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c4f0b011 | 1 | This file contains information about GCC releases up to GCC 2.8.1, and |
62d08205 | 2 | a tiny bit of information on EGCS. |
c4f0b011 | 3 | |
62d08205 GP |
4 | For details of changes in EGCS releases and GCC 2.95 and later releases, |
5 | see the release notes on the GCC web site or the file NEWS which contains | |
6 | the most relevant parts of those release notes in text form. | |
c4f0b011 | 7 | |
62d08205 GP |
8 | Changes in GCC for EGCS (that are not listed in the web release notes) |
9 | --------------------------------------------------------------------- | |
c4f0b011 JM |
10 | |
11 | The compiler now supports the "ADDRESSOF" optimization which can significantly | |
12 | reduce the overhead for certain inline calls (and inline calls in general). | |
13 | ||
c4f0b011 JM |
14 | Compile time for certain programs using large constant initializers has been |
15 | improved (affects glibc significantly). | |
16 | ||
c4f0b011 JM |
17 | Various improvements have been made to better support cross compilations. They |
18 | are still not easy, but they are improving. | |
19 | ||
62d08205 | 20 | Target-specific changes: |
c4f0b011 JM |
21 | |
22 | M32r: Major improvements to this port. | |
23 | ||
24 | Arm: Includes Thumb and super interworking support. | |
25 | ||
c4f0b011 JM |
26 | Noteworthy changes in GCC version 2.8.1 |
27 | --------------------------------------- | |
28 | ||
29 | Numerous bugs have been fixed and some minor performance | |
30 | improvements (compilation speed) have been made. | |
31 | ||
32 | Noteworthy changes in GCC version 2.8.0 | |
33 | --------------------------------------- | |
34 | ||
35 | A major change in this release is the addition of a framework for | |
36 | exception handling, currently used by C++. Many internal changes and | |
37 | optimization improvements have been made. These increase the | |
38 | maintainability and portability of GCC. GCC now uses autoconf to | |
39 | compute many host parameters. | |
40 | ||
41 | The following lists changes that add new features or targets. | |
42 | ||
43 | See cp/NEWS for new features of C++ in this release. | |
44 | ||
45 | New tools and features: | |
46 | ||
47 | The Dwarf 2 debugging information format is supported on ELF systems, and | |
48 | is the default for -ggdb where available. It can also be used for C++. | |
49 | The Dwarf version 1 debugging format is also permitted for C++, but | |
50 | does not work well. | |
51 | ||
52 | gcov.c is provided for test coverage analysis and branch profiling | |
53 | analysis is also supported; see -fprofile-arcs, -ftest-coverage, | |
54 | and -fbranch-probabilities. | |
55 | ||
56 | Support for the Checker memory checking tool. | |
57 | ||
58 | New switch, -fstack-check, to check for stack overflow on systems that | |
59 | don't have such built into their ABI. | |
60 | ||
61 | New switches, -Wundef and -Wno-undef to warn if an undefined identifier | |
62 | is evaluated in an #if directive. | |
63 | ||
64 | Options -Wall and -Wimplicit now cause GCC to warn about implicit int | |
65 | in declarations (e.g. `register i;'), since the C Standard committee | |
66 | has decided to disallow this in the next revision of the standard; | |
67 | -Wimplicit-function-declarations and -Wimplicit-int are subsets of | |
68 | this. | |
69 | ||
70 | Option -Wsign-compare causes GCC to warn about comparison of signed and | |
71 | unsigned values. | |
72 | ||
73 | Add -dI option of cccp for cxref. | |
74 | ||
75 | New features in configuration, installation and specs file handling: | |
76 | ||
77 | New option --enable-c-cpplib to configure script. | |
78 | ||
79 | You can use --with-cpu on the configure command to specify the default | |
80 | CPU that GCC should generate code for. | |
81 | ||
82 | The -specs=file switch allows you to override default specs used in | |
83 | invoking programs like cc1, as, etc. | |
84 | ||
85 | Allow including one specs file from another and renaming a specs | |
86 | variable. | |
87 | ||
88 | You can now relocate all GCC files with a single environment variable | |
89 | or a registry entry under Windows 95 and Windows NT. | |
90 | ||
91 | Changes in Objective-C: | |
92 | ||
93 | The Objective-C Runtime Library has been made thread-safe. | |
94 | ||
95 | The Objective-C Runtime Library contains an interface for creating | |
96 | mutexes, condition mutexes, and threads; it requires a back-end | |
97 | implementation for the specific platform and/or thread package. | |
98 | Currently supported are DEC/OSF1, IRIX, Mach, OS/2, POSIX, PCThreads, | |
99 | Solaris, and Windows32. The --enable-threads parameter can be used | |
100 | when configuring GCC to enable and select a thread back-end. | |
101 | ||
102 | Objective-C is now configured as separate front-end language to GCC, | |
103 | making it more convenient to conditionally build it. | |
104 | ||
105 | The internal structures of the Objective-C Runtime Library have | |
106 | changed sufficiently to warrant a new version number; now version 8. | |
107 | Programs compiled with an older version must be recompiled. | |
108 | ||
109 | The Objective-C Runtime Library can be built as a DLL on Windows 95 | |
110 | and Windows NT systems. | |
111 | ||
112 | The Objective-C Runtime Library implements +load. | |
113 | ||
114 | The following new targets are supported (see also list under each | |
115 | individual CPU below): | |
116 | ||
117 | Embedded target m32r-elf. | |
118 | Embedded Hitachi Super-H using ELF. | |
119 | RTEMS real-time system on various CPU targets. | |
120 | ARC processor. | |
121 | NEC V850 processor. | |
122 | Matsushita MN10200 processor. | |
