1 files changed, 151 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/LoopAnalysisManager.cpp b/llvm/lib/Analysis/LoopAnalysisManager.cpp
new file mode 100644
index 000000000000..02d40fb8d72a
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+++ b/llvm/lib/Analysis/LoopAnalysisManager.cpp
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+//===- LoopAnalysisManager.cpp - Loop analysis 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/Analysis/LoopAnalysisManager.h"
+#include "llvm/Analysis/BasicAliasAnalysis.h"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/MemorySSA.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
+#include "llvm/IR/Dominators.h"
+
+using namespace llvm;
+
+namespace llvm {
+// Explicit template instantiations and specialization definitions for core
+// template typedefs.
+template class AllAnalysesOn<Loop>;
+template class AnalysisManager<Loop, LoopStandardAnalysisResults &>;
+template class InnerAnalysisManagerProxy<LoopAnalysisManager, Function>;
+template class OuterAnalysisManagerProxy<FunctionAnalysisManager, Loop,
+                                         LoopStandardAnalysisResults &>;
+
+bool LoopAnalysisManagerFunctionProxy::Result::invalidate(
+    Function &F, const PreservedAnalyses &PA,
+    FunctionAnalysisManager::Invalidator &Inv) {
+  // First compute the sequence of IR units covered by this proxy. We will want
+  // to visit this in postorder, but because this is a tree structure we can do
+  // this by building a preorder sequence and walking it backwards. We also
+  // want siblings in forward program order to match the LoopPassManager so we
+  // get the preorder with siblings reversed.
+  SmallVector<Loop *, 4> PreOrderLoops = LI->getLoopsInReverseSiblingPreorder();
+
+  // If this proxy or the loop info is going to be invalidated, we also need
+  // to clear all the keys coming from that analysis. We also completely blow
+  // away the loop analyses if any of the standard analyses provided by the
+  // loop pass manager go away so that loop analyses can freely use these
+  // without worrying about declaring dependencies on them etc.
+  // FIXME: It isn't clear if this is the right tradeoff. We could instead make
+  // loop analyses declare any dependencies on these and use the more general
+  // invalidation logic below to act on that.
+  auto PAC = PA.getChecker<LoopAnalysisManagerFunctionProxy>();
+  bool invalidateMemorySSAAnalysis = false;
+  if (MSSAUsed)
+    invalidateMemorySSAAnalysis = Inv.invalidate<MemorySSAAnalysis>(F, PA);
+  if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
+      Inv.invalidate<AAManager>(F, PA) ||
+      Inv.invalidate<AssumptionAnalysis>(F, PA) ||
+      Inv.invalidate<DominatorTreeAnalysis>(F, PA) ||
+      Inv.invalidate<LoopAnalysis>(F, PA) ||
+      Inv.invalidate<ScalarEvolutionAnalysis>(F, PA) ||
+      invalidateMemorySSAAnalysis) {
+    // Note that the LoopInfo may be stale at this point, however the loop
+    // objects themselves remain the only viable keys that could be in the
+    // analysis manager's cache. So we just walk the keys and forcibly clear
+    // those results. Note that the order doesn't matter here as this will just
+    // directly destroy the results without calling methods on them.
+    for (Loop *L : PreOrderLoops) {
+      // NB! `L` may not be in a good enough state to run Loop::getName.
+      InnerAM->clear(*L, "<possibly invalidated loop>");
+    }
+
+    // We also need to null out the inner AM so that when the object gets
+    // destroyed as invalid we don't try to clear the inner AM again. At that
+    // point we won't be able to reliably walk the loops for this function and
+    // only clear results associated with those loops the way we do here.
+    // FIXME: Making InnerAM null at this point isn't very nice. Most analyses
+    // try to remain valid during invalidation. Maybe we should add an
+    // `IsClean` flag?
+    InnerAM = nullptr;
+
+    // Now return true to indicate this *is* invalid and a fresh proxy result
+    // needs to be built. This is especially important given the null InnerAM.
+    return true;
+  }
+
+  // Directly check if the relevant set is preserved so we can short circuit
+  // invalidating loops.
+  bool AreLoopAnalysesPreserved =
+      PA.allAnalysesInSetPreserved<AllAnalysesOn<Loop>>();
+
+  // Since we have a valid LoopInfo we can actually leave the cached results in
+  // the analysis manager associated with the Loop keys, but we need to
+  // propagate any necessary invalidation logic into them. We'd like to
+  // invalidate things in roughly the same order as they were put into the
+  // cache and so we walk the preorder list in reverse to form a valid
+  // postorder.
+  for (Loop *L : reverse(PreOrderLoops)) {
+    Optional<PreservedAnalyses> InnerPA;
+
+    // Check to see whether the preserved set needs to be adjusted based on
+    // function-level analysis invalidation triggering deferred invalidation
+    // for this loop.
+    if (auto *OuterProxy =
+            InnerAM->getCachedResult<FunctionAnalysisManagerLoopProxy>(*L))
+      for (const auto &OuterInvalidationPair :
+           OuterProxy->getOuterInvalidations()) {
+        AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
+        const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
+        if (Inv.invalidate(OuterAnalysisID, F, PA)) {
+          if (!InnerPA)
+            InnerPA = PA;
+          for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
+            InnerPA->abandon(InnerAnalysisID);
+        }
+      }
+
+    // Check if we needed a custom PA set. If so we'll need to run the inner
+    // invalidation.
+    if (InnerPA) {
+      InnerAM->invalidate(*L, *InnerPA);
+      continue;
+    }
+
+    // Otherwise we only need to do invalidation if the original PA set didn't
+    // preserve all Loop analyses.
+    if (!AreLoopAnalysesPreserved)
+      InnerAM->invalidate(*L, PA);
+  }
+
+  // Return false to indicate that this result is still a valid proxy.
+  return false;
+}
+
+template <>
+LoopAnalysisManagerFunctionProxy::Result
+LoopAnalysisManagerFunctionProxy::run(Function &F,
+                                      FunctionAnalysisManager &AM) {
+  return Result(*InnerAM, AM.getResult<LoopAnalysis>(F));
+}
+}
+
+PreservedAnalyses llvm::getLoopPassPreservedAnalyses() {
+  PreservedAnalyses PA;
+  PA.preserve<DominatorTreeAnalysis>();
+  PA.preserve<LoopAnalysis>();
+  PA.preserve<LoopAnalysisManagerFunctionProxy>();
+  PA.preserve<ScalarEvolutionAnalysis>();
+  // FIXME: What we really want to do here is preserve an AA category, but that
+  // concept doesn't exist yet.
+  PA.preserve<AAManager>();
+  PA.preserve<BasicAA>();
+  PA.preserve<GlobalsAA>();
+  PA.preserve<SCEVAA>();
+  return PA;
+}