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Re: patch for compile/991229-3.c -O3 -fomit-frame-pointer -funroll-loops SH failure
- To: Joern Rennecke <amylaar at cygnus dot co dot uk>
- Subject: Re: patch for compile/991229-3.c -O3 -fomit-frame-pointer -funroll-loops SH failure
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Sat, 26 Feb 2000 13:48:19 -0700
- cc: gcc-patches at gcc dot gnu dot org
- Reply-To: law at cygnus dot com
In message <200002171905.TAA10562@phal.cygnus.co.uk>you write:
> > ?!? Shouldn't the set of (reg:SI 62) have been deleted by the call to
> > delete_trivially_dead_insns that occurs after the first loop optimization
> > pass? The whole point of delete_trivially_dead_insns is to remove assign
> ments
> > to pseudos which are never used.
>
> No, the last use of (reg:SI 62) has been removed in the *second* loop
> optimization pass. There was no call to delete_trivially_dead_insns
> between the removal of the last use and the optimization of the outer
> loop. More importantly, there was no new call to reg_scan.
> delete_trivially_dead_insns only deletes the set if it is dead, while
> the reg_scan information can be out of date without *all* uses being
> removed.
Thanks for the clarification. It makes sense now.
jeff