Fix assertion in LICM doFinalization()

The doFinalization method checks that the LoopToAliasSetMap is
empty. LICM populates that map as it runs through the loop nest,
deleting the entries for child loops as it goes. However, if a child
loop is deleted by another pass (e.g. unrolling) then the loop will
never be deleted from the map because LICM walks the loop nest to
find entries it can delete.

The fix is to delete the loop from the map and free the alias set
when the loop is deleted from the loop nest.

Differential Revision: http://reviews.llvm.org/D5305

llvm-svn: 218387

2 files changed, 24 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/LoopPass.cpp b/llvm/lib/Analysis/LoopPass.cpp
index 7bd866e73e1..190abc73fbb 100644
--- a/llvm/lib/Analysis/LoopPass.cpp
+++ b/llvm/lib/Analysis/LoopPass.cpp
@@ -76,6 +76,9 @@ void LPPassManager::deleteLoopFromQueue(Loop *L) {
 
   LI->updateUnloop(L);
 
+  // Notify passes that the loop is being deleted.
+  deleteSimpleAnalysisLoop(L);
+
   // If L is current loop then skip rest of the passes and let
   // runOnFunction remove L from LQ. Otherwise, remove L from LQ now
   // and continue applying other passes on CurrentLoop.
@@ -164,6 +167,14 @@ void LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) {
   }
 }
 
+/// Invoke deleteAnalysisLoop hook for all passes.
+void LPPassManager::deleteSimpleAnalysisLoop(Loop *L) {
+  for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
+    LoopPass *LP = getContainedPass(Index);
+    LP->deleteAnalysisLoop(L);
+  }
+}
+
 
 // Recurse through all subloops and all loops  into LQ.
 static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) {
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index d387b56689a..4952a644ff2 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -130,6 +130,9 @@ namespace {
     /// set.
     void deleteAnalysisValue(Value *V, Loop *L) override;
 
+    /// Simple Analysis hook. Delete loop L from alias set map.
+    void deleteAnalysisLoop(Loop *L) override;
+
     /// SinkRegion - Walk the specified region of the CFG (defined by all blocks
     /// dominated by the specified block, and that are in the current loop) in
     /// reverse depth first order w.r.t the DominatorTree.  This allows us to
@@ -943,3 +946,13 @@ void LICM::deleteAnalysisValue(Value *V, Loop *L) {
 
   AST->deleteValue(V);
 }
+
+/// Simple Analysis hook. Delete value L from alias set map.
+void LICM::deleteAnalysisLoop(Loop *L) {
+  AliasSetTracker *AST = LoopToAliasSetMap.lookup(L);
+  if (!AST)
+    return;
+
+  delete AST;
+  LoopToAliasSetMap.erase(L);
+}