123 | Matsushita MN10300 processor. | |
124 | Sparc and PowerPC running on VxWorks. | |
125 | Support both glibc versions 1 and 2 on Linux-based GNU systems. | |
126 | ||
127 | New features for DEC Alpha systems: | |
128 | ||
129 | Allow detailed specification of IEEE fp support: | |
130 | -mieee, -mieee-with-inexact, and -mieee-conformant | |
131 | -mfp-trap-mode=xxx, -mfp-round-mode=xxx, -mtrap-precision=xxx | |
132 | -mcpu=xxx for CPU selection | |
133 | Support scheduling parameters for EV5. | |
134 | Add support for BWX, CIX, and MAX instruction set extensions. | |
135 | Support Linux-based GNU systems. | |
136 | Support VMS. | |
137 | ||
138 | Additional supported processors and systems for MIPS targets: | |
139 | ||
140 | MIPS4 instruction set. | |
141 | R4100, R4300 and R5000 processors. | |
142 | N32 and N64 ABI. | |
143 | IRIX 6.2. | |
144 | SNI SINIX. | |
145 | ||
146 | New features for Intel x86 family: | |
147 | ||
148 | Add scheduling parameters for Pentium and Pentium Pro. | |
149 | Support stabs on Solaris-x86. | |
150 | Intel x86 processors running the SCO OpenServer 5 family. | |
151 | Intel x86 processors running DG/UX. | |
152 | Intel x86 using Cygwin32 or Mingw32 on Windows 95 and Windows NT. | |
153 | ||
154 | New features for Motorola 68k family: | |
155 | ||
156 | Support for 68060 processor. | |
157 | More consistent switches to specify processor. | |
158 | Motorola 68k family running AUX. | |
159 | 68040 running pSOS, ELF object files, DBX debugging. | |
160 | Coldfire variant of Motorola m68k family. | |
161 | ||
162 | New features for the HP PA RISC: | |
163 | ||
164 | -mspace and -mno-space | |
165 | -mlong-load-store and -mno-long-load-store | |
166 | -mbig-switch -mno-big-switch | |
167 | ||
168 | GCC on the PA requires either gas-2.7 or the HP assembler; for best | |
169 | results using GAS is highly recommended. GAS is required for -g and | |
170 | exception handling support. | |
171 | ||
172 | New features for SPARC-based systems: | |
173 | ||
174 | The ultrasparc cpu. | |
175 | The sparclet cpu, supporting only a.out file format. | |
176 | Sparc running SunOS 4 with the GNU assembler. | |
177 | Sparc running the Linux-based GNU system. | |
178 | Embedded Sparc processors running the ELF object file format. | |
179 | -mcpu=xxx | |
180 | -mtune=xxx | |
181 | -malign-loops=xxx | |
182 | -malign-jumps=xxx | |
183 | -malign-functions=xxx | |
184 | -mimpure-text and -mno-impure-text | |
185 | ||
186 | Options -mno-v8 and -mno-sparclite are no longer supported on SPARC | |
187 | targets. Options -mcypress, -mv8, -msupersparc, -msparclite, -mf930, | |
188 | and -mf934 are deprecated and will be deleted in GCC 2.9. Use | |
189 | -mcpu=xxx instead. | |
190 | ||
191 | New features for rs6000 and PowerPC systems: | |
192 | ||
193 | Solaris 2.51 running on PowerPC's. | |
194 | The Linux-based GNU system running on PowerPC's. | |
195 | -mcpu=604e,602,603e,620,801,823,mpc505,821,860,power2 | |
196 | -mtune=xxx | |
197 | -mrelocatable-lib, -mno-relocatable-lib | |
198 | -msim, -mmve, -memb | |
199 | -mupdate, -mno-update | |
200 | -mfused-madd, -mno-fused-madd | |
201 | ||
202 | -mregnames | |
203 | -meabi | |
204 | -mcall-linux, -mcall-solaris, -mcall-sysv-eabi, -mcall-sysv-noeabi | |
205 | -msdata, -msdata=none, -msdata=default, -msdata=sysv, -msdata=eabi | |
206 | -memb, -msim, -mmvme | |
207 | -myellowknife, -mads | |
208 | wchar_t is now of type long as per the ABI, not unsigned short. | |
209 | -p/-pg support | |
210 | -mcpu=403 now implies -mstrict-align. | |
211 | Implement System V profiling. | |
212 | ||
213 | Aix 4.1 GCC targets now default to -mcpu=common so that programs | |
214 | compiled can be moved between rs6000 and powerpc based systems. A | |
215 | consequence of this is that -static won't work, and that some programs | |
216 | may be slightly slower. | |
217 | ||
218 | You can select the default value to use for -mcpu=xxx on rs6000 and | |
219 | powerpc targets by using the --with-cpu=xxx option when configuring the | |
220 | compiler. In addition, a new options, -mtune=xxx was added that | |
221 | selects the machine to schedule for but does not select the | |
222 | architecture level. | |
223 | ||
224 | Directory names used for storing the multilib libraries on System V | |
225 | and embedded PowerPC systems have been shortened to work with commands | |
226 | like tar that have fixed limits on pathname size. | |
227 | ||
228 | New features for the Hitachi H8/300(H): | |
229 | ||
230 | -malign-300 | |
231 | -ms (for the Hitachi H8/S processor) | |
232 | -mint32 | |
233 | ||
234 | New features for the ARM: | |
235 | ||
236 | -march=xxx, -mtune=xxx, -mcpu=xxx | |
237 | Support interworking with Thumb code. | |
238 | ARM processor with a.out object format, COFF, or AOF assembler. | |
239 | ARM on "semi-hosted" platform. | |
240 | ARM running NetBSD. | |
241 | ARM running the Linux-based GNU system. | |
242 | ||
243 | New feature for Solaris systems: | |
244 | ||
245 | GCC installation no longer makes a copy of system include files, | |
246 | thus insulating GCC better from updates to the operating system. | |
247 | ||
248 | \f | |
249 | Noteworthy changes in GCC version 2.7.2 | |
250 | --------------------------------------- | |
251 | ||
252 | A few bugs have been fixed (most notably the generation of an | |
253 | invalid assembler opcode on some RS/6000 systems). | |
254 | ||
255 | Noteworthy changes in GCC version 2.7.1 | |
256 | --------------------------------------- | |
257 | ||
258 | This release fixes numerous bugs (mostly minor) in GCC 2.7.0, but | |
259 | also contains a few new features, mostly related to specific targets. | |
260 | ||
261 | Major changes have been made in code to support Windows NT. | |
