| //===- ObjCARCUtil.cpp - ObjC ARC Optimization ----------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| /// \file |
| /// This file defines several utility functions used by various ARC |
| /// optimizations which are IMHO too big to be in a header file. |
| /// |
| /// WARNING: This file knows about certain library functions. It recognizes them |
| /// by name, and hardwires knowledge of their semantics. |
| /// |
| /// WARNING: This file knows about how certain Objective-C library functions are |
| /// used. Naive LLVM IR transformations which would otherwise be |
| /// behavior-preserving may break these assumptions. |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #include "ObjCARC.h" |
| #include "llvm/IR/Intrinsics.h" |
| |
| using namespace llvm; |
| using namespace llvm::objcarc; |
| |
| raw_ostream &llvm::objcarc::operator<<(raw_ostream &OS, |
| const InstructionClass Class) { |
| switch (Class) { |
| case IC_Retain: |
| return OS << "IC_Retain"; |
| case IC_RetainRV: |
| return OS << "IC_RetainRV"; |
| case IC_RetainBlock: |
| return OS << "IC_RetainBlock"; |
| case IC_Release: |
| return OS << "IC_Release"; |
| case IC_Autorelease: |
| return OS << "IC_Autorelease"; |
| case IC_AutoreleaseRV: |
| return OS << "IC_AutoreleaseRV"; |
| case IC_AutoreleasepoolPush: |
| return OS << "IC_AutoreleasepoolPush"; |
| case IC_AutoreleasepoolPop: |
| return OS << "IC_AutoreleasepoolPop"; |
| case IC_NoopCast: |
| return OS << "IC_NoopCast"; |
| case IC_FusedRetainAutorelease: |
| return OS << "IC_FusedRetainAutorelease"; |
| case IC_FusedRetainAutoreleaseRV: |
| return OS << "IC_FusedRetainAutoreleaseRV"; |
| case IC_LoadWeakRetained: |
| return OS << "IC_LoadWeakRetained"; |
| case IC_StoreWeak: |
| return OS << "IC_StoreWeak"; |
| case IC_InitWeak: |
| return OS << "IC_InitWeak"; |
| case IC_LoadWeak: |
| return OS << "IC_LoadWeak"; |
| case IC_MoveWeak: |
| return OS << "IC_MoveWeak"; |
| case IC_CopyWeak: |
| return OS << "IC_CopyWeak"; |
| case IC_DestroyWeak: |
| return OS << "IC_DestroyWeak"; |
| case IC_StoreStrong: |
| return OS << "IC_StoreStrong"; |
| case IC_CallOrUser: |
| return OS << "IC_CallOrUser"; |
| case IC_Call: |
| return OS << "IC_Call"; |
| case IC_User: |
| return OS << "IC_User"; |
| case IC_IntrinsicUser: |
| return OS << "IC_IntrinsicUser"; |
| case IC_None: |
| return OS << "IC_None"; |
| } |
| llvm_unreachable("Unknown instruction class!"); |
| } |
| |
| InstructionClass llvm::objcarc::GetFunctionClass(const Function *F) { |
| Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end(); |
| |
| // No (mandatory) arguments. |
| if (AI == AE) |
| return StringSwitch<InstructionClass>(F->getName()) |
| .Case("objc_autoreleasePoolPush", IC_AutoreleasepoolPush) |
| .Case("clang.arc.use", IC_IntrinsicUser) |
| .Default(IC_CallOrUser); |
| |
| // One argument. |
| const Argument *A0 = AI++; |
| if (AI == AE) |
| // Argument is a pointer. |
| if (PointerType *PTy = dyn_cast<PointerType>(A0->getType())) { |
| Type *ETy = PTy->getElementType(); |
| // Argument is i8*. |
| if (ETy->isIntegerTy(8)) |
| return StringSwitch<InstructionClass>(F->getName()) |
| .Case("objc_retain", IC_Retain) |
| .Case("objc_retainAutoreleasedReturnValue", IC_RetainRV) |
| .Case("objc_retainBlock", IC_RetainBlock) |
| .Case("objc_release", IC_Release) |
| .Case("objc_autorelease", IC_Autorelease) |
