1 //===- PhiValues.h - Phi Value Analysis -------------------------*- C++ -*-===//
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 // This file defines the PhiValues class, and associated passes, which can be
11 // used to find the underlying values of the phis in a function, i.e. the
12 // non-phi values that can be found by traversing the phi graph.
14 // This information is computed lazily and cached. If new phis are added to the
15 // function they are handled correctly, but if an existing phi has its operands
16 // modified PhiValues has to be notified by calling invalidateValue.
18 //===----------------------------------------------------------------------===//
20 #ifndef LLVM_ANALYSIS_PHIVALUES_H
21 #define LLVM_ANALYSIS_PHIVALUES_H
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/DenseSet.h"
25 #include "llvm/ADT/SmallPtrSet.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include "llvm/IR/PassManager.h"
28 #include "llvm/IR/ValueHandle.h"
29 #include "llvm/Pass.h"
38 /// Class for calculating and caching the underlying values of phis in a
41 /// Initially the PhiValues is empty, and gets incrementally populated whenever
45 using ValueSet = SmallPtrSet<Value *, 4>;
47 /// Construct an empty PhiValues.
48 PhiValues(const Function &F) : F(F) {}
50 /// Get the underlying values of a phi.
52 /// This returns the cached value if PN has previously been processed,
53 /// otherwise it processes it first.
54 const ValueSet &getValuesForPhi(const PHINode *PN);
56 /// Notify PhiValues that the cached information using V is no longer valid
58 /// Whenever a phi has its operands modified the cached values for that phi
59 /// (and the phis that use that phi) become invalid. A user of PhiValues has
60 /// to notify it of this by calling invalidateValue on either the operand or
61 /// the phi, which will then clear the relevant cached information.
62 void invalidateValue(const Value *V);
64 /// Free the memory used by this class.
67 /// Print out the values currently in the cache.
68 void print(raw_ostream &OS) const;
70 /// Handle invalidation events in the new pass manager.
71 bool invalidate(Function &, const PreservedAnalyses &,
72 FunctionAnalysisManager::Invalidator &);
75 using PhiSet = SmallPtrSet<const PHINode *, 4>;
76 using ConstValueSet = SmallPtrSet<const Value *, 4>;
78 /// The next depth number to be used by processPhi.
79 unsigned int NextDepthNumber = 1;
81 /// Depth numbers of phis. Phis with the same depth number are part of the
82 /// same strongly connected component.
83 DenseMap<const PHINode *, unsigned int> DepthMap;
85 /// Non-phi values reachable from each component.
86 DenseMap<unsigned int, ValueSet> NonPhiReachableMap;
88 /// All values reachable from each component.
89 DenseMap<unsigned int, ConstValueSet> ReachableMap;
91 /// A CallbackVH to notify PhiValues when a value is deleted or replaced, so
92 /// that the cached information for that value can be cleared to avoid
93 /// dangling pointers to invalid values.
94 class PhiValuesCallbackVH final : public CallbackVH {
96 void deleted() override;
97 void allUsesReplacedWith(Value *New) override;
100 PhiValuesCallbackVH(Value *V, PhiValues *PV = nullptr)
101 : CallbackVH(V), PV(PV) {}
104 /// A set of callbacks to the values that processPhi has seen.
105 DenseSet<PhiValuesCallbackVH, DenseMapInfo<Value *>> TrackedValues;
107 /// The function that the PhiValues is for.
110 /// Process a phi so that its entries in the depth and reachable maps are
112 void processPhi(const PHINode *PN, SmallVector<const PHINode *, 8> &Stack);
115 /// The analysis pass which yields a PhiValues
117 /// The analysis does nothing by itself, and just returns an empty PhiValues
118 /// which will get filled in as it's used.
119 class PhiValuesAnalysis : public AnalysisInfoMixin<PhiValuesAnalysis> {
120 friend AnalysisInfoMixin<PhiValuesAnalysis>;
121 static AnalysisKey Key;
124 using Result = PhiValues;
125 PhiValues run(Function &F, FunctionAnalysisManager &);
128 /// A pass for printing the PhiValues for a function.
130 /// This pass doesn't print whatever information the PhiValues happens to hold,
131 /// but instead first uses the PhiValues to analyze all the phis in the function
132 /// so the complete information is printed.
133 class PhiValuesPrinterPass : public PassInfoMixin<PhiValuesPrinterPass> {
137 explicit PhiValuesPrinterPass(raw_ostream &OS) : OS(OS) {}
138 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
141 /// Wrapper pass for the legacy pass manager
142 class PhiValuesWrapperPass : public FunctionPass {
143 std::unique_ptr<PhiValues> Result;
147 PhiValuesWrapperPass();
149 PhiValues &getResult() { return *Result; }
150 const PhiValues &getResult() const { return *Result; }
152 bool runOnFunction(Function &F) override;
153 void releaseMemory() override;
154 void getAnalysisUsage(AnalysisUsage &AU) const override;