[LoopUnswitch] Fix a simple bug which disables loop unswitch for select statement

This is to fix PR34257. rL309059 takes an early return when FindLIVLoopCondition
fails to find a loop invariant condition. This is wrong and it will disable loop
unswitch for select. The patch fixes the bug.

Differential Revision: https://reviews.llvm.org/D36985

llvm-svn: 312045

1 files changed, 2 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
index 4a48d90e716..bf830dd6377 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -705,10 +705,8 @@ bool LoopUnswitch::processCurrentLoop() {
         // unswitch on it if we desire.
         Value *LoopCond = FindLIVLoopCondition(BI->getCondition(),
                                                currentLoop, Changed).first;
-        if (!LoopCond || EqualityPropUnSafe(*LoopCond))
-          continue;
-
-        if (UnswitchIfProfitable(LoopCond, ConstantInt::getTrue(Context), TI)) {
+        if (LoopCond && !EqualityPropUnSafe(*LoopCond) &&
+            UnswitchIfProfitable(LoopCond, ConstantInt::getTrue(Context), TI)) {
           ++NumBranches;
           return true;
         }