[SimplifyCFG] SwitchToLookupTable(): don't increase ret count

The very next SimplifyCFG pass invocation will tail-merge these two ret's
anyways, there is not much point in creating more work for ourselves.

1 files changed, 3 insertions, 15 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index ddee6a0..b32047f 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -5926,7 +5926,6 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
       Updates.push_back({DominatorTree::Delete, BB, SI->getDefaultDest()});
   }
 
-  bool ReturnedEarly = false;
   for (PHINode *PHI : PHIs) {
     const ResultListTy &ResultList = ResultLists[PHI];
 
@@ -5938,15 +5937,6 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
 
     Value *Result = Table.BuildLookup(TableIndex, Builder);
 
-    // If the result is used to return immediately from the function, we want to
-    // do that right here.
-    if (PHI->hasOneUse() && isa<ReturnInst>(*PHI->user_begin()) &&
-        PHI->user_back() == CommonDest->getFirstNonPHIOrDbg()) {
-      Builder.CreateRet(Result);
-      ReturnedEarly = true;
-      break;
-    }
-
     // Do a small peephole optimization: re-use the switch table compare if
     // possible.
     if (!TableHasHoles && HasDefaultResults && RangeCheckBranch) {
@@ -5960,11 +5950,9 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
     PHI->addIncoming(Result, LookupBB);
   }
 
-  if (!ReturnedEarly) {
-    Builder.CreateBr(CommonDest);
-    if (DTU)
-      Updates.push_back({DominatorTree::Insert, LookupBB, CommonDest});
-  }
+  Builder.CreateBr(CommonDest);
+  if (DTU)
+    Updates.push_back({DominatorTree::Insert, LookupBB, CommonDest});
 
   // Remove the switch.
   SmallPtrSet<BasicBlock *, 8> RemovedSuccessors;