lib/Analysis/MemDerefPrinter.cpp

   1 //===- MemDerefPrinter.cpp - Printer for isDereferenceablePointer ---------===//
   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 #include "llvm/Analysis/Loads.h"
  11 #include "llvm/Analysis/Passes.h"
  12 #include "llvm/IR/CallSite.h"
  13 #include "llvm/IR/DataLayout.h"
  14 #include "llvm/IR/InstIterator.h"
  15 #include "llvm/IR/LLVMContext.h"
  16 #include "llvm/IR/Module.h"
  17 #include "llvm/Support/ErrorHandling.h"
  18 #include "llvm/Support/raw_ostream.h"
  19 using namespace llvm;
  20
  21 namespace {
  22   struct MemDerefPrinter : public FunctionPass {
  23     SmallVector<Value *, 4> Deref;
  24     SmallPtrSet<Value *, 4> DerefAndAligned;
  25
  26     static char ID; // Pass identification, replacement for typeid
  27     MemDerefPrinter() : FunctionPass(ID) {
  28       initializeMemDerefPrinterPass(*PassRegistry::getPassRegistry());
  29     }
  30     void getAnalysisUsage(AnalysisUsage &AU) const override {
  31       AU.setPreservesAll();
  32     }
  33     bool runOnFunction(Function &F) override;
  34     void print(raw_ostream &OS, const Module * = nullptr) const override;
  35     void releaseMemory() override {
  36       Deref.clear();
  37       DerefAndAligned.clear();
  38     }
  39   };
  40 }
  41
  42 char MemDerefPrinter::ID = 0;
  43 INITIALIZE_PASS_BEGIN(MemDerefPrinter, "print-memderefs",
  44                       "Memory Dereferenciblity of pointers in function", false, true)
  45 INITIALIZE_PASS_END(MemDerefPrinter, "print-memderefs",
  46                     "Memory Dereferenciblity of pointers in function", false, true)
  47
  48 FunctionPass *llvm::createMemDerefPrinter() {
  49   return new MemDerefPrinter();
  50 }
  51
  52 bool MemDerefPrinter::runOnFunction(Function &F) {
  53   const DataLayout &DL = F.getParent()->getDataLayout();
  54   for (auto &I: instructions(F)) {
  55     if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
  56       Value *PO = LI->getPointerOperand();
  57       if (isDereferenceablePointer(PO, DL))
  58         Deref.push_back(PO);
  59       if (isDereferenceableAndAlignedPointer(PO, LI->getAlignment(), DL))
  60         DerefAndAligned.insert(PO);
  61     }
  62   }
  63   return false;
  64 }
  65
  66 void MemDerefPrinter::print(raw_ostream &OS, const Module *M) const {
  67   OS << "The following are dereferenceable:\n";
  68   for (Value *V: Deref) {
  69     V->print(OS);
  70     if (DerefAndAligned.count(V))
  71       OS << "\t(aligned)";
  72     else
  73       OS << "\t(unaligned)";
  74     OS << "\n\n";
  75   }
  76 }