LLVM  16.0.0git
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 
11 #include "llvm/Analysis/LoopInfo.h"
14 #include "llvm/IR/Dominators.h"
16 #include <optional>
17 
18 using namespace llvm;
19 
20 namespace llvm {
21 // Explicit template instantiations and specialization definitions for core
22 // template typedefs.
23 template class AllAnalysesOn<Loop>;
28 
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();
38 
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;
49  if (MSSAUsed)
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  }
67 
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;
76 
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  }
81 
82  // Directly check if the relevant set is preserved so we can short circuit
83  // invalidating loops.
84  bool AreLoopAnalysesPreserved =
86 
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)) {
94  std::optional<PreservedAnalyses> InnerPA;
95 
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  }
112 
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  }
119 
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  }
125 
126  // Return false to indicate that this result is still a valid proxy.
127  return false;
128 }
129 
130 template <>
134  return Result(*InnerAM, AM.getResult<LoopAnalysis>(F));
135 }
136 }
137 
141  PA.preserve<LoopAnalysis>();
144  return PA;
145 }
llvm::PreservedAnalyses
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:152
llvm::OuterAnalysisManagerProxy
An analysis over an "inner" IR unit that provides access to an analysis manager over a "outer" IR uni...
Definition: PassManager.h:1056
AssumptionCache.h
llvm::AAManager
A manager for alias analyses.
Definition: AliasAnalysis.h:881
llvm::ScalarEvolutionAnalysis
Analysis pass that exposes the ScalarEvolution for a function.
Definition: ScalarEvolution.h:2158
llvm
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
llvm::AnalysisManager::getResult
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:774
llvm::Function
Definition: Function.h:60
llvm::AnalysisManager::Invalidator::invalidate
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:679
llvm::Loop
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:547
llvm::SmallVector
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1199
llvm::InnerAnalysisManagerProxy::Result
Definition: PassManager.h:935
llvm::AllAnalysesOn
This templated class represents "all analyses that operate over <a particular IR unit>" (e....
Definition: PassManager.h:90
llvm::PreservedAnalyses::abandon
void abandon()
Mark an analysis as abandoned.
Definition: PassManager.h:206
ScalarEvolution.h
llvm::LoopStandardAnalysisResults
The adaptor from a function pass to a loop pass computes these analyses and makes them available to t...
Definition: LoopAnalysisManager.h:51
F
#define F(x, y, z)
Definition: MD5.cpp:55
LoopAnalysisManager.h
PassManagerImpl.h
llvm::MemorySSAAnalysis::Result
Definition: MemorySSA.h:945
llvm::AnalysisManager::Invalidator
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:661
LoopInfo.h
llvm::getLoopPassPreservedAnalyses
PreservedAnalyses getLoopPassPreservedAnalyses()
Returns the minimum set of Analyses that all loop passes must preserve.
Definition: LoopAnalysisManager.cpp:138
llvm::AssumptionAnalysis
A function analysis which provides an AssumptionCache.
Definition: AssumptionCache.h:173
llvm::PreservedAnalyses::preserve
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:173
llvm::AnalysisKey
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:69
llvm::InnerAnalysisManagerProxy::Result::invalidate
bool invalidate(IRUnitT &IR, const PreservedAnalyses &PA, typename AnalysisManager< IRUnitT, ExtraArgTs... >::Invalidator &Inv)
Handler for invalidation of the outer IR unit, IRUnitT.
llvm::PreservedAnalyses::allAnalysesInSetPreserved
bool allAnalysesInSetPreserved() const
Directly test whether a set of analyses is preserved.
Definition: PassManager.h:335
llvm::MemorySSAAnalysis
An analysis that produces MemorySSA for a function.
Definition: MemorySSA.h:936
llvm::DominatorTreeAnalysis
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:271
MemorySSA.h
llvm::FunctionAnalysisManager
AnalysisManager< Function > FunctionAnalysisManager
Convenience typedef for the Function analysis manager.
Definition: PassManager.h:912
Dominators.h
llvm::reverse
auto reverse(ContainerTy &&C)
Definition: STLExtras.h:485
llvm::PreservedAnalyses::getChecker
PreservedAnalysisChecker getChecker() const
Build a checker for this PreservedAnalyses and the specified analysis type.
Definition: PassManager.h:310
llvm::AnalysisManager
A container for analyses that lazily runs them and caches their results.
Definition: InstructionSimplify.h:42
llvm::InnerAnalysisManagerProxy
An analysis over an "outer" IR unit that provides access to an analysis manager over an "inner" IR un...
Definition: PassManager.h:931
llvm::InnerAnalysisManagerProxy::run
Result run(IRUnitT &IR, AnalysisManager< IRUnitT, ExtraArgTs... > &AM, ExtraArgTs...)
Run the analysis pass and create our proxy result object.
Definition: PassManager.h:994
llvm::LoopAnalysis
Analysis pass that exposes the LoopInfo for a function.
Definition: LoopInfo.h:1268