| .Case("objc_autoreleaseReturnValue", IC_AutoreleaseRV) |
| .Case("objc_autoreleasePoolPop", IC_AutoreleasepoolPop) |
| .Case("objc_retainedObject", IC_NoopCast) |
| .Case("objc_unretainedObject", IC_NoopCast) |
| .Case("objc_unretainedPointer", IC_NoopCast) |
| .Case("objc_retain_autorelease", IC_FusedRetainAutorelease) |
| .Case("objc_retainAutorelease", IC_FusedRetainAutorelease) |
| .Case("objc_retainAutoreleaseReturnValue",IC_FusedRetainAutoreleaseRV) |
| .Case("objc_sync_enter", IC_User) |
| .Case("objc_sync_exit", IC_User) |
| .Default(IC_CallOrUser); |
| |
| // Argument is i8** |
| if (PointerType *Pte = dyn_cast<PointerType>(ETy)) |
| if (Pte->getElementType()->isIntegerTy(8)) |
| return StringSwitch<InstructionClass>(F->getName()) |
| .Case("objc_loadWeakRetained", IC_LoadWeakRetained) |
| .Case("objc_loadWeak", IC_LoadWeak) |
| .Case("objc_destroyWeak", IC_DestroyWeak) |
| .Default(IC_CallOrUser); |
| } |
| |
| // Two arguments, first is i8**. |
| const Argument *A1 = AI++; |
| if (AI == AE) |
| if (PointerType *PTy = dyn_cast<PointerType>(A0->getType())) |
| if (PointerType *Pte = dyn_cast<PointerType>(PTy->getElementType())) |
| if (Pte->getElementType()->isIntegerTy(8)) |
| if (PointerType *PTy1 = dyn_cast<PointerType>(A1->getType())) { |
| Type *ETy1 = PTy1->getElementType(); |
| // Second argument is i8* |
| if (ETy1->isIntegerTy(8)) |
| return StringSwitch<InstructionClass>(F->getName()) |
| .Case("objc_storeWeak", IC_StoreWeak) |
| .Case("objc_initWeak", IC_InitWeak) |
| .Case("objc_storeStrong", IC_StoreStrong) |
| .Default(IC_CallOrUser); |
| // Second argument is i8**. |
| if (PointerType *Pte1 = dyn_cast<PointerType>(ETy1)) |
| if (Pte1->getElementType()->isIntegerTy(8)) |
| return StringSwitch<InstructionClass>(F->getName()) |
| .Case("objc_moveWeak", IC_MoveWeak) |
| .Case("objc_copyWeak", IC_CopyWeak) |
| // Ignore annotation calls. This is important to stop the |
| // optimizer from treating annotations as uses which would |
| // make the state of the pointers they are attempting to |
| // elucidate to be incorrect. |
| .Case("llvm.arc.annotation.topdown.bbstart", IC_None) |
| .Case("llvm.arc.annotation.topdown.bbend", IC_None) |
| .Case("llvm.arc.annotation.bottomup.bbstart", IC_None) |
| .Case("llvm.arc.annotation.bottomup.bbend", IC_None) |
| .Default(IC_CallOrUser); |
| } |
| |
| // Anything else. |
| return IC_CallOrUser; |
| } |
| |
| /// \brief Determine what kind of construct V is. |
| InstructionClass |
| llvm::objcarc::GetInstructionClass(const Value *V) { |
| if (const Instruction *I = dyn_cast<Instruction>(V)) { |
| // Any instruction other than bitcast and gep with a pointer operand have a |
| // use of an objc pointer. Bitcasts, GEPs, Selects, PHIs transfer a pointer |
| // to a subsequent use, rather than using it themselves, in this sense. |
| // As a short cut, several other opcodes are known to have no pointer |
| // operands of interest. And ret is never followed by a release, so it's |
| // not interesting to examine. |
| switch (I->getOpcode()) { |
| case Instruction::Call: { |
| const CallInst *CI = cast<CallInst>(I); |
| // Check for calls to special functions. |
| if (const Function *F = CI->getCalledFunction()) { |
| InstructionClass Class = GetFunctionClass(F); |
| if (Class != IC_CallOrUser) |
| return Class; |
