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diff --git a/gcc/ONEWS b/gcc/ONEWS new file mode 100644 index 000000000..8489abeb8 --- /dev/null +++ b/gcc/ONEWS @@ -0,0 +1,992 @@ +This file contains information about GCC releases up to GCC 2.8.1, and +a tiny bit of information on EGCS. + +For details of changes in EGCS releases and GCC 2.95 and later releases, +see the release notes on the GCC web site or the file NEWS which contains +the most relevant parts of those release notes in text form. + +Changes in GCC for EGCS (that are not listed in the web release notes) +--------------------------------------------------------------------- + +The compiler now supports the "ADDRESSOF" optimization which can significantly +reduce the overhead for certain inline calls (and inline calls in general). + +Compile time for certain programs using large constant initializers has been +improved (affects glibc significantly). + +Various improvements have been made to better support cross compilations. They +are still not easy, but they are improving. + +Target-specific changes: + + M32r: Major improvements to this port. + + Arm: Includes Thumb and super interworking support. + +Noteworthy changes in GCC version 2.8.1 +--------------------------------------- + +Numerous bugs have been fixed and some minor performance +improvements (compilation speed) have been made. + +Noteworthy changes in GCC version 2.8.0 +--------------------------------------- + +A major change in this release is the addition of a framework for +exception handling, currently used by C++. Many internal changes and +optimization improvements have been made. These increase the +maintainability and portability of GCC. GCC now uses autoconf to +compute many host parameters. + +The following lists changes that add new features or targets. + +See cp/NEWS for new features of C++ in this release. + +New tools and features: + + The Dwarf 2 debugging information format is supported on ELF systems, and + is the default for -ggdb where available. It can also be used for C++. + The Dwarf version 1 debugging format is also permitted for C++, but + does not work well. + + gcov.c is provided for test coverage analysis and branch profiling + analysis is also supported; see -fprofile-arcs, -ftest-coverage, + and -fbranch-probabilities. + + Support for the Checker memory checking tool. + + New switch, -fstack-check, to check for stack overflow on systems that + don't have such built into their ABI. + + New switches, -Wundef and -Wno-undef to warn if an undefined identifier + is evaluated in an #if directive. + + Options -Wall and -Wimplicit now cause GCC to warn about implicit int + in declarations (e.g. `register i;'), since the C Standard committee + has decided to disallow this in the next revision of the standard; + -Wimplicit-function-declarations and -Wimplicit-int are subsets of + this. + + Option -Wsign-compare causes GCC to warn about comparison of signed and + unsigned values. + + Add -dI option of cccp for cxref. + +New features in configuration, installation and specs file handling: + + New option --enable-c-cpplib to configure script. + + You can use --with-cpu on the configure command to specify the default + CPU that GCC should generate code for. + + The -specs=file switch allows you to override default specs used in + invoking programs like cc1, as, etc. + + Allow including one specs file from another and renaming a specs + variable. + + You can now relocate all GCC files with a single environment variable + or a registry entry under Windows 95 and Windows NT. + +Changes in Objective-C: + + The Objective-C Runtime Library has been made thread-safe. + + The Objective-C Runtime Library contains an interface for creating + mutexes, condition mutexes, and threads; it requires a back-end + implementation for the specific platform and/or thread package. + Currently supported are DEC/OSF1, IRIX, Mach, OS/2, POSIX, PCThreads, + Solaris, and Windows32. The --enable-threads parameter can be used + when configuring GCC to enable and select a thread back-end. + + Objective-C is now configured as separate front-end language to GCC, + making it more convenient to conditionally build it. + + The internal structures of the Objective-C Runtime Library have + changed sufficiently to warrant a new version number; now version 8. + Programs compiled with an older version must be recompiled. + + The Objective-C Runtime Library can be built as a DLL on Windows 95 + and Windows NT systems. + + The Objective-C Runtime Library implements +load. + +The following new targets are supported (see also list under each +individual CPU below): + + Embedded target m32r-elf. + Embedded Hitachi Super-H using ELF. + RTEMS real-time system on various CPU