| //===--- CGAtomic.cpp - Emit LLVM IR for atomic operations ----------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains the code for emitting atomic operations. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CodeGenFunction.h" |
| #include "CGCall.h" |
| #include "CodeGenModule.h" |
| #include "clang/AST/ASTContext.h" |
| #include "llvm/IR/DataLayout.h" |
| #include "llvm/IR/Intrinsics.h" |
| |
| using namespace clang; |
| using namespace CodeGen; |
| |
| static void |
| EmitAtomicOp(CodeGenFunction &CGF, AtomicExpr *E, llvm::Value *Dest, |
| llvm::Value *Ptr, llvm::Value *Val1, llvm::Value *Val2, |
| uint64_t Size, unsigned Align, llvm::AtomicOrdering Order) { |
| llvm::AtomicRMWInst::BinOp Op = llvm::AtomicRMWInst::Add; |
| llvm::Instruction::BinaryOps PostOp = (llvm::Instruction::BinaryOps)0; |
| |
| switch (E->getOp()) { |
| case AtomicExpr::AO__c11_atomic_init: |
| llvm_unreachable("Already handled!"); |
| |
| case AtomicExpr::AO__c11_atomic_compare_exchange_strong: |
| case AtomicExpr::AO__c11_atomic_compare_exchange_weak: |
| case AtomicExpr::AO__atomic_compare_exchange: |
| case AtomicExpr::AO__atomic_compare_exchange_n: { |
| // Note that cmpxchg only supports specifying one ordering and |
| // doesn't support weak cmpxchg, at least at the moment. |
| llvm::LoadInst *LoadVal1 = CGF.Builder.CreateLoad(Val1); |
| LoadVal1->setAlignment(Align); |
| llvm::LoadInst *LoadVal2 = CGF.Builder.CreateLoad(Val2); |
| LoadVal2->setAlignment(Align); |
| llvm::AtomicCmpXchgInst *CXI = |
| CGF.Builder.CreateAtomicCmpXchg(Ptr, LoadVal1, LoadVal2, Order); |
| CXI->setVolatile(E->isVolatile()); |
| llvm::StoreInst *StoreVal1 = CGF.Builder.CreateStore(CXI, Val1); |
| StoreVal1->setAlignment(Align); |
| llvm::Value *Cmp = CGF.Builder.CreateICmpEQ(CXI, LoadVal1); |
| CGF.EmitStoreOfScalar(Cmp, CGF.MakeAddrLValue(Dest, E->getType())); |
| return; |
| } |
| |
| case AtomicExpr::AO__c11_atomic_load: |
| case AtomicExpr::AO__atomic_load_n: |
| case AtomicExpr::AO__atomic_load: { |
| llvm::LoadInst *Load = CGF.Builder.CreateLoad(Ptr); |
| Load->setAtomic(Order); |
| Load->setAlignment(Size); |
| Load->setVolatile(E->isVolatile()); |
| llvm::StoreInst *StoreDest = CGF.Builder.CreateStore(Load, Dest); |
| StoreDest->setAlignment(Align); |
| return; |
| } |
| |
| case AtomicExpr::AO__c11_atomic_store: |
| case AtomicExpr::AO__atomic_store: |
| case AtomicExpr::AO__atomic_store_n: { |
| assert(!Dest && "Store does not return a value"); |
| llvm::LoadInst *LoadVal1 = CGF.Builder.CreateLoad(Val1); |
| LoadVal1->setAlignment(Align); |
| llvm::StoreInst *Store = CGF.Builder.CreateStore(LoadVal1, Ptr); |
| Store->setAtomic(Order); |
| Store->setAlignment(Size); |
| Store->setVolatile(E->isVolatile()); |
| return; |
| } |
| |
| case AtomicExpr::AO__c11_atomic_exchange: |
| case AtomicExpr::AO__atomic_exchange_n: |
| case AtomicExpr::AO__atomic_exchange: |
| Op = llvm::AtomicRMWInst::Xchg; |
| break; |
| |
| case AtomicExpr::AO__atomic_add_fetch: |
