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llvm-project/clang/lib/CodeGen/CGAtomic.cpp

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//===--- 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 "clang/CodeGen/CGFunctionInfo.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Operator.h"
using namespace clang;
using namespace CodeGen;
// The ABI values for various atomic memory orderings.
enum AtomicOrderingKind {
AO_ABI_memory_order_relaxed = 0,
AO_ABI_memory_order_consume = 1,
AO_ABI_memory_order_acquire = 2,
AO_ABI_memory_order_release = 3,
AO_ABI_memory_order_acq_rel = 4,
AO_ABI_memory_order_seq_cst = 5
};
namespace {
class AtomicInfo {
CodeGenFunction &CGF;
QualType AtomicTy;
QualType ValueTy;
uint64_t AtomicSizeInBits;
uint64_t ValueSizeInBits;
CharUnits AtomicAlign;
CharUnits ValueAlign;
CharUnits LValueAlign;
TypeEvaluationKind EvaluationKind;
bool UseLibcall;
public:
AtomicInfo(CodeGenFunction &CGF, LValue &lvalue) : CGF(CGF) {
assert(lvalue.isSimple());
AtomicTy = lvalue.getType();
ValueTy = AtomicTy->castAs<AtomicType>()->getValueType();
EvaluationKind = CGF.getEvaluationKind(ValueTy);
ASTContext &C = CGF.getContext();
uint64_t valueAlignInBits;
std::tie(ValueSizeInBits, valueAlignInBits) = C.getTypeInfo(ValueTy);
uint64_t atomicAlignInBits;
std::tie(AtomicSizeInBits, atomicAlignInBits) = C.getTypeInfo(AtomicTy);
assert(ValueSizeInBits <= AtomicSizeInBits);
assert(valueAlignInBits <= atomicAlignInBits);
AtomicAlign = C.toCharUnitsFromBits(atomicAlignInBits);
ValueAlign = C.toCharUnitsFromBits(valueAlignInBits);
if (lvalue.getAlignment().isZero())
lvalue.setAlignment(AtomicAlign);
UseLibcall =
(AtomicSizeInBits > uint64_t(C.toBits(lvalue.getAlignment())) ||
AtomicSizeInBits > C.getTargetInfo().getMaxAtomicInlineWidth());
}
QualType getAtomicType() const { return AtomicTy; }
QualType getValueType() const { return ValueTy; }
CharUnits getAtomicAlignment() const { return AtomicAlign; }
CharUnits getValueAlignment() const { return ValueAlign; }
uint64_t getAtomicSizeInBits() const { return AtomicSizeInBits; }
uint64_t getValueSizeInBits() const { return AtomicSizeInBits; }
TypeEvaluationKind getEvaluationKind() const { return EvaluationKind; }
bool shouldUseLibcall() const { return UseLibcall; }
/// Is the atomic size larger than the underlying value type?
///
/// Note that the absence of padding does not mean that atomic
/// objects are completely interchangeable with non-atomic
/// objects: we might have promoted the alignment of a type
/// without making it bigger.
bool hasPadding() const {
return (ValueSizeInBits != AtomicSizeInBits);
}
bool emitMemSetZeroIfNecessary(LValue dest) const;
llvm::Value *getAtomicSizeValue() const {
CharUnits size = CGF.getContext().toCharUnitsFromBits(AtomicSizeInBits);
return CGF.CGM.getSize(size);
}
/// Cast the given pointer to an integer pointer suitable for
/// atomic operations.
llvm::Value *emitCastToAtomicIntPointer(llvm::Value *addr) const;
/// Turn an atomic-layout object into an r-value.
RValue convertTempToRValue(llvm::Value *addr,
AggValueSlot resultSlot,
SourceLocation loc) const;
/// Copy an atomic r-value into atomic-layout memory.
void emitCopyIntoMemory(RValue rvalue, LValue lvalue) const;
/// Project an l-value down to the value field.
