<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>Sounds like it from your description.<br>
</p>
<div class="moz-cite-prefix">On 8/21/19 9:04 PM, Shreyansh Chouhan
via llvm-dev wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAAQ-SiM8_3QDWQbZmKH-7tY4uN6pc6pbDhsviHQp6q2a_izvHQ@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">According to bug 20811, the GVN pass should replace
a call to a load with `undef` if the load has been made after
the lifetime of a pointer has ended. But, according to the
documentation of `AnalyzeLoadAvailability` function in the GVN
class, the function returns true if there is a value to load and
populates the result with the value. If the load is made
immediately after the start of the lifetime of a pointer, the
function returns true and populates `Res` with `undef`.
<div><br>
<div>If the load is made after the lifetime of a pointer has
been over the function considers it to have a clobbered
instruction dependency and returns false, not populating Res
with anything.</div>
<div><br>
</div>
<div>So in order to fix the issue, should I make the case of
lifetime end the same as lifetime start? i.e. return true
and populate Res with undef? That does seem to fix the
issue, but I don't know if it is the correct way of handling
it.</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
LLVM Developers mailing list
<a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>
<a class="moz-txt-link-freetext" href="https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev">https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a>
</pre>
</blockquote>
</body>
</html>