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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-4.5/index.html

                           GCC 4.5 Release Series

   July 31, 2010

   The [1]GNU project and the GCC developers are pleased to announce the

   release of GCC 4.5.1.

   This release is a bug-fix release, containing fixes for regressions in

   GCC 4.5.0 relative to previous releases of GCC.

Release History

   GCC 4.5.1

          Jul 31, 2010 ([2]changes)

   GCC 4.5.0

          April 14, 2010 ([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.

   Please send FSF & GNU inquiries & questions to [10]gnu@gnu.org. There

   are also [11]other ways to contact the FSF.

   These pages are [12]maintained by the GCC team.

    For questions related to the use of GCC, please consult these web

    pages and the [13]GCC manuals. If that fails, the

    [14]gcc-help@gcc.gnu.org mailing list might help.

    Please send comments on these web pages and the development of GCC to

    our developer mailing list at [15]gcc@gnu.org or [16]gcc@gcc.gnu.org.

    All of our lists have [17]public archives.

   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 2010-07-31 [18]Valid XHTML 1.0

References

   1. http://www.gnu.org/

   2. http://gcc.gnu.org/gcc-4.5/changes.html

   3. http://gcc.gnu.org/gcc-4.5/changes.html

   4. http://gcc.gnu.org/gcc-4.5/buildstat.html

   5. http://gcc.gnu.org/onlinedocs/gcc/Contributors.html

   6. http://gcc.gnu.org/index.html

   7. mailto:gcc@gcc.gnu.org

   8. http://gcc.gnu.org/mirrors.html

   9. http://gcc.gnu.org/svn.html

  10. mailto:gnu@gnu.org

  11. http://www.gnu.org/home.html#ContactInfo

  12. http://gcc.gnu.org/about.html

  13. http://gcc.gnu.org/onlinedocs/

  14. mailto:gcc-help@gcc.gnu.org

  15. mailto:gcc@gnu.org

  16. mailto:gcc@gcc.gnu.org

  17. http://gcc.gnu.org/lists.html

  18. http://validator.w3.org/check/referer

======================================================================

http://gcc.gnu.org/gcc-4.5/changes.html

                           GCC 4.5 Release Series

                      Changes, New Features, and Fixes

Caveats

     * GCC now requires the [1]MPC library in order to build. See the

       [2]prerequisites page for version requirements.

     * Support for a number of older systems and recently unmaintained or

       untested target ports of GCC has been declared obsolete in GCC 4.5.

       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 releases before 6.5 (mips-sgi-irix5*,

            mips-sgi-irix6.[0-4])

          + Solaris 7 (*-*-solaris2.7)

          + Tru64 UNIX releases before V5.1 (alpha*-dec-osf4*,

            alpha-dec-osf5.0*)

          + Details for the IRIX, Solaris 7, and Tru64 UNIX obsoletions

            can be found in the [3]announcement.

       Support for the classic POWER architecture implemented in the

       original RIOS and RIOS2 processors of the old IBM RS/6000 product

       line has been obsoleted in the rs6000 port. This does not affect

       the new generation Power and PowerPC architectures.

     * Support has been removed for all the [4]configurations obsoleted in

       GCC 4.4.

     * Support has been removed for the protoize and unprotoize utilities,

       obsoleted in GCC 4.4.

     * Support has been removed for tuning for Itanium1 (Merced) variants.

       Note that code tuned for Itanium2 should also run correctly on

       Itanium1.

     * GCC now generates unwind info also for epilogues. DWARF debuginfo

       generated by GCC now uses more features of DWARF3 than it used to

       do and also some DWARF4 features. GDB older than 7.0 is not able to

       handle either of these, so to debug GCC 4.5 generated binaries or

       libraries GDB 7.0 or later is needed. You can disable use of DWARF4

       features with -gdwarf-3 -gstrict-dwarf options, or with -gdwarf-2

       -gstrict-dwarf restrict GCC to just DWARF2 standard, but epilogue

       unwind info is emitted unconditionally whenever unwind info is

       emitted.

     * On x86 targets, code containing floating-point calculations may run

       significantly slower when compiled with GCC 4.5 in strict C99

       conformance mode than they did with earlier GCC versions. This is

       due to stricter standard conformance of the compiler and can be

       avoided by using the option -fexcess-precision=fast; also see

       [5]below.

     * The function attribute noinline no longer prevents GCC from cloning

       the function. A new attribute noclone has been introduced for this

       purpose. Cloning a function means that it is duplicated and the new

       copy is specialized for certain contexts (for example when a

       parameter is a known constant).

General Optimizer Improvements

     * The -save-temps now takes an optional argument. The -save-temps and

       -save-temps=cwd switches write the temporary files in the current

       working directory based on the original source file. The

       -save-temps=obj switch will write files into the directory

       specified with the -o option, and the intermediate filenames are

       based on the output file. This will allow the user to get the

       compiler intermediate files when doing parallel builds without two

       builds of the same filename located in different directories from

       interfering with each other.

     * Debugging dumps are now created in the same directory as the object

       file rather than in the current working directory. This allows the

       user to get debugging dumps when doing parallel builds without two

       builds of the same filename interfering with each other.

     * GCC has been integrated with the [6]MPC library. This allows GCC to

       evaluate complex arithmetic at compile time [7]more accurately. It

       also allows GCC to evaluate calls to complex built-in math

       functions having constant arguments and replace them at compile

       time with their mathematically equivalent results. In doing so, GCC

       can generate correct results regardless of the math library

       implementation or floating point precision of the host platform.

