Fix LoopAccessAnalysis when potentially nullptr check are involved

[oota-llvm.git] / lib / Analysis / LoopAccessAnalysis.cpp

diff --git a/lib/Analysis/LoopAccessAnalysis.cpp b/lib/Analysis/LoopAccessAnalysis.cpp
index fd85a908ffb45a59373af355eda4fd0e2a34177a..49b28078c9767c0dce6484d7253b7551c0fcb589 100644 (file)
--- a/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/lib/Analysis/LoopAccessAnalysis.cpp
@@ -268,7 +268,7 @@ void RuntimePointerChecking::groupChecks(
   // ShouldRetryWithRuntimeCheck is set, and therefore UseDependencies
   // is also false. In this case we will use the fallback path and create
   // separate checking groups for all pointers.
- 
+
   // If we don't have the dependency partitions, construct a new
   // checking pointer group for each pointer. This is also required
   // for correctness, because in this case we can have checking between
@@ -743,6 +743,11 @@ void AccessAnalysis::processMemAccesses() {
           GetUnderlyingObjects(Ptr, TempObjects, DL, LI);
           DEBUG(dbgs() << "Underlying objects for pointer " << *Ptr << "\n");
           for (Value *UnderlyingObj : TempObjects) {
+            // nullptr never alias, don't join sets for pointer that have "null"
+            // in their UnderlyingObjects list.
+            if (isa<ConstantPointerNull>(UnderlyingObj))
+              continue;
+
             UnderlyingObjToAccessMap::iterator Prev =
                 ObjToLastAccess.find(UnderlyingObj);
             if (Prev != ObjToLastAccess.end())
@@ -910,14 +915,14 @@ bool MemoryDepChecker::Dependence::isSafeForVectorization(DepType Type) {
   llvm_unreachable("unexpected DepType!");
 }
 
-bool MemoryDepChecker::Dependence::isPossiblyBackward() const {
+bool MemoryDepChecker::Dependence::isBackward() const {
   switch (Type) {
   case NoDep:
   case Forward:
   case ForwardButPreventsForwarding:
+  case Unknown:
     return false;
 
-  case Unknown:
   case BackwardVectorizable:
   case Backward:
   case BackwardVectorizableButPreventsForwarding:
@@ -926,6 +931,26 @@ bool MemoryDepChecker::Dependence::isPossiblyBackward() const {
   llvm_unreachable("unexpected DepType!");
 }
 
+bool MemoryDepChecker::Dependence::isPossiblyBackward() const {
+  return isBackward() || Type == Unknown;
+}
+
+bool MemoryDepChecker::Dependence::isForward() const {
+  switch (Type) {
+  case Forward:
+  case ForwardButPreventsForwarding:
+    return true;
+
+  case NoDep:
+  case Unknown:
+  case BackwardVectorizable:
+  case Backward:
+  case BackwardVectorizableButPreventsForwarding:
+    return false;
+  }
+  llvm_unreachable("unexpected DepType!");
+}
+
 bool MemoryDepChecker::couldPreventStoreLoadForward(unsigned Distance,
                                                     unsigned TypeByteSize) {
   // If loads occur at a distance that is not a multiple of a feasible vector