targets. + ARC processor. + NEC V850 processor. + Matsushita MN10200 processor. + Matsushita MN10300 processor. + Sparc and PowerPC running on VxWorks. + Support both glibc versions 1 and 2 on Linux-based GNU systems. + +New features for DEC Alpha systems: + + Allow detailed specification of IEEE fp support: + -mieee, -mieee-with-inexact, and -mieee-conformant + -mfp-trap-mode=xxx, -mfp-round-mode=xxx, -mtrap-precision=xxx + -mcpu=xxx for CPU selection + Support scheduling parameters for EV5. + Add support for BWX, CIX, and MAX instruction set extensions. + Support Linux-based GNU systems. + Support VMS. + +Additional supported processors and systems for MIPS targets: + + MIPS4 instruction set. + R4100, R4300 and R5000 processors. + N32 and N64 ABI. + IRIX 6.2. + SNI SINIX. + +New features for Intel x86 family: + + Add scheduling parameters for Pentium and Pentium Pro. + Support stabs on Solaris-x86. + Intel x86 processors running the SCO OpenServer 5 family. + Intel x86 processors running DG/UX. + Intel x86 using Cygwin32 or Mingw32 on Windows 95 and Windows NT. + +New features for Motorola 68k family: + + Support for 68060 processor. + More consistent switches to specify processor. + Motorola 68k family running AUX. + 68040 running pSOS, ELF object files, DBX debugging. + Coldfire variant of Motorola m68k family. + +New features for the HP PA RISC: + + -mspace and -mno-space + -mlong-load-store and -mno-long-load-store + -mbig-switch -mno-big-switch + + GCC on the PA requires either gas-2.7 or the HP assembler; for best + results using GAS is highly recommended. GAS is required for -g and + exception handling support. + +New features for SPARC-based systems: + + The ultrasparc cpu. + The sparclet cpu, supporting only a.out file format. + Sparc running SunOS 4 with the GNU assembler. + Sparc running the Linux-based GNU system. + Embedded Sparc processors running the ELF object file format. + -mcpu=xxx + -mtune=xxx + -malign-loops=xxx + -malign-jumps=xxx + -malign-functions=xxx + -mimpure-text and -mno-impure-text + + Options -mno-v8 and -mno-sparclite are no longer supported on SPARC + targets. Options -mcypress, -mv8, -msupersparc, -msparclite, -mf930, + and -mf934 are deprecated and will be deleted in GCC 2.9. Use + -mcpu=xxx instead. + +New features for rs6000 and PowerPC systems: + + Solaris 2.51 running on PowerPC's. + The Linux-based GNU system running on PowerPC's. + -mcpu=604e,602,603e,620,801,823,mpc505,821,860,power2 + -mtune=xxx + -mrelocatable-lib, -mno-relocatable-lib + -msim, -mmve, -memb + -mupdate, -mno-update + -mfused-madd, -mno-fused-madd + + -mregnames + -meabi + -mcall-linux, -mcall-solaris, -mcall-sysv-eabi, -mcall-sysv-noeabi + -msdata, -msdata=none, -msdata=default, -msdata=sysv, -msdata=eabi + -memb, -msim, -mmvme + -myellowknife, -mads + wchar_t is now of type long as per the ABI, not unsigned short. + -p/-pg support + -mcpu=403 now implies -mstrict-align. + Implement System V profiling. + + Aix 4.1 GCC targets now default to -mcpu=common so that programs + compiled can be moved between rs6000 and powerpc based systems. A + consequence of this is that -static won't work, and that some programs + may be slightly slower. + + You can select the default value to use for -mcpu=xxx on rs6000 and + powerpc targets by using the --with-cpu=xxx option when configuring the + compiler. In addition, a new options, -mtune=xxx was added that + selects the machine to schedule for but does not select the + architecture level. + + Directory names used for storing the multilib libraries on System V + and embedded PowerPC systems have been shortened to work with commands + like tar that have fixed limits on pathname size. + +New features for the Hitachi H8/300(H): + + -malign-300 + -ms (for the Hitachi H8/S processor) + -mint32 + +New features for the ARM: + + -march=xxx, -mtune=xxx, -mcpu=xxx + Support interworking with Thumb code. + ARM processor with a.out object format, COFF, or AOF assembler. + ARM on "semi-hosted" platform. + ARM running NetBSD. + ARM running the Linux-based GNU system. + +New feature for Solaris systems: + + GCC installation no longer makes a copy of system include files, + thus insulating GCC better from updates to the operating system. + + +Noteworthy changes in GCC version 2.7.2 +--------------------------------------- + +A few bugs have been fixed (most notably the generation of an +invalid assembler opcode on some RS/6000 systems). + +Noteworthy changes in GCC version 2.7.1 +--------------------------------------- + +This release fixes numerous bugs (mostly minor) in GCC 2.7.0, but +also contains a few new features, mostly related to specific targets. + +Major changes have been made in code to support Windows NT. + +The following new