llvm/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/MemDerefPrinter.h"
  10 #include "llvm/Analysis/Loads.h"
  11 #include "llvm/Analysis/Passes.h"
  12 #include "llvm/IR/InstIterator.h"
  13 #include "llvm/IR/Instructions.h"
  14 #include "llvm/IR/Module.h"
  15 #include "llvm/InitializePasses.h"
  16 #include "llvm/Pass.h"
  17 #include "llvm/Support/raw_ostream.h"
  18
  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, LI->getType(), DL))
  58         Deref.push_back(PO);
  59       if (isDereferenceableAndAlignedPointer(PO, LI->getType(), LI->getAlign(),
  60                                              DL))
  61         DerefAndAligned.insert(PO);
  62     }
  63   }
  64   return false;
  65 }
  66
  67 void MemDerefPrinter::print(raw_ostream &OS, const Module *M) const {
  68   OS << "The following are dereferenceable:\n";
  69   for (Value *V: Deref) {
  70     OS << "  ";
  71     V->print(OS);
  72     if (DerefAndAligned.count(V))
  73       OS << "\t(aligned)";
  74     else
  75       OS << "\t(unaligned)";
  76     OS << "\n";
  77   }
  78 }
  79
  80 PreservedAnalyses MemDerefPrinterPass::run(Function &F,
  81                                            FunctionAnalysisManager &AM) {
  82   OS << "Memory Dereferencibility of pointers in function '" << F.getName()
  83      << "'\n";
  84
  85   SmallVector<Value *, 4> Deref;
  86   SmallPtrSet<Value *, 4> DerefAndAligned;
  87
  88   const DataLayout &DL = F.getParent()->getDataLayout();
  89   for (auto &I : instructions(F)) {
  90     if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
  91       Value *PO = LI->getPointerOperand();
  92       if (isDereferenceablePointer(PO, LI->getType(), DL))
  93         Deref.push_back(PO);
  94       if (isDereferenceableAndAlignedPointer(PO, LI->getType(), LI->getAlign(),
  95                                              DL))
  96         DerefAndAligned.insert(PO);
  97     }
  98   }
  99
 100   OS << "The following are dereferenceable:\n";
 101   for (Value *V : Deref) {
 102     OS << "  ";
 103     V->print(OS);
 104     if (DerefAndAligned.count(V))
 105       OS << "\t(aligned)";
 106     else
 107       OS << "\t(unaligned)";
 108     OS << "\n";
 109   }
 110   return PreservedAnalyses::all();
 111 }