lib/Analysis/ObjCARCInstKind.cpp

   1 //===- ARCInstKind.cpp - ObjC ARC Optimization ----------------------------===//
   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 /// \file
  10 /// This file defines several utility functions used by various ARC
  11 /// optimizations which are IMHO too big to be in a header file.
  12 ///
  13 /// WARNING: This file knows about certain library functions. It recognizes them
  14 /// by name, and hardwires knowledge of their semantics.
  15 ///
  16 /// WARNING: This file knows about how certain Objective-C library functions are
  17 /// used. Naive LLVM IR transformations which would otherwise be
  18 /// behavior-preserving may break these assumptions.
  19 ///
  20 //===----------------------------------------------------------------------===//
  21
  22 #include "llvm/Analysis/ObjCARCInstKind.h"
  23 #include "llvm/ADT/StringSwitch.h"
  24 #include "llvm/Analysis/ObjCARCAnalysisUtils.h"
  25 #include "llvm/IR/Intrinsics.h"
  26
  27 using namespace llvm;
  28 using namespace llvm::objcarc;
  29
  30 raw_ostream &llvm::objcarc::operator<<(raw_ostream &OS,
  31                                        const ARCInstKind Class) {
  32   switch (Class) {
  33   case ARCInstKind::Retain:
  34     return OS << "ARCInstKind::Retain";
  35   case ARCInstKind::RetainRV:
  36     return OS << "ARCInstKind::RetainRV";
  37   case ARCInstKind::ClaimRV:
  38     return OS << "ARCInstKind::ClaimRV";
  39   case ARCInstKind::RetainBlock:
  40     return OS << "ARCInstKind::RetainBlock";
  41   case ARCInstKind::Release:
  42     return OS << "ARCInstKind::Release";
  43   case ARCInstKind::Autorelease:
  44     return OS << "ARCInstKind::Autorelease";
  45   case ARCInstKind::AutoreleaseRV:
  46     return OS << "ARCInstKind::AutoreleaseRV";
  47   case ARCInstKind::AutoreleasepoolPush:
  48     return OS << "ARCInstKind::AutoreleasepoolPush";
  49   case ARCInstKind::AutoreleasepoolPop:
  50     return OS << "ARCInstKind::AutoreleasepoolPop";
  51   case ARCInstKind::NoopCast:
  52     return OS << "ARCInstKind::NoopCast";
  53   case ARCInstKind::FusedRetainAutorelease:
  54     return OS << "ARCInstKind::FusedRetainAutorelease";
  55   case ARCInstKind::FusedRetainAutoreleaseRV:
  56     return OS << "ARCInstKind::FusedRetainAutoreleaseRV";
  57   case ARCInstKind::LoadWeakRetained:
  58     return OS << "ARCInstKind::LoadWeakRetained";
  59   case ARCInstKind::StoreWeak:
  60     return OS << "ARCInstKind::StoreWeak";
  61   case ARCInstKind::InitWeak:
  62     return OS << "ARCInstKind::InitWeak";
  63   case ARCInstKind::LoadWeak:
  64     return OS << "ARCInstKind::LoadWeak";
  65   case ARCInstKind::MoveWeak:
  66     return OS << "ARCInstKind::MoveWeak";
  67   case ARCInstKind::CopyWeak:
  68     return OS << "ARCInstKind::CopyWeak";
  69   case ARCInstKind::DestroyWeak:
  70     return OS << "ARCInstKind::DestroyWeak";
  71   case ARCInstKind::StoreStrong:
  72     return OS << "ARCInstKind::StoreStrong";
  73   case ARCInstKind::CallOrUser:
  74     return OS << "ARCInstKind::CallOrUser";
  75   case ARCInstKind::Call:
  76     return OS << "ARCInstKind::Call";
  77   case ARCInstKind::User:
  78     return OS << "ARCInstKind::User";
  79   case ARCInstKind::IntrinsicUser:
  80     return OS << "ARCInstKind::IntrinsicUser";
  81   case ARCInstKind::None:
  82     return OS << "ARCInstKind::None";
  83   }
  84   llvm_unreachable("Unknown instruction class!");
  85 }
  86
  87 ARCInstKind llvm::objcarc::GetFunctionClass(const Function *F) {
  88   Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
  89
  90   // No (mandatory) arguments.