262 | ||
263 | The following new targets are supported: | |
264 | ||
265 | 2.9 BSD on PDP-11 | |
266 | Linux on m68k | |
267 | HP/UX version 10 on HP PA RISC (treated like version 9) | |
268 | DEC Alpha running Windows NT | |
269 | ||
270 | When parsing C, GCC now recognizes C++ style `//' comments unless you | |
271 | specify `-ansi' or `-traditional'. | |
272 | ||
273 | The PowerPC System V targets (powerpc-*-sysv, powerpc-*-eabi) now use the | |
274 | calling sequence specified in the System V Application Binary Interface | |
275 | Processor Supplement (PowerPC Processor ABI Supplement) rather than the calling | |
276 | sequence used in GCC version 2.7.0. That calling sequence was based on the AIX | |
277 | calling sequence without function descriptors. To compile code for that older | |
278 | calling sequence, either configure the compiler for powerpc-*-eabiaix or use | |
279 | the -mcall-aix switch when compiling and linking. | |
280 | \f | |
281 | Noteworthy changes in GCC version 2.7.0 | |
282 | --------------------------------------- | |
283 | ||
284 | GCC now works better on systems that use ".obj" and ".exe" instead of | |
285 | ".o" and no extension. This involved changes to the driver program, | |
286 | gcc.c, to convert ".o" names to ".obj" and to GCC's Makefile to use | |
287 | ".obj" and ".exe" in filenames that are not targets. In order to | |
288 | build GCC on such systems, you may need versions of GNU make and/or | |
289 | compatible shells. At this point, this support is preliminary. | |
290 | ||
291 | Object file extensions of ".obj" and executable file extensions of | |
292 | ".exe" are allowed when using appropriate version of GNU Make. | |
293 | ||
294 | Numerous enhancements were made to the __attribute__ facility including | |
295 | more attributes and more places that support it. We now support the | |
296 | "packed", "nocommon", "noreturn", "volatile", "const", "unused", | |
297 | "transparent_union", "constructor", "destructor", "mode", "section", | |
298 | "align", "format", "weak", and "alias" attributes. Each of these | |
299 | names may also be specified with added underscores, e.g., "__packed__". | |
300 | __attribute__ may now be applied to parameter definitions, function | |
301 | definitions, and structure, enum, and union definitions. | |
302 | ||
303 | GCC now supports returning more structures in registers, as specified by | |
304 | many calling sequences (ABIs), such as on the HP PA RISC. | |
305 | ||
306 | A new option '-fpack-struct' was added to automatically pack all structure | |
307 | members together without holes. | |
308 | ||
309 | There is a new library (cpplib) and program (cppmain) that at some | |
310 | point will replace cpp (aka cccp). To use cppmain as cpp now, pass | |
311 | the option CCCP=cppmain to make. The library is already used by the | |
312 | fix-header program, which should speed up the fixproto script. | |
313 | ||
314 | New options for supported targets: | |
315 | ||
316 | GNU on many targets. | |
317 | NetBSD on MIPS, m68k, VAX, and x86. | |
318 | LynxOS on x86, m68k, Sparc, and RS/6000. | |
319 | VxWorks on many targets. | |
320 | ||
321 | Windows/NT on x86 architecture. Initial support for Windows/NT on Alpha | |
322 | (not fully working). | |
323 | ||
324 | Many embedded targets, specifically UDI on a29k, aout, coff, elf, | |
325 | and vsta "operating systems" on m68k, m88k, mips, sparc, and x86. | |
326 | ||
327 | Additional support for x86 (i386, i486, and Pentium): | |
328 | ||
329 | Work with old and new linkers for Linux-based GNU systems, | |
330 | supporting both a.out and ELF. | |
331 | FreeBSD on x86. | |
332 | Stdcall convention. | |
333 | -malign-double, -mregparm=, -malign-loops= and -malign-jumps= switches. | |
334 | On ISC systems, support -Xp like -posix. | |
335 | ||
336 | Additions for RS/6000: | |
337 | ||
338 | Instruction scheduling information for PowerPC 403. | |
339 | AIX 4.1 on PowerPC. | |
340 | -mstring and -mno-string. | |
341 | -msoft-float and floating-point emulation included. | |
342 | Preliminary support for PowerPC System V.4 with or without the GNU as. | |
343 | Preliminary support for EABI. | |
344 | Preliminary support for 64-bit systems. | |
345 | Both big and little endian systems. | |
346 | ||
347 | New features for MIPS-based systems: | |
348 | ||
349 | r4650. | |
350 | mips4 and R8000. | |
351 | Irix 6.0. | |
352 | 64-bit ABI. | |
353 | Allow dollar signs in labels on SGI/Irix 5.x. | |
354 | ||
355 | New support for HP PA RISC: | |
356 | ||
357 | Generation of PIC (requires binutils-2.5.2.u6 or later). | |
358 | HP-UX version 9 on HP PA RISC (dynamically links even with -g). | |
359 | Processor variants for HP PA RISC: 700, 7100, and 7100LC. | |
360 | Automatic generation of long calls when needed. | |
361 | -mfast-indirect-calls for kernels and static binaries. | |
362 | ||
363 | The called routine now copies arguments passed by invisible reference, | |
364 | as required by the calling standard. | |
365 | ||
366 | Other new miscellaneous target-specific support: | |
367 | ||
368 | -mno-multm on a29k. | |
369 | -mold-align for i960. | |
370 | Configuration for "semi-hosted" ARM. | |
371 | -momit-leaf-frame-pointer for M88k. | |
372 | SH3 variant of Hitachi Super-H and support both big and little endian. | |
373 | ||
374 | Changes to Objective-C: | |
375 | ||
376 | Bare-bones implementation of NXConstantString has been added, | |
377 | which is invoked by the @"string" directive. | |
378 | ||
379 | Class * has been changed to Class to conform to the NextSTEP and | |
380 | OpenStep runtime. | |
381 | ||
382 | Enhancements to make dynamic loading easier. | |
383 | ||
