[LLVMdev] ScheduleDAG Question

Gaster, Benedict Benedict.Gaster at amd.com
Fri Sep 4 13:53:04 PDT 2009

Hi David,

Interesting... I have come across a problem that looks like edge is
being removed and I'm wondering if it may be related. The problem is
described in http://llvm.org/bugs/show_bug.cgi?id=4891.



-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
On Behalf Of David Greene
Sent: Thursday, September 03, 2009 7:25 PM
To: llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] ScheduleDAG Question

On Thursday 03 September 2009 21:13, David Greene wrote:

> Hmm...except there's a little dashed blue line from the call to the
> (I think) field of the load.  Is that the dependence I want?  I don't
> how to read these graphs.

Interesting.  So with -view-legalize-dags, that little dashed blue line
moved from the load to the store that feeds the load.  That's wrong.

But it's still there with -view-legalize-types-dags, so legalize types
be buggy.  But -disable-legalize-types doesn't fix the problem.  So the 
general legalize code seems to have the same issue.

LLVM 2.5 compiles this fine, so it's something we've altered in the
I did a diff of all of our changes to lib/CodeGen and
but nothing jumpoed out as obviously wrong.  I suppose it's possible we
present slightly different code to the legalize passes than the

Fun times, indeed.

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