[LoopPred] Delete the old condition expressions if unused

LoopPredication was replacing the original condition, but leaving the instructions to compute the old conditions around.  This would get cleaned up by other passes of course, but we might as well do it eagerly.  That also makes the test output less confusing.  

llvm-svn: 357406

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopPredication.cpp b/llvm/lib/Transforms/Scalar/LoopPredication.cpp
index 7695889a4a5..6257f419459 100644
--- a/llvm/lib/Transforms/Scalar/LoopPredication.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopPredication.cpp
@@ -193,6 +193,7 @@
 #include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 
 #define DEBUG_TYPE "loop-predication"
@@ -641,7 +642,9 @@ bool LoopPredication::widenGuardConditions(IntrinsicInst *Guard,
       LastCheck = Check;
     else
       LastCheck = Builder.CreateAnd(LastCheck, Check);
+  auto *OldCond = Guard->getOperand(0);
   Guard->setOperand(0, LastCheck);
+  RecursivelyDeleteTriviallyDeadInstructions(OldCond);
 
   LLVM_DEBUG(dbgs() << "Widened checks = " << NumWidened << "\n");
   return true;
@@ -676,9 +679,11 @@ bool LoopPredication::widenWidenableBranchGuardConditions(
   // Make sure that the check contains widenable condition and therefore can be
   // further widened.
   LastCheck = Builder.CreateAnd(LastCheck, WidenableCondition);
+  auto *OldCond = Guard->getOperand(0);
   Guard->setOperand(0, LastCheck);
   assert(isGuardAsWidenableBranch(Guard) &&
          "Stopped being a guard after transform?");
+  RecursivelyDeleteTriviallyDeadInstructions(OldCond);
 
   LLVM_DEBUG(dbgs() << "Widened checks = " << NumWidened << "\n");
   return true;