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/DataLayout.h"
  13 #include "llvm/IR/InstIterator.h"
  14 #include "llvm/IR/Instructions.h"
  15 #include "llvm/IR/LLVMContext.h"
  16 #include "llvm/IR/Module.h"
  17 #include "llvm/InitializePasses.h"
  18 #include "llvm/Pass.h"
  19 #include "llvm/Support/ErrorHandling.h"
  20 #include "llvm/Support/raw_ostream.h"
  21
  22 using namespace llvm;
  23
  24 namespace {
  25   struct MemDerefPrinter : public FunctionPass {
  26     SmallVector<Value *, 4> Deref;
  27     SmallPtrSet<Value *, 4> DerefAndAligned;
  28
  29     static char ID; // Pass identification, replacement for typeid
  30     MemDerefPrinter() : FunctionPass(ID) {
  31       initializeMemDerefPrinterPass(*PassRegistry::getPassRegistry());
  32     }
  33     void getAnalysisUsage(AnalysisUsage &AU) const override {
  34       AU.setPreservesAll();
  35     }
  36     bool runOnFunction(Function &F) override;
  37     void print(raw_ostream &OS, const Module * = nullptr) const override;
  38     void releaseMemory() override {
  39       Deref.clear();
  40       DerefAndAligned.clear();
  41     }
  42   };
  43 }
  44
  45 char MemDerefPrinter::ID = 0;
  46 INITIALIZE_PASS_BEGIN(MemDerefPrinter, "print-memderefs",
  47                       "Memory Dereferenciblity of pointers in function", false, true)
  48 INITIALIZE_PASS_END(MemDerefPrinter, "print-memderefs",
  49                     "Memory Dereferenciblity of pointers in function", false, true)
  50
  51 FunctionPass *llvm::createMemDerefPrinter() {
  52   return new MemDerefPrinter();
  53 }
  54
  55 bool MemDerefPrinter::runOnFunction(Function &F) {
  56   const DataLayout &DL = F.getParent()->getDataLayout();
  57   for (auto &I: instructions(F)) {
  58     if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
  59       Value *PO = LI->getPointerOperand();
  60       if (isDereferenceablePointer(PO, LI->getType(), DL))
  61         Deref.push_back(PO);
  62       if (isDereferenceableAndAlignedPointer(
  63               PO, LI->getType(), MaybeAlign(LI->getAlignment()), DL))
  64         DerefAndAligned.insert(PO);
  65     }
  66   }
  67   return false;
  68 }
  69
  70 void MemDerefPrinter::print(raw_ostream &OS, const Module *M) const {
  71   OS << "The following are dereferenceable:\n";
  72   for (Value *V: Deref) {
  73     OS << "  ";
  74     V->print(OS);
  75     if (DerefAndAligned.count(V))
  76       OS << "\t(aligned)";
  77     else
  78       OS << "\t(unaligned)";
  79     OS << "\n";
  80   }
  81 }
  82
  83 PreservedAnalyses MemDerefPrinterPass::run(Function &F,
  84                                            FunctionAnalysisManager &AM) {
  85   OS << "Memory Dereferencibility of pointers in function '" << F.getName()
  86      << "'\n";
  87
  88   SmallVector<Value *, 4> Deref;
  89   SmallPtrSet<Value *, 4> DerefAndAligned;
  90
  91   const DataLayout &DL = F.getParent()->getDataLayout();
  92   for (auto &I : instructions(F)) {
  93     if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
  94       Value *PO = LI->getPointerOperand();
  95       if (isDereferenceablePointer(PO, LI->getType(), DL))
  96         Deref.push_back(PO);
  97       if (isDereferenceableAndAlignedPointer(
  98               PO, LI->getType(), MaybeAlign(LI->getAlignment()), DL))
  99         DerefAndAligned.insert(PO);
 100     }
 101   }
 102
 103   OS << "The following are dereferenceable:\n";
 104   for (Value *V : Deref) {
 105     OS << "  ";
 106     V->print(OS);
 107     if (DerefAndAligned.count(V))
 108       OS << "\t(aligned)";
 109     else
 110       OS << "\t(unaligned)";
 111     OS << "\n";
 112   }
 113   return PreservedAnalyses::all();
 114 }