       This also allows GCC to generate identical results regardless of

       whether one compiles in native or cross-compile configurations to a

       particular target. The following built-in functions take advantage

       of this new capability: cacos, cacosh, casin, casinh, catan,

       catanh, ccos, ccosh, cexp, clog, cpow, csin, csinh, csqrt, ctan,

       and ctanh. The float and long double variants of these functions

       (e.g. csinf and csinl) are also handled.

     * A new link-time optimizer has been added ([8]-flto). When this

       option is used, GCC generates a bytecode representation of each

       input file and writes it to special ELF sections in each object

       file. When the object files are linked together, all the function

       bodies are read from these ELF sections and instantiated as if they

       had been part of the same translation unit. This enables

       interprocedural optimizations to work across different files (and

       even different languages), potentially improving the performance of

       the generated code. To use the link-timer optimizer, -flto needs to

       be specified at compile time and during the final link. If the

       program does not require any symbols to be exported, it is possible

       to combine -flto and the experimental [9]-fwhopr with

       [10]-fwhole-program to allow the interprocedural optimizers to use

       more aggressive assumptions.

     * The automatic parallelization pass was enhanced to support

       parallelization of outer loops.

     * Automatic parallelization can be enabled as part of Graphite. In

       addition to -ftree-parallelize-loops=, specify

       -floop-parallelize-all to enable the Graphite-based optimization.

     * The infrastructure for optimizing based on [11]restrict qualified

       pointers has been rewritten and should result in code generation

       improvements. Optimizations based on restrict qualified pointers

       are now also available when using -fno-strict-aliasing.

     * There is a new optimization pass that attempts to change prototype

       of functions to avoid unused parameters, pass only relevant parts

       of structures and turn arguments passed by reference to arguments

       passed by value when possible. It is enabled by -O2 and above as

       well as -Os and can be manually invoked using the new command-line

       switch -fipa-sra.

     * GCC now optimize exception handling code. In particular cleanup

       regions that are proved to not have any effect are optimized out.

New Languages and Language specific improvements

  All languages

     * The -fshow-column option is now on by default. This means error

       messages now have a column associated with them.

  Ada

     * Compilation of programs heavily using discriminated record types

       with variant parts has been sped up and generates more compact

       code.

     * Stack checking now works reasonably well on most plaforms. In some

       specific cases, stack overflows may still fail to be detected, but

       a compile-time warning will be issued for these cases.

  C family

     * If a header named in a #include directive is not found, the

       compiler exits immediately. This avoids a cascade of errors arising

       from declarations expected to be found in that header being

       missing.

     * A new built-in function __builtin_unreachable() has been added that

       tells the compiler that control will never reach that point. It may

       be used after asm statements that terminate by transferring control

       elsewhere, and in other places that are known to be unreachable.

     * The -Wlogical-op option now warns for logical expressions such as

       (c == 1 && c == 2) and (c != 1 || c != 2), which are likely to be

       mistakes. This option is disabled by default.

     * An asm goto feature has been added to allow asm statements that

       jump to C labels.

     * C++0x raw strings are supported for C++ and for C with -std=gnu99.

     * The deprecated attribute now takes an optional string argument, for

       example, __attribute__((deprecated("text string"))), that will be

       printed together with the deprecation warning.

  C

     * The -Wenum-compare option, which warns when comparing values of

       different enum types, now works for C. It formerly only worked for

       C++. This warning is enabled by -Wall. It may be avoided by using a

       type cast.

     * The -Wcast-qual option now warns about casts which are unsafe in

       that they permit const-correctness to be violated without further

       warnings. Specifically, it warns about cases where a qualifier is

       added when all the lower types are not const. For example, it warns

       about a cast from char ** to const char **.

     * The -Wc++-compat option is significantly improved. It issues new

       warnings for:

          + Using C++ reserved operator names as identifiers.

          + Conversions to enum types without explicit casts.

          + Using va_arg with an enum type.

          + Using different enum types in the two branches of ?:.

          + Using ++ or -- on a variable of enum type.

          + Using the same name as both a struct, union or enum tag and a

            typedef, unless the typedef refers to the tagged type itself.

          + Using a struct, union, or enum which is defined within another

            struct or union.

          + A struct field defined using a typedef if there is a field in

            the struct, or an enclosing struct, whose name is the typedef

            name.

          + Duplicate definitions at file scope.

          + Uninitialized const variables.

          + A global variable with an anonymous struct, union, or enum

            type.

          + Using a string constant to initialize a char array whose size

            is the length of the string.

     * The new -Wjump-misses-init option warns about cases where a goto or

       switch skips the initialization of a variable. This sort of branch

       is an error in C++ but not in C. This warning is enabled by

       -Wc++-compat.

     * GCC now ensures that a C99-conforming  is present on most

       targets, and uses information about the types in this header to

       implement the Fortran bindings to those types. GCC does not ensure

       the presence of such a header, and does not implement the Fortran

       bindings, on the following targets: NetBSD, VxWorks, VMS,

       SymbianOS, WinCE, LynxOS, Netware, QNX, Interix, TPF.

     * GCC now implements C90- and C99-conforming rules for constant

       expressions. This may cause warnings or errors for some code using

       expressions that can be folded to a constant but are not constant

       expressions as defined by ISO C.

     * All known target-independent C90 and C90 Amendment 1 conformance

       bugs, and all known target-independent C99 conformance bugs not

       related to floating point or extended identifiers, have been fixed.

     * The C decimal floating point support now includes support for the

       FLOAT_CONST_DECIMAL64 pragma.