| PostOp = llvm::Instruction::Add; |
| // Fall through. |
| case AtomicExpr::AO__c11_atomic_fetch_add: |
| case AtomicExpr::AO__atomic_fetch_add: |
| Op = llvm::AtomicRMWInst::Add; |
| break; |
| |
| case AtomicExpr::AO__atomic_sub_fetch: |
| PostOp = llvm::Instruction::Sub; |
| // Fall through. |
| case AtomicExpr::AO__c11_atomic_fetch_sub: |
| case AtomicExpr::AO__atomic_fetch_sub: |
| Op = llvm::AtomicRMWInst::Sub; |
| break; |
| |
| case AtomicExpr::AO__atomic_and_fetch: |
| PostOp = llvm::Instruction::And; |
| // Fall through. |
| case AtomicExpr::AO__c11_atomic_fetch_and: |
| case AtomicExpr::AO__atomic_fetch_and: |
| Op = llvm::AtomicRMWInst::And; |
| break; |
| |
| case AtomicExpr::AO__atomic_or_fetch: |
| PostOp = llvm::Instruction::Or; |
| // Fall through. |
| case AtomicExpr::AO__c11_atomic_fetch_or: |
| case AtomicExpr::AO__atomic_fetch_or: |
| Op = llvm::AtomicRMWInst::Or; |
| break; |
| |
| case AtomicExpr::AO__atomic_xor_fetch: |
| PostOp = llvm::Instruction::Xor; |
| // Fall through. |
| case AtomicExpr::AO__c11_atomic_fetch_xor: |
| case AtomicExpr::AO__atomic_fetch_xor: |
| Op = llvm::AtomicRMWInst::Xor; |
| break; |
| |
| case AtomicExpr::AO__atomic_nand_fetch: |
| PostOp = llvm::Instruction::And; |
| // Fall through. |
| case AtomicExpr::AO__atomic_fetch_nand: |
| Op = llvm::AtomicRMWInst::Nand; |
| break; |
| } |
| |
| llvm::LoadInst *LoadVal1 = CGF.Builder.CreateLoad(Val1); |
| LoadVal1->setAlignment(Align); |
| llvm::AtomicRMWInst *RMWI = |
| CGF.Builder.CreateAtomicRMW(Op, Ptr, LoadVal1, Order); |
| RMWI->setVolatile(E->isVolatile()); |
| |
| // For __atomic_*_fetch operations, perform the operation again to |
| // determine the value which was written. |
| llvm::Value *Result = RMWI; |
| if (PostOp) |
| Result = CGF.Builder.CreateBinOp(PostOp, RMWI, LoadVal1); |
| if (E->getOp() == AtomicExpr::AO__atomic_nand_fetch) |
| Result = CGF.Builder.CreateNot(Result); |
| llvm::StoreInst *StoreDest = CGF.Builder.CreateStore(Result, Dest); |
| StoreDest->setAlignment(Align); |
| } |
| |
| // This function emits any expression (scalar, complex, or aggregate) |
| // into a temporary alloca. |
| static llvm::Value * |
| EmitValToTemp(CodeGenFunction &CGF, Expr *E) { |
| llvm::Value *DeclPtr = CGF.CreateMemTemp(E->getType(), ".atomictmp"); |
| CGF.EmitAnyExprToMem(E, DeclPtr, E->getType().getQualifiers(), |
| /*Init*/ true); |
| return DeclPtr; |
| } |
| |
| RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E, llvm::Value *Dest) { |
| QualType AtomicTy = E->getPtr()->getType()->getPointeeType(); |
| QualType MemTy = AtomicTy; |
| if (const AtomicType *AT = AtomicTy->getAs<AtomicType>()) |
| MemTy = AT->getValueType(); |
| CharUnits sizeChars = getContext().getTypeSizeInChars(AtomicTy); |
| uint64_t Size = sizeChars.getQuantity(); |
| CharUnits alignChars = getContext().getTypeAlignInChars(AtomicTy); |
| unsigned Align = alignChars.getQuantity(); |
| unsigned MaxInlineWidthInBits = |
| getContext().getTargetInfo().getMaxAtomicInlineWidth(); |