targets are supported: + + 2.9 BSD on PDP-11 + Linux on m68k + HP/UX version 10 on HP PA RISC (treated like version 9) + DEC Alpha running Windows NT + +When parsing C, GCC now recognizes C++ style `//' comments unless you +specify `-ansi' or `-traditional'. + +The PowerPC System V targets (powerpc-*-sysv, powerpc-*-eabi) now use the +calling sequence specified in the System V Application Binary Interface +Processor Supplement (PowerPC Processor ABI Supplement) rather than the calling +sequence used in GCC version 2.7.0. That calling sequence was based on the AIX +calling sequence without function descriptors. To compile code for that older +calling sequence, either configure the compiler for powerpc-*-eabiaix or use +the -mcall-aix switch when compiling and linking. + +Noteworthy changes in GCC version 2.7.0 +--------------------------------------- + +GCC now works better on systems that use ".obj" and ".exe" instead of +".o" and no extension. This involved changes to the driver program, +gcc.c, to convert ".o" names to ".obj" and to GCC's Makefile to use +".obj" and ".exe" in filenames that are not targets. In order to +build GCC on such systems, you may need versions of GNU make and/or +compatible shells. At this point, this support is preliminary. + +Object file extensions of ".obj" and executable file extensions of +".exe" are allowed when using appropriate version of GNU Make. + +Numerous enhancements were made to the __attribute__ facility including +more attributes and more places that support it. We now support the +"packed", "nocommon", "noreturn", "volatile", "const", "unused", +"transparent_union", "constructor", "destructor", "mode", "section", +"align", "format", "weak", and "alias" attributes. Each of these +names may also be specified with added underscores, e.g., "__packed__". +__attribute__ may now be applied to parameter definitions, function +definitions, and structure, enum, and union definitions. + +GCC now supports returning more structures in registers, as specified by +many calling sequences (ABIs), such as on the HP PA RISC. + +A new option '-fpack-struct' was added to automatically pack all structure +members together without holes. + +There is a new library (cpplib) and program (cppmain) that at some +point will replace cpp (aka cccp). To use cppmain as cpp now, pass +the option CCCP=cppmain to make. The library is already used by the +fix-header program, which should speed up the fixproto script. + +New options for supported targets: + + GNU on many targets. + NetBSD on MIPS, m68k, VAX, and x86. + LynxOS on x86, m68k, Sparc, and RS/6000. + VxWorks on many targets. + + Windows/NT on x86 architecture. Initial support for Windows/NT on Alpha + (not fully working). + + Many embedded targets, specifically UDI on a29k, aout, coff, elf, + and vsta "operating systems" on m68k, m88k, mips, sparc, and x86. + +Additional support for x86 (i386, i486, and Pentium): + + Work with old and new linkers for Linux-based GNU systems, + supporting both a.out and ELF. + FreeBSD on x86. + Stdcall convention. + -malign-double, -mregparm=, -malign-loops= and -malign-jumps= switches. + On ISC systems, support -Xp like -posix. + +Additions for RS/6000: + + Instruction scheduling information for PowerPC 403. + AIX 4.1 on PowerPC. + -mstring and -mno-string. + -msoft-float and floating-point emulation included. + Preliminary support for PowerPC System V.4 with or without the GNU as. + Preliminary support for EABI. + Preliminary support for 64-bit systems. + Both big and little endian systems. + +New features for MIPS-based systems: + + r4650. + mips4 and R8000. + Irix 6.0. + 64-bit ABI. + Allow dollar signs in labels on SGI/Irix 5.x. + +New support for HP PA RISC: + + Generation of PIC (requires binutils-2.5.2.u6 or later). + HP-UX version 9 on HP PA RISC (dynamically links even with -g). + Processor variants for HP PA RISC: 700, 7100, and 7100LC. + Automatic generation of long calls when needed. + -mfast-indirect-calls for kernels and static binaries. + + The called routine now copies arguments passed by invisible reference, + as required by the calling standard. + +Other new miscellaneous target-specific support: + + -mno-multm on a29k. + -mold-align for i960. + Configuration for "semi-hosted" ARM. + -momit-leaf-frame-pointer for M88k. + SH3 variant of Hitachi Super-H and support both big and little endian. + +Changes to Objective-C: + + Bare-bones implementation of NXConstantString has been added, + which is invoked by the @"string" directive. + + Class * has been changed to Class to conform to the NextSTEP and + OpenStep runtime. + + Enhancements to make dynamic loading easier. + + The module version number has been updated to Version 7, thus existing + code will need to