     * The named address space feature from ISO/IEC TR 18037 is now

       supported. This is currently only implemented for the SPU

       processor.

  C++

     * Improved [12]experimental support for the upcoming C++0x ISO C++

       standard, including support for raw strings, lambda expressions and

       explicit type conversion operators.

     * When printing the name of a class template specialization, G++ will

       now omit any template arguments which come from default template

       arguments. This behavior (and the pretty-printing of function

       template specializations as template signature and arguments) can

       be disabled with the -fno-pretty-templates option.

     * Access control is now applied to typedef names used in a template,

       which may cause G++ to reject some ill-formed code that was

       accepted by earlier releases. The -fno-access-control option can be

       used as a temporary workaround until the code is corrected.

     * Compilation time for code that uses templates should now scale

       linearly with the number of instantiations rather than

       quadratically, as template instantiations are now looked up using

       hash tables.

     * Declarations of functions that look like builtin declarations of

       library functions are only considered to be redeclarations if they

       are declared with extern "C". This may cause problems with code

       that omits extern "C" on hand-written declarations of C library

       functions such as abort or memcpy. Such code is ill-formed, but was

       accepted by earlier releases.

     * Diagnostics that used to complain about passing non-POD types to

       ... or jumping past the declaration of a non-POD variable now check

       for triviality rather than PODness, as per C++0x.

     * In C++0x mode local and anonymous classes are now allowed as

       template arguments, and in declarations of variables and functions

       with linkage, so long as any such declaration that is used is also

       defined ([13]DR 757).

     * Labels may now have attributes, as has been permitted for a while

       in C. This is only permitted when the label definition and the

       attribute specifier is followed by a semicolon--i.e., the label

       applies to an empty statement. The only useful attribute for a

       label is unused.

     * G++ now implements [14]DR 176. Previously G++ did not support using

       the injected-class-name of a template base class as a type name,

       and lookup of the name found the declaration of the template in the

       enclosing scope. Now lookup of the name finds the

       injected-class-name, which can be used either as a type or as a

       template, depending on whether or not the name is followed by a

       template argument list. As a result of this change, some code that

       was previously accepted may be ill-formed because

         1. The injected-class-name is not accessible because it's from a

            private base, or

         2. The injected-class-name cannot be used as an argument for a

            template template parameter.

       In either of these cases, the code can be fixed by adding a

       nested-name-specifier to explicitly name the template. The first

       can be worked around with -fno-access-control; the second is only

       rejected with -pedantic.

     * A new standard mangling for SIMD vector types has been added, to

       avoid name clashes on systems with vectors of varying length. By

       default the compiler still uses the old mangling, but emits aliases

       with the new mangling on targets that support strong aliases. Users

       can switch over entirely to the new mangling with -fabi-version=4

       or -fabi-version=0. -Wabi will now warn about code that uses the

       old mangling.

     * The command-line option -ftemplate-depth-N is now written as

       -ftemplate-depth=N and the old form is deprecated.

     * Conversions between NULL and non-pointer types are now warned by

       default. The new option -Wno-conversion-null disables these

       warnings. Previously these warnings were only available when using

       -Wconversion explicitly.

    Runtime Library (libstdc++)

     * [15]Improved experimental support for the upcoming ISO C++

       standard, C++0x, including:

          + Support for , , and .

          + Existing facilities now exploit explicit operators and the

            newly implemented core C++0x features.

     * An experimental [16]profile mode has been added. This is an

       implementation of many C++ standard library constructs with an

       additional analysis layer that gives performance improvement advice

       based on recognition of suboptimal usage patterns. For example,

#include 

int main()

{

  std::vector v;

  for (int k = 0; k < 1024; ++k)

    v.insert(v.begin(), k);

}

       When instrumented via the profile mode, can return suggestions

       about the initial size and choice of the container used as follows:

vector-to-list: improvement = 5: call stack = 0x804842c ...

    : advice = change std::vector to std::list

vector-size: improvement = 3: call stack = 0x804842c ...

    : advice = change initial container size from 0 to 1024

       These constructs can be substituted for the normal libstdc++

       constructs on a piecemeal basis, or all existing components can be

       transformed via the -D_GLIBCXX_PROFILE macro.

     * [17]Support for decimal floating-point arithmetic (aka ISO C++ TR

       24733) has been added. This support is in header file

       , uses namespace std::decimal, and includes

       classes decimal32, decimal64, and decimal128.

     * Sources have been audited for application of function attributes

       nothrow, const, pure, and noreturn.

     * Python pretty-printers have been added for many standard library

       components that simplify the internal representation and present a

       more intuitive view of components when used with

       appropriately-advanced versions of GDB. For more information,

       please consult the more [18]detailed description.

     * The default behavior for comparing typeinfo names has changed, so

       in , __GXX_MERGED_TYPEINFO_NAMES now defaults to zero.

     * The new -static-libstdc++ option directs g++ to link the C++

       library statically, even if the default would normally be to link

       it dynamically.

  Fortran

     * The COMMON default padding has been changed - instead of adding the

       padding before a variable it is now added afterwards, which

       increases the compatibility with other vendors and helps to obtain

       the correct output in some cases. Cf. also the -falign-commons

       option ([19]added in 4.4).

     * The -finit-real= option now also supports the value snan for

       signalling not-a-number; to be effective, one additionally needs to

       enable trapping (e.g. via -ffpe-trap=). Note: Compile-time

       optimizations can turn a signalling NaN into a quiet one.

