+2001-01-08 Frank Ch. Eigler <fche@redhat.com>
+
+ * doc/rtl.texi: Deprecate and depreciate the decode-assist construct.
+
2001-01-06 Johan Rydberg <jrydberg@opencores.org>
* openrisc.cpu (or32): Setup semantics for h-delay-insn to
(default-insn-word-bitsize n)
(default-insn-bitsize n)
(base-insn-bitsize n)
- (decode-assist (b0 b1 b2 ...)) ; optional
+ ; (decode-assist (b0 b1 b2 ...)) ; generally unnecessary
(liw-insns n)
(parallel-insns n)
(condition ifield-name expr)
(setup-semantics expr)
- (decode-splits decode-split-list)
+ ; (decode-splits decode-split-list) ; support temporarily disabled
; ??? missing here are fetch/execute specs
)
@end example
@subsubsection decode-assist
@cindex decode-assist
-Override CGEN's guess about which bits to initially use to decode the
-instruction. For example on the SPARC these are bits: 31 30 24 23 22 21 20 19.
-The entire decoder can be machine generated, so this field is entirely
-optional. The intent of @code{decode-assist} is to give the machine
-generated code a head start, to prime the built-in heuristics.
+Override CGEN's heuristics about which bits to initially use to decode
+instructions in a simulator. For example on the SPARC these are bits:
+31 30 24 23 22 21 20 19. The entire decoder can be machine generated,
+so this field is entirely optional. Since the heuristics are quite
+good, you should only use this field if you have evidence that you
+can pick a better set, in which case the CGEN developers would like to
+hear from you!
??? It might be useful to provide greater control, but this is sufficient
for now.
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