[llvm-branch-commits] [polly] 2f1f38b - [Polly] Invalidate passes after Scop processing in NewPM.

[Michael Kruse via llvm-branch-commits]

Author: Michael Kruse
Date: 2021-02-14T16:35:48-06:00
New Revision: 2f1f38b5b949866e1e34a3848a09101c0e7c5963

URL: https://github.com/llvm/llvm-project/commit/2f1f38b5b949866e1e34a3848a09101c0e7c5963
DIFF: https://github.com/llvm/llvm-project/commit/2f1f38b5b949866e1e34a3848a09101c0e7c5963.diff

LOG: [Polly] Invalidate passes after Scop processing in NewPM.

ScopDetection's DetectionContext holds AssertionVH for
RequiredInvariantLoads. An assertion is thrown if the handle's value is
erased and the ScopDetection is not yet invalidated. The ScopDetection
must remain valid durting the ScopPassManager. Enusure that all Scop
analyses are free'd when the ScopPass manager is done.

If IR generation has happened, also invalidate all other passes to avoid
possible issues because, like for the legacy pass manager, Polly does not
yet perfectly preserve them.

Added: 
    

Modified: 
    polly/include/polly/ScopPass.h

Removed: 
    


################################################################################
diff  --git a/polly/include/polly/ScopPass.h b/polly/include/polly/ScopPass.h
index f3c302067bb2..fdcd2a434f80 100644
--- a/polly/include/polly/ScopPass.h
+++ b/polly/include/polly/ScopPass.h
@@ -222,11 +222,17 @@ class FunctionToScopPassAdaptor
   explicit FunctionToScopPassAdaptor(ScopPassT Pass) : Pass(std::move(Pass)) {}
 
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM) {
-    PreservedAnalyses PA = PreservedAnalyses::all();
-    auto &SD = AM.getResult<ScopAnalysis>(F);
-    auto &SI = AM.getResult<ScopInfoAnalysis>(F);
-    if (SI.empty())
-      return PA;
+    ScopDetection &SD = AM.getResult<ScopAnalysis>(F);
+    ScopInfo &SI = AM.getResult<ScopInfoAnalysis>(F);
+    if (SI.empty()) {
+      // With no scops having been detected, no IR changes have been made and
+      // therefore all analyses are preserved. However, we must still free the
+      // Scop analysis results which may hold AssertingVH that cause an error
+      // if its value is destroyed.
+      AM.invalidate<ScopInfoAnalysis>(F);
+      AM.invalidate<ScopAnalysis>(F);
+      return PreservedAnalyses::all();
+    }
 
     SmallPriorityWorklist<Region *, 4> Worklist;
     for (auto &S : SI)
@@ -257,20 +263,18 @@ class FunctionToScopPassAdaptor
       PreservedAnalyses PassPA = Pass.run(*scop, SAM, AR, Updater);
 
       SAM.invalidate(*scop, PassPA);
-      PA.intersect(std::move(PassPA));
       if (Updater.invalidateCurrentScop())
         SI.recompute();
     };
 
-    PA.preserveSet<AllAnalysesOn<Scop>>();
-    PA.preserve<ScopAnalysisManagerFunctionProxy>();
-    PA.preserve<DominatorTreeAnalysis>();
-    PA.preserve<ScopAnalysis>();
-    PA.preserve<ScopInfoAnalysis>();
-    PA.preserve<ScalarEvolutionAnalysis>();
-    PA.preserve<LoopAnalysis>();
-    PA.preserve<RegionInfoAnalysis>();
-    return PA;
+    // FIXME: For the same reason as we add a BarrierNoopPass in the legacy pass
+    // manager, do not preserve any analyses. While CodeGeneration may preserve
+    // IR analyses sufficiently to process another Scop in the same function (it
+    // has to, otherwise the ScopDetection result itself would need to be
+    // invalidated), it is not sufficient for other purposes. For instance,
+    // CodeGeneration does not inform LoopInfo about new loops in the
+    // Polly-generated IR.
+    return PreservedAnalyses::none();
   }
 
 private: