1 //===- AliasDebugger.cpp - Simple Alias Analysis Use Checker --------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This simple pass checks alias analysis users to ensure that if they
11 // create a new value, they do not query AA without informing it of the value.
12 // It acts as a shim over any other AA pass you want.
13 //
14 // Yes keeping track of every value in the program is expensive, but this is
15 // a debugging pass.
16 //
17 //===----------------------------------------------------------------------===//
18
19 #include "llvm/Analysis/Passes.h"
20 #include "llvm/Module.h"
21 #include "llvm/Pass.h"
22 #include "llvm/Instructions.h"
23 #include "llvm/Constants.h"
24 #include "llvm/DerivedTypes.h"
25 #include "llvm/Analysis/AliasAnalysis.h"
26 #include <set>
27 using namespace llvm;
28
29 namespace {
30
31 class AliasDebugger : public ModulePass, public AliasAnalysis {
32
33 //What we do is simple. Keep track of every value the AA could
34 //know about, and verify that queries are one of those.
35 //A query to a value that didn't exist when the AA was created
36 //means someone forgot to update the AA when creating new values
37
38 std::set<const Value*> Vals;
39
40 public:
41 static char ID; // Class identification, replacement for typeinfo
AliasDebugger()42 AliasDebugger() : ModulePass(ID) {
43 initializeAliasDebuggerPass(*PassRegistry::getPassRegistry());
44 }
45
runOnModule(Module & M)46 bool runOnModule(Module &M) {
47 InitializeAliasAnalysis(this); // set up super class
48
49 for(Module::global_iterator I = M.global_begin(),
50 E = M.global_end(); I != E; ++I) {
51 Vals.insert(&*I);
52 for (User::const_op_iterator OI = I->op_begin(),
53 OE = I->op_end(); OI != OE; ++OI)
54 Vals.insert(*OI);
55 }
56
57 for(Module::iterator I = M.begin(),
58 E = M.end(); I != E; ++I){
59 Vals.insert(&*I);
60 if(!I->isDeclaration()) {
61 for (Function::arg_iterator AI = I->arg_begin(), AE = I->arg_end();
62 AI != AE; ++AI)
63 Vals.insert(&*AI);
64 for (Function::const_iterator FI = I->begin(), FE = I->end();
65 FI != FE; ++FI)
66 for (BasicBlock::const_iterator BI = FI->begin(), BE = FI->end();
67 BI != BE; ++BI) {
68 Vals.insert(&*BI);
69 for (User::const_op_iterator OI = BI->op_begin(),
70 OE = BI->op_end(); OI != OE; ++OI)
71 Vals.insert(*OI);
72 }
73 }
74
75 }
76 return false;
77 }
78
getAnalysisUsage(AnalysisUsage & AU) const79 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
80 AliasAnalysis::getAnalysisUsage(AU);
81 AU.setPreservesAll(); // Does not transform code
82 }
83
84 /// getAdjustedAnalysisPointer - This method is used when a pass implements
85 /// an analysis interface through multiple inheritance. If needed, it
86 /// should override this to adjust the this pointer as needed for the
87 /// specified pass info.
getAdjustedAnalysisPointer(AnalysisID PI)88 virtual void *getAdjustedAnalysisPointer(AnalysisID PI) {
89 if (PI == &AliasAnalysis::ID)
90 return (AliasAnalysis*)this;
91 return this;
92 }
93
94 //------------------------------------------------
95 // Implement the AliasAnalysis API
96 //
alias(const Location & LocA,const Location & LocB)97 AliasResult alias(const Location &LocA, const Location &LocB) {
98 assert(Vals.find(LocA.Ptr) != Vals.end() &&
99 "Never seen value in AA before");
100 assert(Vals.find(LocB.Ptr) != Vals.end() &&
101 "Never seen value in AA before");
102 return AliasAnalysis::alias(LocA, LocB);
103 }
104
getModRefInfo(ImmutableCallSite CS,const Location & Loc)105 ModRefResult getModRefInfo(ImmutableCallSite CS,
106 const Location &Loc) {
107 assert(Vals.find(Loc.Ptr) != Vals.end() && "Never seen value in AA before");
108 return AliasAnalysis::getModRefInfo(CS, Loc);
109 }
110
getModRefInfo(ImmutableCallSite CS1,ImmutableCallSite CS2)111 ModRefResult getModRefInfo(ImmutableCallSite CS1,
112 ImmutableCallSite CS2) {
113 return AliasAnalysis::getModRefInfo(CS1,CS2);
114 }
115
pointsToConstantMemory(const Location & Loc,bool OrLocal)116 bool pointsToConstantMemory(const Location &Loc, bool OrLocal) {
117 assert(Vals.find(Loc.Ptr) != Vals.end() && "Never seen value in AA before");
118 return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
119 }
120
deleteValue(Value * V)121 virtual void deleteValue(Value *V) {
122 assert(Vals.find(V) != Vals.end() && "Never seen value in AA before");
123 AliasAnalysis::deleteValue(V);
124 }
copyValue(Value * From,Value * To)125 virtual void copyValue(Value *From, Value *To) {
126 Vals.insert(To);
127 AliasAnalysis::copyValue(From, To);
128 }
129
130 };
131 }
132
133 char AliasDebugger::ID = 0;
134 INITIALIZE_AG_PASS(AliasDebugger, AliasAnalysis, "debug-aa",
135 "AA use debugger", false, true, false)
136
createAliasDebugger()137 Pass *llvm::createAliasDebugger() { return new AliasDebugger(); }
138
139