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<div class="moz-cite-prefix">On 12/04/2014 09:12 AM, David Blaikie
wrote:<br>
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<div class="gmail_quote">On Thu, Dec 4, 2014 at 1:23 AM,
Chandler Carruth <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:chandlerc@google.com" target="_blank">chandlerc@google.com</a>></span>
wrote:<br>
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<div class="gmail_extra"><span class=""><br>
<div class="gmail_quote">On Thu, Dec 4, 2014 at 1:18
AM, Hal Finkel <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:hfinkel@anl.gov" target="_blank">hfinkel@anl.gov</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0
0 .8ex;border-left:1px #ccc
solid;padding-left:1ex">+1 -- We don't need
types on pointers -- they don't convey any
information to the optimizer. FWIW, it would not
surprise me if the elimination of all of the
unnecessary pointer bitcasts produces measurable
compile-time savings.</blockquote>
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<br>
</span>Indeed.</div>
<div class="gmail_extra"><br>
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<div class="gmail_extra">I'm actually interested in
looking at this if no one else gets to it first. (for
me, it's after the pass manager at the least) If
someone else is able to hack on this though, it would
be awesome. I think it'll actually help LTO quite a
lot by reducing the footprint of the IR.</div>
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<div><br>
This sounds potentially like the sort of monkey work I
could do/dabble in - might chat with you more about it to
see if I'm figuring that correctly before diving in.<br>
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A couple of comments on the thread so far:<br>
- Semantically, I have no objection to the removal of the type from
the pointer. I agree that this gets us very little and gives a
deceptive appearance of type safety where there is none. The only
strong distinction between pointer types is via address spaces; as
long as that's preserved, I have no objection.<br>
- From a readability perspective, typed pointers do actually help a
lot. Looking at the IR and figuring out what a particular pointer
describes would be far harder without them. If we do move to a
typeless pointer, I would argue in favor of having the types still
be present, but make it legal to cast between pointer types without
a bitcast. (i.e. all pointer 'names' refer to a single underlying
type)<br>
- This is a large enough change in the IR that a true proposal
should be sent to the mailing list & given a week or two to
propagate before any work is done. <br>
<br>
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