From 609529cd0c54e3c8faf38b5c31331dc6b7017cbb Mon Sep 17 00:00:00 2001 From: "Frank Ch. Eigler" Date: Mon, 8 Jan 2001 18:37:18 +0000 Subject: [PATCH] 2001-01-08 Frank Ch. Eigler * doc/rtl.texi: Deprecate and depreciate the decode-assist construct. --- ChangeLog | 4 ++++ doc/rtl.texi | 16 +++++++++------- 2 files changed, 13 insertions(+), 7 deletions(-) diff --git a/ChangeLog b/ChangeLog index 5836a95..af9f50b 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,7 @@ +2001-01-08 Frank Ch. Eigler + + * doc/rtl.texi: Deprecate and depreciate the decode-assist construct. + 2001-01-06 Johan Rydberg * openrisc.cpu (or32): Setup semantics for h-delay-insn to diff --git a/doc/rtl.texi b/doc/rtl.texi index e32b5e8..5c685f7 100644 --- a/doc/rtl.texi +++ b/doc/rtl.texi @@ -401,12 +401,12 @@ The syntax of @code{define-isa} is: (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 @@ -455,11 +455,13 @@ at a time as 16 bit instructions always come in pairs. @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. -- 2.43.5