<div dir="ltr">Seems broken, I think r256338 fixes it.</div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Dec 23, 2015 at 9:48 AM, Sanjoy Das via llvm-commits <span dir="ltr"><<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: sanjoy<br>
Date: Wed Dec 23 11:48:14 2015<br>
New Revision: 256338<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=256338&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project?rev=256338&view=rev</a><br>
Log:<br>
[SCEV] Fix getLoopBackedgeTakenCounts<br>
<br>
The way `getLoopBackedgeTakenCounts` is written right now isn't<br>
correct. It will try to compute and store the BE counts of a Loop<br>
 #{child loop} number of times (which may be zero).<br>
<br>
Modified:<br>
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp<br>
<br>
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=256338&r1=256337&r2=256338&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=256338&r1=256337&r2=256338&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)<br>
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Wed Dec 23 11:48:14 2015<br>
@@ -9439,23 +9439,22 @@ static void replaceSubString(std::string<br>
 /// getLoopBackedgeTakenCounts - Helper method for verifyAnalysis.<br>
 static void<br>
 getLoopBackedgeTakenCounts(Loop *L, VerifyMap &Map, ScalarEvolution &SE) {<br>
-  for (Loop::reverse_iterator I = L->rbegin(), E = L->rend(); I != E; ++I) {<br>
-    getLoopBackedgeTakenCounts(*I, Map, SE); // recurse.<br>
+  std::string &S = Map[L];<br>
+  if (S.empty()) {<br>
+    raw_string_ostream OS(S);<br>
+    SE.getBackedgeTakenCount(L)->print(OS);<br>
<br>
-    std::string &S = Map[L];<br>
-    if (S.empty()) {<br>
-      raw_string_ostream OS(S);<br>
-      SE.getBackedgeTakenCount(L)->print(OS);<br>
-<br>
-      // false and 0 are semantically equivalent. This can happen in dead loops.<br>
-      replaceSubString(OS.str(), "false", "0");<br>
-      // Remove wrap flags, their use in SCEV is highly fragile.<br>
-      // FIXME: Remove this when SCEV gets smarter about them.<br>
-      replaceSubString(OS.str(), "<nw>", "");<br>
-      replaceSubString(OS.str(), "<nsw>", "");<br>
-      replaceSubString(OS.str(), "<nuw>", "");<br>
-    }<br>
+    // false and 0 are semantically equivalent. This can happen in dead loops.<br>
+    replaceSubString(OS.str(), "false", "0");<br>
+    // Remove wrap flags, their use in SCEV is highly fragile.<br>
+    // FIXME: Remove this when SCEV gets smarter about them.<br>
+    replaceSubString(OS.str(), "<nw>", "");<br>
+    replaceSubString(OS.str(), "<nsw>", "");<br>
+    replaceSubString(OS.str(), "<nuw>", "");<br>
   }<br>
+<br>
+  for (auto *L : reverse(*L))<br>
+    getLoopBackedgeTakenCounts(L, Map, SE); // recurse.<br>
 }<br>
<br>
 void ScalarEvolution::verify() const {<br>
<br>
<br>
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</blockquote></div><br></div>