From a022e3fc2f2faec2982ac184c98fee28d85a448a Mon Sep 17 00:00:00 2001
From: David Greene <greened@obbligato.org>
Date: Wed, 2 Apr 2008 18:24:46 +0000
Subject: [PATCH] Iterators folloring a SmallVector erased element are
 invalidated so don't access cached iterators from after the erased element.

Re-apply 49056 with SmallVector support.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@49106 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/ADT/SmallVector.h           |  8 ++++++--
 lib/Transforms/Scalar/LoopIndexSplit.cpp | 10 ++++------
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/include/llvm/ADT/SmallVector.h b/include/llvm/ADT/SmallVector.h
index a6b65dd58b4..c2de17a881b 100644
--- a/include/llvm/ADT/SmallVector.h
+++ b/include/llvm/ADT/SmallVector.h
@@ -208,19 +208,23 @@ public:
     construct_range(Begin, End, Elt);
   }
   
-  void erase(iterator I) {
+  iterator erase(iterator I) {
+    iterator N = I;
     // Shift all elts down one.
     std::copy(I+1, End, I);
     // Drop the last elt.
     pop_back();
+    return(N);
   }
   
-  void erase(iterator S, iterator E) {
+  iterator erase(iterator S, iterator E) {
+    iterator N = S;
     // Shift all elts down.
     iterator I = std::copy(E, End, S);
     // Drop the last elts.
     destroy_range(I, End);
     End = I;
+    return(N);
   }
   
   iterator insert(iterator I, const T &Elt) {
diff --git a/lib/Transforms/Scalar/LoopIndexSplit.cpp b/lib/Transforms/Scalar/LoopIndexSplit.cpp
index 8053554c17c..48b45351a0f 100644
--- a/lib/Transforms/Scalar/LoopIndexSplit.cpp
+++ b/lib/Transforms/Scalar/LoopIndexSplit.cpp
@@ -232,8 +232,8 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
     return false;
 
   // First see if it is possible to eliminate loop itself or not.
-  for (SmallVector<SplitInfo, 4>::iterator SI = SplitData.begin(),
-         E = SplitData.end(); SI != E;) {
+  for (SmallVector<SplitInfo, 4>::iterator SI = SplitData.begin();
+       SI != SplitData.end();) {
     SplitInfo &SD = *SI;
     ICmpInst *CI = dyn_cast<ICmpInst>(SD.SplitCondition);
     if (SD.SplitCondition->getOpcode() == Instruction::And) {
@@ -244,8 +244,7 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
         return Changed;
       } else {
         SmallVector<SplitInfo, 4>::iterator Delete_SI = SI;
-        ++SI;
-        SplitData.erase(Delete_SI);
+        SI = SplitData.erase(Delete_SI);
       }
     }
     else if (CI && CI->getPredicate() == ICmpInst::ICMP_EQ) {
@@ -256,8 +255,7 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
         return Changed;
       } else {
         SmallVector<SplitInfo, 4>::iterator Delete_SI = SI;
-        ++SI;
-        SplitData.erase(Delete_SI);
+        SI = SplitData.erase(Delete_SI);
       }
     } else
       ++SI;