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<p class="MsoNormal">This is really a codegen problem. You can decompose the load/store however you like in the backend. InstCombine should still combine the loads as a canonicalization.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">-Matt <o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">llvm-dev <llvm-dev-bounces@lists.llvm.org> on behalf of llvm-dev <llvm-dev@lists.llvm.org><br>
<b>Reply-To: </b>Neil Ryan <neilryan@cs.washington.edu><br>
<b>Date: </b>Wednesday, April 17, 2019 at 9:28 PM<br>
<b>To: </b>llvm-dev <llvm-dev@lists.llvm.org>, "tstellar@redhat.com" <tstellar@redhat.com><br>
<b>Subject: </b>Re: [llvm-dev] Disable combining of loads and stores in instcombine<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">I’m writing a pass for some custom hardware — we’d like to split arrays across hardware elements; this doesn’t work if consecutive writes to characters get combined to a word.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">On Apr 16, 2019, 8:17 PM -0700, Tom Stellard <tstellar@redhat.com>, wrote:<br>
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<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">On 04/16/2019 11:38 AM, Neil Ryan via llvm-dev wrote:<br>
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<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">LLVM's optimizer combines stores to consecutive characters into a write of a single word. For instance, if I have char A[4] and I write some static
value to each element, these writes would be combined into a single 32-bit word write. I found this thread <http://llvm.1065342.n5.nabble.com/disabling-combining-load-stores-in-optimizer-td37560.html> from 2009 -- it seems like it wasn't possible then. Has
anything changed since?<o:p></o:p></span></p>
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Why do you want to disable this optimization?<br>
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-Tom<br>
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<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Neil<br>
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<br>
_______________________________________________<br>
LLVM Developers mailing list<br>
llvm-dev@lists.llvm.org<br>
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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