[LoopStrengthReduce] Reuse utility method to clean dead instructions. [NFCI]

Create a utility wrapper for the RecursivelyDeleteTriviallyDeadInstructions utility
method, which sets to nullptr the instructions that are not trivially
dead. Use the new method in LoopStrengthReduce.
Alternative: add a bool to the same method; this option adds a marginal
amount of overhead to the other callers, and the method needs to be
updated to return a bool status when it removes/doesn't remove
instructions.

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 10afed3..aad9602 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -450,6 +450,23 @@ bool llvm::RecursivelyDeleteTriviallyDeadInstructions(
   return true;
 }
 
+bool llvm::RecursivelyDeleteTriviallyDeadInstructionsPermissive(
+    SmallVectorImpl<WeakTrackingVH> &DeadInsts, const TargetLibraryInfo *TLI,
+    MemorySSAUpdater *MSSAU) {
+  unsigned S = 0, E = DeadInsts.size(), Alive = 0;
+  for (; S != E; ++S) {
+    auto *I = cast<Instruction>(DeadInsts[S]);
+    if (!isInstructionTriviallyDead(I)) {
+      DeadInsts[S] = nullptr;
+      ++Alive;
+    }
+  }
+  if (Alive == E)
+    return false;
+  RecursivelyDeleteTriviallyDeadInstructions(DeadInsts, TLI, MSSAU);
+  return true;
+}
+
 void llvm::RecursivelyDeleteTriviallyDeadInstructions(
     SmallVectorImpl<WeakTrackingVH> &DeadInsts, const TargetLibraryInfo *TLI,
     MemorySSAUpdater *MSSAU) {