[PATCH/RFC] gut Interoperation section of trouble.texi

[PATCH/RFC] gut Interoperation section of trouble.texi

[Janis Johnson]

Most of the information in the Trouble/Interoperation section of the GCC
manual is very old, and I suspect that much of it is no longer relevant.
I propose that we remove everything that was there in egcs 1.1.2 unless
someone comes forward soon to say a particular item still needs to be
there.

The current organization of this section makes it difficult to easily
find information that is relevant to a particular platform.  I propose
splitting the items by platform, using the labeling convention now used
for the list of supported targets in java/status.html.  The patch below
uses nested bullets, which doesn't fit into the current formatting of
the manual, but I'm sure Joseph will have a good idea about how it ought
to be done.

Unlike the host/target specific information in the install instructions,
this section is aimed at GCC users and can be useful if it's not
overwhelmed by outdated cruft.  In particular it would be a nice place
to record information about interoperability with other C++ compilers
and libraries.

Tested with "make dvi" and "make info" on i686-pc-linux-gnu.

2002-10-30  Janis Johnson  <janis187@us.ibm.com>

	* doc/trouble.texi (Interoperation): Remove everything that's been
	there since egcs 1.1.2.

Index: doc/trouble.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/trouble.texi,v
retrieving revision 1.12
diff -u -r1.12 trouble.texi
--- doc/trouble.texi	15 Sep 2002 22:48:05 -0000	1.12
+++ doc/trouble.texi	31 Oct 2002 00:23:17 -0000
@@ -103,6 +103,10 @@
 together with other compilers or with the assemblers, linkers,
 libraries and debuggers on certain systems.
 
+@itemize
+@item
+Issues that affect many platforms
+
 @itemize @bullet
 @item
 On many platforms, GCC supports a different ABI for C++ than do other
@@ -120,178 +124,12 @@
 run.  Incompatible libraries are then detected at link time, rather than
 at run time.
 
