[NewPM] Verify LoopAnalysisResults after a loop pass

[aeubanks]

Summary

All loop passes should preserve all analyses in LoopAnalysisResults. Add
checks for those.

Note that due to PR44815, we don't check LAR's ScalarEvolution.
Apparently calling SE.verify() can change its results.

Only verify MSSA when VerifyMemorySSA, normally it's very expensive.

[aeubanks]

rebase past revert

[uabelho]

I wrote
https://bugs.llvm.org/show_bug.cgi?id=51020
about a case where the verifier finds something to complain about.

[uabelho]

In D98820#2864043, @uabelho wrote:

I wrote
https://bugs.llvm.org/show_bug.cgi?id=51020
about a case where the verifier finds something to complain about.

The original reproducer in PR51020 used loop-unroll-full but I've found cases failing the same way with loop-reroll. I updated the PR with this case too.

llvm/lib/Transforms/Scalar/LoopPassManager.cpp

 //===- LoopPassManager.cpp - Loop pass management -------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Scalar/LoopPassManager.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/BasicAliasAnalysis.h"
 #include "llvm/Analysis/BlockFrequencyInfo.h"
 #include "llvm/Analysis/GlobalsModRef.h"
 #include "llvm/Analysis/MemorySSA.h"
 #include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/TimeProfiler.h"
 
 using namespace llvm;
 
 namespace llvm {
 
 /// Explicitly specialize the pass manager's run method to handle loop nest
 /// structure updates.
#endif
     }
 
     // Do not pass deleted Loop into the instrumentation.
     if (Updater.skipCurrentLoop())
       PI.runAfterPassInvalidated<Loop>(*Pass, PassPA);
     else
       PI.runAfterPass<Loop>(*Pass, *L, PassPA);
 
-    // FIXME: We should verify the set of analyses relevant to Loop passes
-    // are preserved.
+#ifndef NDEBUG
+    // LoopAnalysisResults should always be valid.
+    // Note that we don't LAR.SE.verify() because that can change observed SE
+    // queries. See PR44815.
+    LAR.DT.verify();
+    LAR.LI.verify(LAR.DT);
+    if (LAR.MSSA && VerifyMemorySSA)
+      LAR.MSSA->verifyMemorySSA();
+#endif
 
     // If the loop hasn't been deleted, we need to handle invalidation here.
     if (!Updater.skipCurrentLoop())
       // We know that the loop pass couldn't have invalidated any other
       // loop's analyses (that's the contract of a loop pass), so directly
       // handle the loop analysis manager's invalidation here.
       LAM.invalidate(*L, PassPA);