lib/Analysis/AliasDebugger.cpp

   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 "llvm/Support/Compiler.h"
  27 #include <set>
  28 using namespace llvm;
  29
  30 namespace {
  31
  32   class VISIBILITY_HIDDEN AliasDebugger
  33       : public ModulePass, public AliasAnalysis {
  34
  35     //What we do is simple.  Keep track of every value the AA could
  36     //know about, and verify that queries are one of those.
  37     //A query to a value that didn't exist when the AA was created
  38     //means someone forgot to update the AA when creating new values
  39
  40     std::set<const Value*> Vals;
  41
  42   public:
  43     static char ID; // Class identification, replacement for typeinfo
  44     AliasDebugger() : ModulePass(&ID) {}
  45
  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
  53       for(Module::iterator I = M.begin(),
  54             E = M.end(); I != E; ++I){
  55         Vals.insert(&*I);
  56         if(!I->isDeclaration()) {
  57           for (Function::arg_iterator AI = I->arg_begin(), AE = I->arg_end();
  58                AI != AE; ++AI)
  59             Vals.insert(&*AI);
  60           for (Function::const_iterator FI = I->begin(), FE = I->end();
  61                FI != FE; ++FI)
  62             for (BasicBlock::const_iterator BI = FI->begin(), BE = FI->end();
  63                  BI != BE; ++BI)
  64               Vals.insert(&*BI);
  65         }
  66
  67       }
  68       return false;
  69     }
  70
  71     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
  72       AliasAnalysis::getAnalysisUsage(AU);
  73       AU.setPreservesAll();                         // Does not transform code
  74     }
  75
  76     //------------------------------------------------
  77     // Implement the AliasAnalysis API
  78     //
  79     AliasResult alias(const Value *V1, unsigned V1Size,
  80                       const Value *V2, unsigned V2Size) {
  81       assert(Vals.find(V1) != Vals.end() && "Never seen value in AA before");
  82       assert(Vals.find(V2) != Vals.end() && "Never seen value in AA before");
  83       return AliasAnalysis::alias(V1, V1Size, V2, V2Size);
  84     }
  85
  86     ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
  87       assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
  88       return AliasAnalysis::getModRefInfo(CS, P, Size);
  89     }
  90
  91     ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
  92       return AliasAnalysis::getModRefInfo(CS1,CS2);
  93     }
  94
  95     void getMustAliases(Value *P, std::vector<Value*> &RetVals) {
  96       assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
  97       return AliasAnalysis::getMustAliases(P, RetVals);
  98     }
  99
 100     bool pointsToConstantMemory(const Value *P) {
 101       assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
 102       return AliasAnalysis::pointsToConstantMemory(P);
 103     }
 104
 105     virtual void deleteValue(Value *V) {
 106       assert(Vals.find(V) != Vals.end() && "Never seen value in AA before");
 107       AliasAnalysis::deleteValue(V);
 108     }
 109     virtual void copyValue(Value *From, Value *To) {
 110       Vals.insert(To);
 111       AliasAnalysis::copyValue(From, To);
 112     }
 113
 114   };
 115 }
 116
 117 char AliasDebugger::ID = 0;
 118 static RegisterPass<AliasDebugger>
 119 X("debug-aa", "AA use debugger", false, true);
 120 static RegisterAnalysisGroup<AliasAnalysis> Y(X);
 121
 122 Pass *llvm::createAliasDebugger() { return new AliasDebugger(); }
 123