384 | The module version number has been updated to Version 7, thus existing | |
385 | code will need to be recompiled to use the current run-time library. | |
386 | ||
387 | GCC now supports the ISO Normative Addendum 1 to the C Standard. | |
388 | As a result: | |
389 | ||
390 | The header <iso646.h> defines macros for C programs written | |
391 | in national variants of ISO 646. | |
392 | ||
393 | The following digraph tokens are supported: | |
394 | <: :> <% %> %: %:%: | |
395 | These behave like the following, respectively: | |
396 | [ ] { } # ## | |
397 | ||
398 | Digraph tokens are supported unless you specify the `-traditional' | |
399 | option; you do not need to specify `-ansi' or `-trigraphs'. Except | |
400 | for contrived and unlikely examples involving preprocessor | |
401 | stringizing, digraph interpretation doesn't change the meaning of | |
402 | programs; this is unlike trigraph interpretation, which changes the | |
403 | meanings of relatively common strings. | |
404 | ||
405 | The macro __STDC_VERSION__ has the value 199409L. | |
406 | ||
407 | As usual, for full conformance to the standard, you also need a | |
408 | C library that conforms. | |
409 | ||
410 | The following lists changes that have been made to g++. If some | |
411 | features mentioned below sound unfamiliar, you will probably want to | |
412 | look at the recently-released public review copy of the C++ Working | |
413 | Paper. For PostScript and PDF (Adobe Acrobat) versions, see the | |
414 | archive at ftp://research.att.com/dist/stdc++/WP. For HTML and ASCII | |
415 | versions, see ftp://ftp.cygnus.com/pub/g++. On the web, see | |
416 | http://www.cygnus.com/~mrs/wp-draft. | |
417 | ||
418 | The scope of variables declared in the for-init-statement has been changed | |
419 | to conform to http://www.cygnus.com/~mrs/wp-draft/stmt.html#stmt.for; as a | |
420 | result, packages such as groff 1.09 will not compile unless you specify the | |
421 | -fno-for-scope flag. PLEASE DO NOT REPORT THIS AS A BUG; this is a change | |
422 | mandated by the C++ standardization committee. | |
423 | ||
424 | Binary incompatibilities: | |
425 | ||
426 | The builtin 'bool' type is now the size of a machine word on RISC targets, | |
427 | for code efficiency; it remains one byte long on CISC targets. | |
428 | ||
429 | Code that does not use #pragma interface/implementation will most | |
430 | likely shrink dramatically, as g++ now only emits the vtable for a | |
431 | class in the translation unit where its first non-inline, non-abstract | |
432 | virtual function is defined. | |
433 | ||
434 | Classes that do not define the copy constructor will sometimes be | |
435 | passed and returned in registers. This may illuminate latent bugs in | |
436 | your code. | |
437 | ||
438 | Support for automatic template instantiation has *NOT* been added, due | |
439 | to a disagreement over design philosophies. | |
440 | ||
441 | Support for exception handling has been improved; more targets are now | |
442 | supported, and throws will use the RTTI mechanism to match against the | |
443 | catch parameter type. Optimization is NOT SUPPORTED with | |
444 | -fhandle-exceptions; no need to report this as a bug. | |
445 | ||
446 | Support for Run-Time Type Identification has been added with -frtti. | |
447 | This support is still in alpha; one major restriction is that any file | |
448 | compiled with -frtti must include <typeinfo.h>. | |
449 | ||
450 | Preliminary support for namespaces has been added. This support is far | |
451 | from complete, and probably not useful. | |
452 | ||
453 | Synthesis of compiler-generated constructors, destructors and | |
454 | assignment operators is now deferred until the functions are used. | |
455 | ||
456 | The parsing of expressions such as `a ? b : c = 1' has changed from | |
457 | `(a ? b : c) = 1' to `a : b ? (c = 1)'. | |
458 | ||
459 | The code generated for testing conditions, especially those using || | |
460 | and &&, is now more efficient. | |
461 | ||
462 | The operator keywords and, and_eq, bitand, bitor, compl, not, not_eq, | |
463 | or, or_eq, xor and xor_eq are now supported. Use -ansi or | |
464 | -foperator-names to enable them. | |
465 | ||
466 | The 'explicit' keyword is now supported. 'explicit' is used to mark | |
467 | constructors and type conversion operators that should not be used | |
468 | implicitly. | |
469 | ||
470 | g++ now accepts the typename keyword, though it currently has no | |
471 | semantics; it can be a no-op in the current template implementation. | |
472 | You may want to start using it in your code, however, since the | |
473 | pending rewrite of the template implementation to compile STL properly | |
474 | (perhaps for 2.8.0, perhaps not) will require you to use it as | |
475 | indicated by the current draft. | |
476 | ||
477 | Handling of user-defined type conversion has been overhauled so that | |
478 | type conversion operators are now found and used properly in | |
479 | expressions and function calls. | |
480 | ||
481 | -fno-strict-prototype now only applies to function declarations with | |
482 | "C" linkage. | |
483 | ||
484 | g++ now warns about 'if (x=0)' with -Wparentheses or -Wall. | |
485 | ||
486 | #pragma weak and #pragma pack are supported on System V R4 targets, as | |
487 | are various other target-specific #pragmas supported by gcc. | |
488 | ||
489 | new and delete of const types is now allowed (with no additional | |
490 | semantics). | |
491 | ||
492 | Explicit instantiation of template methods is now supported. Also, | |
493 | 'inline template class foo<int>;' can be used to emit only the vtable | |
494 | for a template class. | |
495 | ||
496 | With -fcheck-new, g++ will check the return value of all calls to | |
