Do not ifcvt if either true / false path is a backedge. Not profitable in almost all cases.
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 c0c6b38..9a35d1d 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -237,6 +237,9 @@
!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()];