Re-apply 70645, converting ScalarEvolution to use

CallbackVH, with fixes. allUsesReplacedWith need to
walk the def-use chains and invalidate all users of a
value that is replaced. SCEVs of users need to be
recalcualted even if the new value is equivalent. Also,
make forgetLoopPHIs walk def-use chains, since any
SCEV that depends on a PHI should be recalculated when
more information about that PHI becomes available.

llvm-svn: 70927

2 files changed, 6 insertions, 22 deletions

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 0a6d7ef5dbf..6d1180d0dd9 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -78,9 +78,8 @@ void llvm::FoldSingleEntryPHINodes(BasicBlock *BB) {
 /// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it
 /// 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.  If a
-/// ValueDeletionListener is specified, it is notified of the deletions.
-void llvm::DeleteDeadPHIs(BasicBlock *BB, ValueDeletionListener *VDL) {
+/// it is ultimately unused or if it reaches an unused cycle.
+void 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;
@@ -90,7 +89,7 @@ void llvm::DeleteDeadPHIs(BasicBlock *BB, ValueDeletionListener *VDL) {
 
   for (unsigned i = 0, e = PHIs.size(); i != e; ++i)
     if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*()))
-      RecursivelyDeleteDeadPHINode(PN, VDL);
+      RecursivelyDeleteDeadPHINode(PN);
 }
 
 /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 3b36362bb39..fea739cb46b 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -178,18 +178,10 @@ bool llvm::isInstructionTriviallyDead(Instruction *I) {
   return false;
 }
 
-/// ~ValueDeletionListener - A trivial dtor, defined out of line to give the
-/// class a home.
-llvm::ValueDeletionListener::~ValueDeletionListener() {}
-
 /// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
 /// trivially dead instruction, delete it.  If that makes any of its operands
 /// trivially dead, delete them too, recursively.
-///
-/// If a ValueDeletionListener is specified, it is notified of instructions that
-/// are actually deleted (before they are actually deleted).
-void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V,
-                                                   ValueDeletionListener *VDL) {
+void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V) {
   Instruction *I = dyn_cast<Instruction>(V);
   if (!I || !I->use_empty() || !isInstructionTriviallyDead(I))
     return;
@@ -201,10 +193,6 @@ void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V,
     I = DeadInsts.back();
     DeadInsts.pop_back();
 
-    // If the client wanted to know, tell it about deleted instructions.
-    if (VDL)
-      VDL->ValueWillBeDeleted(I);
-    
     // Null out all of the instruction's operands to see if any operand becomes
     // dead as we go.
     for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
@@ -230,11 +218,8 @@ void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V,
 /// either forms a cycle or is terminated by a trivially dead instruction,
 /// delete it.  If that makes any of its operands trivially dead, delete them
 /// too, recursively.
-///
-/// If a ValueDeletionListener is specified, it is notified of instructions that
-/// are actually deleted (before they are actually deleted).
 void
-llvm::RecursivelyDeleteDeadPHINode(PHINode *PN, ValueDeletionListener *VDL) {
+llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) {
 
   // We can remove a PHI if it is on a cycle in the def-use graph
   // where each node in the cycle has degree one, i.e. only one use,
@@ -253,7 +238,7 @@ llvm::RecursivelyDeleteDeadPHINode(PHINode *PN, ValueDeletionListener *VDL) {
       if (!PHIs.insert(cast<PHINode>(JP))) {
         // Break the cycle and delete the PHI and its operands.
         JP->replaceAllUsesWith(UndefValue::get(JP->getType()));
-        RecursivelyDeleteTriviallyDeadInstructions(JP, VDL);
+        RecursivelyDeleteTriviallyDeadInstructions(JP);
         break;
       }
 }