bitset attribute handling reorg

[Doug Evans <dje at sebabeach dot org>]

Hi.

I changed how the bitset attribute is represented.
Internally it's no longer "a,b,c" and is instead (a b c).
Externally one can still use "a,b,c" in description files
but the preferred way is now (a b c).
a,b,c (i.e. a symbol, no quotes) is still supported but it is deprecated,
a,b,c is not a valid R6RS symbol.

Tested by regenerating the world, no changes.
[world: opcodes, sim, sid, intrinsics, docs]

2009-10-25  Doug Evans  <dje@sebabeach.org>

	Record bitset attributes internally as a list.
	Record rtx attribute values internally as ((rtx-expr)).
	* attr.scm (bitset-attr?): Delete, unused.
	(<bitset-attribute> parse-value): Rewrite.
	(/attr-parse): Rewrite bitset default value processing.
	(/attr-read): Pick out values of scalar attributes to distinguish
	them from bitset values which are a list.
	Fix spelling errors for processing of default values.
	Handle string attributes.
	(bitset-attr->list): Delete, all callers updated.
	(/bitset-attr->charmask): Renamed from bitset-attr->charmask.
	All callers updated.
	(atlist-source-form): Rewrite.
	* hardware.scm (<hardware-base> 'get-isas): Update recognition
	of all isas.
	(hardware-builtin!): Update spec of ISA attribute, (ISA foo,bar)
	-> (ISA foo bar).
	* intrinsics.scm (target:belongs-to-group?): Update, bitset attribute
	values are now lists.
	* mach.scm (def-isa-attr!): Update, bitset attribute values,
	including the default, are now lists.
	(all-isas-attr-value): Result is now a list.
	* doc/rtl.texi: Clean up pass over attribute docs.

	Change internal representation of rtx attribute values.
	* attr.scm (/attr-val-is-rtx?): New function.
	(attr-value): Call it.
	(atlist-attr-value-no-default, attr-lookup-default): Ditto.
	(/attr-parse): Use /attr-val-is-rtx? to detect rtx values.
	Disallow rtx values for bitset attributes.
	(/attr-read): Record rtx in default value as ((rtx-expr)).
	(/attr-eval): Update.