From: Joern Rennecke <amylaar@cygnus.co.uk>
To: John Wehle <john@feith.com>
Cc: amylaar@pasanda.cygnus.co.uk, gcc@gcc.gnu.org
Subject: Re: local-alloc update_equiv_regs and moving register initialization
Date: Thu, 14 Sep 2000 16:22:00 -0000 [thread overview]
Message-ID: <200009142322.AAA30419@phal.cygnus.co.uk> (raw)
In-Reply-To: <200009142304.TAA18391@jwlab.FEITH.COM>
> > Because then you might change the semantics of the program.
>
> That's a good reason, however I'm feeling a bit dense. How could it
> change the semantics of the program? If it's safe to change:
>
> a = 3;
> ...
> c = a + b;
>
> to
>
> ...
> a = 3;
> c = a + b;
>
> when a = 3 and c = a + b are outside a loop, why isn't it safe to make
> the same change when both are inside the same loop?
consider
if (i)
c = a + b;
a = i * 3;
next prev parent reply other threads:[~2000-09-14 16:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-09-14 16:04 John Wehle
2000-09-14 16:22 ` Joern Rennecke [this message]
-- strict thread matches above, loose matches on Subject: below --
2000-09-14 17:03 John Wehle
2000-09-14 16:41 John Wehle
2000-09-14 16:54 ` Joern Rennecke
2000-09-14 15:44 John Wehle
2000-09-14 15:56 ` Joern Rennecke
2000-09-14 16:02 ` Jeffrey A Law
2000-09-14 16:09 ` Jeffrey A Law
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