be recompiled to use the current run-time library. + +GCC now supports the ISO Normative Addendum 1 to the C Standard. +As a result: + + The header <iso646.h> defines macros for C programs written + in national variants of ISO 646. + + The following digraph tokens are supported: + <: :> <% %> %: %:%: + These behave like the following, respectively: + [ ] { } # ## + + Digraph tokens are supported unless you specify the `-traditional' + option; you do not need to specify `-ansi' or `-trigraphs'. Except + for contrived and unlikely examples involving preprocessor + stringizing, digraph interpretation doesn't change the meaning of + programs; this is unlike trigraph interpretation, which changes the + meanings of relatively common strings. + + The macro __STDC_VERSION__ has the value 199409L. + + As usual, for full conformance to the standard, you also need a + C library that conforms. + +The following lists changes that have been made to g++. If some +features mentioned below sound unfamiliar, you will probably want to +look at the recently-released public review copy of the C++ Working +Paper. For PostScript and PDF (Adobe Acrobat) versions, see the +archive at ftp://research.att.com/dist/stdc++/WP. For HTML and ASCII +versions, see ftp://ftp.cygnus.com/pub/g++. On the web, see +http://www.cygnus.com/~mrs/wp-draft. + +The scope of variables declared in the for-init-statement has been changed +to conform to http://www.cygnus.com/~mrs/wp-draft/stmt.html#stmt.for; as a +result, packages such as groff 1.09 will not compile unless you specify the +-fno-for-scope flag. PLEASE DO NOT REPORT THIS AS A BUG; this is a change +mandated by the C++ standardization committee. + +Binary incompatibilities: + + The builtin 'bool' type is now the size of a machine word on RISC targets, + for code efficiency; it remains one byte long on CISC targets. + + Code that does not use #pragma interface/implementation will most + likely shrink dramatically, as g++ now only emits the vtable for a + class in the translation unit where its first non-inline, non-abstract + virtual function is defined. + + Classes that do not define the copy constructor will sometimes be + passed and returned in registers. This may illuminate latent bugs in + your code. + +Support for automatic template instantiation has *NOT* been added, due +to a disagreement over design philosophies. + +Support for exception handling has been improved; more targets are now +supported, and throws will use the RTTI mechanism to match against the +catch parameter type. Optimization is NOT SUPPORTED with +-fhandle-exceptions; no need to report this as a bug. + +Support for Run-Time Type Identification has been added with -frtti. +This support is still in alpha; one major restriction is that any file +compiled with -frtti must include <typeinfo.h>. + +Preliminary support for namespaces has been added. This support is far +from complete, and probably not useful. + +Synthesis of compiler-generated constructors, destructors and +assignment operators is now deferred until the functions are used. + +The parsing of expressions such as `a ? b : c = 1' has changed from +`(a ? b : c) = 1' to `a : b ? (c = 1)'. + +The code generated for testing conditions, especially those using || +and &&, is now more efficient. + +The operator keywords and, and_eq, bitand, bitor, compl, not, not_eq, +or, or_eq, xor and xor_eq are now supported. Use -ansi or +-foperator-names to enable them. + +The 'explicit' keyword is now supported. 'explicit' is used to mark +constructors and type conversion operators that should not be used +implicitly. + +g++ now accepts the typename keyword, though it currently has no +semantics; it can be a no-op in the current template implementation. +You may want to start using it in your code, however, since the +pending rewrite of the template implementation to compile STL properly +(perhaps for 2.8.0, perhaps not) will require you to use it as +indicated by the current draft. + +Handling of user-defined type conversion has been overhauled so that +type conversion operators are now found and used properly in +expressions and function calls. + +-fno-strict-prototype now only applies to function declarations with +"C" linkage. + +g++ now warns about 'if (x=0)' with -Wparentheses or -Wall. + +#pragma weak and #pragma pack are supported on System V R4 targets, as +are various other target-specific #pragmas supported by gcc. + +new and delete of const types is now allowed (with no additional +semantics). + +Explicit instantiation of template methods is now supported. Also, +'inline template class foo<int>;' can be used to emit only the vtable +for a template class. + +With -fcheck-new, g++ will check the return value of all calls to +operator