497 | operator new, and not attempt to modify a returned null pointer. | |
498 | ||
499 | The template instantiation code now handles more conversions when | |
500 | passing to a parameter that does not depend on template arguments. | |
501 | This means that code like 'string s; cout << s;' now works. | |
502 | ||
503 | Invalid jumps in a switch statement past declarations that require | |
504 | initializations are now caught. | |
505 | ||
506 | Functions declared 'extern inline' now have the same linkage semantics | |
507 | as inline member functions. On supported targets, where previously | |
508 | these functions (and vtables, and template instantiations) would have | |
509 | been defined statically, they will now be defined as weak symbols so | |
510 | that only one out-of-line definition is used. | |
511 | ||
512 | collect2 now demangles linker output, and c++filt has become part of | |
513 | the gcc distribution. | |
514 | \f | |
515 | Noteworthy changes in GCC version 2.6.3: | |
516 | ||
517 | A few more bugs have been fixed. | |
518 | ||
519 | Noteworthy changes in GCC version 2.6.2: | |
520 | ||
521 | A few bugs have been fixed. | |
522 | ||
523 | Names of attributes can now be preceded and followed by double underscores. | |
524 | ||
525 | Noteworthy changes in GCC version 2.6.1: | |
526 | ||
527 | Numerous (mostly minor) bugs have been fixed. | |
528 | ||
529 | The following new configurations are supported: | |
530 | ||
531 | GNU on x86 (instead of treating it like MACH) | |
532 | NetBSD on Sparc and Motorola 68k | |
533 | AIX 4.1 on RS/6000 and PowerPC systems | |
534 | Sequent DYNIX/ptx 1.x and 2.x. | |
535 | Both COFF and ELF configurations on AViiON without using /bin/gcc | |
536 | Windows/NT on x86 architecture; preliminary | |
537 | AT&T DSP1610 digital signal processor chips | |
538 | i960 systems on bare boards using COFF | |
539 | PDP11; target only and not extensively tested | |
540 | ||
541 | The -pg option is now supported for Alpha under OSF/1 V3.0 or later. | |
542 | ||
543 | Files with an extension of ".c++" are treated as C++ code. | |
544 | ||
545 | The -Xlinker and -Wl arguments are now passed to the linker in the | |
546 | position they were specified on the command line. This makes it | |
547 | possible, for example, to pass flags to the linker about specific | |
548 | object files. | |
549 | ||
550 | The use of positional arguments to the configure script is no longer | |
551 | recommended. Use --target= to specify the target; see the GCC manual. | |
552 | ||
553 | The 386 now supports two new switches: -mreg-alloc=<string> changes | |
554 | the default register allocation order used by the compiler, and | |
555 | -mno-wide-multiply disables the use of the mul/imul instructions that | |
556 | produce 64 bit results in EAX:EDX from 32 bit operands to do long long | |
557 | multiplies and 32-bit division by constants. | |
558 | \f | |
559 | Noteworthy changes in GCC version 2.6.0: | |
560 | ||
561 | Numerous bugs have been fixed, in the C and C++ front-ends, as | |
562 | well as in the common compiler code. | |
563 | ||
564 | This release includes the C, Objective-C, and C++ compilers. However, | |
565 | we have moved the files for the C++ compiler (G++) files to a | |
566 | subdirectory, cp. Subsequent releases of GCC will split these files | |
567 | to a separate TAR file. | |
568 | ||
569 | The G++ team has been tracking the development of the ANSI standard for C++. | |
570 | Here are some new features added from the latest working paper: | |
571 | ||
572 | * built-in boolean type 'bool', with constants 'true' and 'false'. | |
573 | * array new and delete (operator new [] and delete []). | |
574 | * WP-conforming lifetime of temporaries. | |
575 | * explicit instantiation of templates (template class A<int>;), | |
576 | along with an option (-fno-implicit-templates) to disable emission | |
577 | of implicitly instantiated templates, obsoletes -fexternal-templates. | |
578 | * static member constants (static const int foo = 4; within the | |
579 | class declaration). | |
580 | ||
581 | Many error messages have been improved to tell the user more about the | |
582 | problem. Conformance checking with -pedantic-errors has been | |
583 | improved. G++ now compiles Fresco. | |
584 | ||
585 | There is now an experimental implementation of virtual functions using | |
586 | thunks instead of Cfront-style vtables, enabled with -fvtable-thunks. | |
587 | This option also enables a heuristic which causes the compiler to only | |
588 | emit the vtable in the translation unit where its first non-inline | |
589 | virtual function is defined; using this option and | |
590 | -fno-implicit-templates, users should be able to avoid #pragma | |
591 | interface/implementation altogether. | |
592 | ||
593 | Signatures have been added as a GNU C++ extension. Using the option | |
594 | -fhandle-signatures, users are able to turn on recognition of | |
595 | signatures. A short introduction on signatures is in the section | |
596 | `Extension to the C++ Language' in the manual. | |
597 | ||
598 | The `g++' program is now a C program, rather than a shell script. | |
599 | ||
600 | Lots and lots and lots of bugs fixes, in nested types, access control, | |
601 | pointers to member functions, the parser, templates, overload | |
602 | resolution, etc, etc. | |
603 | ||
604 | There have been two major enhancements to the Objective-C compiler: | |
605 | ||
606 | 1) Added portability. It now runs on Alpha, and some problems with | |
607 | message forwarding have been addressed on other platforms. | |
608 | ||
609 | 2) Selectors have been redefined to be pointers to structs like: | |
