[Bug tree-optimization/18694] [4.0 regression] loop miscompilation at -O1 (-ftree-ch)
------- Additional Comments From law at redhat dot com 2004-12-10 21:42 -------
Subject: Re: [4.0 regression] loop
miscompilation at -O1 (-ftree-ch)
On Fri, 2004-12-10 at 21:31 +0000, kazu at cs dot umass dot edu wrote:
> Can you come up with a hypothetical scenario?
No need. It's fundamentally broken in that it's recording
an invalid equivalence. It's recording that tmp_1 = next_2
which is totally bogus.
The only reason it works is because we don't walk through
all the SSA_NAME_VALUEs back to the oldest.
jeff
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18694
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