[SCEV] Verify block disposition cache.

[fhahn]

Summary

This extends the existing SCEV verification to catch cache invalidation
issues as in #57837.

The validation logic is similar to the recently added loop disposition
cache validation in bb68b2402daa9.

[nikic]

llvm/lib/Analysis/ScalarEvolution.cpp

14032

Hm, do we have issues with dangling blocks here? Did you check whether enabling scev verification + asan works (or maybe quicker: add a manual check that the BB is in the function block set).

[fhahn]

llvm/lib/Analysis/ScalarEvolution.cpp

14032

I think the last issue should be fixed with D134663, at least when bootstrapping clang with ASAN on arm64 macOS

[nikic]

LGTM

[fhahn]

Rebased, will land shortly.

llvm/lib/Analysis/ScalarEvolution.cpp

for (auto &V : Values) {
         dbgs() << "Cached disposition of " << *S << " for loop " << *Loop
                << " is incorrect: cached "
                << loopDispositionToStr(CachedDisposition) << ", actual "
                << loopDispositionToStr(RecomputedDisposition) << "\n";
         std::abort();
       }
     }
   }
+
+  // Verify integrity of the block disposition cache.
+  for (const auto &It : BlockDispositions) {
+    const SCEV *S = It.first;
+    auto &Values = It.second;
+    for (auto &V : Values) {
+      auto CachedDisposition = V.getInt();
+      const BasicBlock *BB = V.getPointer();
+      const auto RecomputedDisposition = SE2.getBlockDisposition(S, BB);
+      if (CachedDisposition != RecomputedDisposition) {
+        dbgs() << "Cached disposition of " << *S << " for block %"
+               << BB->getName() << " is incorrect! \n";
+        std::abort();
+      }
+    }
+  }
 }
 
 bool ScalarEvolution::invalidate(
     Function &F, const PreservedAnalyses &PA,
     FunctionAnalysisManager::Invalidator &Inv) {
   // Invalidate the ScalarEvolution object whenever it isn't preserved or one
   // of its dependencies is invalidated.
   auto PAC = PA.getChecker<ScalarEvolutionAnalysis>();