LLVM  12.0.0git
LoopAnalysisManager.cpp
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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 //===----------------------------------------------------------------------===//
8 
12 #include "llvm/Analysis/LoopInfo.h"
16 #include "llvm/IR/Dominators.h"
18 
19 using namespace llvm;
20 
21 namespace llvm {
22 // Explicit template instantiations and specialization definitions for core
23 // template typedefs.
24 template class AllAnalysesOn<Loop>;
29 
31  Function &F, const PreservedAnalyses &PA,
33  // First compute the sequence of IR units covered by this proxy. We will want
34  // to visit this in postorder, but because this is a tree structure we can do
35  // this by building a preorder sequence and walking it backwards. We also
36  // want siblings in forward program order to match the LoopPassManager so we
37  // get the preorder with siblings reversed.
38  SmallVector<Loop *, 4> PreOrderLoops = LI->getLoopsInReverseSiblingPreorder();
39 
40  // If this proxy or the loop info is going to be invalidated, we also need
41  // to clear all the keys coming from that analysis. We also completely blow
42  // away the loop analyses if any of the standard analyses provided by the
43  // loop pass manager go away so that loop analyses can freely use these
44  // without worrying about declaring dependencies on them etc.
45  // FIXME: It isn't clear if this is the right tradeoff. We could instead make
46  // loop analyses declare any dependencies on these and use the more general
47  // invalidation logic below to act on that.
49  bool invalidateMemorySSAAnalysis = false;
50  if (MSSAUsed)
51  invalidateMemorySSAAnalysis = Inv.invalidate<MemorySSAAnalysis>(F, PA);
52  if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
53  Inv.invalidate<AAManager>(F, PA) ||
54  Inv.invalidate<AssumptionAnalysis>(F, PA) ||
56  Inv.invalidate<LoopAnalysis>(F, PA) ||
58  invalidateMemorySSAAnalysis) {
59  // Note that the LoopInfo may be stale at this point, however the loop
60  // objects themselves remain the only viable keys that could be in the
61  // analysis manager's cache. So we just walk the keys and forcibly clear
62  // those results. Note that the order doesn't matter here as this will just
63  // directly destroy the results without calling methods on them.
64  for (Loop *L : PreOrderLoops) {
65  // NB! `L` may not be in a good enough state to run Loop::getName.
66  InnerAM->clear(*L, "<possibly invalidated loop>");
67  }
68 
69  // We also need to null out the inner AM so that when the object gets
70  // destroyed as invalid we don't try to clear the inner AM again. At that
71  // point we won't be able to reliably walk the loops for this function and
72  // only clear results associated with those loops the way we do here.
73  // FIXME: Making InnerAM null at this point isn't very nice. Most analyses
74  // try to remain valid during invalidation. Maybe we should add an
75  // `IsClean` flag?
76  InnerAM = nullptr;
77 
78  // Now return true to indicate this *is* invalid and a fresh proxy result
79  // needs to be built. This is especially important given the null InnerAM.
80  return true;
81  }
82 
83  // Directly check if the relevant set is preserved so we can short circuit
84  // invalidating loops.
85  bool AreLoopAnalysesPreserved =
87 
88  // Since we have a valid LoopInfo we can actually leave the cached results in
89  // the analysis manager associated with the Loop keys, but we need to
90  // propagate any necessary invalidation logic into them. We'd like to
91  // invalidate things in roughly the same order as they were put into the
92  // cache and so we walk the preorder list in reverse to form a valid
93  // postorder.
94  for (Loop *L : reverse(PreOrderLoops)) {
96 
97  // Check to see whether the preserved set needs to be adjusted based on
98  // function-level analysis invalidation triggering deferred invalidation
99  // for this loop.
100  if (auto *OuterProxy =
101  InnerAM->getCachedResult<FunctionAnalysisManagerLoopProxy>(*L))
102  for (const auto &OuterInvalidationPair :
103  OuterProxy->getOuterInvalidations()) {
104  AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
105  const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
106  if (Inv.invalidate(OuterAnalysisID, F, PA)) {
107  if (!InnerPA)
108  InnerPA = PA;
109  for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
110  InnerPA->abandon(InnerAnalysisID);
111  }
112  }
113 
114  // Check if we needed a custom PA set. If so we'll need to run the inner
115  // invalidation.
116  if (InnerPA) {
117  InnerAM->invalidate(*L, *InnerPA);
118  continue;
119  }
120 
121  // Otherwise we only need to do invalidation if the original PA set didn't
122  // preserve all Loop analyses.
123  if (!AreLoopAnalysesPreserved)
124  InnerAM->invalidate(*L, PA);
125  }
126 
127  // Return false to indicate that this result is still a valid proxy.
128  return false;
129 }
130 
131 template <>
134  FunctionAnalysisManager &AM) {
135  return Result(*InnerAM, AM.getResult<LoopAnalysis>(F));
136 }
137 }
138 
142  PA.preserve<LoopAnalysis>();
145  // FIXME: What we really want to do here is preserve an AA category, but that
146  // concept doesn't exist yet.
147  PA.preserve<AAManager>();
148  PA.preserve<BasicAA>();
149  PA.preserve<GlobalsAA>();
150  PA.preserve<SCEVAA>();
151  return PA;
152 }
void abandon()
Mark an analysis as abandoned.
Definition: PassManager.h:208
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:672
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:769
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:233
F(f)
PreservedAnalysisChecker getChecker() const
Build a checker for this PreservedAnalyses and the specified analysis type.
Definition: PassManager.h:312
This is the interface for a SCEV-based alias analysis.
Analysis pass that exposes the LoopInfo for a function.
Definition: LoopInfo.h:1208
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:154
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:934
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:1069
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:883
Result run(IRUnitT &IR, AnalysisManager< IRUnitT, ExtraArgTs... > &AM, ExtraArgTs...)
Run the analysis pass and create our proxy result object.
Definition: PassManager.h:1016
An analysis that produces MemorySSA for a function.
Definition: MemorySSA.h:924
Result(AnalysisManagerT &InnerAM)
Definition: PassManager.h:959
Analysis pass that exposes the ScalarEvolution for a function.
Analysis pass providing a never-invalidated alias analysis result.
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:516
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:175
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:654
This templated class represents "all analyses that operate over <a particular IR unit>" (e...
Definition: PassManager.h:92
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.
auto reverse(ContainerTy &&C, std::enable_if_t< has_rbegin< ContainerTy >::value > *=nullptr)
Definition: STLExtras.h:341
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:71
bool allAnalysesInSetPreserved() const
Directly test whether a set of analyses is preserved.
Definition: PassManager.h:337
An analysis over an "outer" IR unit that provides access to an analysis manager over an "inner" IR un...
Definition: PassManager.h:953