mirror of
https://git.FreeBSD.org/src.git
synced 2024-11-27 08:00:11 +00:00
1064 lines
40 KiB
Plaintext
1064 lines
40 KiB
Plaintext
Noteworthy changes in GCC for EGCS 1.1.
|
||
---------------------------------------
|
||
|
||
The compiler now implements global common subexpression elimination (gcse) as
|
||
well as global constant/copy propagation. (link to gcse page).
|
||
|
||
More major improvements have been made to the alias analysis code. A new
|
||
option to allow front-ends to provide alias information to the optimizers
|
||
has also been added (-fstrict-aliasing). -fstrict-aliasing is off by default
|
||
now, but will be enabled by default in the future. (link to alias page)
|
||
|
||
Major changes continue in the exception handling support. This release
|
||
includes some changes to reduce static overhead for exception handling. It
|
||
also includes some major changes to the setjmp/longjmp based EH mechanism to
|
||
make it less pessimistic. And finally, major infrastructure improvements
|
||
to the dwarf2 EH mechanism have been made to make our EH support extensible.
|
||
|
||
We have fixed the infamous security problems with temporary files.
|
||
|
||
The "regmove" optimization pass has been nearly completely rewritten. It now
|
||
uses much more information about the target to determine profitability of
|
||
transformations.
|
||
|
||
The compiler now recomputes register usage information immediately before
|
||
register allocation. Previously such information was only not kept up to
|
||
date after instruction combination which led to poor register allocation
|
||
choices by our priority based register allocator.
|
||
|
||
The register reloading phase of the compiler has been improved to better
|
||
optimize spill code. This primarily helps targets which generate lots of
|
||
spills (like the x86 ports and many register poor embedded ports).
|
||
|
||
A few changes in the heuristics used by the register allocator and scheduler
|
||
have been made which can significantly improve performance for certain
|
||
applications.
|
||
|
||
The compiler's branch shortening algorithms have been significantly improved
|
||
to work better on targets which align jump targets.
|
||
|
||
The compiler now supports the "ADDRESSOF" optimization which can significantly
|
||
reduce the overhead for certain inline calls (and inline calls in general).
|
||
|
||
The compiler now supports a code size optimization switch (-Os). When enabled
|
||
the compiler will prefer optimizations which improve code size over those
|
||
which improve code speed.
|
||
|
||
The compiler has been improved to completely eliminate library calls which
|
||
compute constant values. This is particularly useful on machines which
|
||
do not have integer mul/div or floating point support on-chip.
|
||
|
||
GCC now supports a "--help" option to print detailed help information.
|
||
|
||
cpplib has been greatly improved. It is probably useable for some sites now
|
||
(major missing feature is trigraphs).
|
||
|
||
Memory footprint for the compiler has been significantly reduced for certain
|
||
pathalogical cases.
|
||
|
||
Build time improvements for targets which support lots of sched parameters
|
||
(alpha and mips primarily).
|
||
|
||
Compile time for certain programs using large constant initializers has been
|
||
improved (effects glibc significantly).
|
||
|
||
Plus an incredible number of infrastructure changes, warning fixes, bugfixes
|
||
and local optimizations.
|
||
|
||
Various improvements have been made to better support cross compilations. They
|
||
are still not easy, but they are improving.
|
||
|
||
Target specific NEWS
|
||
|
||
Sparc: Now includes V8 plus and V9 support, lots of tuning for Ultrasparcs
|
||
and uses the Haifa scheduler by default.
|
||
|
||
Alpha: EV6 tuned, optimized expansion of memcpy/bzero.
|
||
|
||
x86: Data in the static store is aligned per Intel recommendations. Jump
|
||
targets are aligned per Intel recommendations. Improved epilogue
|
||
sequences for Pentium chips. Backend improvements which should help
|
||
register allocation on all x86 variants. Support for PPro conditional
|
||
move instructions has been fixed and enabled. Random changes
|
||
throughout the port to make generated code more Pentium friendly.
|
||
Improved support for 64bit integer operations.
|
||
Unixware 7, a System V Release 5 target is now supported.
|
||
SCO OpenServer targets can support GAS. See gcc/INSTALL for details.
|
||
|
||
RS6000/PowerPC: Includes AIX4.3 support as well as PowerPC64 support.
|
||
Haifa instruction scheduling is enabled by default now.
|
||
|
||
MIPS: Multiply/Multiply-Add support has been largely rewritten to generate
|
||
more efficient code. Includes mips16 support.
|
||
|
||
M68K: Various micro-optimizations and Coldfire fixes.
|
||
|
||
M32r: Major improvements to this port.
|
||
|
||
Arm: Includes Thumb and super interworking support.
|
||
|
||
EGCS includes all gcc2 changes up to and including the June 9, 1998 snapshot.
|
||
|
||
|
||
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).
|
||
|