  91   if (AI == AE)
  92     return StringSwitch<ARCInstKind>(F->getName())
  93         .Case("objc_autoreleasePoolPush", ARCInstKind::AutoreleasepoolPush)
  94         .Case("clang.arc.use", ARCInstKind::IntrinsicUser)
  95         .Default(ARCInstKind::CallOrUser);
  96
  97   // One argument.
  98   const Argument *A0 = &*AI++;
  99   if (AI == AE) {
 100     // Argument is a pointer.
 101     PointerType *PTy = dyn_cast<PointerType>(A0->getType());
 102     if (!PTy)
 103       return ARCInstKind::CallOrUser;
 104
 105     Type *ETy = PTy->getElementType();
 106     // Argument is i8*.
 107     if (ETy->isIntegerTy(8))
 108       return StringSwitch<ARCInstKind>(F->getName())
 109           .Case("objc_retain", ARCInstKind::Retain)
 110           .Case("objc_retainAutoreleasedReturnValue", ARCInstKind::RetainRV)
 111           .Case("objc_unsafeClaimAutoreleasedReturnValue", ARCInstKind::ClaimRV)
 112           .Case("objc_retainBlock", ARCInstKind::RetainBlock)
 113           .Case("objc_release", ARCInstKind::Release)
 114           .Case("objc_autorelease", ARCInstKind::Autorelease)
 115           .Case("objc_autoreleaseReturnValue", ARCInstKind::AutoreleaseRV)
 116           .Case("objc_autoreleasePoolPop", ARCInstKind::AutoreleasepoolPop)
 117           .Case("objc_retainedObject", ARCInstKind::NoopCast)
 118           .Case("objc_unretainedObject", ARCInstKind::NoopCast)
 119           .Case("objc_unretainedPointer", ARCInstKind::NoopCast)
 120           .Case("objc_retain_autorelease", ARCInstKind::FusedRetainAutorelease)
 121           .Case("objc_retainAutorelease", ARCInstKind::FusedRetainAutorelease)
 122           .Case("objc_retainAutoreleaseReturnValue",
 123                 ARCInstKind::FusedRetainAutoreleaseRV)
 124           .Case("objc_sync_enter", ARCInstKind::User)
 125           .Case("objc_sync_exit", ARCInstKind::User)
 126           .Default(ARCInstKind::CallOrUser);
 127
 128     // Argument is i8**
 129     if (PointerType *Pte = dyn_cast<PointerType>(ETy))
 130       if (Pte->getElementType()->isIntegerTy(8))
 131         return StringSwitch<ARCInstKind>(F->getName())
 132             .Case("objc_loadWeakRetained", ARCInstKind::LoadWeakRetained)
 133             .Case("objc_loadWeak", ARCInstKind::LoadWeak)
 134             .Case("objc_destroyWeak", ARCInstKind::DestroyWeak)
 135             .Default(ARCInstKind::CallOrUser);
 136
 137     // Anything else with one argument.
 138     return ARCInstKind::CallOrUser;
 139   }
 140
 141   // Two arguments, first is i8**.
 142   const Argument *A1 = &*AI++;
 143   if (AI == AE)
 144     if (PointerType *PTy = dyn_cast<PointerType>(A0->getType()))
 145       if (PointerType *Pte = dyn_cast<PointerType>(PTy->getElementType()))
 146         if (Pte->getElementType()->isIntegerTy(8))
 147           if (PointerType *PTy1 = dyn_cast<PointerType>(A1->getType())) {
 148             Type *ETy1 = PTy1->getElementType();
 149             // Second argument is i8*
 150             if (ETy1->isIntegerTy(8))
 151               return StringSwitch<ARCInstKind>(F->getName())
 152                   .Case("objc_storeWeak", ARCInstKind::StoreWeak)
 153                   .Case("objc_initWeak", ARCInstKind::InitWeak)
 154                   .Case("objc_storeStrong", ARCInstKind::StoreStrong)
 155                   .Default(ARCInstKind::CallOrUser);
 156             // Second argument is i8**.