     * The new option -fcheck= has been added with the options bounds,

       array-temps, do, pointer, and recursive. The bounds and array-temps

       options are equivalent to -fbounds-check and

       -fcheck-array-temporaries. The do option checks for invalid

       modification of loop iteration variables, and the recursive option

       tests for recursive calls to subroutines/functions which are not

       marked as recursive. With pointer pointer association checks in

       calls are performed; however, neither undefined pointers nor

       pointers in expressions are handled. Using -fcheck=all enables all

       these run-time checks.

     * The run-time checking -fcheck=bounds now warns about invalid string

       lengths of character dummy arguments. Additionally, more

       compile-time checks have been added.

     * The new option [20]-fno-protect-parens has been added; if set, the

       compiler may reorder REAL and COMPLEX expressions without regard to

       parentheses.

     * GNU Fortran no longer links against libgfortranbegin. As before,

       MAIN__ (assembler symbol name) is the actual Fortran main program,

       which is invoked by the main function. However, main is now

       generated and put in the same object file as MAIN__. For the time

       being, libgfortranbegin still exists for backward compatibility.

       For details see the new [21]Mixed-Language Programming chapter in

       the manual.

     * The I/O library was restructured for performance and cleaner code.

     * Array assignments and WHERE are now run in parallel when OpenMP's

       WORKSHARE is used.

     * The experimental option -fwhole-file was added. The option allows

       whole-file checking of procedure arguments and allows for better

       optimizations. It can also be used with -fwhole-program, which is

       now also supported in gfortran.

     * More Fortran 2003 and Fortran 2008 mathematical functions can now

       be used as initialization expressions.

     * Some extended attributes such as STDCALL are now supported via the

       [22]GCC$ compiler directive.

     * For Fortran 77 compatibility: If -fno-sign-zero is used, the SIGN

       intrinsic behaves now as if zero were always positive.

     * For legacy compatibiliy: On Cygwin and MinGW, the special files

       CONOUT$ and CONIN$ (and CONERR$ which maps to CONOUT$) are now

       supported.

     * Fortran 2003 support has been extended:

          + Procedure-pointer function results and procedure-pointer

            components (including PASS),

          + allocatable scalars (experimental),

          + DEFERRED type-bound procedures,

          + the ERRMSG= argument of the ALLOCATE and DEALLOCATE statements

            have been implemented.

          + The ALLOCATE statement supports type-specs and the SOURCE=

            argument.

          + OPERATOR(*) and ASSIGNMENT(=) are now allowed as GENERIC

            type-bound procedure (i.e. as type-bound operators).

          + Rounding (ROUND=, RZ, ...) for output is now supported.

          + The INT_FAST{8,16,32,64,128}_T kind type parameters of the

            intrinsic module ISO_C_BINDING are now supported, except for

            the targets listed above as ones where GCC does not have

             type information.

          + Extensible derived types with type-bound procedure or

            procedure pointer with PASS attribute now have to use CLASS in

            line with the Fortran 2003 standard; the workaround to use

            TYPE is no longer supported.

          + [23]Experimental, incomplete support for polymorphism,

            including CLASS, SELECT TYPE and dynamic dispatch of

            type-bound procedure calls. Some features do not work yet such

            as unlimited polymorphism (CLASS(*)).

     * Fortran 2008 support has been extended:

          + The OPEN statement now supports the NEWUNIT= option, which

            returns a unique file unit, thus preventing inadvertent use of

            the same unit in different parts of the program.

          + Support for unlimited format items has been added.

          + The INT{8,16,32} and REAL{32,64,128} kind type parameters of

            the intrinsic module ISO_FORTRAN_ENV are now supported.

          + Using complex arguments with TAN, SINH, COSH, TANH, ASIN,

            ACOS, and ATAN is now possible; the functions ASINH, ACOSH,

            and ATANH have been added (for real and complex arguments) and

            ATAN(Y,X) is now an alias for ATAN2(Y,X).

          + The BLOCK construct has been implemented.

  Java (GCJ)

New Targets and Target Specific Improvements

  AIX

     * Full cross-toolchain support now available with GNU Binutils

  ARM

     * GCC now supports the Cortex-M0 and Cortex-A5 processors.

     * GCC now supports the ARM v7E-M architecture.

     * GCC now supports VFPv4-based FPUs and FPUs with

       single-precision-only VFP.

     * GCC has many improvements to optimization for other ARM processors,

       including scheduling support for the integer pipeline on Cortex-A9.

     * GCC now supports the IEEE 754-2008 half-precision floating-point

       type, and a variant ARM-specific half-precision type. This type is

       specified using __fp16, with the layout determined by

       -mfp16-format. With appropriate -mfpu options, the Cortex-A9 and

       VFPv4 half-precision instructions will be used.

     * GCC now supports the variant of AAPCS that uses VFP registers for

       parameter passing and return values.

  AVR

     * The -mno-tablejump option has been removed because it has the same

       effect as the -fno-jump-tables option.

     * Added support for these new AVR devices:

          + ATmega8U2

          + ATmega16U2

          + ATmega32U2

  IA-32/x86-64

     * GCC now will set the default for -march= based on the configure

       target.

     * GCC now supports handling floating-point excess precision arising

       from use of the x87 floating-point unit in a way that conforms to

       ISO C99. This is enabled with -fexcess-precision=standard and with

       standards conformance options such as -std=c99, and may be disabled

       using -fexcess-precision=fast.

     * Support for the Intel Atom processor is now available through the

       -march=atom and -mtune=atom options.

     * A new -mcrc32 option is now available to enable crc32 intrinsics.

