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//===- ObjCARCUtil.cpp - ObjC ARC Optimization --------*- mode: c++ -*-----===//
//
// 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)
.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;
}
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