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<div class="moz-cite-prefix">On 03/09/2017 12:58 PM, Flamedoge
wrote:<br>
</div>
<blockquote
cite="mid:CAFPbgSbrsxfdch_Y4yeddVwr8MadHiyh7j7+WahE8jORpYP1JA@mail.gmail.com"
type="cite">
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<div dir="ltr">As far as my limited understanding goes, this
should be a bugfix (correctness) and it should trump backward
compatibility requirement. It makes no sense to me to continue
backward compatible incorrectness.</div>
</blockquote>
<br>
The TBAA scheme is internally self-consistent and there are other
(non-C/C++) frontends that are using it in a completely well-defined
way. The bug, as such, is in the mapping between C/C++ and the TBAA
metadata. That, indeed, we'll just change once we have something to
target that can correctly represent the required semantics.<br>
<br>
-Hal<br>
<br>
<blockquote
cite="mid:CAFPbgSbrsxfdch_Y4yeddVwr8MadHiyh7j7+WahE8jORpYP1JA@mail.gmail.com"
type="cite">
<div dir="ltr">
<div><br>
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<div>Kevin</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Thu, Mar 9, 2017 at 10:21 AM, Steven
Perron via llvm-dev <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="m_8596073351940825992socmaildefaultfont"
dir="ltr"
style="font-family:Arial,Helvetica,sans-serif;font-size:10.5pt">
<div dir="ltr">I could make something like Daniel's
suggestion work. The main question I still have is how
we tell the difference between the "old-style" DAG and
the "new-style" DAG? I don't know if there is some
standard way of doing this. Do we just base it on the
version of llvm-ir?</div>
<div dir="ltr"> </div>
<div dir="ltr">Would there be a need to maintain different
code for both type of DAG? If we change clang to
generate the new-style DAG, things will be fine for
C/C++. However, will this force other components that
generate llvm-ir to change?</div>
<div dir="ltr"> </div>
<div dir="ltr">In general, what kind of backwards
compatibility do we need to keep?</div>
<div dir="ltr"> </div>
<div dir="ltr">Later,</div>
<div dir="ltr">Steven Perron</div>
</div>
<br>
<br>
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<br>
</blockquote>
</div>
<br>
</div>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory</pre>
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