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1 //===- LoopAnalysisManager.cpp - Loop analysis management -----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
12 #include "llvm/Analysis/LoopInfo.h"
16 #include "llvm/IR/Dominators.h"
18 using namespace llvm;
20 namespace llvm {
21 // Explicit template instantiations and specialization definitions for core
22 // template typedefs.
23 template class AllAnalysesOn<Loop>;
30  Function &F, const PreservedAnalyses &PA,
32  // First compute the sequence of IR units covered by this proxy. We will want
33  // to visit this in postorder, but because this is a tree structure we can do
34  // this by building a preorder sequence and walking it backwards. We also
35  // want siblings in forward program order to match the LoopPassManager so we
36  // get the preorder with siblings reversed.
37  SmallVector<Loop *, 4> PreOrderLoops = LI->getLoopsInReverseSiblingPreorder();
39  // If this proxy or the loop info is going to be invalidated, we also need
40  // to clear all the keys coming from that analysis. We also completely blow
41  // away the loop analyses if any of the standard analyses provided by the
42  // loop pass manager go away so that loop analyses can freely use these
43  // without worrying about declaring dependencies on them etc.
44  // FIXME: It isn't clear if this is the right tradeoff. We could instead make
45  // loop analyses declare any dependencies on these and use the more general
46  // invalidation logic below to act on that.
48  bool invalidateMemorySSAAnalysis = false;
50  invalidateMemorySSAAnalysis = Inv.invalidate<MemorySSAAnalysis>(F, PA);
51  if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
52  Inv.invalidate<AAManager>(F, PA) ||
53  Inv.invalidate<AssumptionAnalysis>(F, PA) ||
55  Inv.invalidate<LoopAnalysis>(F, PA) ||
57  invalidateMemorySSAAnalysis) {
58  // Note that the LoopInfo may be stale at this point, however the loop
59  // objects themselves remain the only viable keys that could be in the
60  // analysis manager's cache. So we just walk the keys and forcibly clear
61  // those results. Note that the order doesn't matter here as this will just
62  // directly destroy the results without calling methods on them.
63  for (Loop *L : PreOrderLoops) {
64  // NB! `L` may not be in a good enough state to run Loop::getName.
65  InnerAM->clear(*L, "<possibly invalidated loop>");
66  }
68  // We also need to null out the inner AM so that when the object gets
69  // destroyed as invalid we don't try to clear the inner AM again. At that
70  // point we won't be able to reliably walk the loops for this function and
71  // only clear results associated with those loops the way we do here.
72  // FIXME: Making InnerAM null at this point isn't very nice. Most analyses
73  // try to remain valid during invalidation. Maybe we should add an
74  // `IsClean` flag?
75  InnerAM = nullptr;
77  // Now return true to indicate this *is* invalid and a fresh proxy result
78  // needs to be built. This is especially important given the null InnerAM.
79  return true;
80  }
82  // Directly check if the relevant set is preserved so we can short circuit
83  // invalidating loops.
84  bool AreLoopAnalysesPreserved =
87  // Since we have a valid LoopInfo we can actually leave the cached results in
88  // the analysis manager associated with the Loop keys, but we need to
89  // propagate any necessary invalidation logic into them. We'd like to
90  // invalidate things in roughly the same order as they were put into the
91  // cache and so we walk the preorder list in reverse to form a valid
92  // postorder.
93  for (Loop *L : reverse(PreOrderLoops)) {
96  // Check to see whether the preserved set needs to be adjusted based on
97  // function-level analysis invalidation triggering deferred invalidation
98  // for this loop.
99  if (auto *OuterProxy =
100  InnerAM->getCachedResult<FunctionAnalysisManagerLoopProxy>(*L))
101  for (const auto &OuterInvalidationPair :
102  OuterProxy->getOuterInvalidations()) {
103  AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
104  const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
105  if (Inv.invalidate(OuterAnalysisID, F, PA)) {
106  if (!InnerPA)
107  InnerPA = PA;
108  for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
109  InnerPA->abandon(InnerAnalysisID);
110  }
111  }
113  // Check if we needed a custom PA set. If so we'll need to run the inner
114  // invalidation.