| bool UseLibcall = (Size != Align || |
| getContext().toBits(sizeChars) > MaxInlineWidthInBits); |
| |
| llvm::Value *Ptr, *Order, *OrderFail = 0, *Val1 = 0, *Val2 = 0; |
| Ptr = EmitScalarExpr(E->getPtr()); |
| |
| if (E->getOp() == AtomicExpr::AO__c11_atomic_init) { |
| assert(!Dest && "Init does not return a value"); |
| LValue LV = MakeAddrLValue(Ptr, AtomicTy, alignChars); |
| switch (getEvaluationKind(E->getVal1()->getType())) { |
| case TEK_Scalar: |
| EmitScalarInit(EmitScalarExpr(E->getVal1()), LV); |
| return RValue::get(0); |
| case TEK_Complex: |
| EmitComplexExprIntoLValue(E->getVal1(), LV, /*isInit*/ true); |
| return RValue::get(0); |
| case TEK_Aggregate: { |
| AggValueSlot Slot = AggValueSlot::forLValue(LV, |
| AggValueSlot::IsNotDestructed, |
| AggValueSlot::DoesNotNeedGCBarriers, |
| AggValueSlot::IsNotAliased); |
| EmitAggExpr(E->getVal1(), Slot); |
| return RValue::get(0); |
| } |
| } |
| llvm_unreachable("bad evaluation kind"); |
| } |
| |
| Order = EmitScalarExpr(E->getOrder()); |
| |
| switch (E->getOp()) { |
| case AtomicExpr::AO__c11_atomic_init: |
| llvm_unreachable("Already handled!"); |
| |
| case AtomicExpr::AO__c11_atomic_load: |
| case AtomicExpr::AO__atomic_load_n: |
| break; |
| |
| case AtomicExpr::AO__atomic_load: |
| Dest = EmitScalarExpr(E->getVal1()); |
| break; |
| |
| case AtomicExpr::AO__atomic_store: |
| Val1 = EmitScalarExpr(E->getVal1()); |
| break; |
| |
| case AtomicExpr::AO__atomic_exchange: |
| Val1 = EmitScalarExpr(E->getVal1()); |
| Dest = EmitScalarExpr(E->getVal2()); |
| break; |
| |
| case AtomicExpr::AO__c11_atomic_compare_exchange_strong: |
| case AtomicExpr::AO__c11_atomic_compare_exchange_weak: |
| case AtomicExpr::AO__atomic_compare_exchange_n: |
| case AtomicExpr::AO__atomic_compare_exchange: |
| Val1 = EmitScalarExpr(E->getVal1()); |
| if (E->getOp() == AtomicExpr::AO__atomic_compare_exchange) |
| Val2 = EmitScalarExpr(E->getVal2()); |
| else |
| Val2 = EmitValToTemp(*this, E->getVal2()); |
| OrderFail = EmitScalarExpr(E->getOrderFail()); |
| // Evaluate and discard the 'weak' argument. |
| if (E->getNumSubExprs() == 6) |
| EmitScalarExpr(E->getWeak()); |
| break; |
| |
| case AtomicExpr::AO__c11_atomic_fetch_add: |
| case AtomicExpr::AO__c11_atomic_fetch_sub: |
| if (MemTy->isPointerType()) { |
| // For pointer arithmetic, we're required to do a bit of math: |
| // adding 1 to an int* is not the same as adding 1 to a uintptr_t. |
| // ... but only for the C11 builtins. The GNU builtins expect the |
| // user to multiply by sizeof(T). |
| QualType Val1Ty = E->getVal1()->getType(); |
| llvm::Value *Val1Scalar = EmitScalarExpr(E->getVal1()); |
| CharUnits PointeeIncAmt = |
| getContext().getTypeSizeInChars(MemTy->getPointeeType()); |
| Val1Scalar = Builder.CreateMul(Val1Scalar, CGM.getSize(PointeeIncAmt)); |
| Val1 = CreateMemTemp(Val1Ty, ".atomictmp"); |
| EmitStoreOfScalar(Val1Scalar, MakeAddrLValue(Val1, Val1Ty)); |
| break; |
| } |
| // Fall through. |