     * A new -mmovbe option is now available to enable GCC to use the

       movbe instruction to implement __builtin_bswap32 and

       __builtin_bswap64.

     * SSE math now can be enabled by default at configure time with the

       new --with-fpmath=sse option.

     * There is a new intrinsic header file, . It should be

       included before using any IA-32/x86-64 intrinsics.

     * Support for the XOP, FMA4, and LWP instruction sets for the AMD

       Orochi processors are now available with the -mxop, -mfma4, and

       -mlwp options.

     * The -mabm option enables GCC to use the popcnt and lzcnt

       instructions on AMD processors.

     * The -mpopcnt option enables GCC to use the popcnt instructions on

       both AMD and Intel processors.

  M68K/ColdFire

     * GCC now supports ColdFire 51xx, 5221x, 5225x, 52274, 52277, 5301x

       and 5441x devices.

     * GCC now supports thread-local storage (TLS) on M68K and ColdFire

       processors.

  MeP

   Support has been added for the Toshiba Media embedded Processor (MeP,

   or mep-elf) embedded target.

  MIPS

     * GCC now supports MIPS 1004K processors.

     * GCC can now be configured with options --with-arch-32,

       --with-arch-64, --with-tune-32 and --with-tune-64 to control the

       default optimization separately for 32-bit and 64-bit modes.

     * MIPS targets now support an alternative _mcount interface, in which

       register $12 points to the function's save slot for register $31.

       This interface is selected by the -mcount-ra-address option; see

       the documentation for more details.

     * GNU/Linux targets can now generate read-only .eh_frame sections.

       This optimization requires GNU binutils 2.20 or above, and is only

       available if GCC is configured with a suitable version of binutils.

     * GNU/Linux targets can now attach special relocations to indirect

       calls, so that the linker can turn them into direct jumps or

       branches. This optimization requires GNU binutils 2.20 or later,

       and is automatically selected if GCC is configured with an

       appropriate version of binutils. It can be explicitly enabled or

       disabled using the -mrelax-pic-calls command-line option.

     * GCC now generates more heavily-optimized atomic operations on

       Octeon processors.

     * MIPS targets now support the -fstack-protector option.

     * GCC now supports an -msynci option, which specifies that synci is

       enough to flush the instruction cache, without help from the

       operating system. GCC uses this information to optimize

       automatically-generated cache flush operations, such as those used

       for nested functions in C. There is also a --with-synci

       configure-time option, which makes -msynci the default.

     * GCC supports four new function attributes for interrupt handlers:

       interrupt, use_shadow_register_set, keep_interrupts_masked and

       use_debug_exception_return. See the documentation for more details

       about these attributes.

  OpenRISC 1000

     * GCC now generates global variables and functions without a leading

       underscore.

     * GCC now generates DWARF 2 debugging output by default (with -g).

     * -mhard-mul is enabled by default.

     * The -mor32-newlib and -mor32-newlib-uart options enable support for the

       OpenRISC newlib library implementations.

  picochip

  RS/6000 (POWER/PowerPC)

     * GCC now supports the Power ISA 2.06, which includes the VSX

       instructions that add vector 64-bit floating point support, new

       population count instructions, and conversions between floating

       point and unsigned types.

     * Support for the power7 processor is now available through the

       -mcpu=power7 and -mtune=power7.

     * GCC will now vectorize loops that contain simple math functions

       like copysign when generating code for altivec or VSX targets.

     * Support for the A2 processor is now available through the -mcpu=a2

       and -mtune=a2 options.

     * Support for the 476 processor is now available through the

       -mcpu={476,476fp} and -mtune={476,476fp} options.

     * Support for the e500mc64 processor is now available through the

       -mcpu=e500mc64 and -mtune=e500mc64 options.

     * GCC can now be configured with options --with-cpu-32,

       --with-cpu-64, --with-tune-32 and --with-tune-64 to control the

       default optimization separately for 32-bit and 64-bit modes.

  RX

   Support has been added for the Renesas RX Processor (rx-elf) target.

Operating Systems

  Windows (Cygwin and MinGW)

     * GCC now installs all the major language runtime libraries as DLLs

       when configured with the --enable-shared option.

     * GCC now makes use of the new support for aligned common variables

       in versions of binutils >= 2.20 to fix bugs in the support for SSE

       data types.

     * Improvements to the libffi support library increase the reliability

       of code generated by GCJ on all Windows platforms. Libgcj is

       enabled by default for the first time.

     * Libtool improvements simplify installation by placing the generated

       DLLs in the correct binaries directory.

     * Numerous other minor bugfixes and improvements, and substantial

       enhancements to the Fortran language support library.

Documentation improvements

Other significant improvements

  Plugins

     * It is now possible to extend the compiler without having to modify

       its source code. A new option -fplugin=file.so tells GCC to load

       the shared object file.so and execute it as part of the compiler.

       The internal documentation describes the details on how plugins can

       interact with the compiler.

  Installation changes

     * The move to newer autotools changed default installation

       directories and switches to control them: The --with-datarootdir,

       --with-docdir, --with-pdfdir, and --with-htmldir switches are not

       used any more. Instead, you can now use --datarootdir, --docdir,

       --htmldir, and --pdfdir. The default installation directories have

       changed as follows according to the GNU Coding Standards:

       datarootdir read-only architecture-independent data root [PREFIX/share]

       localedir   locale-specific message catalogs [DATAROOTDIR/locale]

       docdir      documentation root [DATAROOTDIR/doc/PACKAGE]

       htmldir     html documentation [DOCDIR]

       dvidir      dvi documentation [DOCDIR]

       pdfdir      pdf documentation [DOCDIR]

       psdir       ps documentation [DOCDIR]

       The following variables have new default values:

       datadir read-only architecture-independent data [DATAROOTDIR]

       infodir info documentation [DATAROOTDIR/info]

       mandir  man documentation [DATAROOTDIR/man]

GCC 4.5.1

   This is the [24]list of problem reports (PRs) from GCC's bug tracking

   system that are known to be fixed in the 4.5.1 release. This list might

   not be complete (that is, it is possible that some PRs that have been

   fixed are not listed here).