| |
| // None of the intrinsic functions do objc_release. For intrinsics, the |
| // only question is whether or not they may be users. |
| switch (F->getIntrinsicID()) { |
| case Intrinsic::returnaddress: case Intrinsic::frameaddress: |
| case Intrinsic::stacksave: case Intrinsic::stackrestore: |
| case Intrinsic::vastart: case Intrinsic::vacopy: case Intrinsic::vaend: |
| case Intrinsic::objectsize: case Intrinsic::prefetch: |
| case Intrinsic::stackprotector: |
| case Intrinsic::eh_return_i32: case Intrinsic::eh_return_i64: |
| case Intrinsic::eh_typeid_for: case Intrinsic::eh_dwarf_cfa: |
| case Intrinsic::eh_sjlj_lsda: case Intrinsic::eh_sjlj_functioncontext: |
| case Intrinsic::init_trampoline: case Intrinsic::adjust_trampoline: |
| case Intrinsic::lifetime_start: case Intrinsic::lifetime_end: |
| case Intrinsic::invariant_start: case Intrinsic::invariant_end: |
| // Don't let dbg info affect our results. |
| case Intrinsic::dbg_declare: case Intrinsic::dbg_value: |
| // Short cut: Some intrinsics obviously don't use ObjC pointers. |
| return IC_None; |
| default: |
| break; |
| } |
| } |
| return GetCallSiteClass(CI); |
| } |
| case Instruction::Invoke: |
| return GetCallSiteClass(cast<InvokeInst>(I)); |
| case Instruction::BitCast: |
| case Instruction::GetElementPtr: |
| case Instruction::Select: case Instruction::PHI: |
| case Instruction::Ret: case Instruction::Br: |
| case Instruction::Switch: case Instruction::IndirectBr: |
| case Instruction::Alloca: case Instruction::VAArg: |
| case Instruction::Add: case Instruction::FAdd: |
| case Instruction::Sub: case Instruction::FSub: |
| case Instruction::Mul: case Instruction::FMul: |
| case Instruction::SDiv: case Instruction::UDiv: case Instruction::FDiv: |
| case Instruction::SRem: case Instruction::URem: case Instruction::FRem: |
| case Instruction::Shl: case Instruction::LShr: case Instruction::AShr: |
| case Instruction::And: case Instruction::Or: case Instruction::Xor: |
| case Instruction::SExt: case Instruction::ZExt: case Instruction::Trunc: |
| case Instruction::IntToPtr: case Instruction::FCmp: |
| case Instruction::FPTrunc: case Instruction::FPExt: |
| case Instruction::FPToUI: case Instruction::FPToSI: |
| case Instruction::UIToFP: case Instruction::SIToFP: |
| case Instruction::InsertElement: case Instruction::ExtractElement: |
| case Instruction::ShuffleVector: |
| case Instruction::ExtractValue: |
| break; |
| case Instruction::ICmp: |
| // Comparing a pointer with null, or any other constant, isn't an |
| // interesting use, because we don't care what the pointer points to, or |
| // about the values of any other dynamic reference-counted pointers. |
| if (IsPotentialRetainableObjPtr(I->getOperand(1))) |
| return IC_User; |
| break; |
| default: |
| // For anything else, check all the operands. |
| // Note that this includes both operands of a Store: while the first |
| // operand isn't actually being dereferenced, it is being stored to |
| // memory where we can no longer track who might read it and dereference |
| // it, so we have to consider it potentially used. |
| for (User::const_op_iterator OI = I->op_begin(), OE = I->op_end(); |
| OI != OE; ++OI) |
| if (IsPotentialRetainableObjPtr(*OI)) |
| return IC_User; |
| } |
| } |
| |
| // Otherwise, it's totally inert for ARC purposes. |
| return IC_None; |
| } |
