From: Dale Johannesen <dalej@apple.com>
To: Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz>
Cc: "gcc@gcc.gnu.org list" <gcc@gcc.gnu.org>,
Dale Johannesen <dalej@apple.com>
Subject: Re: [tree-ssa vs lno] who is right?
Date: Fri, 26 Mar 2004 20:15:00 -0000 [thread overview]
Message-ID: <99B44A2E-7F52-11D8-8C7F-000A95D7CD40@apple.com> (raw)
In-Reply-To: <20040326181034.GA24586@atrey.karlin.mff.cuni.cz>
On Mar 26, 2004, at 10:10 AM, Zdenek Dvorak wrote:
> Hello,
>
>> When the LNO branch copies a loop, it attempts to fix up the phi nodes
>> with
>> an algorithm that assumes there is only one phi per block per
>> variable.
>> That is, it
>> won't see code like this:
>
> (i.e. what do you mean by "copying a loop")?
tree_duplicate_loop_to_header_edge (called from unswitching in the
failing case)
> where do we assume this
lv_adjust_loop_header_phi . The assumption is explicit:
/* There can not be second phi node for the same
variable.
Get out of the for loop that walks phi nodes
of 'first'.
*/
There isn't any way to find the right phi at that point AFAICT, so I'm
thinking
along the lines of making sure the phi lists are in the same order when
doing
the loop duplication earlier (they aren't now).
> While this certainly is unlikely to happen, there probably is nothing
> that would prevent it.
> Zdenek
>
>> ;; basic block 19, loop depth 0, count 0
>> ;; prev block 9, next block 20
>> ;; pred: 10 [100.0%] (fallthru)
>> ;; succ: 28 [50.0%] (true,exec) 29 [50.0%] (false,exec)
>> # maxmin_Result_140 = PHI <1(10)>;
>> # maxmin_Result_142 = PHI <2(10)>;
>> # lsm_tmp.19_144 = PHI <lsm_tmp.19_84(10)>;
>> <L28>:;
>> if (m__10 == 0) goto <L26>; else goto <L27>;
>>
>> Is that suppose to be a valid assumption? The dup is created by
>> copyrename, and
>> I see no code there that's intended to stop dups from being created
>> (on
>> the
>> contrary, but surely it's unusual for the live ranges to overlap).
>>
next prev parent reply other threads:[~2004-03-26 18:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-26 5:32 Dale Johannesen
2004-03-26 6:34 ` Diego Novillo
2004-03-26 6:35 ` Dale Johannesen
2004-03-26 7:08 ` Diego Novillo
2004-03-26 7:27 ` Andrew Pinski
2004-03-26 16:21 ` Andrew MacLeod
2004-03-26 16:31 ` Diego Novillo
2004-03-26 16:40 ` Andrew MacLeod
2004-03-26 17:48 ` law
2004-03-26 18:08 ` Andrew MacLeod
2004-03-26 18:10 ` law
2004-03-26 18:49 ` Dale Johannesen
2004-03-26 16:44 ` law
2004-03-26 17:42 ` Diego Novillo
2004-03-26 18:51 ` Zdenek Dvorak
2004-03-26 20:15 ` Dale Johannesen [this message]
2004-03-26 21:09 ` Devang Patel
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