Revert r70645 for now; it's causing a variety of regressions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70661 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 3 deletions

diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index fea739cb46..3b36362bb3 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -178,10 +178,18 @@ 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.
-void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V) {
+///
+/// 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) {
   Instruction *I = dyn_cast<Instruction>(V);
   if (!I || !I->use_empty() || !isInstructionTriviallyDead(I))
     return;
@@ -193,6 +201,10 @@ 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) {
@@ -218,8 +230,11 @@ 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) {
+llvm::RecursivelyDeleteDeadPHINode(PHINode *PN, ValueDeletionListener *VDL) {
 
   // 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,
@@ -238,7 +253,7 @@ llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) {
       if (!PHIs.insert(cast<PHINode>(JP))) {
         // Break the cycle and delete the PHI and its operands.
         JP->replaceAllUsesWith(UndefValue::get(JP->getType()));
-        RecursivelyDeleteTriviallyDeadInstructions(JP);
+        RecursivelyDeleteTriviallyDeadInstructions(JP, VDL);
         break;
       }
 }