-@item
-Older GDB versions sometimes fail to read the output of GCC version
-2.  If you have trouble, get GDB version 4.4 or later.
-
-@item
-@cindex DBX
-DBX rejects some files produced by GCC, though it accepts similar
-constructs in output from PCC@.  Until someone can supply a coherent
-description of what is valid DBX input and what is not, there is
-nothing I can do about these problems.  You are on your own.
-
-@item
-The GNU assembler (GAS) does not support PIC@.  To generate PIC code, you
-must use some other assembler, such as @file{/bin/as}.
-
-@item
-On some BSD systems, including some versions of Ultrix, use of profiling
-causes static variable destructors (currently used only in C++) not to
-be run.
-
-@ignore
-@cindex @code{vfork}, for the Sun-4
-@item
-There is a bug in @code{vfork} on the Sun-4 which causes the registers
-of the child process to clobber those of the parent.  Because of this,
-programs that call @code{vfork} are likely to lose when compiled
-optimized with GCC when the child code alters registers which contain
-C variables in the parent.  This affects variables which are live in the
-parent across the call to @code{vfork}.
-
-If you encounter this, you can work around the problem by declaring
-variables @code{volatile} in the function that calls @code{vfork}, until
-the problem goes away, or by not declaring them @code{register} and not
-using @option{-O} for those source files.
-@end ignore
-
-@item
-On some SGI systems, when you use @option{-lgl_s} as an option,
-it gets translated magically to @samp{-lgl_s -lX11_s -lc_s}.
-Naturally, this does not happen when you use GCC@.
-You must specify all three options explicitly.
-
-@item
-On a SPARC, GCC aligns all values of type @code{double} on an 8-byte
-boundary, and it expects every @code{double} to be so aligned.  The Sun
-compiler usually gives @code{double} values 8-byte alignment, with one
-exception: function arguments of type @code{double} may not be aligned.
-
-As a result, if a function compiled with Sun CC takes the address of an
-argument of type @code{double} and passes this pointer of type
-@code{double *} to a function compiled with GCC, dereferencing the
-pointer may cause a fatal signal.
-
-One way to solve this problem is to compile your entire program with GCC@.
-Another solution is to modify the function that is compiled with
-Sun CC to copy the argument into a local variable; local variables
-are always properly aligned.  A third solution is to modify the function
-that uses the pointer to dereference it via the following function
-@code{access_double} instead of directly with @samp{*}:
-
-@smallexample
-inline double
-access_double (double *unaligned_ptr)
-@{
-  union d2i @{ double d; int i[2]; @};
-
-  union d2i *p = (union d2i *) unaligned_ptr;
-  union d2i u;
-
-  u.i[0] = p->i[0];
-  u.i[1] = p->i[1];
-
-  return u.d;
-@}
-@end smallexample
-
-@noindent
-Storing into the pointer can be done likewise with the same union.
-
-@item
-On Solaris, the @code{malloc} function in the @file{libmalloc.a} library
-may allocate memory that is only 4 byte aligned.  Since GCC on the
-SPARC assumes that doubles are 8 byte aligned, this may result in a
-fatal signal if doubles are stored in memory allocated by the
-@file{libmalloc.a} library.
-
-The solution is to not use the @file{libmalloc.a} library.  Use instead
-@code{malloc} and related functions from @file{libc.a}; they do not have
-this problem.
-
-@item
-Sun forgot to include a static version of @file{libdl.a} with some
-versions of SunOS (mainly 4.1).  This results in undefined symbols when
-linking static binaries (that is, if you use @option{-static}).  If you
-see undefined symbols @code{_dlclose}, @code{_dlsym} or @code{_dlopen}
-when linking, compile and link against the file
-@file{mit/util/misc/dlsym.c} from the MIT version of X windows.
-
-@item
-The 128-bit long double format that the SPARC port supports currently
-works by using the architecturally defined quad-word floating point
-instructions.  Since there is no hardware that supports these
-instructions they must be emulated by the operating system.  Long
-doubles do not work in Sun OS versions 4.0.3 and earlier, because the
-kernel emulator uses an obsolete and incompatible format.  Long doubles
-do not work in Sun OS version 4.1.1 due to a problem in a Sun library.
-Long doubles do work on Sun OS versions 4.1.2 and higher, but GCC
-does not enable them by default.  Long doubles appear to work in Sun OS
-5.x (Solaris 2.x).
-
-@item
-On HP-UX version 9.01 on the HP PA, the HP compiler @code{cc} does not
-compile GCC correctly.  We do not yet know why.  However, GCC
-compiled on earlier HP-UX versions works properly on HP-UX 9.01 and can
-compile itself properly on 9.01.
-
-@item
-On the HP PA machine, ADB sometimes fails to work on functions compiled
-with GCC@.  Specifically, it fails to work on functions that use
-@code{alloca} or variable-size arrays.  This is because GCC doesn't
-generate HP-UX unwind descriptors for such functions.  It may even be
-impossible to generate them.
-
-@item
-Debugging (@option{-g}) is not supported on the HP PA machine, unless you use
-the preliminary GNU tools.
-
-@item
-Taking the address of a label may generate errors from the HP-UX
-PA assembler.  GAS for the PA does not have this problem.
-
-@item
-Using floating point parameters for indirect calls to static functions
-will not work when using the HP assembler.  There simply is no way for GCC
-to specify what registers hold arguments for static functions when using
-the HP assembler.  GAS for the PA does not have this problem.
-
-@item
-In extremely rare cases involving some very large functions you may
-receive errors from the HP linker complaining about an out of bounds
-unconditional branch offset.  This used to occur more often in previous
-versions of GCC, but is now exceptionally rare.  If you should run
-into it, you can work around by making your function smaller.
-
-@item
-GCC compiled code sometimes emits warnings from the HP-UX assembler of
-the form:
-
-@smallexample
-(warning) Use of GR3 when
-  frame >= 8192 may cause conflict.
-@end smallexample
-
-These warnings are harmless and can be safely ignored.
+@end itemize
 