 157             if (PointerType *Pte1 = dyn_cast<PointerType>(ETy1))
 158               if (Pte1->getElementType()->isIntegerTy(8))
 159                 return StringSwitch<ARCInstKind>(F->getName())
 160                     .Case("objc_moveWeak", ARCInstKind::MoveWeak)
 161                     .Case("objc_copyWeak", ARCInstKind::CopyWeak)
 162                     // Ignore annotation calls. This is important to stop the
 163                     // optimizer from treating annotations as uses which would
 164                     // make the state of the pointers they are attempting to
 165                     // elucidate to be incorrect.
 166                     .Case("llvm.arc.annotation.topdown.bbstart",
 167                           ARCInstKind::None)
 168                     .Case("llvm.arc.annotation.topdown.bbend",
 169                           ARCInstKind::None)
 170                     .Case("llvm.arc.annotation.bottomup.bbstart",
 171                           ARCInstKind::None)
 172                     .Case("llvm.arc.annotation.bottomup.bbend",
 173                           ARCInstKind::None)
 174                     .Default(ARCInstKind::CallOrUser);
 175           }
 176
 177   // Anything else.
 178   return ARCInstKind::CallOrUser;
 179 }
 180
 181 // A whitelist of intrinsics that we know do not use objc pointers or decrement
 182 // ref counts.
 183 static bool isInertIntrinsic(unsigned ID) {
 184   // TODO: Make this into a covered switch.
 185   switch (ID) {
 186   case Intrinsic::returnaddress:
 187   case Intrinsic::addressofreturnaddress:
 188   case Intrinsic::frameaddress:
 189   case Intrinsic::stacksave:
 190   case Intrinsic::stackrestore:
 191   case Intrinsic::vastart:
 192   case Intrinsic::vacopy:
 193   case Intrinsic::vaend:
 194   case Intrinsic::objectsize:
 195   case Intrinsic::prefetch:
 196   case Intrinsic::stackprotector:
 197   case Intrinsic::eh_return_i32:
 198   case Intrinsic::eh_return_i64:
 199   case Intrinsic::eh_typeid_for:
 200   case Intrinsic::eh_dwarf_cfa:
 201   case Intrinsic::eh_sjlj_lsda:
 202   case Intrinsic::eh_sjlj_functioncontext:
 203   case Intrinsic::init_trampoline:
 204   case Intrinsic::adjust_trampoline:
 205   case Intrinsic::lifetime_start:
 206   case Intrinsic::lifetime_end:
 207   case Intrinsic::invariant_start:
 208   case Intrinsic::invariant_end:
 209   // Don't let dbg info affect our results.
 210   case Intrinsic::dbg_declare:
 211   case Intrinsic::dbg_value:
 212   case Intrinsic::dbg_label:
 213     // Short cut: Some intrinsics obviously don't use ObjC pointers.
 214     return true;
 215   default:
 216     return false;
 217   }
 218 }
 219
 220 // A whitelist of intrinsics that we know do not use objc pointers or decrement
 221 // ref counts.
 222 static bool isUseOnlyIntrinsic(unsigned ID) {
 223   // We are conservative and even though intrinsics are unlikely to touch
 224   // reference counts, we white list them for safety.
 225   //
 226   // TODO: Expand this into a covered switch. There is a lot more here.
 227   switch (ID) {
 228   case Intrinsic::memcpy:
 229   case Intrinsic::memmove:
 230   case Intrinsic::memset:
 231     return true;
 232   default:
 233     return false;
 234   }
 235 }
 236
 237 /// Determine what kind of construct V is.
 238 ARCInstKind llvm::objcarc::GetARCInstKind(const Value *V) {
 239   if (const Instruction *I = dyn_cast<Instruction>(V)) {
 240     // Any instruction other than bitcast and gep with a pointer operand have a
 241     // use of an objc pointer. Bitcasts, GEPs, Selects, PHIs transfer a pointer
 242     // to a subsequent use, rather than using it themselves, in this sense.
