This adjusts equate handling by
- allowing true forward references (which will always assume the
referenced
  symbols have at the point of use) through the new .eqv pseudo-op and
the
  new == operator
- disallowing changing .equiv-generated equates (so that the protection
this
  provides is both forward and backward)
- snapshotting equates when their value gets changed so that previous
uses
  don't get affected by the new value.
- allowing expressions in places where absolute expressions (or
register
  names) are needed which were not completely resolvable at the point
of
  their definition but which are fully resolvable at the point of use

In addition it fixes PR/288.

Built and tested on i686-pc-linux-gnu, x86_64-unknown-linux-gnu,
ia64-unknown-linux-gnu, and for a large number of cross targets.

Jan

gas/
2005-09-29  Jan Beulich  <jbeulich@novell.com>

	* expr.h (enum expr_mode): New.
	(expression): Pass thrid argument to expr.
	(expression_and_evaluate): New.
	(deferred_expression): New.
	(expr): Add third parameter.
	(resolve_expression): New.
	* struc-symbol.h (struct symbol): New members sy_volatile and
	sy_forward_ref.
	* symbols.c, symbols.h (symbol_clone): New.
	(symbol_clone_if_forward_ref): New.
	(snapshot_symbol): New.
	(S_IS_VOLATILE): New.
	(S_IS_FORWARD_REF): New.
	(S_SET_VOLATILE): New.
	(S_SET_FORWARD_REF): New.
	* as.c (macro_expr): Use expression_and_evaluate.
	* cond.c (s_if): Likewise.
	(s_elseif): Likewise.
	* dw2gencfi.c (cfi_parse_reg): Likewise.
	* expr.c (operand): Add second parameter. Optionally call
	deferred_expression. Pass mode argument to itself and
md_parse_name.
	Check mode before trying to evaluate symbol. Call
	symbol_clone_if_forward_ref for both operands.
	(expr): Add thrid parameter. Pass mode to operand and itself.
	Optionally call resolve_expression.
	(resolve_expression): New.
	(get_single_number): Pass second argument to operand.
	* read.c (potable): New entry for .eqv.
	(read_a_source_file): Handle new == operator.
	(get_absolute_expr): Use expression_and_evaluate.
	(s_lsym): Likewise.
	(assign_symbol): Rename second parameter. Call symbol_clone on
	legal and illegal redefinition. Call S_SET_VOLATILE and
	S_SET_FORWARD_REF depending on mode.
	(s_set): Update description.
	(s_space): Call resolve_expression.
	(pseudo_set): Optionally call deferred_expression. Check
	S_IS_FORWARD_REF before trying to simplify/resolve an
expression.
	(equals): Handle ==.
	* config/tc-ia64.h (md_parse_name): Add mode parameter.
	* config/tc-m32r.h (md_parse_name): Likewise.
	(m32r_parse_name): Likewise.
	* config/tc-mmix.h (md_parse_name): Likewise.
	* config/tc-mn10300.h (md_parse_name): Likewise.
	(mn10300_parse_name): Likewise.
	* config/tc-ppc.h (md_parse_name): Likewise.
	* config/tc-sh.h (md_parse_name): Likewise.
	(sh_parse_name): Likewise.
	* config/tc-sh64.h (md_parse_name): Likewise.
	(sh64_consume_datalabel): Likewise.
	* config/tc-tic54x.h (md_parse_name): Likewise.
	* config/tc-m32r.c (m32r_parse_name): Add mode parameter. Check
it
	before trying to evaluate symbol.
	* config/tc-mn10300.c (mn10300_parse_name): Likewise.
	* config/tc-sh.c (sh_parse_name): Likewise.
	* config/tc-sh64.c (sh64_consume_datalabel): Add mode parameter.
Pass
	second argument to operandf. Pass mode parameter to
sh_parse_name.
	* doc/as.texinfo: Document .eqv and the == assignment operator.

gas/testsuite/
2005-09-29  Jan Beulich  <jbeulich@novell.com>

	* gas/all/cond.s: Add test for resolution of fully resolvable
	forward references in .if/.endif.
	* gas/all/cond.d: Adjust.
	* gas/all/assign-bad.s: New.
	* gas/all/assign-ok.s: New.
	* gas/all/equ-bad.s: New.
	* gas/all/equ-ok.s: New.
	* gas/all/equiv1.s: New.
	* gas/all/equiv2.s: New.
	* gas/all/eqv-bad.s: New.
	* gas/all/eqv-ok.s: New.
	* gas/all/forward.[sd]: New.
	* gas/all/redef.[sd]: New.
	* gas/all/gas.exp: Run new tests, but xfail equiv1 (PR/1387).

(actual patch attached)