 @item
-On the IBM RS/6000, compiling code of the form
-
-@smallexample
-extern int foo;
-
-@dots{} foo @dots{}
-
-static int foo;
-@end smallexample
-
-@noindent
-will cause the linker to report an undefined symbol @code{foo}.
-Although this behavior differs from most other systems, it is not a
-bug because redefining an @code{extern} variable as @code{static}
-is undefined in ISO C@.
+AIX on IBM pSeries (PowerPC) architecture (rs6000-ibm-aix*, powerpc-ibm-aix*)
 
+@itemize @bullet
 @item
 In extremely rare cases involving some very large functions you may
 receive errors from the AIX Assembler complaining about a displacement
@@ -321,116 +159,7 @@
 with ``runtime-linking'' option and the functions explicitly must be
 exported by the application (@option{-Wl,-brtl,-bE:exportfile}).
 
-@item
-AIX on the RS/6000 provides support (NLS) for environments outside of
-the United States.  Compilers and assemblers use NLS to support
-locale-specific representations of various objects including
-floating-point numbers (@samp{.} vs @samp{,} for separating decimal
-fractions). There have been problems reported where the library linked
-with GCC does not produce the same floating-point formats that the
-assembler accepts. If you have this problem, set the @env{LANG}
-environment variable to @samp{C} or @samp{En_US}.
-
-@item
-@opindex fdollars-in-identifiers
-Even if you specify @option{-fdollars-in-identifiers},
-you cannot successfully use @samp{$} in identifiers on the RS/6000 due
-to a restriction in the IBM assembler.  GAS supports these
-identifiers.
-
-@item
-@opindex mno-serialize-volatile
-There is an assembler bug in versions of DG/UX prior to 5.4.2.01 that
-occurs when the @samp{fldcr} instruction is used.  GCC uses
-@samp{fldcr} on the 88100 to serialize volatile memory references.  Use
-the option @option{-mno-serialize-volatile} if your version of the
-assembler has this bug.
-
-@item
-On VMS, GAS versions 1.38.1 and earlier may cause spurious warning
-messages from the linker.  These warning messages complain of mismatched
-psect attributes.  You can ignore them.
-
-@item
-On NewsOS version 3, if you include both of the files @file{stddef.h}
-and @file{sys/types.h}, you get an error because there are two typedefs
-of @code{size_t}.  You should change @file{sys/types.h} by adding these
-lines around the definition of @code{size_t}:
-
-@smallexample
-#ifndef _SIZE_T
-#define _SIZE_T
-@var{actual-typedef-here}
-#endif
-@end smallexample
-
-@cindex Alliant
-@item
-On the Alliant, the system's own convention for returning structures
-and unions is unusual, and is not compatible with GCC no matter
-what options are used.
-
-@cindex RT PC
-@cindex IBM RT PC
-@item
-@opindex mhc-struct-return
-On the IBM RT PC, the MetaWare HighC compiler (hc) uses a different
-convention for structure and union returning.  Use the option
-@option{-mhc-struct-return} to tell GCC to use a convention compatible
-with it.
-
-@cindex VAX calling convention
-@cindex Ultrix calling convention
-@item
-@opindex fcall-saved
-On Ultrix, the Fortran compiler expects registers 2 through 5 to be saved
-by function calls.  However, the C compiler uses conventions compatible
-with BSD Unix: registers 2 through 5 may be clobbered by function calls.
-
-GCC uses the same convention as the Ultrix C compiler.  You can use
-these options to produce code compatible with the Fortran compiler:
-
-@smallexample
--fcall-saved-r2 -fcall-saved-r3 -fcall-saved-r4 -fcall-saved-r5
-@end smallexample
-
-@item
-On the WE32k, you may find that programs compiled with GCC do not
-work with the standard shared C library.  You may need to link with
-the ordinary C compiler.  If you do so, you must specify the following
-options:
-
-@smallexample
--L/usr/local/lib/gcc-lib/we32k-att-sysv/2.8.1 -lgcc -lc_s
-@end smallexample
-
-The first specifies where to find the library @file{libgcc.a}
-specified with the @option{-lgcc} option.
-
-GCC does linking by invoking @command{ld}, just as @command{cc} does, and
-there is no reason why it @emph{should} matter which compilation program
-you use to invoke @command{ld}.  If someone tracks this problem down,
-it can probably be fixed easily.
-
-@item
-On the Alpha, you may get assembler errors about invalid syntax as a
-result of floating point constants.  This is due to a bug in the C
-library functions @code{ecvt}, @code{fcvt} and @code{gcvt}.  Given valid
-floating point numbers, they sometimes print @samp{NaN}.
-
-@item
-On Irix 4.0.5F (and perhaps in some other versions), an assembler bug
-sometimes reorders instructions incorrectly when optimization is turned
-on.  If you think this may be happening to you, try using the GNU
-assembler; GAS version 2.1 supports ECOFF on Irix.
-
-@opindex noasmopt
-Or use the @option{-noasmopt} option when you compile GCC with itself,
-and then again when you compile your program.  (This is a temporary
-kludge to turn off assembler optimization on Irix.)  If this proves to
-be what you need, edit the assembler spec in the file @file{specs} so
-that it unconditionally passes @option{-O0} to the assembler, and never
-passes @option{-O2} or @option{-O3}.
+@end itemize
 @end itemize
 