| case AtomicExpr::AO__atomic_fetch_add: |
| case AtomicExpr::AO__atomic_fetch_sub: |
| case AtomicExpr::AO__atomic_add_fetch: |
| case AtomicExpr::AO__atomic_sub_fetch: |
| case AtomicExpr::AO__c11_atomic_store: |
| case AtomicExpr::AO__c11_atomic_exchange: |
| case AtomicExpr::AO__atomic_store_n: |
| case AtomicExpr::AO__atomic_exchange_n: |
| case AtomicExpr::AO__c11_atomic_fetch_and: |
| case AtomicExpr::AO__c11_atomic_fetch_or: |
| case AtomicExpr::AO__c11_atomic_fetch_xor: |
| case AtomicExpr::AO__atomic_fetch_and: |
| case AtomicExpr::AO__atomic_fetch_or: |
| case AtomicExpr::AO__atomic_fetch_xor: |
| case AtomicExpr::AO__atomic_fetch_nand: |
| case AtomicExpr::AO__atomic_and_fetch: |
| case AtomicExpr::AO__atomic_or_fetch: |
| case AtomicExpr::AO__atomic_xor_fetch: |
| case AtomicExpr::AO__atomic_nand_fetch: |
| Val1 = EmitValToTemp(*this, E->getVal1()); |
| break; |
| } |
| |
| if (!E->getType()->isVoidType() && !Dest) |
| Dest = CreateMemTemp(E->getType(), ".atomicdst"); |
| |
| // Use a library call. See: http://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary . |
| if (UseLibcall) { |
| |
| SmallVector<QualType, 5> Params; |
| CallArgList Args; |
| // Size is always the first parameter |
| Args.add(RValue::get(llvm::ConstantInt::get(SizeTy, Size)), |
| getContext().getSizeType()); |
| // Atomic address is always the second parameter |
| Args.add(RValue::get(EmitCastToVoidPtr(Ptr)), |
| getContext().VoidPtrTy); |
| |
| const char* LibCallName; |
| QualType RetTy = getContext().VoidTy; |
| switch (E->getOp()) { |
| // There is only one libcall for compare an exchange, because there is no |
| // optimisation benefit possible from a libcall version of a weak compare |
| // and exchange. |
| // bool __atomic_compare_exchange(size_t size, void *obj, void *expected, |
| // void *desired, int success, int failure) |
| case AtomicExpr::AO__c11_atomic_compare_exchange_weak: |
| case AtomicExpr::AO__c11_atomic_compare_exchange_strong: |
| case AtomicExpr::AO__atomic_compare_exchange: |
| case AtomicExpr::AO__atomic_compare_exchange_n: |
| LibCallName = "__atomic_compare_exchange"; |
| RetTy = getContext().BoolTy; |
| Args.add(RValue::get(EmitCastToVoidPtr(Val1)), |
| getContext().VoidPtrTy); |
| Args.add(RValue::get(EmitCastToVoidPtr(Val2)), |
| getContext().VoidPtrTy); |
| Args.add(RValue::get(Order), |
| getContext().IntTy); |
| Order = OrderFail; |
| break; |
| // void __atomic_exchange(size_t size, void *mem, void *val, void *return, |
| // int order) |
| case AtomicExpr::AO__c11_atomic_exchange: |
| case AtomicExpr::AO__atomic_exchange_n: |
| case AtomicExpr::AO__atomic_exchange: |
| LibCallName = "__atomic_exchange"; |
| Args.add(RValue::get(EmitCastToVoidPtr(Val1)), |
| getContext().VoidPtrTy); |
| Args.add(RValue::get(EmitCastToVoidPtr(Dest)), |
| getContext().VoidPtrTy); |
| break; |
| // void __atomic_store(size_t size, void *mem, void *val, int order) |
| case AtomicExpr::AO__c11_atomic_store: |
| case AtomicExpr::AO__atomic_store: |
