<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>By default, nothing. (i.e. everything across AS is mayalias)
But individual AS pairs may define alternate aliasing rules. I
don't know that we have a good way to make that plugable today
though. <br>
</p>
<div class="moz-cite-prefix">On 7/31/19 10:58 AM,
<a class="moz-txt-link-abbreviated" href="mailto:paul.robinson@sony.com">paul.robinson@sony.com</a> wrote:<br>
</div>
<blockquote type="cite"
cite="mid:E3B07FDB86BFF041819DC057DEED8FEA0141FD59B2@USCULXMSG13.am.sony.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta name="Generator" content="Microsoft Word 14 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri","sans-serif";}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
really hate to dip my toe in here, because it will only
reveal my total ignorance, but….<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Do
the "usual rules around addrspacecast" say when different
address spaces can alias? I remember somebody using address
spaces to represent something like special off-to-the-side
device memory, which obviously could never alias main
memory, whereas other uses like the 32/64-bit thing will
certainly have the 32-bit space aliasing (likely disjoint
parts of) the 64-bit space, and the exact mapping of
32-to-64 might vary across OSes.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--paulr<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"
moz-do-not-send="true"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></a></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in
0in 0in 4.0pt">
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
llvm-dev [<a class="moz-txt-link-freetext" href="mailto:llvm-dev-bounces@lists.llvm.org">mailto:llvm-dev-bounces@lists.llvm.org</a>]
<b>On Behalf Of </b>Reid Kleckner via llvm-dev<br>
<b>Sent:</b> Wednesday, July 31, 2019 1:44 PM<br>
<b>To:</b> Philip Reames<br>
<b>Cc:</b> llvm-dev; John Reagan<br>
<b>Subject:</b> Re: [llvm-dev] [RFC] Changing X86 data
layout for address spaces<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">On Wed, Jul 31, 2019 at 10:29 AM
Philip Reames via llvm-dev <<a
href="mailto:llvm-dev@lists.llvm.org"
moz-do-not-send="true">llvm-dev@lists.llvm.org</a>>
wrote:<o:p></o:p></p>
</div>
<div>
<blockquote style="border:none;border-left:solid #CCCCCC
1.0pt;padding:0in 0in 0in
6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<p>Looks like I made my point in an accidentally
really confusing way. Let me try again w/Matt's
correction in mind.<o:p></o:p></p>
<p>I want to make sure that the middle end optimizer
code is *driven by the data layout*. I am not
trying to express an opinion on how that data layout
is populated (frontend, backedge, black magic, what
have you). I just want to make sure that we don't
end with the middle end having to know that address
space "56" has special meaning beyond what is
encoded in the data layout. To say it differently,
I want to make sure that a different frontend
targeting a different backend is not effected by the
proposed changes.<o:p></o:p></p>
</div>
</blockquote>
<div>
<p class="MsoNormal">Got it. :) Yes, we have no
intention of teaching the middle end about these
address spaces. The usual rules around addrspacecast
should apply.<o:p></o:p></p>
</div>
</div>
</div>
</div>
</div>
</blockquote>
</body>
</html>