From 95bb00414eba82cc1c058b558cd28bc28134c561 Mon Sep 17 00:00:00 2001
From: Cameron Zwarich <zwarich@apple.com>
Date: Tue, 4 Jan 2011 04:43:31 +0000
Subject: [PATCH] Avoid finding loop back edges when we are not splitting
 critical edges in CodeGenPrepare (which is the default behavior).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122801 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/CodeGenPrepare.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index f4edcc76ec5..8df0b3ce47a 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -119,8 +119,10 @@ bool CodeGenPrepare::runOnFunction(Function &F) {
   // unconditional branch.
   EverMadeChange |= EliminateMostlyEmptyBlocks(F);
 
-  // Now find loop back edges.
-  findLoopBackEdges(F);
+  // Now find loop back edges, but only if they are being used to decide which
+  // critical edges to split.
+  if (CriticalEdgeSplit)
+    findLoopBackEdges(F);
 
   bool MadeChange = true;
   while (MadeChange) {