| case AtomicExpr::AO__atomic_store_n: |
| LibCallName = "__atomic_store"; |
| Args.add(RValue::get(EmitCastToVoidPtr(Val1)), |
| getContext().VoidPtrTy); |
| break; |
| // void __atomic_load(size_t size, void *mem, void *return, int order) |
| case AtomicExpr::AO__c11_atomic_load: |
| case AtomicExpr::AO__atomic_load: |
| case AtomicExpr::AO__atomic_load_n: |
| LibCallName = "__atomic_load"; |
| Args.add(RValue::get(EmitCastToVoidPtr(Dest)), |
| getContext().VoidPtrTy); |
| break; |
| #if 0 |
| // These are only defined for 1-16 byte integers. It is not clear what |
| // their semantics would be on anything else... |
| case AtomicExpr::Add: LibCallName = "__atomic_fetch_add_generic"; break; |
| case AtomicExpr::Sub: LibCallName = "__atomic_fetch_sub_generic"; break; |
| case AtomicExpr::And: LibCallName = "__atomic_fetch_and_generic"; break; |
| case AtomicExpr::Or: LibCallName = "__atomic_fetch_or_generic"; break; |
| case AtomicExpr::Xor: LibCallName = "__atomic_fetch_xor_generic"; break; |
| #endif |
| default: return EmitUnsupportedRValue(E, "atomic library call"); |
| } |
| // order is always the last parameter |
| Args.add(RValue::get(Order), |
| getContext().IntTy); |
| |
| const CGFunctionInfo &FuncInfo = |
| CGM.getTypes().arrangeFreeFunctionCall(RetTy, Args, |
| FunctionType::ExtInfo(), RequiredArgs::All); |
| llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FuncInfo); |
| llvm::Constant *Func = CGM.CreateRuntimeFunction(FTy, LibCallName); |
| RValue Res = EmitCall(FuncInfo, Func, ReturnValueSlot(), Args); |
| if (E->isCmpXChg()) |
| return Res; |
| if (E->getType()->isVoidType()) |
| return RValue::get(0); |
| return convertTempToRValue(Dest, E->getType()); |
| } |
| |
| bool IsStore = E->getOp() == AtomicExpr::AO__c11_atomic_store || |
| E->getOp() == AtomicExpr::AO__atomic_store || |
| E->getOp() == AtomicExpr::AO__atomic_store_n; |
| bool IsLoad = E->getOp() == AtomicExpr::AO__c11_atomic_load || |
| E->getOp() == AtomicExpr::AO__atomic_load || |
| E->getOp() == AtomicExpr::AO__atomic_load_n; |
| |
| llvm::Type *IPtrTy = |
| llvm::IntegerType::get(getLLVMContext(), Size * 8)->getPointerTo(); |
| llvm::Value *OrigDest = Dest; |
| Ptr = Builder.CreateBitCast(Ptr, IPtrTy); |
| if (Val1) Val1 = Builder.CreateBitCast(Val1, IPtrTy); |
| if (Val2) Val2 = Builder.CreateBitCast(Val2, IPtrTy); |
| if (Dest && !E->isCmpXChg()) Dest = Builder.CreateBitCast(Dest, IPtrTy); |
| |
| if (isa<llvm::ConstantInt>(Order)) { |
| int ord = cast<llvm::ConstantInt>(Order)->getZExtValue(); |
| switch (ord) { |
| case 0: // memory_order_relaxed |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::Monotonic); |
| break; |
| case 1: // memory_order_consume |
| case 2: // memory_order_acquire |
| if (IsStore) |
| break; // Avoid crashing on code with undefined behavior |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::Acquire); |
| break; |
| case 3: // memory_order_release |
| if (IsLoad) |
