AliasDebugger.cpp revision 8ba15cb7099d9eadcb345328228d77ffa5afa42d 
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>
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    static char ID; // Class identification, replacement for typeinfo
42    AliasDebugger() : ModulePass(&ID) {}
43
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
77    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.
86    virtual void *getAdjustedAnalysisPointer(const StaticPassInfo *PI) {
87      if (PI->isPassID(&AliasAnalysis::ID))
88        return (AliasAnalysis*)this;
89      return this;
90    }
91
92    //------------------------------------------------
93    // Implement the AliasAnalysis API
94    //
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
102    ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
103      assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
104      return AliasAnalysis::getModRefInfo(CS, P, Size);
105    }
106
107    ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
108      return AliasAnalysis::getModRefInfo(CS1,CS2);
109    }
110
111    bool pointsToConstantMemory(const Value *P) {
112      assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
113      return AliasAnalysis::pointsToConstantMemory(P);
114    }
115
116    virtual void deleteValue(Value *V) {
117      assert(Vals.find(V) != Vals.end() && "Never seen value in AA before");
118      AliasAnalysis::deleteValue(V);
119    }
120    virtual void copyValue(Value *From, Value *To) {
121      Vals.insert(To);
122      AliasAnalysis::copyValue(From, To);
123    }
124
125  };
126}
127
128char AliasDebugger::ID = 0;
129static RegisterPass<AliasDebugger>
130X("debug-aa", "AA use debugger", false, true);
131static RegisterAnalysisGroup<AliasAnalysis> Y(X);
132
133Pass *llvm::createAliasDebugger() { return new AliasDebugger(); }
134
135