 @node External Bugs

Re: [PATCH/RFC] gut Interoperation section of trouble.texi

[Andrew Pinski]

On Wednesday, Oct 30, 2002, at 16:37 US/Pacific, Janis Johnson wrote:

>
> -@item
> -Older GDB versions sometimes fail to read the output of GCC version
> -2.  If you have trouble, get GDB version 4.4 or later.

I think this still applies except for gcc needs at least gdb 5.1 I think

Thanks,
Andrew Pinski

Re: [PATCH/RFC] gut Interoperation section of trouble.texi

[Joseph S. Myers]

On Wed, 30 Oct 2002, Janis Johnson wrote:

> Most of the information in the Trouble/Interoperation section of the GCC
> manual is very old, and I suspect that much of it is no longer relevant.
> I propose that we remove everything that was there in egcs 1.1.2 unless
> someone comes forward soon to say a particular item still needs to be
> there.

I propose the more conservative fix of removing everything relating only
to systems for which support has been removed, or to obsolete versions of
other GNU tools.  I don't think Zack did this when removing support for
those systems.

At least the AIX information which you remove parts of has been more
recently than egcs 1.1.2 been checked and obsolete parts already removed
by the relevant maintainer.  Checking for what's in egcs 1.1.2 therefore
isn't in any case an appropriate check, it's whether the relevant
maintainers have checked the information for their systems and removed the
obsolete parts.

> -@item
> -On VMS, GAS versions 1.38.1 and earlier may cause spurious warning
> -messages from the linker.  These warning messages complain of mismatched
> -psect attributes.  You can ignore them.

This, for example, and the next few items, can be removed.

-- 
Joseph S. Myers
jsm28@cam.ac.uk

Re: [PATCH/RFC] gut Interoperation section of trouble.texi

[Janis Johnson]

On Thu, Oct 31, 2002 at 10:43:08AM +0000, Joseph S. Myers wrote:
> On Wed, 30 Oct 2002, Janis Johnson wrote:
> 
> > Most of the information in the Trouble/Interoperation section of the GCC
> > manual is very old, and I suspect that much of it is no longer relevant.
> > I propose that we remove everything that was there in egcs 1.1.2 unless
> > someone comes forward soon to say a particular item still needs to be
> > there.
> 
> I propose the more conservative fix of removing everything relating only
> to systems for which support has been removed, or to obsolete versions of
> other GNU tools.  I don't think Zack did this when removing support for
> those systems.

I plan to do this but haven't gotten around to it yet.  I'd like to
change the format to make it easier to identify which platforms are
being described; do you have suggestions for that, Joseph?  Would it
be OK to use nested lists?

Is there a complete list of obsolete targets somewhere?

Janis