610 | { void *sel_id, char *sel_types }, where the sel_id is the unique | |
611 | identifier, the selector itself is no longer unique. | |
612 | ||
613 | Programmers should use the new function sel_eq to test selector | |
614 | equivalence. | |
615 | ||
616 | The following major changes have been made to the base compiler and | |
617 | machine-specific files. | |
618 | ||
619 | - The MIL-STD-1750A is a new port, but still preliminary. | |
620 | ||
621 | - The h8/300h is now supported; both the h8/300 and h8/300h ports come | |
622 | with 32 bit IEEE 754 software floating point support. | |
623 | ||
624 | - The 64-bit Sparc (v9) and 64-bit MIPS chips are supported. | |
625 | ||
626 | - NetBSD is supported on m68k, Intel x86, and pc523 systems and FreeBSD | |
627 | on x86. | |
628 | ||
629 | - COFF is supported on x86, m68k, and Sparc systems running LynxOS. | |
630 | ||
631 | - 68K systems from Bull and Concurrent are supported and System V | |
632 | Release 4 is supported on the Atari. | |
633 | ||
634 | - GCC supports GAS on the Motorola 3300 (sysV68) and debugging | |
635 | (assuming GAS) on the Plexus 68K system. (However, GAS does not yet | |
636 | work on those systems). | |
637 | ||
638 | - System V Release 4 is supported on MIPS (Tandem). | |
639 | ||
640 | - For DG/UX, an ELF configuration is now supported, and both the ELF | |
641 | and BCS configurations support ELF and COFF object file formats. | |
642 | ||
643 | - OSF/1 V2.0 is supported on Alpha. | |
644 | ||
645 | - Function profiling is also supported on Alpha. | |
646 | ||
647 | - GAS and GDB is supported for Irix 5 (MIPS). | |
648 | ||
649 | - "common mode" (code that will run on both POWER and PowerPC | |
650 | architectures) is now supported for the RS/6000 family; the | |
651 | compiler knows about more PPC chips. | |
652 | ||
653 | - Both NeXTStep 2.1 and 3 are supported on 68k-based architectures. | |
654 | ||
655 | - On the AMD 29k, the -msoft-float is now supported, as well as | |
656 | -mno-sum-in-toc for RS/6000, -mapp-regs and -mflat for Sparc, and | |
657 | -membedded-pic for MIPS. | |
658 | ||
659 | - GCC can now convert division by integer constants into the equivalent | |
660 | multiplication and shift operations when that is faster than the | |
661 | division. | |
662 | ||
663 | - Two new warning options, -Wbad-function-cast and | |
664 | -Wmissing-declarations have been added. | |
665 | ||
666 | - Configurations may now add machine-specific __attribute__ options on | |
667 | type; many machines support the `section' attribute. | |
668 | ||
669 | - The -ffast-math flag permits some optimization that violate strict | |
670 | IEEE rules, such as converting X * 0.0 to 0.0. | |
671 | \f | |
672 | Noteworthy changes in GCC version 2.5.8: | |
673 | ||
674 | This release only fixes a few serious bugs. These include fixes for a | |
675 | bug that prevented most programs from working on the RS/6000, a bug | |
676 | that caused invalid assembler code for programs with a `switch' | |
677 | statement on the NS32K, a G++ problem that caused undefined names in | |
678 | some configurations, and several less serious problems, some of which | |
679 | can affect most configuration. | |
680 | ||
681 | Noteworthy change in GCC version 2.5.7: | |
682 | ||
683 | This release only fixes a few bugs, one of which was causing bootstrap | |
684 | compare errors on some systems. | |
685 | ||
686 | Noteworthy change in GCC version 2.5.6: | |
687 | ||
688 | A few backend bugs have been fixed, some of which only occur on one | |
689 | machine. | |
690 | ||
691 | The C++ compiler in 2.5.6 includes: | |
692 | ||
693 | * fixes for some common crashes | |
694 | * correct handling of nested types that are referenced as `foo::bar' | |
695 | * spurious warnings about friends being declared static and never | |
696 | defined should no longer appear | |
697 | * enums that are local to a method in a class, or a class that's | |
698 | local to a function, are now handled correctly. For example: | |
699 | class foo { void bar () { enum { x, y } E; x; } }; | |
700 | void bar () { class foo { enum { x, y } E; E baz; }; } | |
701 | ||
702 | Noteworthy change in GCC version 2.5.5: | |
703 | ||
704 | A large number of C++ bugs have been fixed. | |
705 | ||
706 | The fixproto script adds prototypes conditionally on __cplusplus. | |
707 | ||
708 | Noteworthy change in GCC version 2.5.4: | |
709 | ||
710 | A bug fix in passing of structure arguments for the HP-PA architecture | |
711 | makes code compiled with GCC 2.5.4 incompatible with code compiled | |
712 | with earlier versions (if it passes struct arguments of 33 to 64 bits, | |
713 | interspersed with other types of arguments). | |
714 | ||
715 | Noteworthy change in gcc version 2.5.3: | |
716 | ||
717 | The method of "mangling" C++ function names has been changed. So you | |
718 | must recompile all C++ programs completely when you start using GCC | |
719 | 2.5. Also, GCC 2.5 requires libg++ version 2.5. Earlier libg++ | |
720 | versions won't work with GCC 2.5. (This is generally true--GCC | |
721 | version M.N requires libg++ version M.N.) | |
722 | \f | |
723 | Noteworthy GCC changes in version 2.5: | |
724 | ||
725 | * There is now support for the IBM 370 architecture as a target. | |
726 | Currently the only operating system supported is MVS; GCC does not run | |
727 | on MVS, so you must produce .s files using GCC as a cross compiler, | |
728 | then transfer them to MVS to assemble them. This port is not reliable | |
729 | yet. | |
730 | ||
731 | * The Power PC is now supported. | |
732 | ||
733 | * The i860-based Paragon machine is now supported. | |
734 | ||
735 | * The Hitachi 3050 (an HP-PA machine) is now supported. | |
