1 files changed, 18 insertions, 4 deletions
diff --git a/llvm/lib/Analysis/LoopPass.cpp b/llvm/lib/Analysis/LoopPass.cpp
index 520f06003dd2..9e470e998e67 100644
--- a/llvm/lib/Analysis/LoopPass.cpp
+++ b/llvm/lib/Analysis/LoopPass.cpp
@@ -15,11 +15,12 @@
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/Analysis/LoopAnalysisManager.h"
 #include "llvm/IR/Dominators.h"
-#include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/OptBisect.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/PassTimingInfo.h"
+#include "llvm/IR/PrintPasses.h"
+#include "llvm/IR/StructuralHash.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/TimeProfiler.h"
@@ -76,7 +77,7 @@ LPPassManager::LPPassManager()
 
 // Insert loop into loop nest (LoopInfo) and loop queue (LQ).
 void LPPassManager::addLoop(Loop &L) {
-  if (!L.getParentLoop()) {
+  if (L.isOutermost()) {
     // This is the top level loop.
     LQ.push_front(&L);
     return;
@@ -116,7 +117,7 @@ void LPPassManager::markLoopAsDeleted(Loop &L) {
   // there. However, we have to be careful to not remove the back of the queue
   // as that is assumed to match the current loop.
   assert(LQ.back() == CurrentLoop && "Loop queue back isn't the current loop!");
-  LQ.erase(std::remove(LQ.begin(), LQ.end(), &L), LQ.end());
+  llvm::erase_value(LQ, &L);
 
   if (&L == CurrentLoop) {
     CurrentLoopDeleted = true;
@@ -191,7 +192,19 @@ bool LPPassManager::runOnFunction(Function &F) {
       {
         PassManagerPrettyStackEntry X(P, *CurrentLoop->getHeader());
         TimeRegion PassTimer(getPassTimer(P));
+#ifdef EXPENSIVE_CHECKS
+        uint64_t RefHash = StructuralHash(F);
+#endif
         LocalChanged = P->runOnLoop(CurrentLoop, *this);
+
+#ifdef EXPENSIVE_CHECKS
+        if (!LocalChanged && (RefHash != StructuralHash(F))) {
+          llvm::errs() << "Pass modifies its input and doesn't report it: "
+                       << P->getPassName() << "\n";
+          llvm_unreachable("Pass modifies its input and doesn't report it");
+        }
+#endif
+
         Changed |= LocalChanged;
         if (EmitICRemark) {
           unsigned NewSize = F.getInstructionCount();
@@ -241,7 +254,8 @@ bool LPPassManager::runOnFunction(Function &F) {
         F.getContext().yield();
       }
 
-      removeNotPreservedAnalysis(P);
+      if (LocalChanged)
+        removeNotPreservedAnalysis(P);
       recordAvailableAnalysis(P);
       removeDeadPasses(P,
                        CurrentLoopDeleted ? "<deleted>"