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 <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
  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
  51       for(Module::iterator I = M.begin(),
  52             E = M.end(); I != E; ++I){
  53         Vals.insert(&*I);
  54         if(!I->isDeclaration()) {
  55           for (Function::arg_iterator AI = I->arg_begin(), AE = I->arg_end();
  56                AI != AE; ++AI)
  57             Vals.insert(&*AI);
  58           for (Function::const_iterator FI = I->begin(), FE = I->end();
  59                FI != FE; ++FI)
  60             for (BasicBlock::const_iterator BI = FI->begin(), BE = FI->end();
  61                  BI != BE; ++BI)
  62               Vals.insert(&*BI);
  63         }
  64
  65       }
  66       return false;
  67     }
  68
  69     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
  70       AliasAnalysis::getAnalysisUsage(AU);
  71       AU.setPreservesAll();                         // Does not transform code
  72     }
  73
  74     //------------------------------------------------
  75     // Implement the AliasAnalysis API
  76     //
  77     AliasResult alias(const Value *V1, unsigned V1Size,
  78                       const Value *V2, unsigned V2Size) {
  79       assert(Vals.find(V1) != Vals.end() && "Never seen value in AA before");
  80       assert(Vals.find(V2) != Vals.end() && "Never seen value in AA before");
  81       return AliasAnalysis::alias(V1, V1Size, V2, V2Size);
  82     }
  83
  84     ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
  85       assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
  86       return AliasAnalysis::getModRefInfo(CS, P, Size);
  87     }
  88
  89     ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
  90       return AliasAnalysis::getModRefInfo(CS1,CS2);
  91     }
  92
  93     void getMustAliases(Value *P, std::vector<Value*> &RetVals) {
  94       assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
  95       return AliasAnalysis::getMustAliases(P, RetVals);
  96     }
  97
  98     bool pointsToConstantMemory(const Value *P) {
  99       assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
 100       return AliasAnalysis::pointsToConstantMemory(P);
 101     }
 102
 103     virtual void deleteValue(Value *V) {
 104       assert(Vals.find(V) != Vals.end() && "Never seen value in AA before");
 105       AliasAnalysis::deleteValue(V);
 106     }
 107     virtual void copyValue(Value *From, Value *To) {
 108       Vals.insert(To);
 109       AliasAnalysis::copyValue(From, To);
 110     }
 111
 112   };
 113 }
 114
 115 char AliasDebugger::ID = 0;
 116 static RegisterPass<AliasDebugger>
 117 X("debug-aa", "AA use debugger", false, true);
 118 static RegisterAnalysisGroup<AliasAnalysis> Y(X);
 119
 120 Pass *llvm::createAliasDebugger() { return new AliasDebugger(); }
 121