 243     // As a short cut, several other opcodes are known to have no pointer
 244     // operands of interest. And ret is never followed by a release, so it's
 245     // not interesting to examine.
 246     switch (I->getOpcode()) {
 247     case Instruction::Call: {
 248       const CallInst *CI = cast<CallInst>(I);
 249       // See if we have a function that we know something about.
 250       if (const Function *F = CI->getCalledFunction()) {
 251         ARCInstKind Class = GetFunctionClass(F);
 252         if (Class != ARCInstKind::CallOrUser)
 253           return Class;
 254         Intrinsic::ID ID = F->getIntrinsicID();
 255         if (isInertIntrinsic(ID))
 256           return ARCInstKind::None;
 257         if (isUseOnlyIntrinsic(ID))
 258           return ARCInstKind::User;
 259       }
 260
 261       // Otherwise, be conservative.
 262       return GetCallSiteClass(CI);
 263     }
 264     case Instruction::Invoke:
 265       // Otherwise, be conservative.
 266       return GetCallSiteClass(cast<InvokeInst>(I));
 267     case Instruction::BitCast:
 268     case Instruction::GetElementPtr:
 269     case Instruction::Select:
 270     case Instruction::PHI:
 271     case Instruction::Ret:
 272     case Instruction::Br:
 273     case Instruction::Switch:
 274     case Instruction::IndirectBr:
 275     case Instruction::Alloca:
 276     case Instruction::VAArg:
 277     case Instruction::Add:
 278     case Instruction::FAdd:
 279     case Instruction::Sub:
 280     case Instruction::FSub:
 281     case Instruction::Mul:
 282     case Instruction::FMul:
 283     case Instruction::SDiv:
 284     case Instruction::UDiv:
 285     case Instruction::FDiv:
 286     case Instruction::SRem:
 287     case Instruction::URem:
 288     case Instruction::FRem:
 289     case Instruction::Shl:
 290     case Instruction::LShr:
 291     case Instruction::AShr:
 292     case Instruction::And:
 293     case Instruction::Or:
 294     case Instruction::Xor:
 295     case Instruction::SExt:
 296     case Instruction::ZExt:
 297     case Instruction::Trunc:
 298     case Instruction::IntToPtr:
 299     case Instruction::FCmp:
 300     case Instruction::FPTrunc:
 301     case Instruction::FPExt:
 302     case Instruction::FPToUI:
 303     case Instruction::FPToSI:
 304     case Instruction::UIToFP:
 305     case Instruction::SIToFP:
 306     case Instruction::InsertElement:
 307     case Instruction::ExtractElement:
 308     case Instruction::ShuffleVector:
 309     case Instruction::ExtractValue:
 310       break;
 311     case Instruction::ICmp:
 312       // Comparing a pointer with null, or any other constant, isn't an
 313       // interesting use, because we don't care what the pointer points to, or
 314       // about the values of any other dynamic reference-counted pointers.
 315       if (IsPotentialRetainableObjPtr(I->getOperand(1)))
 316         return ARCInstKind::User;
 317       break;
 318     default:
 319       // For anything else, check all the operands.
 320       // Note that this includes both operands of a Store: while the first
 321       // operand isn't actually being dereferenced, it is being stored to
 322       // memory where we can no longer track who might read it and dereference
 323       // it, so we have to consider it potentially used.
 324       for (User::const_op_iterator OI = I->op_begin(), OE = I->op_end();
 325            OI != OE; ++OI)
 326         if (IsPotentialRetainableObjPtr(*OI))
 327           return ARCInstKind::User;
 328     }
 329   }
 330
 331   // Otherwise, it's totally inert for ARC purposes.
 332   return ARCInstKind::None;
 333 }
 334
 335 /// Test if the given class is a kind of user.