  All languages

     * GCC's new link-time optimizer ([25]-flto) now also works on a few

       non-ELF targets:

          + Cygwin (*-cygwin*)

          + MinGW (*-mingw*)

          + Darwin on x86-64 (x86_64-apple-darwin*)

       LTO is not enabled by default for these targets. To enable LTO, you

       should configure with the --enable-lto option.

   Please send FSF & GNU inquiries & questions to [26]gnu@gnu.org. There

   are also [27]other ways to contact the FSF.

   These pages are [28]maintained by the GCC team.

    For questions related to the use of GCC, please consult these web

    pages and the [29]GCC manuals. If that fails, the

    [30]gcc-help@gcc.gnu.org mailing list might help.

    Please send comments on these web pages and the development of GCC to

    our developer mailing list at [31]gcc@gnu.org or [32]gcc@gcc.gnu.org.

    All of our lists have [33]public archives.

   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 2010-07-31 [34]Valid XHTML 1.0

References

   1. http://www.multiprecision.org/

   2. http://gcc.gnu.org/install/prerequisites.html

   3. http://gcc.gnu.org/ml/gcc/2010-01/msg00510.html

   4. http://gcc.gnu.org/gcc-4.4/changes.html#obsoleted

   5. http://gcc.gnu.org/gcc-4.5/changes.html#x86

   6. http://www.multiprecision.org/

   7. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30789

   8. http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-flto-801

   9. http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fwhopr-802

  10. http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fwhole-program-800

  11. http://gcc.gnu.org/onlinedocs/gcc/Restricted-Pointers.html

  12. http://gcc.gnu.org/gcc-4.5/cxx0x_status.html

  13. http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#757

  14. http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#176

  15. http://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.200x

  16. http://gcc.gnu.org/onlinedocs/libstdc++/manual/profile_mode.html

  17. http://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.tr24733

  18. http://sourceware.org/gdb/wiki/STLSupport

  19. http://gcc.gnu.org/gcc-4.4/changes.html

  20. http://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html

  21. http://gcc.gnu.org/onlinedocs/gfortran/Mixed-Language-Programming.html

  22. http://gcc.gnu.org/onlinedocs/gfortran/GNU-Fortran-Compiler-Directives.html

  23. http://gcc.gnu.org/wiki/OOP

  24. http://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.5.1

  25. http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-flto-801

  26. mailto:gnu@gnu.org

  27. http://www.gnu.org/home.html#ContactInfo

  28. http://gcc.gnu.org/about.html

  29. http://gcc.gnu.org/onlinedocs/

  30. mailto:gcc-help@gcc.gnu.org

  31. mailto:gcc@gnu.org

  32. mailto:gcc@gcc.gnu.org

  33. http://gcc.gnu.org/lists.html

  34. http://validator.w3.org/check/referer

======================================================================

http://gcc.gnu.org/gcc-4.4/index.html

                           GCC 4.4 Release Series

   April 29, 2010

   The [1]GNU project and the GCC developers are pleased to announce the

   release of GCC 4.4.4.

   This release is a bug-fix release, containing fixes for regressions in

   GCC 4.4.3 relative to previous releases of GCC.

Release History

   GCC 4.4.4

          April 29, 2010 ([2]changes)

   GCC 4.4.3

          January 21, 2010 ([3]changes)

   GCC 4.4.2

          October 15, 2009 ([4]changes)

   GCC 4.4.1

          July 22, 2009 ([5]changes)

   GCC 4.4.0

          April 21, 2009 ([6]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 [7]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 [8]amazing group of volunteers is

   what makes GCC successful.

   For additional information about GCC please refer to the [9]GCC project

   web site or contact the [10]GCC development mailing list.

   To obtain GCC please use [11]our mirror sites or [12]our SVN server.

   Please send FSF & GNU inquiries & questions to [13]gnu@gnu.org. There

   are also [14]other ways to contact the FSF.

   These pages are [15]maintained by the GCC team.

    For questions related to the use of GCC, please consult these web

    pages and the [16]GCC manuals. If that fails, the

    [17]gcc-help@gcc.gnu.org mailing list might help.

    Please send comments on these web pages and the development of GCC to

    our developer mailing list at [18]gcc@gnu.org or [19]gcc@gcc.gnu.org.

    All of our lists have [20]public archives.

