html
8. http://gcc.gnu.org/index.html
9. mailto:[email protected]
10. http://gcc.gnu.org/mirrors.html
11. http://gcc.gnu.org/svn.html
12. http://gcc.gnu.org/onlinedocs/
13. mailto:[email protected]
14. mailto:[email protected]
15. http://gcc.gnu.org/lists.html
16. http://www.fsf.org/
17. http://gcc.gnu.org/about.html
18. http://validator.w3.org/check/referer
======================================================================
http://gcc.gnu.org/gcc-4.6/changes.html
GCC 4.6 Release Series
Changes, New Features, and Fixes
Caveats
* The options -b <machine> and -V <version> have been removed because
they were unreliable. Instead, users should directly run
<machine>-gcc when cross-compiling, or <machine>-gcc-<version> to
run a different version of gcc.
* GCC now has stricter checks for invalid command-line options. In
particular, when gcc was called to link object files rather than
compile source code, it would previously accept and ignore all
options starting with --, including linker options such as
--as-needed and --export-dynamic, although such options would
result in errors if any source code was compiled. Such options, if
unknown to the compiler, are now rejected in all cases; if the
intent was to pass them to the linker, options such as
-Wl,--as-needed should be used.
* Versions of the GNU C library up to and including 2.11.1 included
an [1]incorrect implementation of the cproj function. GCC optimizes
its builtin cproj according to the behavior specified and allowed
by the ISO C99 standard. If you want to avoid discrepancies between
the C library and GCC's builtin transformations when using cproj in
your code, use GLIBC 2.12 or later. If you are using an older GLIBC
and actually rely on the incorrect behavior of cproj, then you can
disable GCC's transformations using -fno-builtin-cproj.
* The C-only intermodule optimization framework (IMA, enabled by
-combine) has been removed in favor of the new generic link-time
optimization framework (LTO) introduced in [2]GCC 4.5.0.
* GCC now ships with the LGPL-licensed libquadmath library, which
provides quad-precision mathematical functions for targets with a
__float128 datatype. __float128 is available for targets on 32-bit
x86, x86-64 and Itanium architectures. The libquadmath library is
automatically built on such targets when building the Fortran
compiler.
* New -Wunused-but-set-variable and -Wunused-but-set-parameter
warnings were added for C, C++, Objective-C and Objective-C++.
These warnings diagnose variables respective parameters which are
only set in the code and never otherwise used. Usually such
variables are useless and often even the value assigned to them is
computed needlessly, sometimes expensively. The
-Wunused-but-set-variable warning is enabled by default by -Wall
flag and -Wunused-but-set-parameter by -Wall -Wextra flags.
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 4.6.
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:
+ Argonaut ARC (arc-*)
+ National Semiconductor CRX (crx-*)
+ Motorola 68HC11 and 68HC12 (m68hc11-*-*, m6811-*-*,
m68hc12-*-*, m6812-*-*)
+ Sunplus S+core (score-*)
The following ports for individual systems on particular
architectures have been obsoleted:
+ Interix (i[34567]86-*-interix3*)
+ NetWare x86 (i[3456x]86-*-netware*)
+ Generic ARM PE (arm-*-pe* other than arm*-wince-pe*)
+ MCore PE (mcore-*-pe*)
+ SH SymbianOS (sh*-*-symbianelf*)
+ GNU Hurd on Alpha and PowerPC (alpha*-*-gnu*, powerpc*-*-gnu*)
+ M68K uClinux old ABI (m68k-*-uclinuxoldabi*)
+ a.out NetBSD (arm*-*-netbsd*, i[34567]86-*-netbsd*,
vax-*-netbsd*, but not *-*-netbsdelf*)
The i[34567]86-*-pe alias for Cygwin targets has also been
obsoleted; users should configure for i[34567]86-*-cygwin* instead.
Certain configure options to control the set of libraries built
with GCC on some targets have been obsoleted. On ARM targets, the
options --disable-fpu, --disable-26bit, --disable-underscore,