From: John Wehle <john@feith.com>
To: amylaar@cygnus.co.uk
Cc: gcc@gcc.gnu.org
Subject: Re: local-alloc update_equiv_regs and moving register initialization
Date: Thu, 14 Sep 2000 16:04:00 -0000 [thread overview]
Message-ID: <200009142304.TAA18391@jwlab.FEITH.COM> (raw)
>> Why isn't desirable to move the register initialization just before the
>> use when both are within the same loop?
>
> 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?
-- John
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next reply other threads:[~2000-09-14 16:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-09-14 16:04 John Wehle [this message]
2000-09-14 16:22 ` Joern Rennecke
-- 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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