   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 2010-07-01 [21]Valid XHTML 1.0

References

   1. http://www.gnu.org/

   2. http://gcc.gnu.org/gcc-4.4/changes.html

   3. http://gcc.gnu.org/gcc-4.4/changes.html

   4. http://gcc.gnu.org/gcc-4.4/changes.html

   5. http://gcc.gnu.org/gcc-4.4/changes.html

   6. http://gcc.gnu.org/gcc-4.4/changes.html

   7. http://gcc.gnu.org/gcc-4.4/buildstat.html

   8. http://gcc.gnu.org/onlinedocs/gcc/Contributors.html

   9. http://gcc.gnu.org/index.html

  10. mailto:gcc@gcc.gnu.org

  11. http://gcc.gnu.org/mirrors.html

  12. http://gcc.gnu.org/svn.html

  13. mailto:gnu@gnu.org

  14. http://www.gnu.org/home.html#ContactInfo

  15. http://gcc.gnu.org/about.html

  16. http://gcc.gnu.org/onlinedocs/

  17. mailto:gcc-help@gcc.gnu.org

  18. mailto:gcc@gnu.org

  19. mailto:gcc@gcc.gnu.org

  20. http://gcc.gnu.org/lists.html

  21. http://validator.w3.org/check/referer

======================================================================

http://gcc.gnu.org/gcc-4.4/changes.html

                           GCC 4.4 Release Series

                      Changes, New Features, and Fixes

   The latest release in the 4.4 release series is [1]GCC 4.4.4.

Caveats

     * __builtin_stdarg_start has been completely removed from GCC.

       Support for  had been deprecated since GCC 4.0. Use

       __builtin_va_start as a replacement.

     * Some of the errors issued by the C++ front end that could be

       downgraded to warnings in previous releases by using -fpermissive

       are now warnings by default. They can be converted into errors by

       using -pedantic-errors.

     * Use of the cpp assertion extension will now emit a warning when

       -Wdeprecated or -pedantic is used. This extension has been

       deprecated for many years, but never warned about.

     * Packed bit-fields of type char were not properly bit-packed on many

       targets prior to GCC 4.4. On these targets, the fix in GCC 4.4

       causes an ABI change. For example there is no longer a 4-bit

       padding between field a and b in this structure:

    struct foo

    {

      char a:4;

      char b:8;

    } __attribute__ ((packed));

       There is a new warning to help identify fields that are affected:

    foo.c:5: note: Offset of packed bit-field 'b' has changed in GCC 4.4

       The warning can be disabled with -Wno-packed-bitfield-compat.

     * On ARM EABI targets, the C++ mangling of the va_list type has been

       changed to conform to the current revision of the EABI. This does

       not affect the libstdc++ library included with GCC.

     * The SCOUNT and POS bits of the MIPS DSP control register are now

       treated as global. Previous versions of GCC treated these fields as

       call-clobbered instead.

     * The MIPS port no longer recognizes the h asm constraint. It was

       necessary to remove this constraint in order to avoid generating

       unpredictable code sequences.

       One of the main uses of the h constraint was to extract the high

       part of a multiplication on 64-bit targets. For example:

    asm ("dmultu\t%1,%2" : "=h" (result) : "r" (x), "r" (y));

       You can now achieve the same effect using 128-bit types:

    typedef unsigned int uint128_t __attribute__((mode(TI)));

    result = ((uint128_t) x * y) >> 64;

       The second sequence is better in many ways. For example, if x and y

       are constants, the compiler can perform the multiplication at

       compile time. If x and y are not constants, the compiler can

       schedule the runtime multiplication better than it can schedule an

       asm statement.

     * Support for a number of older systems and recently unmaintained or

       untested target ports of GCC has been declared obsolete in GCC 4.4.

       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:

          + Generic a.out on IA32 and m68k (i[34567]86-*-aout*,

            m68k-*-aout*)

          + Generic COFF on ARM, H8300, IA32, m68k and SH (arm-*-coff*,

            armel-*-coff*, h8300-*-*, i[34567]86-*-coff*, m68k-*-coff*,

            sh-*-*). This does not affect other more specific targets

            using the COFF object format on those architectures, or the

            more specific H8300 and SH targets (h8300-*-rtems*,

            h8300-*-elf*, sh-*-elf*, sh-*-symbianelf*, sh-*-linux*,

            sh-*-netbsdelf*, sh-*-rtems*, sh-wrs-vxworks).

          + 2BSD on PDP-11 (pdp11-*-bsd)

          + AIX 4.1 and 4.2 on PowerPC (rs6000-ibm-aix4.[12]*,

            powerpc-ibm-aix4.[12]*)

          + Tuning support for Itanium1 (Merced) variants. Note that code

            tuned for Itanium2 should also run correctly on Itanium1.

     * The protoize and unprotoize utilities have been obsoleted and will

       be removed in GCC 4.5. These utilities have not been installed by

       default since GCC 3.0.

     * Support has been removed for all the [2]configurations obsoleted in

       GCC 4.3.

     * Unknown -Wno-* options are now silently ignored by GCC if no other

       diagnostics are issued. If other diagnostics are issued, then GCC

       warns about the unknown options.

     * More information on porting to GCC 4.4 from previous versions of

       GCC can be found in the [3]porting guide for this release.

General Optimizer Improvements

     * A new command-line switch -findirect-inlining has been added. When

       turned on it allows the inliner to also inline indirect calls that

       are discovered to have known targets at compile time thanks to

       previous inlining.

     * A new command-line switch -ftree-switch-conversion has been added.

       This new pass turns simple initializations of scalar variables in

       switch statements into initializations from a static array, given

       that all the values are known at compile time and the ratio between

       the new array size and the original switch branches does not exceed

       the parameter --param switch-conversion-max-branch-ratio (default

       is eight).

     * A new command-line switch -ftree-builtin-call-dce has been added.

       This optimization eliminates unnecessary calls to certain builtin

       functions when the return value is not used, in cases where the

       calls can not be eliminated entirely because the function may set

       errno. This optimization is on by default at -O2 and above.

     * A new command-line switch -fconserve-stack directs the compiler to

       minimize stack usage even if it makes the generated code slower.

       This affects inlining decisions.

