<div style="font-family:arial,helvetica,sans-serif;font-size:10pt"><div>On 28 November 2012 15:23, Bill Wendling <span dir="ltr"><<a href="mailto:isanbard@gmail.com" target="_blank">isanbard@gmail.com</a>></span> wrote:</div>

<div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: void<br>
Date: Wed Nov 28 17:23:48 2012<br>
New Revision: 168829<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=168829&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=168829&view=rev</a><br>
Log:<br>
When we delete a dead basic block, see if any of its successors are dead and<br>
delete those as well.<br>
<br>
Modified:<br>
    llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp<br>
<br>
Modified: llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp?rev=168829&r1=168828&r2=168829&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp?rev=168829&r1=168828&r2=168829&view=diff</a><br>


==============================================================================<br>
--- llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp (original)<br>
+++ llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp Wed Nov 28 17:23:48 2012<br>
@@ -194,9 +194,19 @@<br>
           WorkList.insert(*II);<br>
     }<br>
<br>
-    for (SmallPtrSet<BasicBlock*, 8>::iterator<br>
-           I = WorkList.begin(), E = WorkList.end(); I != E; ++I)<br>
-      DeleteDeadBlock(*I);<br>
+    // Delete the dead blocks and any of their dead successors.<br>
+    while (!WorkList.empty()) {<br>
+      BasicBlock *BB = *WorkList.begin();<br>
+      WorkList.erase(BB);<br>
+      SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));<br>
+<br>
+      DeleteDeadBlock(BB);<br></blockquote><div><br></div><div>I think you need to set MadeChange = true here. I think this bug could actually manifest because we use MadeChange later on to decide whether we need to recalculate the domtree.</div>

<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
+<br>
+      for (SmallVectorImpl<BasicBlock*>::iterator<br>
+             II = Successors.begin(), IE = Successors.end(); II != IE; ++II)<br>
+        if (pred_begin(*II) == pred_end(*II))<br></blockquote><div><br></div><div>What if the block includes a branch to itself?</div><div><br></div><div>Nick</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">


+          WorkList.insert(*II);<br>
+    }<br>
<br>
     // Merge pairs of basic blocks with unconditional branches, connected by<br>
     // a single edge.<br>
<br>
<br>
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</blockquote></div><br></div>