736 | ||
737 | * The variable __GNUC_MINOR__ holds the minor version number of GCC, as | |
738 | an integer. For version 2.5.X, the value is 5. | |
739 | ||
740 | * In C, initializers for static and global variables are now processed | |
741 | an element at a time, so that they don't need a lot of storage. | |
742 | ||
743 | * The C syntax for specifying which structure field comes next in an | |
744 | initializer is now `.FIELDNAME='. The corresponding syntax for | |
745 | array initializers is now `[INDEX]='. For example, | |
746 | ||
747 | char whitespace[256] | |
748 | = { [' '] = 1, ['\t'] = 1, ['\n'] = 1 }; | |
749 | ||
750 | This was changed to accord with the syntax proposed by the Numerical | |
751 | C Extensions Group (NCEG). | |
752 | ||
753 | * Complex numbers are now supported in C. Use the keyword __complex__ | |
754 | to declare complex data types. See the manual for details. | |
755 | ||
756 | * GCC now supports `long double' meaningfully on the Sparc (128-bit | |
757 | floating point) and on the 386 (96-bit floating point). The Sparc | |
758 | support is enabled on Solaris 2.x because earlier system versions | |
759 | (SunOS 4) have bugs in the emulation. | |
760 | ||
761 | * All targets now have assertions for cpu, machine and system. So you | |
762 | can now use assertions to distinguish among all supported targets. | |
763 | ||
764 | * Nested functions in C may now be inline. Just declare them inline | |
765 | in the usual way. | |
766 | ||
767 | * Packed structure members are now supported fully; it should be possible | |
768 | to access them on any supported target, no matter how little alignment | |
769 | they have. | |
770 | ||
771 | * To declare that a function does not return, you must now write | |
772 | something like this (works only in 2.5): | |
773 | ||
774 | void fatal () __attribute__ ((noreturn)); | |
775 | ||
776 | or like this (works in older versions too): | |
777 | ||
778 | typedef void voidfn (); | |
779 | ||
780 | volatile voidfn fatal; | |
781 | ||
782 | It used to be possible to do so by writing this: | |
783 | ||
784 | volatile void fatal (); | |
785 | ||
786 | but it turns out that ANSI C requires that to mean something | |
787 | else (which is useless). | |
788 | ||
789 | Likewise, to declare that a function is side-effect-free | |
790 | so that calls may be deleted or combined, write | |
791 | something like this (works only in 2.5): | |
792 | ||
793 | int computation () __attribute__ ((const)); | |
794 | ||
795 | or like this (works in older versions too): | |
796 | ||
797 | typedef int intfn (); | |
798 | ||
799 | const intfn computation; | |
800 | ||
801 | * The new option -iwithprefixbefore specifies a directory to add to | |
802 | the search path for include files in the same position where -I would | |
803 | put it, but uses the specified prefix just like -iwithprefix. | |
804 | ||
805 | * Basic block profiling has been enhanced to record the function the | |
806 | basic block comes from, and if the module was compiled for debugging, | |
807 | the line number and filename. A default version of the basic block | |
808 | support module has been added to libgcc2 that appends the basic block | |
809 | information to a text file 'bb.out'. Machine descriptions can now | |
810 | override the basic block support module in the target macro file. | |
811 | ||
812 | New features in g++: | |
813 | ||
814 | * The new flag `-fansi-overloading' for C++. Use a newly implemented | |
815 | scheme of argument matching for C++. It makes g++ more accurately | |
816 | obey the rules set down in Chapter 13 of the Annotated C++ Reference | |
817 | Manual (the ARM). This option will be turned on by default in a | |
818 | future release. | |
819 | ||
820 | * The -finline-debug flag is now gone (it was never really used by the | |
821 | compiler). | |
822 | ||
823 | * Recognizing the syntax for pointers to members, e.g., "foo::*bar", has been | |
824 | dramatically improved. You should not get any syntax errors or incorrect | |
825 | runtime results while using pointers to members correctly; if you do, it's | |
826 | a definite bug. | |
827 | ||
828 | * Forward declaration of an enum is now flagged as an error. | |
829 | ||
830 | * Class-local typedefs are now working properly. | |
831 | ||
832 | * Nested class support has been significantly improved. The compiler | |
833 | will now (in theory) support up to 240 nested classes before hitting | |
834 | other system limits (like memory size). | |
835 | ||
836 | * There is a new C version of the `g++' driver, to replace the old | |
837 | shell script. This should significantly improve the performance of | |
838 | executing g++ on a system where a user's PATH environment variable | |
839 | references many NFS-mounted filesystems. This driver also works | |
840 | under MS-DOS and OS/2. | |
841 | ||
842 | * The ANSI committee working on the C++ standard has adopted a new | |
843 | keyword `mutable'. This will allow you to make a specific member be | |
844 | modifiable in an otherwise const class. | |
845 | \f | |
846 | Noteworthy GCC changes in version 2.4.4: | |
847 | ||
848 | A crash building g++ on various hosts (including m68k) has been | |
849 | fixed. Also the g++ compiler no longer reports incorrect | |
850 | ambiguities in some situations where they do not exist, and | |
851 | const template member functions are now being found properly. | |
852 | ||
853 | Noteworthy GCC changes in version 2.4: | |
854 | ||
855 | * On each target, the default is now to return short structures | |
856 | compatibly with the "usual" compiler on that target. | |
857 | ||
858 | For most targets, this means the default is to return all structures | |
