lib/Analysis/MemDerefPrinter.cpp

   1 //===- MemDerefPrinter.cpp - Printer for isDereferenceablePointer ---------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Analysis/Loads.h"
  10 #include "llvm/Analysis/Passes.h"
  11 #include "llvm/IR/CallSite.h"
  12 #include "llvm/IR/DataLayout.h"
  13 #include "llvm/IR/InstIterator.h"
  14 #include "llvm/IR/LLVMContext.h"
  15 #include "llvm/IR/Module.h"
  16 #include "llvm/Support/ErrorHandling.h"
  17 #include "llvm/Support/raw_ostream.h"
  18 using namespace llvm;
  19
  20 namespace {
  21   struct MemDerefPrinter : public FunctionPass {
  22     SmallVector<Value *, 4> Deref;
  23     SmallPtrSet<Value *, 4> DerefAndAligned;
  24
  25     static char ID; // Pass identification, replacement for typeid
  26     MemDerefPrinter() : FunctionPass(ID) {
  27       initializeMemDerefPrinterPass(*PassRegistry::getPassRegistry());
  28     }
  29     void getAnalysisUsage(AnalysisUsage &AU) const override {
  30       AU.setPreservesAll();
  31     }
  32     bool runOnFunction(Function &F) override;
  33     void print(raw_ostream &OS, const Module * = nullptr) const override;
  34     void releaseMemory() override {
  35       Deref.clear();
  36       DerefAndAligned.clear();
  37     }
  38   };
  39 }
  40
  41 char MemDerefPrinter::ID = 0;
  42 INITIALIZE_PASS_BEGIN(MemDerefPrinter, "print-memderefs",
  43                       "Memory Dereferenciblity of pointers in function", false, true)
  44 INITIALIZE_PASS_END(MemDerefPrinter, "print-memderefs",
  45                     "Memory Dereferenciblity of pointers in function", false, true)
  46
  47 FunctionPass *llvm::createMemDerefPrinter() {
  48   return new MemDerefPrinter();
  49 }
  50
  51 bool MemDerefPrinter::runOnFunction(Function &F) {
  52   const DataLayout &DL = F.getParent()->getDataLayout();
  53   for (auto &I: instructions(F)) {
  54     if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
  55       Value *PO = LI->getPointerOperand();
  56       if (isDereferenceablePointer(PO, LI->getType(), DL))
  57         Deref.push_back(PO);
  58       if (isDereferenceableAndAlignedPointer(
  59               PO, LI->getType(), MaybeAlign(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 }