From 9d0332f7b4d8aa8e07544506eb26d1e155c3745a Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Wed, 6 Jun 2007 04:12:20 +0000
Subject: [PATCH] Fix PR1487 and
 Transforms/IndVar/2007-06-06-DeleteDanglesPtr.ll

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37459 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/ScalarEvolution.cpp | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 1ff21a75f94..b1c3a177273 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -1196,9 +1196,28 @@ namespace {
 /// client before it removes an instruction from the program, to make sure
 /// that no dangling references are left around.
 void ScalarEvolutionsImpl::deleteInstructionFromRecords(Instruction *I) {
-  Scalars.erase(I);
-  if (PHINode *PN = dyn_cast<PHINode>(I))
-    ConstantEvolutionLoopExitValue.erase(PN);
+  SmallVector<Instruction *, 16> Worklist;
+
+  if (Scalars.erase(I)) {
+    if (PHINode *PN = dyn_cast<PHINode>(I))
+      ConstantEvolutionLoopExitValue.erase(PN);
+    Worklist.push_back(I);
+  }
+
+  while (!Worklist.empty()) {
+    Instruction *II = Worklist.back();
+    Worklist.pop_back();
+
+    for (Instruction::use_iterator UI = II->use_begin(), UE = II->use_end();
+         UI != UE; ++UI) {
+      Instruction *Inst = dyn_cast<Instruction>(*UI);
+      if (Inst && hasSCEV(Inst) && Scalars.erase(Inst)) {
+        if (PHINode *PN = dyn_cast<PHINode>(II))
+          ConstantEvolutionLoopExitValue.erase(PN);
+        Worklist.push_back(Inst);
+      }
+    }
+  }
 }