115  if (InnerPA) {
116  InnerAM->invalidate(*L, *InnerPA);
117  continue;
118  }
120  // Otherwise we only need to do invalidation if the original PA set didn't
121  // preserve all Loop analyses.
122  if (!AreLoopAnalysesPreserved)
123  InnerAM->invalidate(*L, PA);
124  }
126  // Return false to indicate that this result is still a valid proxy.
127  return false;
128 }
130 template <>
133  FunctionAnalysisManager &AM) {
134  return Result(*InnerAM, AM.getResult<LoopAnalysis>(F));
135 }
136 }
141  PA.preserve<LoopAnalysis>();
144  // FIXME: What we really want to do here is preserve an AA category, but that
145  // concept doesn't exist yet.
146  PA.preserve<AAManager>();
147  PA.preserve<BasicAA>();
148  PA.preserve<GlobalsAA>();
149  PA.preserve<SCEVAA>();
150  return PA;
151 }
void abandon()
Mark an analysis as abandoned.
Definition: PassManager.h:207
bool invalidate(IRUnitT &IR, const PreservedAnalyses &PA)
Trigger the invalidation of some other analysis pass if not already handled and return whether it was...
Definition: PassManager.h:666
PreservedAnalyses getLoopPassPreservedAnalyses()
Returns the minimum set of Analyses that all loop passes must preserve.
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:776
This class represents lattice values for constants.
Definition: AllocatorList.h:23
This is the interface for a simple mod/ref and alias analysis over globals.
bool invalidate(IRUnitT &IR, const PreservedAnalyses &PA, typename AnalysisManager< IRUnitT, ExtraArgTs... >::Invalidator &Inv)
Handler for invalidation of the outer IR unit, IRUnitT.
The adaptor from a function pass to a loop pass computes these analyses and makes them available to t...
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:230
PreservedAnalysisChecker getChecker() const
Build a checker for this PreservedAnalyses and the specified analysis type.
Definition: PassManager.h:311
This is the interface for a SCEV-based alias analysis.
Analysis pass that exposes the LoopInfo for a function.
Definition: LoopInfo.h:1113
auto reverse(ContainerTy &&C, typename std::enable_if< has_rbegin< ContainerTy >::value >::type *=nullptr) -> decltype(make_range(C.rbegin(), C.rend()))
Definition: STLExtras.h:273
This header provides classes for managing per-loop analyses.
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
A manager for alias analyses.
Analysis pass providing a never-invalidated alias analysis result.
AnalysisManager< Function > FunctionAnalysisManager
Convenience typedef for the Function analysis manager.
Definition: PassManager.h:1025
Analysis pass providing a never-invalidated alias analysis result.
A function analysis which provides an AssumptionCache.
An analysis over an "inner" IR unit that provides access to an analysis manager over a "outer" IR uni...
Definition: PassManager.h:1160
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
Result run(IRUnitT &IR, AnalysisManager< IRUnitT, ExtraArgTs... > &AM, ExtraArgTs...)
Run the analysis pass and create our proxy result object.
Definition: PassManager.h:1107
An analysis that produces MemorySSA for a function.
Definition: MemorySSA.h:924
Result(AnalysisManagerT &InnerAM)
Definition: PassManager.h:1050
Analysis pass that exposes the ScalarEvolution for a function.
Analysis pass providing a never-invalidated alias analysis result.
cl::opt< bool > EnableMSSALoopDependency
Enables memory ssa as a dependency for loop passes.
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:467
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:174
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:648
This templated class represents "all analyses that operate over <a particular IR unit>" (e...
Definition: PassManager.h:91
This file exposes an interface to building/using memory SSA to walk memory instructions using a use/d...
This is the interface for LLVM&#39;s primary stateless and local alias analysis.
A container for analyses that lazily runs them and caches their results.
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:70
bool allAnalysesInSetPreserved() const
Directly test whether a set of analyses is preserved.
Definition: PassManager.h:336
An analysis over an "outer" IR unit that provides access to an analysis manager over an "inner" IR un...
Definition: PassManager.h:1044