Detect overflow in the path count computation. rdar://12277446.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163739 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/ObjCARC.cpp b/lib/Transforms/Scalar/ObjCARC.cpp
index dce8e8b..27c94dc 100644
--- a/lib/Transforms/Scalar/ObjCARC.cpp
+++ b/lib/Transforms/Scalar/ObjCARC.cpp
@@ -29,6 +29,7 @@
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "objc-arc"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/ADT/DenseMap.h"
using namespace llvm;
@@ -1597,6 +1598,12 @@
// loop backedge. Loop backedges are special.
TopDownPathCount += Other.TopDownPathCount;
+ // Check for overflow. If we have overflow, fall back to conservative behavior.
+ if (TopDownPathCount < Other.TopDownPathCount) {
+ clearTopDownPointers();
+ return;
+ }
+
// For each entry in the other set, if our set has an entry with the same key,
// merge the entries. Otherwise, copy the entry and merge it with an empty
// entry.
@@ -1622,6 +1629,12 @@
// loop backedge. Loop backedges are special.
BottomUpPathCount += Other.BottomUpPathCount;
+ // Check for overflow. If we have overflow, fall back to conservative behavior.
+ if (BottomUpPathCount < Other.BottomUpPathCount) {
+ clearBottomUpPointers();
+ return;
+ }
+
// For each entry in the other set, if our set has an entry with the
// same key, merge the entries. Otherwise, copy the entry and merge
// it with an empty entry.