<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Dec 22, 2014 at 8:15 PM, Alexey Samsonov <span dir="ltr"><<a href="mailto:vonosmas@gmail.com" target="_blank">vonosmas@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: samsonov<br>
Date: Mon Dec 22 22:15:47 2014<br>
New Revision: 224751<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=224751&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=224751&view=rev</a><br>
Log:<br>
Fix UBSan bootstrap: don't bind reference to nullptr.<br>
<br>
Modified:<br>
    llvm/trunk/include/llvm/CodeGen/RegAllocPBQP.h<br>
<br>
Modified: llvm/trunk/include/llvm/CodeGen/RegAllocPBQP.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/RegAllocPBQP.h?rev=224751&r1=224750&r2=224751&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/RegAllocPBQP.h?rev=224751&r1=224750&r2=224751&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/include/llvm/CodeGen/RegAllocPBQP.h (original)<br>
+++ llvm/trunk/include/llvm/CodeGen/RegAllocPBQP.h Mon Dec 22 22:15:47 2014<br>
@@ -192,8 +192,10 @@ public:<br>
     : RS(Other.RS), NumOpts(Other.NumOpts), DeniedOpts(Other.DeniedOpts),<br>
       OptUnsafeEdges(new unsigned[NumOpts]), VReg(Other.VReg),<br>
       AllowedRegs(Other.AllowedRegs) {<br>
-    std::copy(&Other.OptUnsafeEdges[0], &Other.OptUnsafeEdges[NumOpts],<br>
-              &OptUnsafeEdges[0]);<br>
+    if (NumOpts > 0) {<br>
+      std::copy(&Other.OptUnsafeEdges[0], &Other.OptUnsafeEdges[NumOpts],<br>
+                &OptUnsafeEdges[0]);<br>
+    }<br></blockquote><div><br>(+Lang in case he wants to fix this some other way)<br><br>We could avoid adding the conditional/branch by using pointer arithmetic instead, perhaps? (assuming OptUnsafeEdges is just a raw array)<br><br>If it's not a raw pointer to sequence, then std::begin/std::end would be anotehr option, etc.<br> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
   }<br>
<br>
   // FIXME: Re-implementing default behavior to work around MSVC. Remove once<br>
<br>
<br>
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</blockquote></div><br></div></div>