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Re: Autoincrement examples
- To: Joern Rennecke <amylaar at cygnus dot co dot uk>
- Subject: Re: Autoincrement examples
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Thu, 18 Nov 1999 11:55:15 -0700
- cc: m dot hayes at elec dot canterbury dot ac dot nz (Michael Hayes), gcc at gcc dot gnu dot org, amylaar at cygnus dot com
- Reply-To: law at cygnus dot com
In message <199911181532.PAA09078@phal.cygnus.co.uk>you write:
> However, we are not supposed to generate autoincrement before flow. The
> point of doin this in regmove is that we alerady got constraint information
> there - using autoincrement instead of three-address-adds is much more
> useful when you don't actually have a three-address add to start with.
It seems to me that we can get this information during flow/life analysis
just as easily as in regmove.c
The interactions between loop & autoinc are clearly something we need to
deal with. Both of you have noted the fact that loop opts tend to
disguise autoinc opportunities.
But I believe we can attack the problems separately -- ie, we can improve
autoinc detection separately from making the loop optimizer generate code that
is more autoinc friendly. The biggest obstacle in doing that is deciding
precisely what sequences we want to detect for autoinc opts and which ones
we're going to depend on loop generating autoinc friendly code.