 336 bool llvm::objcarc::IsUser(ARCInstKind Class) {
 337   switch (Class) {
 338   case ARCInstKind::User:
 339   case ARCInstKind::CallOrUser:
 340   case ARCInstKind::IntrinsicUser:
 341     return true;
 342   case ARCInstKind::Retain:
 343   case ARCInstKind::RetainRV:
 344   case ARCInstKind::RetainBlock:
 345   case ARCInstKind::Release:
 346   case ARCInstKind::Autorelease:
 347   case ARCInstKind::AutoreleaseRV:
 348   case ARCInstKind::AutoreleasepoolPush:
 349   case ARCInstKind::AutoreleasepoolPop:
 350   case ARCInstKind::NoopCast:
 351   case ARCInstKind::FusedRetainAutorelease:
 352   case ARCInstKind::FusedRetainAutoreleaseRV:
 353   case ARCInstKind::LoadWeakRetained:
 354   case ARCInstKind::StoreWeak:
 355   case ARCInstKind::InitWeak:
 356   case ARCInstKind::LoadWeak:
 357   case ARCInstKind::MoveWeak:
 358   case ARCInstKind::CopyWeak:
 359   case ARCInstKind::DestroyWeak:
 360   case ARCInstKind::StoreStrong:
 361   case ARCInstKind::Call:
 362   case ARCInstKind::None:
 363   case ARCInstKind::ClaimRV:
 364     return false;
 365   }
 366   llvm_unreachable("covered switch isn't covered?");
 367 }
 368
 369 /// Test if the given class is objc_retain or equivalent.
 370 bool llvm::objcarc::IsRetain(ARCInstKind Class) {
 371   switch (Class) {
 372   case ARCInstKind::Retain:
 373   case ARCInstKind::RetainRV:
 374     return true;
 375   // I believe we treat retain block as not a retain since it can copy its
 376   // block.
 377   case ARCInstKind::RetainBlock:
 378   case ARCInstKind::Release:
 379   case ARCInstKind::Autorelease:
 380   case ARCInstKind::AutoreleaseRV:
 381   case ARCInstKind::AutoreleasepoolPush:
 382   case ARCInstKind::AutoreleasepoolPop:
 383   case ARCInstKind::NoopCast:
 384   case ARCInstKind::FusedRetainAutorelease:
 385   case ARCInstKind::FusedRetainAutoreleaseRV:
 386   case ARCInstKind::LoadWeakRetained:
 387   case ARCInstKind::StoreWeak:
 388   case ARCInstKind::InitWeak:
 389   case ARCInstKind::LoadWeak:
 390   case ARCInstKind::MoveWeak:
 391   case ARCInstKind::CopyWeak:
 392   case ARCInstKind::DestroyWeak:
 393   case ARCInstKind::StoreStrong:
 394   case ARCInstKind::IntrinsicUser:
 395   case ARCInstKind::CallOrUser:
 396   case ARCInstKind::Call:
 397   case ARCInstKind::User:
 398   case ARCInstKind::None:
 399   case ARCInstKind::ClaimRV:
 400     return false;
 401   }
 402   llvm_unreachable("covered switch isn't covered?");
 403 }
 404
 405 /// Test if the given class is objc_autorelease or equivalent.
 406 bool llvm::objcarc::IsAutorelease(ARCInstKind Class) {
 407   switch (Class) {
 408   case ARCInstKind::Autorelease:
 409   case ARCInstKind::AutoreleaseRV:
 410     return true;
 411   case ARCInstKind::Retain:
 412   case ARCInstKind::RetainRV:
 413   case ARCInstKind::ClaimRV:
 414   case ARCInstKind::RetainBlock:
 415   case ARCInstKind::Release:
 416   case ARCInstKind::AutoreleasepoolPush:
 417   case ARCInstKind::AutoreleasepoolPop:
 418   case ARCInstKind::NoopCast:
 419   case ARCInstKind::FusedRetainAutorelease:
 420   case ARCInstKind::FusedRetainAutoreleaseRV:
 421   case ARCInstKind::LoadWeakRetained:
 422   case ARCInstKind::StoreWeak:
 423   case ARCInstKind::InitWeak:
 424   case ARCInstKind::LoadWeak:
 425   case ARCInstKind::MoveWeak:
 426   case ARCInstKind::CopyWeak:
 427   case ARCInstKind::DestroyWeak:
 428   case ARCInstKind::StoreStrong:
 429   case ARCInstKind::IntrinsicUser:
 430   case ARCInstKind::CallOrUser:
 431   case ARCInstKind::Call:
 432   case ARCInstKind::User:
 433   case ARCInstKind::None:
 434     return false;
 435   }
 436   llvm_unreachable("covered switch isn't covered?");
 437 }
 438
 439 /// Test if the given class represents instructions which return their
 440 /// argument verbatim.