859 | in memory, like long structures, in whatever way is used on that | |
860 | target. Use -freg-struct-return to enable returning short structures | |
861 | (and unions) in registers. | |
862 | ||
863 | This change means that newly compiled binaries are incompatible with | |
864 | binaries compiled with previous versions of GCC. | |
865 | ||
866 | On some targets, GCC is itself the usual compiler. On these targets, | |
867 | the default way to return short structures is still in registers. | |
868 | Use -fpcc-struct-return to tell GCC to return them in memory. | |
869 | ||
870 | * There is now a floating point emulator which can imitate the way all | |
871 | supported target machines do floating point arithmetic. | |
872 | ||
873 | This makes it possible to have cross compilation to and from the VAX, | |
874 | and between machines of different endianness. However, this works | |
875 | only when the target machine description is updated to use the new | |
876 | facilities, and not all have been updated. | |
877 | ||
878 | This also makes possible support for longer floating point types. | |
879 | GCC 2.4 supports extended format on the 68K if you use `long double', | |
880 | for targets that have a 68881. (When we have run time library | |
881 | routines for extended floating point, then `long double' will use | |
882 | extended format on all 68K targets.) | |
883 | ||
884 | We expect to support extended floating point on the i386 and Sparc in | |
885 | future versions. | |
886 | ||
887 | * Building GCC now automatically fixes the system's header files. | |
888 | This should require no attention. | |
889 | ||
890 | * GCC now installs an unsigned data type as size_t when it fixes the | |
891 | header files (on all but a handful of old target machines). | |
892 | Therefore, the bug that size_t failed to be unsigned is fixed. | |
893 | ||
894 | * Building and installation are now completely separate. | |
895 | All new files are constructed during the build process; | |
896 | installation just copies them. | |
897 | ||
898 | * New targets supported: Clipper, Hitachi SH, Hitachi 8300, and Sparc | |
899 | Lite. | |
900 | ||
901 | * A totally new and much better Objective C run time system is included. | |
902 | ||
903 | * Objective C supports many new features. Alas, I can't describe them | |
904 | since I don't use that language; however, they are the same ones | |
905 | supported in recent versions of the NeXT operating system. | |
906 | ||
907 | * The builtin functions __builtin_apply_args, __builtin_apply and | |
908 | __builtin_return let you record the arguments and returned | |
909 | value of a function without knowing their number or type. | |
910 | ||
911 | * The builtin string variables __FUNCTION__ and __PRETTY_FUNCTION__ | |
912 | give the name of the function in the source, and a pretty-printed | |
913 | version of the name. The two are the same in C, but differ in C++. | |
914 | ||
915 | * Casts to union types do not yield lvalues. | |
916 | ||
917 | * ## before an empty rest argument discards the preceding sequence | |
918 | of non-whitespace characters from the macro definition. | |
919 | (This feature is subject to change.) | |
920 | ||
921 | ||
922 | New features specific to C++: | |
923 | ||
924 | * The manual contains a new section ``Common Misunderstandings with | |
925 | GNU C++'' that C++ users should read. | |
926 | ||
927 | * #pragma interface and #pragma implementation let you use the same | |
928 | C++ source file for both interface and implementation. | |
929 | However, this mechanism is still in transition. | |
930 | ||
931 | * Named returned values let you avoid an extra constructor call | |
932 | when a function result has a class type. | |
933 | ||
934 | * The C++ operators <? and >? yield min and max, respectively. | |
935 | ||
936 | * C++ gotos can exit a block safely even if the block has | |
937 | aggregates that require destructors. | |
938 | ||
939 | * gcc defines the macro __GNUG__ when compiling C++ programs. | |
940 | ||
941 | * GNU C++ now correctly distinguishes between the prefix and postfix | |
942 | forms of overloaded operator ++ and --. To avoid breaking old | |
943 | code, if a class defines only the prefix form, the compiler | |
944 | accepts either ++obj or obj++, unless -pedantic is used. | |
945 | ||
946 | * If you are using version 2.3 of libg++, you need to rebuild it with | |
947 | `make CC=gcc' to avoid mismatches in the definition of `size_t'. | |
948 | ||
949 | Newly documented compiler options: | |
950 | ||
951 | -fnostartfiles | |
952 | Omit the standard system startup files when linking. | |
953 | ||
954 | -fvolatile-global | |
955 | Consider memory references to extern and global data items to | |
956 | be volatile. | |
957 | ||
958 | -idirafter DIR | |
959 | Add DIR to the second include path. | |
960 | ||
961 | -iprefix PREFIX | |
962 | Specify PREFIX for later -iwithprefix options. | |
963 | ||
964 | -iwithprefix DIR | |
965 | Add PREFIX/DIR to the second include path. | |
966 | ||
967 | -mv8 | |
968 | Emit Sparc v8 code (with integer multiply and divide). | |
969 | -msparclite | |
970 | Emit Sparclite code (roughly v7.5). | |
971 | ||
972 | -print-libgcc-file-name | |
973 | Search for the libgcc.a file, print its absolute file name, and exit. | |
974 | ||
975 | -Woverloaded-virtual | |
976 | Warn when a derived class function declaration may be an error | |
977 | in defining a C++ virtual function. | |
978 | ||
979 | -Wtemplate-debugging | |
980 | When using templates in a C++ program, warn if debugging is | |
981 | not yet fully available. | |
982 | ||
983 | +eN | |
984 | Control how C++ virtual function definitions are used | |
985 | (like cfront 1.x). | |
986 |