AliasDebugger.cpp revision 472c7918b0bc155e002db6f682c899e21bff852c 
1//===- AliasDebugger.cpp - Simple Alias Analysis Use Checker --------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by Andrew Lenharth and is distributed under
6// the University of Illinois Open Source 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>
27using namespace llvm;
28
29namespace {
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    bool runOnModule(Module &M) {
42      InitializeAliasAnalysis(this);                 // set up super class
43
44      for(Module::global_iterator I = M.global_begin(),
45            E = M.global_end(); I != E; ++I)
46        Vals.insert(&*I);
47
48      for(Module::iterator I = M.begin(),
49            E = M.end(); I != E; ++I){
50        Vals.insert(&*I);
51        if(!I->isExternal()) {
52          for (Function::arg_iterator AI = I->arg_begin(), AE = I->arg_end();
53               AI != AE; ++AI)
54            Vals.insert(&*AI);
55          for (Function::const_iterator FI = I->begin(), FE = I->end();
56               FI != FE; ++FI)
57            for (BasicBlock::const_iterator BI = FI->begin(), BE = FI->end();
58                 BI != BE; ++BI)
59              Vals.insert(&*BI);
60        }
61
62      }
63      return false;
64    }
65
66    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
67      AliasAnalysis::getAnalysisUsage(AU);
68      AU.setPreservesAll();                         // Does not transform code
69    }
70
71    //------------------------------------------------
72    // Implement the AliasAnalysis API
73    //
74    AliasResult alias(const Value *V1, unsigned V1Size,
75                      const Value *V2, unsigned V2Size) {
76      assert(Vals.find(V1) != Vals.end() && "Never seen value in AA before");
77      assert(Vals.find(V2) != Vals.end() && "Never seen value in AA before");
78      return AliasAnalysis::alias(V1, V1Size, V2, V2Size);
79    }
80
81    ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
82      assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
83      return AliasAnalysis::getModRefInfo(CS, P, Size);
84    }
85
86    ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
87      return AliasAnalysis::getModRefInfo(CS1,CS2);
88    }
89
90    void getMustAliases(Value *P, std::vector<Value*> &RetVals) {
91      assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
92      return AliasAnalysis::getMustAliases(P, RetVals);
93    }
94
95    bool pointsToConstantMemory(const Value *P) {
96      assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
97      return AliasAnalysis::pointsToConstantMemory(P);
98    }
99
100    /// getModRefBehavior - Return the behavior of the specified function if
101    /// called from the specified call site.  The call site may be null in which
102    /// case the most generic behavior of this function should be returned.
103    virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS,
104                                         std::vector<PointerAccessInfo> *Info) {
105      assert(Vals.find(F) != Vals.end() && "Never seen value in AA before");
106      return AliasAnalysis::getModRefBehavior(F, CS, Info);
107    }
108
109    virtual void deleteValue(Value *V) {
110      assert(Vals.find(V) != Vals.end() && "Never seen value in AA before");
111      AliasAnalysis::deleteValue(V);
112    }
113    virtual void copyValue(Value *From, Value *To) {
114      Vals.insert(To);
115      AliasAnalysis::copyValue(From, To);
116    }
117
118  };
119
120  RegisterPass<AliasDebugger> X("debug-aa", "AA use debugger");
121  RegisterAnalysisGroup<AliasAnalysis> Y(X);
122}
123
124Pass *llvm::createAliasDebugger() { return new AliasDebugger(); }
125
126