 441 bool llvm::objcarc::IsForwarding(ARCInstKind Class) {
 442   switch (Class) {
 443   case ARCInstKind::Retain:
 444   case ARCInstKind::RetainRV:
 445   case ARCInstKind::ClaimRV:
 446   case ARCInstKind::Autorelease:
 447   case ARCInstKind::AutoreleaseRV:
 448   case ARCInstKind::NoopCast:
 449     return true;
 450   case ARCInstKind::RetainBlock:
 451   case ARCInstKind::Release:
 452   case ARCInstKind::AutoreleasepoolPush:
 453   case ARCInstKind::AutoreleasepoolPop:
 454   case ARCInstKind::FusedRetainAutorelease:
 455   case ARCInstKind::FusedRetainAutoreleaseRV:
 456   case ARCInstKind::LoadWeakRetained:
 457   case ARCInstKind::StoreWeak:
 458   case ARCInstKind::InitWeak:
 459   case ARCInstKind::LoadWeak:
 460   case ARCInstKind::MoveWeak:
 461   case ARCInstKind::CopyWeak:
 462   case ARCInstKind::DestroyWeak:
 463   case ARCInstKind::StoreStrong:
 464   case ARCInstKind::IntrinsicUser:
 465   case ARCInstKind::CallOrUser:
 466   case ARCInstKind::Call:
 467   case ARCInstKind::User:
 468   case ARCInstKind::None:
 469     return false;
 470   }
 471   llvm_unreachable("covered switch isn't covered?");
 472 }
 473
 474 /// Test if the given class represents instructions which do nothing if
 475 /// passed a null pointer.
 476 bool llvm::objcarc::IsNoopOnNull(ARCInstKind Class) {
 477   switch (Class) {
 478   case ARCInstKind::Retain:
 479   case ARCInstKind::RetainRV:
 480   case ARCInstKind::ClaimRV:
 481   case ARCInstKind::Release:
 482   case ARCInstKind::Autorelease:
 483   case ARCInstKind::AutoreleaseRV:
 484   case ARCInstKind::RetainBlock:
 485     return true;
 486   case ARCInstKind::AutoreleasepoolPush:
 487   case ARCInstKind::AutoreleasepoolPop:
 488   case ARCInstKind::FusedRetainAutorelease:
 489   case ARCInstKind::FusedRetainAutoreleaseRV:
 490   case ARCInstKind::LoadWeakRetained:
 491   case ARCInstKind::StoreWeak:
 492   case ARCInstKind::InitWeak:
 493   case ARCInstKind::LoadWeak:
 494   case ARCInstKind::MoveWeak:
 495   case ARCInstKind::CopyWeak:
 496   case ARCInstKind::DestroyWeak:
 497   case ARCInstKind::StoreStrong:
 498   case ARCInstKind::IntrinsicUser:
 499   case ARCInstKind::CallOrUser:
 500   case ARCInstKind::Call:
 501   case ARCInstKind::User:
 502   case ARCInstKind::None:
 503   case ARCInstKind::NoopCast:
 504     return false;
 505   }
 506   llvm_unreachable("covered switch isn't covered?");
 507 }
 508
 509 /// Test if the given class represents instructions which are always safe
 510 /// to mark with the "tail" keyword.
 511 bool llvm::objcarc::IsAlwaysTail(ARCInstKind Class) {
 512   // ARCInstKind::RetainBlock may be given a stack argument.
