`alpha-*-osf1':

	Systems using processors that implement the DEC Alpha architecture
	and are running the DEC Unix (OSF/1) operating system, for example
	the DEC Alpha AXP systems.CC.)

	GNU CC writes a `.verstamp' directive to the assembler output file
	unless it is built as a cross-compiler.  It gets the version to
	use from the system header file `/usr/include/stamp.h'.  If you
	install a new version of DEC Unix, you should rebuild GCC to pick
	up the new version stamp.

	Note that since the Alpha is a 64-bit architecture,
	cross-compilers from 32-bit machines will not generate code as
	efficient as that generated when the compiler is running on a
	64-bit machine because many optimizations that depend on being
	able to represent a word on the target in an integral value on the
	host cannot be performed.  Building cross-compilers on the Alpha
	for 32-bit machines has only been tested in a few cases and may
	not work properly.

	`make compare' may fail on old versions of DEC Unix unless you add
	`-save-temps' to `CFLAGS'.  On these systems, the name of the
	assembler input file is stored in the object file, and that makes
	comparison fail if it differs between the `stage1' and `stage2'
	compilations.  The option `-save-temps' forces a fixed name to be
	used for the assembler input file, instead of a randomly chosen
	name in `/tmp'.  Do not add `-save-temps' unless the comparisons
	fail without that option.  If you add `-save-temps', you will have
	to manually delete the `.i' and `.s' files after each series of
	compilations.

	GNU CC now supports both the native (ECOFF) debugging format used
	by DBX and GDB and an encapsulated STABS format for use only with
	GDB.  See the discussion of the `--with-stabs' option of
	`configure' below for more information on these formats and how to
	select them.

	There is a bug in DEC's assembler that produces incorrect line
	numbers for ECOFF format when the `.align' directive is used.  To
	work around this problem, GNU CC will not emit such alignment
	directives while writing ECOFF format debugging information even
	if optimization is being performed.  Unfortunately, this has the
	very undesirable side-effect that code addresses when `-O' is
	specified are different depending on whether or not `-g' is also
	specified.

	To avoid this behavior, specify `-gstabs+' and use GDB instead of
	DBX.  DEC is now aware of this problem with the assembler and
	hopes to provide a fix shortly.


--with-stabs option of configure:

	On MIPS based systems and on Alphas, you must specify whether
	you want GNU CC to create the normal ECOFF debugging format,
	or to use BSD-style stabs passed through the ECOFF symbol
	table.  The normal ECOFF debug format cannot fully handle
	languages other than C.  BSD stabs format can handle other
	languages, but it only works with the GNU debugger GDB.

	Normally, GNU CC uses the ECOFF debugging format by default;
	if you prefer BSD stabs, specify `--with-stabs' when you
	configure GNU CC.

	No matter which default you choose when you configure GNU CC,
	the user can use the `-gcoff' and `-gstabs+' options to
	specify explicitly the debug format for a particular
	compilation.

	`--with-stabs' is meaningful on the ISC system on the 386,
	also, if `--with-gas' is used.  It selects use of stabs
	debugging information embedded in COFF output.  This kind of
	debugging information supports C++ well; ordinary COFF
	debugging information does not.

	`--with-stabs' is also meaningful on 386 systems running
	SVR4.  It selects use of stabs debugging information embedded
	in ELF output.  The C++ compiler currently (2.6.0) does not
	support the DWARF debugging information normally used on 386
	SVR4 platforms; stabs provide a workable alternative.  This
	requires gas and gdb, as the normal SVR4 tools can not
	generate or interpret stabs.