Make RecursivelyDeleteTriviallyDeadInstructions,

RecursivelyDeleteDeadPHINode, and DeleteDeadPHIs return a flag
indicating whether they made any changes.

llvm-svn: 92732

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index ac29de6f288..e902688f206 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -78,7 +78,7 @@ void llvm::FoldSingleEntryPHINodes(BasicBlock *BB) {
 /// is dead. Also recursively delete any operands that become dead as
 /// a result. This includes tracing the def-use list from the PHI to see if
 /// it is ultimately unused or if it reaches an unused cycle.
-void llvm::DeleteDeadPHIs(BasicBlock *BB) {
+bool llvm::DeleteDeadPHIs(BasicBlock *BB) {
   // Recursively deleting a PHI may cause multiple PHIs to be deleted
   // or RAUW'd undef, so use an array of WeakVH for the PHIs to delete.
   SmallVector<WeakVH, 8> PHIs;
@@ -86,9 +86,12 @@ void llvm::DeleteDeadPHIs(BasicBlock *BB) {
        PHINode *PN = dyn_cast<PHINode>(I); ++I)
     PHIs.push_back(PN);
 
+  bool Changed = false;
   for (unsigned i = 0, e = PHIs.size(); i != e; ++i)
     if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*()))
-      RecursivelyDeleteDeadPHINode(PN);
+      Changed |= RecursivelyDeleteDeadPHINode(PN);
+
+  return Changed;
 }
 
 /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,