| break; // Avoid crashing on code with undefined behavior |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::Release); |
| break; |
| case 4: // memory_order_acq_rel |
| if (IsLoad || IsStore) |
| break; // Avoid crashing on code with undefined behavior |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::AcquireRelease); |
| break; |
| case 5: // memory_order_seq_cst |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::SequentiallyConsistent); |
| break; |
| default: // invalid order |
| // We should not ever get here normally, but it's hard to |
| // enforce that in general. |
| break; |
| } |
| if (E->getType()->isVoidType()) |
| return RValue::get(0); |
| return convertTempToRValue(OrigDest, E->getType()); |
| } |
| |
| // Long case, when Order isn't obviously constant. |
| |
| // Create all the relevant BB's |
| llvm::BasicBlock *MonotonicBB = 0, *AcquireBB = 0, *ReleaseBB = 0, |
| *AcqRelBB = 0, *SeqCstBB = 0; |
| MonotonicBB = createBasicBlock("monotonic", CurFn); |
| if (!IsStore) |
| AcquireBB = createBasicBlock("acquire", CurFn); |
| if (!IsLoad) |
| ReleaseBB = createBasicBlock("release", CurFn); |
| if (!IsLoad && !IsStore) |
| AcqRelBB = createBasicBlock("acqrel", CurFn); |
| SeqCstBB = createBasicBlock("seqcst", CurFn); |
| llvm::BasicBlock *ContBB = createBasicBlock("atomic.continue", CurFn); |
| |
| // Create the switch for the split |
| // MonotonicBB is arbitrarily chosen as the default case; in practice, this |
| // doesn't matter unless someone is crazy enough to use something that |
| // doesn't fold to a constant for the ordering. |
| Order = Builder.CreateIntCast(Order, Builder.getInt32Ty(), false); |
| llvm::SwitchInst *SI = Builder.CreateSwitch(Order, MonotonicBB); |
| |
| // Emit all the different atomics |
| Builder.SetInsertPoint(MonotonicBB); |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::Monotonic); |
| Builder.CreateBr(ContBB); |
| if (!IsStore) { |
| Builder.SetInsertPoint(AcquireBB); |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::Acquire); |
| Builder.CreateBr(ContBB); |
| SI->addCase(Builder.getInt32(1), AcquireBB); |
| SI->addCase(Builder.getInt32(2), AcquireBB); |
| } |
| if (!IsLoad) { |
| Builder.SetInsertPoint(ReleaseBB); |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::Release); |
| Builder.CreateBr(ContBB); |
| SI->addCase(Builder.getInt32(3), ReleaseBB); |
| } |
| if (!IsLoad && !IsStore) { |
| Builder.SetInsertPoint(AcqRelBB); |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::AcquireRelease); |
| Builder.CreateBr(ContBB); |
| SI->addCase(Builder.getInt32(4), AcqRelBB); |
| } |
| Builder.SetInsertPoint(SeqCstBB); |
| EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align, |
| llvm::SequentiallyConsistent); |
| Builder.CreateBr(ContBB); |
| SI->addCase(Builder.getInt32(5), SeqCstBB); |
| |
| // Cleanup and return |
| Builder.SetInsertPoint(ContBB); |
| if (E->getType()->isVoidType()) |
| return RValue::get(0); |
| return convertTempToRValue(OrigDest, E->getType()); |
| } |
