[objc-arc] Convert the one directional retain/release relation assert to a conditional check + fail.

Due to the previously added overflow checks, we can have a retain/release
relation that is one directional. This occurs specifically when we run into an
additive overflow causing us to drop state in only one direction. If that
occurs, we should bail and not optimize that retain/release instead of
asserting.

Apologies for the size of the testcase. It is necessary to cause the additive
cfg overflow to trigger.

rdar://15377890

llvm-svn: 194083

1 files changed, 18 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
index b419a7ecc8a..1cc665b2e02 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
@@ -2405,7 +2405,15 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState>
         if (Jt == Releases.end())
           return false;
         const RRInfo &NewRetainReleaseRRI = Jt->second;
-        assert(NewRetainReleaseRRI.Calls.count(NewRetain));
+
+        // If the release does not have a reference to the retain as well,
+        // something happened which is unaccounted for. Do not do anything.
+        //
+        // This can happen if we catch an additive overflow during path count
+        // merging.
+        if (!NewRetainReleaseRRI.Calls.count(NewRetain))
+          return false;
+
         if (ReleasesToMove.Calls.insert(NewRetainRelease)) {
 
           // If we overflow when we compute the path count, don't remove/move
@@ -2481,9 +2489,16 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState>
         if (Jt == Retains.end())
           return false;
         const RRInfo &NewReleaseRetainRRI = Jt->second;
-        assert(NewReleaseRetainRRI.Calls.count(NewRelease));
-        if (RetainsToMove.Calls.insert(NewReleaseRetain)) {
 
+        // If the retain does not have a reference to the release as well,
+        // something happened which is unaccounted for. Do not do anything.
+        //
+        // This can happen if we catch an additive overflow during path count
+        // merging.
+        if (!NewReleaseRetainRRI.Calls.count(NewRelease))
+          return false;
+
+        if (RetainsToMove.Calls.insert(NewReleaseRetain)) {
           // If we overflow when we compute the path count, don't remove/move
           // anything.
           const BBState &NRRBBState = BBStates[NewReleaseRetain->getParent()];