From: Dan Gohman <gohman@apple.com>
Date: Fri, 13 Aug 2010 20:11:39 +0000 (+0000)
Subject: An add recurrence is loop-invariant in any loop inside of its
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=71c4144076d35bd45f8a5103357532f958de6757;p=oota-llvm.git

An add recurrence is loop-invariant in any loop inside of its
associated loop. This avoids potentially expensive traversals
of the add recurrence's operands.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111034 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 394e0159db8..dee7a1f8d93 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -303,6 +303,10 @@ bool SCEVAddRecExpr::isLoopInvariant(const Loop *QueryLoop) const {
   if (QueryLoop->contains(L))
     return false;
 
+  // This recurrence is invariant w.r.t. QueryLoop if L contains QueryLoop.
+  if (L->contains(QueryLoop))
+    return true;
+
   // This recurrence is variant w.r.t. QueryLoop if any of its operands
   // are variant.
   for (unsigned i = 0, e = getNumOperands(); i != e; ++i)