<div dir="ltr">On Sat, Sep 14, 2013 at 4:15 PM, reed kotler <span dir="ltr"><<a href="mailto:rkotler@mips.com" target="_blank" class="cremed">rkotler@mips.com</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote">
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<div>On 09/14/2013 04:05 PM, Chandler
Carruth wrote:<br>
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<div dir="ltr">On Sat, Sep 14, 2013 at 3:57 PM, Reed Kotler <span dir="ltr"><<a href="mailto:rkotler@mips.com" target="_blank" class="cremed">rkotler@mips.com</a>></span> wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi
Chandler,<br>
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What changes are you planning to make?<br>
<br>
Are you going to submit a proposal and RFC?<br>
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<div>There have been several RFCs...</div>
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<div>What's your specific question?</div>
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Which RFCs cover this?<br></div></blockquote><div><br></div><div>The primary one was 'Pass Manager Redux', but over the past year the planned design has shifted some. But not in ways that I think will impact you at all.</div>
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Will the new system allow for passes to be inserted dynamically
after startup?<br></div></blockquote><div><br></div><div>Yes.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div text="#000000" bgcolor="#FFFFFF">
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I have some delicate things that I did to make this ability to
switch between mips 32 and mips16 ( they are different instruction
sets) that relies on the pass manager working the way it does now.
I'm not sure what you are planning to do and how it might affect
what I did. It was very tricky to get that to work and a lot of
things depend on it working now.<br></div></blockquote><div><br></div><div>As long as this is tested in the tree, it won't break.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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I don't think that we need to see how this will be implemented but I
think that it would be helpful to list what you are trying to
accomplish at a high level and what new features will be there and
how the behavior will change from now.</div></blockquote><div><br></div><div>Sure. Some of this is covered in my RFC. Others will be covered with the new code and documentation that explain the micro-level differences. Most of the things that are different from the RFC are the obvious consequence of me and others looking at how it would be implemented. That's why I want to implement it before committing to a lot more details.</div>
<div><br></div><div>The flip side is that I'd like code review of my implementation in a reasonable incremental manner, and so it is likely to go directly into the tree, and merely be disabled. I think that's a reasonable path forward, and it will still leave lots of time for discussion about the exact design and implementation before we make any switch.</div>
<div><br></div><div>-Chandler</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div text="#000000" bgcolor="#FFFFFF"><div><div class="h5"><br>
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<div>I'm planning to essentially try to build a new pass
management layer that doesn't suffer from the problems the
existing one does. I could describe every interface I plan
in prose and email it out, but I'm not sure that's really
the most effective way to do it. My plan has been to work
on implementing the new system in-tree, and let folks code
review it and pick it apart as usual. When folks are happy
with it, and it works, then we can look at switching over.</div>
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Reed
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On 09/14/2013 03:46 PM, Chandler Carruth wrote:<br>
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I just wanted to give everyone a head up. I'm
starting work on the pass<br>
manager based on numerous list discussions and some
IRC discussions.<br>
<br>
The first steps will be marking the existing code as
"legacy" and<br>
clearing a path to build new facilities here. From
there I'll start<br>
building the new facilities without enabling them.<br>
<br>
Some explicit legacy support goals:<br>
<br>
1) I'm going to build a bridge so that an existing
Pass can be inserted<br>
into the new pass manager with some adaptors and
everything will just<br>
work. This may require touching the code that sets
up the pass manager,<br>
but not the code that defines a pass. This will work
even once the new<br>
pass manager bits are enabled if at all possible.<br>
<br>
2) If you have code that includes the current
PassManager headers,<br>
nothing should break right away, but when the new
manager infrastructure<br>
is enabled, I'll likely remove the old PassManager
headers, breaking<br>
this code. My goal is to only break code that
directly interacts with<br>
the management layer.<br>
<br>
3) I'm going to play namespace games so that we
don't end up with<br>
PassManagerV2 and other silly names. The legacy
headers will paper over<br>
this to keep legacy code compiling without change.<br>
<br>
-Chandler<br>
<br>
<br>
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