Do not ifcvt if either true / false path is a backedge. Not profitable in almost...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37440 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index c0c6b383e6c233112a83234ffe834e7285b29c2c..9a35d1d11e9906d64d432240326737f31f3fa558 100644 (file)
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -237,6 +237,9 @@ void IfConverter::StructuralAnalysis(MachineBasicBlock *BB) {
     !TII->AnalyzeBranch(*BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond);
   if (!BBI.IsAnalyzable || BBI.BrCond.size() == 0)
     return;
+  // Do not ifcvt if either path is a back edge to the entry block.
+  if (BBI.TrueBB == BB || BBI.FalseBB == BB)
+    return;
 
   StructuralAnalysis(BBI.TrueBB);
   BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];