LoopInfo: Simplify ownership of Loop objects

It's strange that LoopInfo mostly owns the Loop objects, but that it
defers deleting them to the loop pass manager. Instead, change the
oddly named "updateUnloop" to "markAsRemoved" and have it queue the
Loop object for deletion. We can't delete the Loop immediately when we
remove it, since we need its pointer identity still, so we'll mark the
object as "invalid" so that clients can see what's going on.

llvm-svn: 257191

1 files changed, 10 insertions, 11 deletions

diff --git a/llvm/lib/Analysis/LoopPass.cpp b/llvm/lib/Analysis/LoopPass.cpp
index e24a9e46fc1..8163231c332 100644
--- a/llvm/lib/Analysis/LoopPass.cpp
+++ b/llvm/lib/Analysis/LoopPass.cpp
@@ -178,8 +178,9 @@ bool LPPassManager::runOnFunction(Function &F) {
 
   // Walk Loops
   while (!LQ.empty()) {
-
+    bool LoopWasDeleted = false;
     CurrentLoop = LQ.back();
+
     // Run all passes on the current Loop.
     for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
       LoopPass *P = getContainedPass(Index);
@@ -196,15 +197,15 @@ bool LPPassManager::runOnFunction(Function &F) {
 
         Changed |= P->runOnLoop(CurrentLoop, *this);
       }
+      LoopWasDeleted = CurrentLoop->isInvalid();
 
       if (Changed)
         dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG,
-                     CurrentLoop->isUnloop()
-                         ? "<deleted>"
-                         : CurrentLoop->getHeader()->getName());
+                     LoopWasDeleted ? "<deleted>"
+                                    : CurrentLoop->getHeader()->getName());
       dumpPreservedSet(P);
 
-      if (CurrentLoop->isUnloop()) {
+      if (LoopWasDeleted) {
         // Notify passes that the loop is being deleted.
         deleteSimpleAnalysisLoop(CurrentLoop);
       } else {
@@ -226,12 +227,11 @@ bool LPPassManager::runOnFunction(Function &F) {
 
       removeNotPreservedAnalysis(P);
       recordAvailableAnalysis(P);
-      removeDeadPasses(P, CurrentLoop->isUnloop()
-                              ? "<deleted>"
-                              : CurrentLoop->getHeader()->getName(),
+      removeDeadPasses(P, LoopWasDeleted ? "<deleted>"
+                                         : CurrentLoop->getHeader()->getName(),
                        ON_LOOP_MSG);
 
-      if (CurrentLoop->isUnloop())
+      if (LoopWasDeleted)
         // Do not run other passes on this loop.
         break;
     }
@@ -239,12 +239,11 @@ bool LPPassManager::runOnFunction(Function &F) {
     // If the loop was deleted, release all the loop passes. This frees up
     // some memory, and avoids trouble with the pass manager trying to call
     // verifyAnalysis on them.
-    if (CurrentLoop->isUnloop()) {
+    if (LoopWasDeleted) {
       for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
         Pass *P = getContainedPass(Index);
         freePass(P, "<deleted>", ON_LOOP_MSG);
       }
-      delete CurrentLoop;
     }
 
     // Pop the loop from queue after running all passes.