vendor/llvm-project/llvmorg-17.0.1-25-g098e653a5bed

1 files changed, 24 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index f153ace5d3fc..eeb0446c1197 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1247,7 +1247,9 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
   return true;
 }
 
-static bool EliminateDuplicatePHINodesNaiveImpl(BasicBlock *BB) {
+static bool
+EliminateDuplicatePHINodesNaiveImpl(BasicBlock *BB,
+                                    SmallPtrSetImpl<PHINode *> &ToRemove) {
   // This implementation doesn't currently consider undef operands
   // specially. Theoretically, two phis which are identical except for
   // one having an undef where the other doesn't could be collapsed.
@@ -1263,12 +1265,14 @@ static bool EliminateDuplicatePHINodesNaiveImpl(BasicBlock *BB) {
     // Note that we only look in the upper square's triangle,
     // we already checked that the lower triangle PHI's aren't identical.
     for (auto J = I; PHINode *DuplicatePN = dyn_cast<PHINode>(J); ++J) {
+      if (ToRemove.contains(DuplicatePN))
+        continue;
       if (!DuplicatePN->isIdenticalToWhenDefined(PN))
         continue;
       // A duplicate. Replace this PHI with the base PHI.
       ++NumPHICSEs;
       DuplicatePN->replaceAllUsesWith(PN);
-      DuplicatePN->eraseFromParent();
+      ToRemove.insert(DuplicatePN);
       Changed = true;
 
       // The RAUW can change PHIs that we already visited.
@@ -1279,7 +1283,9 @@ static bool EliminateDuplicatePHINodesNaiveImpl(BasicBlock *BB) {
   return Changed;
 }
 
-static bool EliminateDuplicatePHINodesSetBasedImpl(BasicBlock *BB) {
+static bool
+EliminateDuplicatePHINodesSetBasedImpl(BasicBlock *BB,
+                                       SmallPtrSetImpl<PHINode *> &ToRemove) {
   // This implementation doesn't currently consider undef operands
   // specially. Theoretically, two phis which are identical except for
   // one having an undef where the other doesn't could be collapsed.
@@ -1343,12 +1349,14 @@ static bool EliminateDuplicatePHINodesSetBasedImpl(BasicBlock *BB) {
   // Examine each PHI.
   bool Changed = false;
   for (auto I = BB->begin(); PHINode *PN = dyn_cast<PHINode>(I++);) {
+    if (ToRemove.contains(PN))
+      continue;
     auto Inserted = PHISet.insert(PN);
     if (!Inserted.second) {
       // A duplicate. Replace this PHI with its duplicate.
       ++NumPHICSEs;
       PN->replaceAllUsesWith(*Inserted.first);
-      PN->eraseFromParent();
+      ToRemove.insert(PN);
       Changed = true;
 
       // The RAUW can change PHIs that we already visited. Start over from the
@@ -1361,14 +1369,23 @@ static bool EliminateDuplicatePHINodesSetBasedImpl(BasicBlock *BB) {
   return Changed;
 }
 
-bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB) {
+bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB,
+                                      SmallPtrSetImpl<PHINode *> &ToRemove) {
   if (
 #ifndef NDEBUG
       !PHICSEDebugHash &&
 #endif
       hasNItemsOrLess(BB->phis(), PHICSENumPHISmallSize))
-    return EliminateDuplicatePHINodesNaiveImpl(BB);
-  return EliminateDuplicatePHINodesSetBasedImpl(BB);
+    return EliminateDuplicatePHINodesNaiveImpl(BB, ToRemove);
+  return EliminateDuplicatePHINodesSetBasedImpl(BB, ToRemove);
+}
+
+bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB) {
+  SmallPtrSet<PHINode *, 8> ToRemove;
+  bool Changed = EliminateDuplicatePHINodes(BB, ToRemove);
+  for (PHINode *PN : ToRemove)
+    PN->eraseFromParent();
+  return Changed;
 }
 
 /// If the specified pointer points to an object that we control, try to modify