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<div class="moz-cite-prefix">The example looks like there's a bug in
the handling of truncstores:
DAGCombiner::MergeStoresOfConstantsOrVecElts does "StoreInt |=
C->getAPIntValue().zextOrTrunc(SizeInBits);", which doesn't
correctly mask away the extra bits of a truncstore. Not sure how
to write a testcase, though.<br>
<br>
-Eli<br>
<br>
On 11/29/2017 11:01 AM, Nirav Davé wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAEQ+OH9pcYu7U6=tgBii_xEASt1uDyL_WkhkjZrrRO__9TCSrQ@mail.gmail.com">
<div dir="ltr">Disabled in ARM in r319331.</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Nov 29, 2017 at 12:31 PM, Nirav
Davé <span dir="ltr"><<a href="mailto:niravd@google.com"
target="_blank" moz-do-not-send="true">niravd@google.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Sure If no one objects I'll disable this for
just the ARM target. <span class="HOEnZb"><font
color="#888888">
<div><br>
</div>
<div>-Nirav</div>
</font></span></div>
<div class="HOEnZb">
<div class="h5">
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Nov 29, 2017 at 12:23
PM, Evgeny Astigeevich via Phabricator <span
dir="ltr"><<a
href="mailto:reviews@reviews.llvm.org"
target="_blank" moz-do-not-send="true">reviews@reviews.llvm.org</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">eastig
added a comment.<br>
<br>
Hi Nirav,<br>
<br>
Could you please revert the changes? They affected
Arm targets (Thumb2 code).<br>
The following sequence of stores:<br>
<br>
MOVS r0,#0xe5<br>
STRB r0,[r6,#0x1e5]<br>
MOVS r0,#0xe4<br>
STRB r0,[r6,#0x1e4]<br>
MOVS r0,#0xe6<br>
STRB r0,[r6,#0x1e6]<br>
MOVS r0,#0xe7<br>
STRB r0,[r6,#0x1e7]<br>
<br>
is optimised into<br>
<br>
MVN r0,#0x1b<br>
STR r0,[r6,#0x1e4]<br>
<br>
causing incorrect data to be written.<br>
<br>
We are working on a reproducer.<br>
<br>
Thanks,<br>
Evgeny Astigeevich<br>
The Arm Compiler Optimisation team<br>
<div class="m_3935825366907052374HOEnZb">
<div class="m_3935825366907052374h5"><br>
<br>
Repository:<br>
rL LLVM<br>
<br>
<a href="https://reviews.llvm.org/D33675"
rel="noreferrer" target="_blank"
moz-do-not-send="true">https://reviews.llvm.org/D3367<wbr>5</a><br>
<br>
<br>
<br>
</div>
</div>
</blockquote>
</div>
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</blockquote>
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<br>
</div>
</blockquote>
<p><br>
</p>
<pre class="moz-signature" cols="72">--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project</pre>
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