 513   switch (Class) {
 514   case ARCInstKind::Retain:
 515   case ARCInstKind::RetainRV:
 516   case ARCInstKind::ClaimRV:
 517   case ARCInstKind::AutoreleaseRV:
 518     return true;
 519   case ARCInstKind::Release:
 520   case ARCInstKind::Autorelease:
 521   case ARCInstKind::RetainBlock:
 522   case ARCInstKind::AutoreleasepoolPush:
 523   case ARCInstKind::AutoreleasepoolPop:
 524   case ARCInstKind::FusedRetainAutorelease:
 525   case ARCInstKind::FusedRetainAutoreleaseRV:
 526   case ARCInstKind::LoadWeakRetained:
 527   case ARCInstKind::StoreWeak:
 528   case ARCInstKind::InitWeak:
 529   case ARCInstKind::LoadWeak:
 530   case ARCInstKind::MoveWeak:
 531   case ARCInstKind::CopyWeak:
 532   case ARCInstKind::DestroyWeak:
 533   case ARCInstKind::StoreStrong:
 534   case ARCInstKind::IntrinsicUser:
 535   case ARCInstKind::CallOrUser:
 536   case ARCInstKind::Call:
 537   case ARCInstKind::User:
 538   case ARCInstKind::None:
 539   case ARCInstKind::NoopCast:
 540     return false;
 541   }
 542   llvm_unreachable("covered switch isn't covered?");
 543 }
 544
 545 /// Test if the given class represents instructions which are never safe
 546 /// to mark with the "tail" keyword.
 547 bool llvm::objcarc::IsNeverTail(ARCInstKind Class) {
 548   /// It is never safe to tail call objc_autorelease since by tail calling
 549   /// objc_autorelease: fast autoreleasing causing our object to be potentially
 550   /// reclaimed from the autorelease pool which violates the semantics of
 551   /// __autoreleasing types in ARC.
 552   switch (Class) {
 553   case ARCInstKind::Autorelease:
 554     return true;
 555   case ARCInstKind::Retain:
 556   case ARCInstKind::RetainRV:
 557   case ARCInstKind::ClaimRV:
 558   case ARCInstKind::AutoreleaseRV:
 559   case ARCInstKind::Release:
 560   case ARCInstKind::RetainBlock:
 561   case ARCInstKind::AutoreleasepoolPush:
 562   case ARCInstKind::AutoreleasepoolPop:
 563   case ARCInstKind::FusedRetainAutorelease:
 564   case ARCInstKind::FusedRetainAutoreleaseRV:
 565   case ARCInstKind::LoadWeakRetained:
 566   case ARCInstKind::StoreWeak:
 567   case ARCInstKind::InitWeak:
 568   case ARCInstKind::LoadWeak:
 569   case ARCInstKind::MoveWeak:
 570   case ARCInstKind::CopyWeak:
 571   case ARCInstKind::DestroyWeak:
 572   case ARCInstKind::StoreStrong:
 573   case ARCInstKind::IntrinsicUser:
 574   case ARCInstKind::CallOrUser:
 575   case ARCInstKind::Call:
 576   case ARCInstKind::User:
 577   case ARCInstKind::None:
 578   case ARCInstKind::NoopCast:
 579     return false;
 580   }
 581   llvm_unreachable("covered switch isn't covered?");
 582 }
 583
 584 /// Test if the given class represents instructions which are always safe
 585 /// to mark with the nounwind attribute.
 586 bool llvm::objcarc::IsNoThrow(ARCInstKind Class) {
 587   // objc_retainBlock is not nounwind because it calls user copy constructors
 588   // which could theoretically throw.
