This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: A plan for eliminating cc0
- From: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- To: ian at airs dot com
- Cc: gcc at gcc dot gnu dot org
- Date: Wed, 23 Mar 05 11:13:19 EST
- Subject: Re: A plan for eliminating cc0
3) Write a new optimization pass enabled on targets which define
NOTICE_UPDATE_CC. I think this pass would be run just before
machine dependent reorg, although perhaps there is a better place
for it. Walk through the instructions, calling NOTICE_UPDATE_CC on
each one. When we find an instruction which sets CC_REG, check the
source of the set with the current CC status, just as
final_scan_insn does now. If the current CC status is the same,
delete the instruction which sets CC_REG.
My gut feeling is that we shouldn't need to do this: the present
optimization passes should do this when we have an explicit register.