From 190673610f41be171589be8a0263d8c10a8f3edf Mon Sep 17 00:00:00 2001
From: Joerg Sonnenberger <joerg@bec.de>
Date: Sat, 17 Aug 2013 11:04:47 +0000
Subject: [PATCH] PR 16899: Do not modify the basic block using the iterator,
 but keep the next value. This avoids crashes due to invalidation.

Patch by Joey Gouly.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188605 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Vectorize/SLPVectorizer.cpp | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/Transforms/Vectorize/SLPVectorizer.cpp b/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 506346d3583..ee9c5f2de7d 100644
--- a/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -1895,12 +1895,14 @@ bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
   if (Incoming.size() > 1)
     Changed |= tryToVectorizeList(Incoming, R);
 
-  for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
-    if (isa<DbgInfoIntrinsic>(it))
+  llvm::Instruction *I;
+  for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e;) {
+    I = it++;
+    if (isa<DbgInfoIntrinsic>(I))
       continue;
 
     // Try to vectorize reductions that use PHINodes.
-    if (PHINode *P = dyn_cast<PHINode>(it)) {
+    if (PHINode *P = dyn_cast<PHINode>(I)) {
       // Check that the PHI is a reduction PHI.
       if (P->getNumIncomingValues() != 2)
         return Changed;
@@ -1922,7 +1924,7 @@ bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
     }
 
     // Try to vectorize trees that start at compare instructions.
-    if (CmpInst *CI = dyn_cast<CmpInst>(it)) {
+    if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
       if (tryToVectorizePair(CI->getOperand(0), CI->getOperand(1), R)) {
         Changed |= true;
         continue;