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
runOnModule(Module & M)44 bool runOnModule(Module &M) {
45 InitializeAliasAnalysis(this); // set up super class
46
47 for(Module::global_iterator I = M.global_begin(),
48 E = M.global_end(); I != E; ++I) {
49 Vals.insert(&*I);
50 for (User::const_op_iterator OI = I->op_begin(),
51 OE = I->op_end(); OI != OE; ++OI)
52 Vals.insert(*OI);
53 }
54
55 for(Module::iterator I = M.begin(),
56 E = M.end(); I != E; ++I){
57 Vals.insert(&*I);
58 if(!I->isDeclaration()) {
59 for (Function::arg_iterator AI = I->arg_begin(), AE = I->arg_end();
60 AI != AE; ++AI)
61 Vals.insert(&*AI);
62 for (Function::const_iterator FI = I->begin(), FE = I->end();
63 FI != FE; ++FI)
64 for (BasicBlock::const_iterator BI = FI->begin(), BE = FI->end();
65 BI != BE; ++BI) {
66 Vals.insert(&*BI);
67 for (User::const_op_iterator OI = BI->op_begin(),
68 OE = BI->op_end(); OI != OE; ++OI)
69 Vals.insert(*OI);
70 }
71 }
72
73 }
74 return false;
75 }
76
getAnalysisUsage(AnalysisUsage & AU) const77 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
78 AliasAnalysis::getAnalysisUsage(AU);
79 AU.setPreservesAll(); // Does not transform code
80 }
81
82 /// getAdjustedAnalysisPointer - This method is used when a pass implements
83 /// an analysis interface through multiple inheritance. If needed, it
84 /// should override this to adjust the this pointer as needed for the
85 /// specified pass info.
getAdjustedAnalysisPointer(AnalysisID PI)86 virtual void *getAdjustedAnalysisPointer(AnalysisID PI) {
87 if (PI == &AliasAnalysis::ID)
88 return (AliasAnalysis*)this;
89 return this;
90 }
91
92 //------------------------------------------------
93 // Implement the AliasAnalysis API
94 //
alias(const Value * V1,unsigned V1Size,const Value * V2,unsigned V2Size)95 AliasResult alias(const Value *V1, unsigned V1Size,
96 const Value *V2, unsigned V2Size) {
97 assert(Vals.find(V1) != Vals.end() && "Never seen value in AA before");
98 assert(Vals.find(V2) != Vals.end() && "Never seen value in AA before");
99 return AliasAnalysis::alias(V1, V1Size, V2, V2Size);
100 }
101
getModRefInfo(ImmutableCallSite CS,const Value * P,unsigned Size)102 ModRefResult getModRefInfo(ImmutableCallSite CS,
103 const Value *P, unsigned Size) {
104 assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
105 return AliasAnalysis::getModRefInfo(CS, P, Size);
106 }
107
getModRefInfo(ImmutableCallSite CS1,ImmutableCallSite CS2)108 ModRefResult getModRefInfo(ImmutableCallSite CS1,
109 ImmutableCallSite CS2) {
110 return AliasAnalysis::getModRefInfo(CS1,CS2);
111 }
112
pointsToConstantMemory(const Value * P)113 bool pointsToConstantMemory(const Value *P) {
114 assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
115 return AliasAnalysis::pointsToConstantMemory(P);
116 }
117
deleteValue(Value * V)118 virtual void deleteValue(Value *V) {
119 assert(Vals.find(V) != Vals.end() && "Never seen value in AA before");
120 AliasAnalysis::deleteValue(V);
121 }
copyValue(Value * From,Value * To)122 virtual void copyValue(Value *From, Value *To) {
123 Vals.insert(To);
124 AliasAnalysis::copyValue(From, To);
125 }
126
127 };
128 }
129
130 char AliasDebugger::ID = 0;
131 INITIALIZE_AG_PASS(AliasDebugger, AliasAnalysis, "debug-aa",
132 "AA use debugger", false, true, false);
133
createAliasDebugger()134 Pass *llvm::createAliasDebugger() { return new AliasDebugger(); }
135
136