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/Passes.h"
  11 #include "llvm/ADT/SetVector.h"
  12 #include "llvm/Analysis/MemoryDependenceAnalysis.h"
  13 #include "llvm/Analysis/ValueTracking.h"
  14 #include "llvm/IR/CallSite.h"
  15 #include "llvm/IR/DataLayout.h"
  16 #include "llvm/IR/InstIterator.h"
  17 #include "llvm/IR/LLVMContext.h"
  18 #include "llvm/IR/Module.h"
  19 #include "llvm/Support/ErrorHandling.h"
  20 #include "llvm/Support/raw_ostream.h"
  21 using namespace llvm;
  22
  23 namespace {
  24   struct MemDerefPrinter : public FunctionPass {
  25     SmallVector<Value *, 4> Deref;
  26     SmallPtrSet<Value *, 4> DerefAndAligned;
  27
  28     static char ID; // Pass identification, replacement for typeid
  29     MemDerefPrinter() : FunctionPass(ID) {
  30       initializeMemDerefPrinterPass(*PassRegistry::getPassRegistry());
  31     }
  32     void getAnalysisUsage(AnalysisUsage &AU) const override {
  33       AU.setPreservesAll();
  34     }
  35     bool runOnFunction(Function &F) override;
  36     void print(raw_ostream &OS, const Module * = nullptr) const override;
  37     void releaseMemory() override {
  38       Deref.clear();
  39       DerefAndAligned.clear();
  40     }
  41   };
  42 }
  43
  44 char MemDerefPrinter::ID = 0;
  45 INITIALIZE_PASS_BEGIN(MemDerefPrinter, "print-memderefs",
  46                       "Memory Dereferenciblity of pointers in function", false, true)
  47 INITIALIZE_PASS_END(MemDerefPrinter, "print-memderefs",
  48                     "Memory Dereferenciblity of pointers in function", false, true)
  49
  50 FunctionPass *llvm::createMemDerefPrinter() {
  51   return new MemDerefPrinter();
  52 }
  53
  54 bool MemDerefPrinter::runOnFunction(Function &F) {
  55   const DataLayout &DL = F.getParent()->getDataLayout();
  56   for (auto &I: instructions(F)) {
  57     if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
  58       Value *PO = LI->getPointerOperand();
  59       if (isDereferenceablePointer(PO, DL))
  60         Deref.push_back(PO);
  61       if (isDereferenceableAndAlignedPointer(PO, LI->getAlignment(), DL))
  62         DerefAndAligned.insert(PO);
  63     }
  64   }
  65   return false;
  66 }
  67
  68 void MemDerefPrinter::print(raw_ostream &OS, const Module *M) const {
  69   OS << "The following are dereferenceable:\n";
  70   for (Value *V: Deref) {
  71     V->print(OS);
  72     if (DerefAndAligned.count(V))
  73       OS << "\t(aligned)";
  74     else
  75       OS << "\t(unaligned)";
  76     OS << "\n\n";
  77   }
  78 }