Index: llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
+++ llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
@@ -553,13 +553,23 @@
   if (!Previous || !TheLoop->contains(Previous) || isa<PHINode>(Previous))
     return false;
 
-  // Ensure every user of the phi node is dominated by the previous value. The
-  // dominance requirement ensures the loop vectorizer will not need to
-  // vectorize the initial value prior to the first iteration of the loop.
   for (User *U : Phi->users())
-    if (auto *I = dyn_cast<Instruction>(U))
+    if (auto *I = dyn_cast<Instruction>(U)) {
+      // Ensure every user of the phi node is dominated by the previous value.
+      // The dominance requirement ensures the loop vectorizer will not need to
+      // vectorize the initial value prior to the first iteration of the loop.
       if (!DT->dominates(Previous, I))
         return false;
+      // When the phi node has users outside the loop, the current logic for
+      // fixFirstOrderRecurrences may generate incorrect code. Specifically, we
+      // extract the last element from the vectorized phi, which would be the
+      // update to the phi before exiting the loop. However, what we want is the
+      // previous phi value before the update (i.e. the second last update
+      // before end of the vectorized loop).
+      // See added test cases in first-order-recurrence.ll
+      if (!TheLoop->contains(I))
+        return false;
+    }
 
   return true;
 }
Index: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4069,7 +4069,12 @@
   VecPhi->addIncoming(Incoming, LI->getLoopFor(LoopVectorBody)->getLoopLatch());
 
   // Extract the last vector element in the middle block. This will be the
-  // initial value for the recurrence when jumping to the scalar loop.
+  // initial value for the recurrence when jumping to the scalar loop. 
+  // FIXME: Note that the last vector element need not always be the correct one:
+  // consider a loop  where we have phi uses outside the loop - we need the
+  // second last iteration value and not the last one). For now, we avoid
+  // considering such cases as firstOrderRecurrences (see
+  // isFirstOrderRecurrence).
   auto *Extract = Incoming;
   if (VF > 1) {
     Builder.SetInsertPoint(LoopMiddleBlock->getTerminator());
Index: llvm/trunk/test/Transforms/LoopVectorize/AArch64/loop-vectorization-factors.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/AArch64/loop-vectorization-factors.ll
+++ llvm/trunk/test/Transforms/LoopVectorize/AArch64/loop-vectorization-factors.ll
@@ -235,10 +235,13 @@
 }
 
 ; CHECK-LABEL: @add_phifail2(
-; CHECK: load <16 x i8>, <16 x i8>*
-; CHECK: add nuw nsw <16 x i32>
-; CHECK: store <16 x i8>
+; CHECK-NOT: load <16 x i8>, <16 x i8>*
+; CHECK-NOT: add nuw nsw <16 x i32>
+; CHECK-NOT: store <16 x i8>
 ; Function Attrs: nounwind
+; FIXME: Currently, if we vectorize this loop, we will generate incorrect code
+; if %len evenly divides VF. Vectorized loop code gen returns a_phi = p[len -1],
+; whereas it should be the previous value a_phi = p[len -2]
 define i8 @add_phifail2(i8* noalias nocapture readonly %p, i8* noalias nocapture %q, i32 %len) #0 {
 entry:
   br label %for.body
Index: llvm/trunk/test/Transforms/LoopVectorize/first-order-recurrence.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/first-order-recurrence.ll
+++ llvm/trunk/test/Transforms/LoopVectorize/first-order-recurrence.ll
@@ -349,3 +349,25 @@
 for.end:
   ret void
 }
+
+; FIXME: we can vectorize this first order recurrence, by generating two
+; extracts - one for the phi `val.phi` and other for the phi update `addx`.
+; val.phi at end of loop is 94 + x.
+; CHECK-LABEL: extract_second_last_iteration
+; CHECK-NOT: vector.body
+define i32 @extract_second_last_iteration(i32* %cval, i32 %x)  {
+entry:
+  br label %for.body
+
+for.body:
+  %inc.phi = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %val.phi = phi i32 [ 0, %entry ], [ %addx, %for.body ]
+  %inc = add i32 %inc.phi, 1
+  %bc = zext i32 %inc.phi to i64
+  %addx = add i32 %inc.phi, %x
+  %cmp = icmp eq i32 %inc.phi, 95
+  br i1 %cmp, label %for.end, label %for.body
+
+for.end:
+  ret i32 %val.phi
+}