new, and not attempt to modify a returned null pointer. + +The template instantiation code now handles more conversions when +passing to a parameter that does not depend on template arguments. +This means that code like 'string s; cout << s;' now works. + +Invalid jumps in a switch statement past declarations that require +initializations are now caught. + +Functions declared 'extern inline' now have the same linkage semantics +as inline member functions. On supported targets, where previously +these functions (and vtables, and template instantiations) would have +been defined statically, they will now be defined as weak symbols so +that only one out-of-line definition is used. + +collect2 now demangles linker output, and c++filt has become part of +the gcc distribution. + +Noteworthy changes in GCC version 2.6.3: + +A few more bugs have been fixed. + +Noteworthy changes in GCC version 2.6.2: + +A few bugs have been fixed. + +Names of attributes can now be preceded and followed by double underscores. + +Noteworthy changes in GCC version 2.6.1: + +Numerous (mostly minor) bugs have been fixed. + +The following new configurations are supported: + + GNU on x86 (instead of treating it like MACH) + NetBSD on Sparc and Motorola 68k + AIX 4.1 on RS/6000 and PowerPC systems + Sequent DYNIX/ptx 1.x and 2.x. + Both COFF and ELF configurations on AViiON without using /bin/gcc + Windows/NT on x86 architecture; preliminary + AT&T DSP1610 digital signal processor chips + i960 systems on bare boards using COFF + PDP11; target only and not extensively tested + +The -pg option is now supported for Alpha under OSF/1 V3.0 or later. + +Files with an extension of ".c++" are treated as C++ code. + +The -Xlinker and -Wl arguments are now passed to the linker in the +position they were specified on the command line. This makes it +possible, for example, to pass flags to the linker about specific +object files. + +The use of positional arguments to the configure script is no longer +recommended. Use --target= to specify the target; see the GCC manual. + +The 386 now supports two new switches: -mreg-alloc=<string> changes +the default register allocation order used by the compiler, and +-mno-wide-multiply disables the use of the mul/imul instructions that +produce 64 bit results in EAX:EDX from 32 bit operands to do long long +multiplies and 32-bit division by constants. + +Noteworthy changes in GCC version 2.6.0: + +Numerous bugs have been fixed, in the C and C++ front-ends, as +well as in the common compiler code. + +This release includes the C, Objective-C, and C++ compilers. However, +we have moved the files for the C++ compiler (G++) files to a +subdirectory, cp. Subsequent releases of GCC will split these files +to a separate TAR file. + +The G++ team has been tracking the development of the ANSI standard for C++. +Here are some new features added from the latest working paper: + + * built-in boolean type 'bool', with constants 'true' and 'false'. + * array new and delete (operator new [] and delete []). + * WP-conforming lifetime of temporaries. + * explicit instantiation of templates (template class A<int>;), + along with an option (-fno-implicit-templates) to disable emission + of implicitly instantiated templates, obsoletes -fexternal-templates. + * static member constants (static const int foo = 4; within the + class declaration). + +Many error messages have been improved to tell the user more about the +problem. Conformance checking with -pedantic-errors has been +improved. G++ now compiles Fresco. + +There is now an experimental implementation of virtual functions using +thunks instead of Cfront-style vtables, enabled with -fvtable-thunks. +This option also enables a heuristic which causes the compiler to only +emit the vtable in the translation unit where its first non-inline +virtual function is defined; using this option and +-fno-implicit-templates, users should be able to avoid #pragma +interface/implementation altogether. + +Signatures have been added as a GNU C++ extension. Using the option +-fhandle-signatures, users are able to turn on recognition of +signatures. A short introduction on signatures is in the section +`Extension to the C++ Language' in the manual. + +The `g++' program is now a C program, rather than a shell script. + +Lots and lots and lots of bugs fixes, in nested types, access control, +pointers to member functions, the parser, templates, overload +resolution, etc, etc. + +There have been two major enhancements to the Objective-C compiler: + +1) Added portability. It now runs on Alpha, and some problems with + message forwarding have been addressed on other platforms. + +2) Selectors have been redefined to be pointers to structs like: + { void *sel_id, char *sel_types }, where the sel_id is the unique + identifier, the selector itself is no longer unique. + + Programmers should use the new function sel_eq to test selector + equivalence. + +The following major changes have been made to the base compiler and +machine-specific files. + +- The MIL-STD-1750A is a new port, but still preliminary. + +- The h8/300h is now supported; both the h8/300 and h8/300h ports come + with 32 bit IEEE 754 software floating point support. + +- The 64-bit Sparc (v9) and 64-bit MIPS chips are supported. + +- NetBSD is supported on m68k, Intel x86, and pc523 systems and FreeBSD + on x86. + +- COFF is supported on x86, m68k, and Sparc systems running LynxOS. + +- 68K systems from Bull and Concurrent are supported and System V + Release 4 is supported on the Atari. + +- GCC supports GAS on the Motorola 3300 (sysV68) and debugging + (assuming GAS) on the Plexus 68K system. (However, GAS does not yet + work on those systems). + +- System V Release 4 is supported on MIPS (Tandem). + +- For DG/UX, an ELF configuration is now supported, and both the ELF + and BCS configurations support ELF and COFF object file formats. + +- OSF/1 V2.0 is supported on Alpha. + +- Function profiling is also supported on Alpha. + +- GAS and GDB is supported for Irix 5 (MIPS). + +- "common mode" (code that will run on both POWER and PowerPC + architectures) is now supported for the RS/6000 family; the + compiler knows about more PPC chips. + +- Both NeXTStep 2.1 and 3 are supported on 68k-based architectures. + +- On the AMD 29k, the -msoft-float is now supported, as well as + -mno-sum-in-toc for RS/6000, -mapp-regs and -mflat for Sparc, and + -membedded-pic for MIPS. + +- GCC can now convert division by integer constants into the equivalent + multiplication and shift operations when that is faster than the + division. + +- Two new warning options, -Wbad-function-cast and + -Wmissing-declarations have been added. + +- Configurations may now add machine-specific __attribute__ options on + type; many machines support the `section' attribute. + +- The -ffast-math flag permits some optimization that violate strict + IEEE rules, such as converting X * 0.0 to 0.0. + +Noteworthy changes in GCC version 2.5.8: + +This release only fixes a few serious bugs. These include fixes for a +bug that prevented most programs from working on the RS/6000, a bug +that caused invalid assembler code for programs with a `switch' +statement on the NS32K, a G++ problem that caused undefined names in +some configurations, and several less serious problems, some of which +can affect most configuration. + +Noteworthy change in GCC version 2.5.7: + +This release only fixes a few bugs, one of which was causing bootstrap +compare errors on some systems. + +Noteworthy change in GCC version 2.5.6: + +A few backend bugs have been fixed, some of which only occur on one +machine. + +The C++ compiler in 2.5.6 includes: + + * fixes for some common crashes + * correct handling of nested types that are referenced as `foo::bar' + * spurious warnings about friends being declared static and never + defined should no longer appear + * enums that are local to a method in a class, or a class that's + local to a function, are now handled correctly. For example: + class foo { void bar () { enum { x, y } E; x; } }; + void bar () { class foo { enum { x, y } E; E baz; }; } + +Noteworthy change in GCC version 2.5.5: + +A large number of C++ bugs have been fixed. + +The fixproto script adds prototypes conditionally on __cplusplus. + +Noteworthy change in GCC version 2.5.4: + +A bug fix in passing of structure arguments for the HP-PA architecture +makes code compiled with GCC 2.5.4 incompatible with code compiled +with earlier versions (if it passes struct arguments of 33 to 64 bits, +interspersed with other types of arguments). + +Noteworthy change in gcc version 2.5.3: + +The method of "mangling" C++ function names has been changed. So you +must recompile all C++ programs completely when you start using GCC +2.5. Also, GCC 2.5 requires libg++ version 2.5. Earlier libg++ +versions won't work with GCC 2.5. (This is generally true--GCC +version M.N requires libg++ version M.N.) + +Noteworthy GCC changes in version 2.5: + +* There is now support for the IBM 370 architecture as a target. +Currently the only operating system supported is MVS; GCC does not run +on MVS, so you must produce .s files using GCC as a cross compiler, +then transfer them to MVS to assemble them. This port is not reliable +yet. + +* The Power PC is now supported. + +* The i860-based Paragon machine is now supported. + +* The Hitachi 3050 (an HP-PA machine) is now supported. + +* The variable __GNUC_MINOR__ holds the minor version number of GCC, as +an integer. For