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       initializeAliasDebuggerPass(*PassRegistry::getPassRegistry());
  44     }
  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         for (User::const_op_iterator OI = I->op_begin(),
  53              OE = I->op_end(); OI != OE; ++OI)
  54           Vals.insert(*OI);
  55       }
  56
  57       for(Module::iterator I = M.begin(),
  58             E = M.end(); I != E; ++I){
  59         Vals.insert(&*I);
  60         if(!I->isDeclaration()) {
  61           for (Function::arg_iterator AI = I->arg_begin(), AE = I->arg_end();
  62                AI != AE; ++AI)
  63             Vals.insert(&*AI);
  64           for (Function::const_iterator FI = I->begin(), FE = I->end();
  65                FI != FE; ++FI)
  66             for (BasicBlock::const_iterator BI = FI->begin(), BE = FI->end();
  67                  BI != BE; ++BI) {
  68               Vals.insert(&*BI);
  69               for (User::const_op_iterator OI = BI->op_begin(),
  70                    OE = BI->op_end(); OI != OE; ++OI)
  71                 Vals.insert(*OI);
  72             }
  73         }
  74
  75       }
  76       return false;
  77     }
  78
  79     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
  80       AliasAnalysis::getAnalysisUsage(AU);
  81       AU.setPreservesAll();                         // Does not transform code
  82     }
  83
  84     /// getAdjustedAnalysisPointer - This method is used when a pass implements
  85     /// an analysis interface through multiple inheritance.  If needed, it
  86     /// should override this to adjust the this pointer as needed for the
  87     /// specified pass info.
  88     virtual void *getAdjustedAnalysisPointer(AnalysisID PI) {
  89       if (PI == &AliasAnalysis::ID)
  90         return (AliasAnalysis*)this;
  91       return this;
  92     }
  93
  94     //------------------------------------------------
  95     // Implement the AliasAnalysis API
  96     //
  97     AliasResult alias(const Location &LocA, const Location &LocB) {
  98       assert(Vals.find(LocA.Ptr) != Vals.end() &&
  99              "Never seen value in AA before");
 100       assert(Vals.find(LocB.Ptr) != Vals.end() &&
 101              "Never seen value in AA before");
 102       return AliasAnalysis::alias(LocA, LocB);
 103     }
 104
 105     ModRefResult getModRefInfo(ImmutableCallSite CS,
 106                                const Location &Loc) {
 107       assert(Vals.find(Loc.Ptr) != Vals.end() && "Never seen value in AA before");
 108       return AliasAnalysis::getModRefInfo(CS, Loc);
 109     }
 110
 111     ModRefResult getModRefInfo(ImmutableCallSite CS1,
 112                                ImmutableCallSite CS2) {
 113       return AliasAnalysis::getModRefInfo(CS1,CS2);
 114     }
 115
 116     bool pointsToConstantMemory(const Location &Loc) {
 117       assert(Vals.find(Loc.Ptr) != Vals.end() && "Never seen value in AA before");
 118       return AliasAnalysis::pointsToConstantMemory(Loc);
 119     }
 120
 121     virtual void deleteValue(Value *V) {
 122       assert(Vals.find(V) != Vals.end() && "Never seen value in AA before");
 123       AliasAnalysis::deleteValue(V);
 124     }
 125     virtual void copyValue(Value *From, Value *To) {
 126       Vals.insert(To);
 127       AliasAnalysis::copyValue(From, To);
 128     }
 129
 130   };
 131 }
 132
 133 char AliasDebugger::ID = 0;
 134 INITIALIZE_AG_PASS(AliasDebugger, AliasAnalysis, "debug-aa",
 135                    "AA use debugger", false, true, false)
 136
 137 Pass *llvm::createAliasDebugger() { return new AliasDebugger(); }
 138