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/IR/CallSite.h"
14 #include "llvm/IR/DataLayout.h"
15 #include "llvm/IR/InstIterator.h"
16 #include "llvm/IR/LLVMContext.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> Vec;
24 
25     static char ID; // Pass identifcation, replacement for typeid
26     MemDerefPrinter() : FunctionPass(ID) {
27       initializeMemDerefPrinterPass(*PassRegistry::getPassRegistry());
28     }
29     void getAnalysisUsage(AnalysisUsage &AU) const override {
30       AU.addRequired<DataLayoutPass>();
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       Vec.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_DEPENDENCY(DataLayoutPass)
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 = &getAnalysis<DataLayoutPass>().getDataLayout();
54   for (auto &I: inst_range(F)) {
55     if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
56       Value *PO = LI->getPointerOperand();
57       if (PO->isDereferenceablePointer(DL))
58         Vec.push_back(PO);
59     }
60   }
61   return false;
62 }
63 
64 void MemDerefPrinter::print(raw_ostream &OS, const Module *M) const {
65   OS << "The following are dereferenceable:\n";
66   for (auto &V: Vec) {
67     V->print(OS);
68     OS << "\n\n";
69   }
70 }
71