 589   switch (Class) {
 590   case ARCInstKind::Retain:
 591   case ARCInstKind::RetainRV:
 592   case ARCInstKind::ClaimRV:
 593   case ARCInstKind::Release:
 594   case ARCInstKind::Autorelease:
 595   case ARCInstKind::AutoreleaseRV:
 596   case ARCInstKind::AutoreleasepoolPush:
 597   case ARCInstKind::AutoreleasepoolPop:
 598     return true;
 599   case ARCInstKind::RetainBlock:
 600   case ARCInstKind::FusedRetainAutorelease:
 601   case ARCInstKind::FusedRetainAutoreleaseRV:
 602   case ARCInstKind::LoadWeakRetained:
 603   case ARCInstKind::StoreWeak:
 604   case ARCInstKind::InitWeak:
 605   case ARCInstKind::LoadWeak:
 606   case ARCInstKind::MoveWeak:
 607   case ARCInstKind::CopyWeak:
 608   case ARCInstKind::DestroyWeak:
 609   case ARCInstKind::StoreStrong:
 610   case ARCInstKind::IntrinsicUser:
 611   case ARCInstKind::CallOrUser:
 612   case ARCInstKind::Call:
 613   case ARCInstKind::User:
 614   case ARCInstKind::None:
 615   case ARCInstKind::NoopCast:
 616     return false;
 617   }
 618   llvm_unreachable("covered switch isn't covered?");
 619 }
 620
 621 /// Test whether the given instruction can autorelease any pointer or cause an
 622 /// autoreleasepool pop.
 623 ///
 624 /// This means that it *could* interrupt the RV optimization.
 625 bool llvm::objcarc::CanInterruptRV(ARCInstKind Class) {
 626   switch (Class) {
 627   case ARCInstKind::AutoreleasepoolPop:
 628   case ARCInstKind::CallOrUser:
 629   case ARCInstKind::Call:
 630   case ARCInstKind::Autorelease:
 631   case ARCInstKind::AutoreleaseRV:
 632   case ARCInstKind::FusedRetainAutorelease:
 633   case ARCInstKind::FusedRetainAutoreleaseRV:
 634     return true;
 635   case ARCInstKind::Retain:
 636   case ARCInstKind::RetainRV:
 637   case ARCInstKind::ClaimRV:
 638   case ARCInstKind::Release:
 639   case ARCInstKind::AutoreleasepoolPush:
 640   case ARCInstKind::RetainBlock:
 641   case ARCInstKind::LoadWeakRetained:
 642   case ARCInstKind::StoreWeak:
 643   case ARCInstKind::InitWeak:
 644   case ARCInstKind::LoadWeak:
 645   case ARCInstKind::MoveWeak:
 646   case ARCInstKind::CopyWeak:
 647   case ARCInstKind::DestroyWeak:
 648   case ARCInstKind::StoreStrong:
 649   case ARCInstKind::IntrinsicUser:
 650   case ARCInstKind::User:
 651   case ARCInstKind::None:
 652   case ARCInstKind::NoopCast:
 653     return false;
 654   }
 655   llvm_unreachable("covered switch isn't covered?");
 656 }
 657
 658 bool llvm::objcarc::CanDecrementRefCount(ARCInstKind Kind) {
 659   switch (Kind) {
 660   case ARCInstKind::Retain:
 661   case ARCInstKind::RetainRV:
 662   case ARCInstKind::Autorelease:
 663   case ARCInstKind::AutoreleaseRV:
 664   case ARCInstKind::NoopCast:
 665   case ARCInstKind::FusedRetainAutorelease:
 666   case ARCInstKind::FusedRetainAutoreleaseRV:
 667   case ARCInstKind::IntrinsicUser:
 668   case ARCInstKind::User:
 669   case ARCInstKind::None:
 670     return false;
 671
 672   // The cases below are conservative.
 673
 674   // RetainBlock can result in user defined copy constructors being called
 675   // implying releases may occur.
 676   case ARCInstKind::RetainBlock:
 677   case ARCInstKind::Release:
 678   case ARCInstKind::AutoreleasepoolPush:
 679   case ARCInstKind::AutoreleasepoolPop:
 680   case ARCInstKind::LoadWeakRetained:
 681   case ARCInstKind::StoreWeak:
 682   case ARCInstKind::InitWeak:
 683   case ARCInstKind::LoadWeak:
 684   case ARCInstKind::MoveWeak:
 685   case ARCInstKind::CopyWeak:
 686   case ARCInstKind::DestroyWeak:
 687   case ARCInstKind::StoreStrong:
 688   case ARCInstKind::CallOrUser:
 689   case ARCInstKind::Call:
 690   case ARCInstKind::ClaimRV:
 691     return true;
 692   }
 693
 694   llvm_unreachable("covered switch isn't covered?");
 695 }