version 2.5.X, the value is 5. + +* In C, initializers for static and global variables are now processed +an element at a time, so that they don't need a lot of storage. + +* The C syntax for specifying which structure field comes next in an +initializer is now `.FIELDNAME='. The corresponding syntax for +array initializers is now `[INDEX]='. For example, + + char whitespace[256] + = { [' '] = 1, ['\t'] = 1, ['\n'] = 1 }; + +This was changed to accord with the syntax proposed by the Numerical +C Extensions Group (NCEG). + +* Complex numbers are now supported in C. Use the keyword __complex__ +to declare complex data types. See the manual for details. + +* GCC now supports `long double' meaningfully on the Sparc (128-bit +floating point) and on the 386 (96-bit floating point). The Sparc +support is enabled on Solaris 2.x because earlier system versions +(SunOS 4) have bugs in the emulation. + +* All targets now have assertions for cpu, machine and system. So you +can now use assertions to distinguish among all supported targets. + +* Nested functions in C may now be inline. Just declare them inline +in the usual way. + +* Packed structure members are now supported fully; it should be possible +to access them on any supported target, no matter how little alignment +they have. + +* To declare that a function does not return, you must now write +something like this (works only in 2.5): + + void fatal () __attribute__ ((noreturn)); + +or like this (works in older versions too): + + typedef void voidfn (); + + volatile voidfn fatal; + +It used to be possible to do so by writing this: + + volatile void fatal (); + +but it turns out that ANSI C requires that to mean something +else (which is useless). + +Likewise, to declare that a function is side-effect-free +so that calls may be deleted or combined, write +something like this (works only in 2.5): + + int computation () __attribute__ ((const)); + +or like this (works in older versions too): + + typedef int intfn (); + + const intfn computation; + +* The new option -iwithprefixbefore specifies a directory to add to +the search path for include files in the same position where -I would +put it, but uses the specified prefix just like -iwithprefix. + +* Basic block profiling has been enhanced to record the function the +basic block comes from, and if the module was compiled for debugging, +the line number and filename. A default version of the basic block +support module has been added to libgcc2 that appends the basic block +information to a text file 'bb.out'. Machine descriptions can now +override the basic block support module in the target macro file. + +New features in g++: + +* The new flag `-fansi-overloading' for C++. Use a newly implemented +scheme of argument matching for C++. It makes g++ more accurately +obey the rules set down in Chapter 13 of the Annotated C++ Reference +Manual (the ARM). This option will be turned on by default in a +future release. + +* The -finline-debug flag is now gone (it was never really used by the + compiler). + +* Recognizing the syntax for pointers to members, e.g., "foo::*bar", has been + dramatically improved. You should not get any syntax errors or incorrect + runtime results while using pointers to members correctly; if you do, it's + a definite bug. + +* Forward declaration of an enum is now flagged as an error. + +* Class-local typedefs are now working properly. + +* Nested class support has been significantly improved. The compiler + will now (in theory) support up to 240 nested classes before hitting + other system limits (like memory size). + +* There is a new C version of the `g++' driver, to replace the old + shell script. This should significantly improve the performance of + executing g++ on a system where a user's PATH environment variable + references many NFS-mounted filesystems. This driver also works + under MS-DOS and OS/2. + +* The ANSI committee working on the C++ standard has adopted a new + keyword `mutable'. This will allow you to make a specific member be + modifiable in an otherwise const class. + +Noteworthy GCC changes in version 2.4.4: + + A crash building g++ on various hosts (including m68k) has been + fixed. Also the g++ compiler no longer reports incorrect + ambiguities in some situations where they do not exist, and + const template member functions are now being found properly. + +Noteworthy GCC changes in version 2.4: + +* On each target, the default is now to return short structures +compatibly with the "usual" compiler on that target. + +For most targets, this means the default is to return all structures +in memory, like long structures, in whatever way is used on that +target. Use -freg-struct-return to enable returning short structures +(and unions) in