llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp

   1 //===- ObjCARCAnalysisUtils.cpp -------------------------------------------===//
   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 // This file implements common infrastructure for libLLVMObjCARCOpts.a, which
  10 // implements several scalar transformations over the LLVM intermediate
  11 // representation, including the C bindings for that library.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/Analysis/ObjCARCAnalysisUtils.h"
  16 #include "llvm/Analysis/AliasAnalysis.h"
  17 #include "llvm/Support/CommandLine.h"
  18
  19 using namespace llvm;
  20 using namespace llvm::objcarc;
  21
  22 /// A handy option to enable/disable all ARC Optimizations.
  23 bool llvm::objcarc::EnableARCOpts;
  24 static cl::opt<bool, true> EnableARCOptimizations(
  25     "enable-objc-arc-opts", cl::desc("enable/disable all ARC Optimizations"),
  26     cl::location(EnableARCOpts), cl::init(true), cl::Hidden);
  27
  28 bool llvm::objcarc::IsPotentialRetainableObjPtr(const Value *Op,
  29                                                 AAResults &AA) {
  30   // First make the rudimentary check.
  31   if (!IsPotentialRetainableObjPtr(Op))
  32     return false;
  33
  34   // Objects in constant memory are not reference-counted.
  35   if (AA.pointsToConstantMemory(Op))
  36     return false;
  37
  38   // Pointers in constant memory are not pointing to reference-counted objects.
  39   if (const LoadInst *LI = dyn_cast<LoadInst>(Op))
  40     if (AA.pointsToConstantMemory(LI->getPointerOperand()))
  41       return false;
  42
  43   // Otherwise assume the worst.
  44   return true;
  45 }