On 28/10/11 17:59, Richard Henderson wrote:
On 10/28/2011 06:49 AM, Peter Bigot wrote:
I'm inclined to follow sparc's lead, but is one or another of the choices
more likely to help combine/reload/etc do a better job?
I don't know.
In the case of RX, we don't model CC_REG until after reload, so combine really
doesn't get a shot at it.
Be careful here. If you explicitly model the carry flag before reload, you need
to have an ADD instruction that can avoid any flags modification. Reload needs
to generate such instructions in some cases, and needs to be able to insert them
between any two arbitrary insns.
I followed rx model but instead RCC before clobber in some cases.
To solve this problem
I have the following insn_and_split:
(define_insn_and_split "addqi3_noclobber"
[(set (match_operand:QI 0 "register_operand" "=c")
(plus:QI (match_operand:QI 1 "register_operand")
(match_operand:QI 2 "immediate_operand")))]
"reload_in_progress"
"#"
"reload_completed"
[(parallel [(set (match_dup 0) (match_dup 1))
(clobber (reg:CC RCC))])
(parallel [(set (match_dup 0) (plus:QI (match_dup 0) (match_dup 2)))
(clobber (reg:CC RCC))])])
Cheers,
--
PMatos
