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Re: Question on -fbounds-check
- To: "Tim Prince" <tprince at computer dot org>
- Subject: Re: Question on -fbounds-check
- From: Geoff Keating <geoffk at cygnus dot com>
- Date: 11 Jun 2000 18:49:23 -0700
- CC: gcc at gcc dot gnu dot org
- References: <001101bfd402$8d7213f0$0100000a@TIMYX18EWDT6RQ>
"Tim Prince" <tprince@computer.org> writes:
> Am I correct in believing that -fbounds-check disables certain other
> (possibly buggy) optimizations, including -funroll-loops? I notice that
> bugs associated with -funroll-loops (in gcc-2.96 snapshots) disappear
> when -fbounds-check is invoked.
Most likely this is just the loop optimizer deciding that unrolling
the loop is too hard with the extra bounds-checking code.
> As a slight digression, should it be possible to step code and examine
> loop counters under gdb, when code has been compiled
> with -funroll-loops? Does the answer differ between gcc and g77?
Step code, yes. Examine loop counters, probably not, since you may
have more than one of them.
--
- Geoffrey Keating <geoffk@cygnus.com>