     * When the assembler supports it, the compiler will now emit unwind

       information using assembler .cfi directives. This makes it possible

       to use such directives in inline assembler code. The new option

       -fno-dwarf2-cfi-asm directs the compiler to not use .cfi

       directives.

     * The [4]Graphite branch has been merged. This merge has brought in a

       new framework for loop optimizations based on a polyhedral

       intermediate representation. These optimizations apply to all the

       languages supported by GCC. The following new code transformations

       are available in GCC 4.4:

          + -floop-interchange performs loop interchange transformations

            on loops. Interchanging two nested loops switches the inner

            and outer loops. For example, given a loop like:

          DO J = 1, M

            DO I = 1, N

              A(J, I) = A(J, I) * C

            ENDDO

          ENDDO

            loop interchange will transform the loop as if the user had

            written:

          DO I = 1, N

            DO J = 1, M

              A(J, I) = A(J, I) * C

            ENDDO

          ENDDO

            which can be beneficial when N is larger than the caches,

            because in Fortran, the elements of an array are stored in

            memory contiguously by column, and the original loop iterates

            over rows, potentially creating at each access a cache miss.

          + -floop-strip-mine performs loop strip mining transformations

            on loops. Strip mining splits a loop into two nested loops.

            The outer loop has strides equal to the strip size and the

            inner loop has strides of the original loop within a strip.

            For example, given a loop like:

          DO I = 1, N

            A(I) = A(I) + C

          ENDDO

            loop strip mining will transform the loop as if the user had

            written:

          DO II = 1, N, 4

            DO I = II, min (II + 3, N)

              A(I) = A(I) + C

            ENDDO

          ENDDO

          + -floop-block performs loop blocking transformations on loops.

            Blocking strip mines each loop in the loop nest such that the

            memory accesses of the element loops fit inside caches. For

            example, given a loop like:

          DO I = 1, N

            DO J = 1, M

              A(J, I) = B(I) + C(J)

            ENDDO

          ENDDO

            loop blocking will transform the loop as if the user had

            written:

          DO II = 1, N, 64

            DO JJ = 1, M, 64

              DO I = II, min (II + 63, N)

                DO J = JJ, min (JJ + 63, M)

                  A(J, I) = B(I) + C(J)

                ENDDO

              ENDDO

            ENDDO

          ENDDO

            which can be beneficial when M is larger than the caches,

            because the innermost loop will iterate over a smaller amount

            of data that can be kept in the caches.

     * A new register allocator has replaced the old one. It is called

       integrated register allocator (IRA) because coalescing, register

       live range splitting, and hard register preferencing are done

       on-the-fly during coloring. It also has better integration with the

       reload pass. IRA is a regional register allocator which uses modern

       Chaitin-Briggs coloring instead of Chow's priority coloring used in

       the old register allocator. More info about IRA internals and

       options can be found in the GCC manuals.

     * A new instruction scheduler and software pipeliner, based on the

       selective scheduling approach, has been added. The new pass

       performs instruction unification, register renaming, substitution

       through register copies, and speculation during scheduling. The

       software pipeliner is able to pipeline non-countable loops. The new

       pass is targeted at scheduling-eager in-order platforms. In GCC 4.4

       it is available for the Intel Itanium platform working by default

       as the second scheduling pass (after register allocation) at the

       -O3 optimization level.

     * When using -fprofile-generate with a multi-threaded program, the

       profile counts may be slightly wrong due to race conditions. The

       new -fprofile-correction option directs the compiler to apply

       heuristics to smooth out the inconsistencies. By default the

       compiler will give an error message when it finds an inconsistent

       profile.

     * The new -fprofile-dir=PATH option permits setting the directory

       where profile data files are stored when using -fprofile-generate

       and friends, and the directory used when reading profile data files

       using -fprofile-use and friends.

New warning options

     * The new -Wframe-larger-than=NUMBER option directs GCC to emit a

       warning if any stack frame is larger than NUMBER bytes. This may be

       used to help ensure that code fits within a limited amount of stack

       space.

     * The command-line option -Wlarger-than-N is now written as

       -Wlarger-than=N and the old form is deprecated.

     * The new -Wno-mudflap option disables warnings about constructs

       which can not be instrumented when using -fmudflap.

New Languages and Language specific improvements

     * Version 3.0 of the [5]OpenMP specification is now supported for the

       C, C++, and Fortran compilers.

     * New character data types, per [6]TR 19769: New character types in

       C, are now supported for the C compiler in -std=gnu99 mode, as

       __CHAR16_TYPE__ and __CHAR32_TYPE__, and for the C++ compiler in

       -std=c++0x and -std=gnu++0x modes, as char16_t and char32_t too.

  C family

     * A new optimize attribute was added to allow programmers to change

       the optimization level and particular optimization options for an

       individual function. You can also change the optimization options

       via the GCC optimize pragma for functions defined after the pragma.

       The GCC push_options pragma and the GCC pop_options pragma allow

       you temporarily save and restore the options used. The GCC

       reset_options pragma restores the options to what was specified on

       the command line.

     * Uninitialized warnings do not require enabling optimization

       anymore, that is, -Wuninitialized can be used together with -O0.

       Nonetheless, the warnings given by -Wuninitialized will probably be

       more accurate if optimization is enabled.

     * -Wparentheses now warns about expressions such as (!x | y) and (!x

       & y). Using explicit parentheses, such as in ((!x) | y), silences

       this warning.

     * -Wsequence-point now warns within if, while,do while and for

       conditions, and within for begin/end expressions.

     * A new option -dU is available to dump definitions of preprocessor

       macros that are tested or expanded.