1 //===- LoopAnalysisManager.cpp - Loop analysis management -----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/Analysis/LoopAnalysisManager.h"
11 #include "llvm/Analysis/BasicAliasAnalysis.h"
12 #include "llvm/Analysis/GlobalsModRef.h"
13 #include "llvm/Analysis/LoopInfo.h"
14 #include "llvm/Analysis/ScalarEvolution.h"
15 #include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
16 #include "llvm/IR/Dominators.h"
20 // Explicit template instantiations and specialization defininitions for core
23 template class AllAnalysesOn<Loop>;
24 template class AnalysisManager<Loop, LoopStandardAnalysisResults &>;
25 template class InnerAnalysisManagerProxy<LoopAnalysisManager, Function>;
26 template class OuterAnalysisManagerProxy<FunctionAnalysisManager, Loop,
27 LoopStandardAnalysisResults &>;
29 bool LoopAnalysisManagerFunctionProxy::Result::invalidate(
30 Function &F, const PreservedAnalyses &PA,
31 FunctionAnalysisManager::Invalidator &Inv) {
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 in reverse.
35 SmallVector<Loop *, 4> PreOrderLoops, PreOrderWorklist;
36 // Note that we want to walk the roots in reverse order because we will end
37 // up reversing the preorder sequence. However, it happens that the loop nest
38 // roots are in reverse order within the LoopInfo object. So we just walk
40 // FIXME: If we change the order of LoopInfo we will want to add a reverse
42 for (Loop *RootL : *LI) {
43 assert(PreOrderWorklist.empty() &&
44 "Must start with an empty preorder walk worklist.");
45 PreOrderWorklist.push_back(RootL);
47 Loop *L = PreOrderWorklist.pop_back_val();
48 PreOrderWorklist.append(L->begin(), L->end());
49 PreOrderLoops.push_back(L);
50 } while (!PreOrderWorklist.empty());
53 // If this proxy or the loop info is going to be invalidated, we also need
54 // to clear all the keys coming from that analysis. We also completely blow
55 // away the loop analyses if any of the standard analyses provided by the
56 // loop pass manager go away so that loop analyses can freely use these
57 // without worrying about declaring dependencies on them etc.
58 // FIXME: It isn't clear if this is the right tradeoff. We could instead make
59 // loop analyses declare any dependencies on these and use the more general
60 // invalidation logic below to act on that.
61 auto PAC = PA.getChecker<LoopAnalysisManagerFunctionProxy>();
62 if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
63 Inv.invalidate<AAManager>(F, PA) ||
64 Inv.invalidate<AssumptionAnalysis>(F, PA) ||
65 Inv.invalidate<DominatorTreeAnalysis>(F, PA) ||
66 Inv.invalidate<LoopAnalysis>(F, PA) ||
67 Inv.invalidate<ScalarEvolutionAnalysis>(F, PA)) {
68 // Note that the LoopInfo may be stale at this point, however the loop
69 // objects themselves remain the only viable keys that could be in the
70 // analysis manager's cache. So we just walk the keys and forcibly clear
71 // those results. Note that the order doesn't matter here as this will just
72 // directly destroy the results without calling methods on them.
73 for (Loop *L : PreOrderLoops)
76 // We also need to null out the inner AM so that when the object gets
77 // destroyed as invalid we don't try to clear the inner AM again. At that
78 // point we won't be able to reliably walk the loops for this function and
79 // only clear results associated with those loops the way we do here.
80 // FIXME: Making InnerAM null at this point isn't very nice. Most analyses
81 // try to remain valid during invalidation. Maybe we should add an
85 // Now return true to indicate this *is* invalid and a fresh proxy result
86 // needs to be built. This is especially important given the null InnerAM.
90 // Directly check if the relevant set is preserved so we can short circuit
91 // invalidating loops.
92 bool AreLoopAnalysesPreserved =
93 PA.allAnalysesInSetPreserved<AllAnalysesOn<Loop>>();
95 // Since we have a valid LoopInfo we can actually leave the cached results in
96 // the analysis manager associated with the Loop keys, but we need to
97 // propagate any necessary invalidation logic into them. We'd like to
98 // invalidate things in roughly the same order as they were put into the
99 // cache and so we walk the preorder list in reverse to form a valid
101 for (Loop *L : reverse(PreOrderLoops)) {
102 Optional<PreservedAnalyses> InnerPA;
104 // Check to see whether the preserved set needs to be adjusted based on
105 // function-level analysis invalidation triggering deferred invalidation
107 if (auto *OuterProxy =
108 InnerAM->getCachedResult<FunctionAnalysisManagerLoopProxy>(*L))
109 for (const auto &OuterInvalidationPair :
110 OuterProxy->getOuterInvalidations()) {
111 AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
112 const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
113 if (Inv.invalidate(OuterAnalysisID, F, PA)) {
116 for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
117 InnerPA->abandon(InnerAnalysisID);
121 // Check if we needed a custom PA set. If so we'll need to run the inner
124 InnerAM->invalidate(*L, *InnerPA);
128 // Otherwise we only need to do invalidation if the original PA set didn't
129 // preserve all Loop analyses.
130 if (!AreLoopAnalysesPreserved)
131 InnerAM->invalidate(*L, PA);
134 // Return false to indicate that this result is still a valid proxy.
139 LoopAnalysisManagerFunctionProxy::Result
140 LoopAnalysisManagerFunctionProxy::run(Function &F,
141 FunctionAnalysisManager &AM) {
142 return Result(*InnerAM, AM.getResult<LoopAnalysis>(F));
146 PreservedAnalyses llvm::getLoopPassPreservedAnalyses() {
147 PreservedAnalyses PA;
148 PA.preserve<AssumptionAnalysis>();
149 PA.preserve<DominatorTreeAnalysis>();
150 PA.preserve<LoopAnalysis>();
151 PA.preserve<LoopAnalysisManagerFunctionProxy>();
152 PA.preserve<ScalarEvolutionAnalysis>();
153 // TODO: What we really want to do here is preserve an AA category, but that
154 // concept doesn't exist yet.
155 PA.preserve<AAManager>();
156 PA.preserve<BasicAA>();
157 PA.preserve<GlobalsAA>();
158 PA.preserve<SCEVAA>();