registers. + +This change means that newly compiled binaries are incompatible with +binaries compiled with previous versions of GCC. + +On some targets, GCC is itself the usual compiler. On these targets, +the default way to return short structures is still in registers. +Use -fpcc-struct-return to tell GCC to return them in memory. + +* There is now a floating point emulator which can imitate the way all +supported target machines do floating point arithmetic. + +This makes it possible to have cross compilation to and from the VAX, +and between machines of different endianness. However, this works +only when the target machine description is updated to use the new +facilities, and not all have been updated. + +This also makes possible support for longer floating point types. +GCC 2.4 supports extended format on the 68K if you use `long double', +for targets that have a 68881. (When we have run time library +routines for extended floating point, then `long double' will use +extended format on all 68K targets.) + +We expect to support extended floating point on the i386 and Sparc in +future versions. + +* Building GCC now automatically fixes the system's header files. +This should require no attention. + +* GCC now installs an unsigned data type as size_t when it fixes the +header files (on all but a handful of old target machines). +Therefore, the bug that size_t failed to be unsigned is fixed. + +* Building and installation are now completely separate. +All new files are constructed during the build process; +installation just copies them. + +* New targets supported: Clipper, Hitachi SH, Hitachi 8300, and Sparc +Lite. + +* A totally new and much better Objective C run time system is included. + +* Objective C supports many new features. Alas, I can't describe them +since I don't use that language; however, they are the same ones +supported in recent versions of the NeXT operating system. + +* The builtin functions __builtin_apply_args, __builtin_apply and +__builtin_return let you record the arguments and returned +value of a function without knowing their number or type. + +* The builtin string variables __FUNCTION__ and __PRETTY_FUNCTION__ +give the name of the function in the source, and a pretty-printed +version of the name. The two are the same in C, but differ in C++. + +* Casts to union types do not yield lvalues. + +* ## before an empty rest argument discards the preceding sequence +of non-whitespace characters from the macro definition. +(This feature is subject to change.) + + +New features specific to C++: + +* The manual contains a new section ``Common Misunderstandings with +GNU C++'' that C++ users should read. + +* #pragma interface and #pragma implementation let you use the same +C++ source file for both interface and implementation. +However, this mechanism is still in transition. + +* Named returned values let you avoid an extra constructor call +when a function result has a class type. + +* The C++ operators <? and >? yield min and max, respectively. + +* C++ gotos can exit a block safely even if the block has +aggregates that require destructors. + +* gcc defines the macro __GNUG__ when compiling C++ programs. + +* GNU C++ now correctly distinguishes between the prefix and postfix +forms of overloaded operator ++ and --. To avoid breaking old +code, if a class defines only the prefix form, the compiler +accepts either ++obj or obj++, unless -pedantic is used. + +* If you are using version 2.3 of libg++, you need to rebuild it with +`make CC=gcc' to avoid mismatches in the definition of `size_t'. + +Newly documented compiler options: + +-fnostartfiles + Omit the standard system startup files when linking. + +-fvolatile-global + Consider memory references to extern and global data items to + be volatile. + +-idirafter DIR + Add DIR to the second include path. + +-iprefix PREFIX + Specify PREFIX for later -iwithprefix options. + +-iwithprefix DIR + Add PREFIX/DIR to the second include path. + +-mv8 + Emit Sparc v8 code (with integer multiply and divide). +-msparclite + Emit Sparclite code (roughly v7.5). + +-print-libgcc-file-name + Search for the libgcc.a file, print its absolute file name, and exit. + +-Woverloaded-virtual + Warn when a derived class function declaration may be an error + in defining a C++ virtual function. + +-Wtemplate-debugging + When using templates in a C++ program, warn if debugging is + not yet fully available. + ++eN + Control how C++ virtual function definitions are used + (like cfront 1.x). + + +Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc. + +Copying and distribution of this file, with or without modification, +are permitted in any medium without royalty provided the copyright +notice and this notice are preserved. |