LValue projectValue(LValue lvalue) const {
llvm::Value *addr = lvalue.getAddress();
if (hasPadding())
addr = CGF.Builder.CreateStructGEP(addr, 0);
return LValue::MakeAddr(addr, getValueType(), lvalue.getAlignment(),
CGF.getContext(), lvalue.getTBAAInfo());
}
/// Materialize an atomic r-value in atomic-layout memory.
llvm::Value *materializeRValue(RValue rvalue) const;
private:
bool requiresMemSetZero(llvm::Type *type) const;
};
}
static RValue emitAtomicLibcall(CodeGenFunction &CGF,
StringRef fnName,
QualType resultType,
CallArgList &args) {
const CGFunctionInfo &fnInfo =
CGF.CGM.getTypes().arrangeFreeFunctionCall(resultType, args,
FunctionType::ExtInfo(), RequiredArgs::All);
llvm::FunctionType *fnTy = CGF.CGM.getTypes().GetFunctionType(fnInfo);
llvm::Constant *fn = CGF.CGM.CreateRuntimeFunction(fnTy, fnName);
return CGF.EmitCall(fnInfo, fn, ReturnValueSlot(), args);
}
/// Does a store of the given IR type modify the full expected width?
static bool isFullSizeType(CodeGenModule &CGM, llvm::Type *type,
uint64_t expectedSize) {
return (CGM.getDataLayout().getTypeStoreSize(type) * 8 == expectedSize);
}
/// Does the atomic type require memsetting to zero before initialization?
///
/// The IR type is provided as a way of making certain queries faster.
bool AtomicInfo::requiresMemSetZero(llvm::Type *type) const {
// If the atomic type has size padding, we definitely need a memset.
if (hasPadding()) return true;
// Otherwise, do some simple heuristics to try to avoid it:
switch (getEvaluationKind()) {
// For scalars and complexes, check whether the store size of the
// type uses the full size.
case TEK_Scalar:
return !isFullSizeType(CGF.CGM, type, AtomicSizeInBits);
case TEK_Complex:
return !isFullSizeType(CGF.CGM, type->getStructElementType(0),
AtomicSizeInBits / 2);
// Padding in structs has an undefined bit pattern. User beware.
case TEK_Aggregate:
return false;
}
llvm_unreachable("bad evaluation kind");
}
bool AtomicInfo::emitMemSetZeroIfNecessary(LValue dest) const {
llvm::Value *addr = dest.getAddress();
if (!requiresMemSetZero(addr->getType()->getPointerElementType()))
return false;
CGF.Builder.CreateMemSet(addr, llvm::ConstantInt::get(CGF.Int8Ty, 0),
AtomicSizeInBits / 8,
dest.getAlignment().getQuantity());
return true;
}
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 *Expected = CGF.Builder.CreateLoad(Val1);
Expected->setAlignment(Align);
llvm::LoadInst *Desired = CGF.Builder.CreateLoad(Val2);
Desired->setAlignment(Align);
llvm::AtomicCmpXchgInst *Old =
CGF.Builder.CreateAtomicCmpXchg(Ptr, Expected, Desired, Order);
Old->setVolatile(E->isVolatile());
// Cmp holds the result of the compare-exchange operation: true on success,
// false on failure.
llvm::Value *Cmp = CGF.Builder.CreateICmpEQ(Old, Expected);
// This basic block is used to hold the store instruction if the operation
// failed.
llvm::BasicBlock *StoreExpectedBB =
CGF.createBasicBlock("cmpxchg.store_expected", CGF.CurFn);
// This basic block is the exit point of the operation, we should end up
// here regardless of whether or not the operation succeeded.
llvm::BasicBlock *ContinueBB =
CGF.createBasicBlock("cmpxchg.continue", CGF.CurFn);
// Update Expected if Expected isn't equal to Old, otherwise branch to the
// exit point.
CGF.Builder.CreateCondBr(Cmp, ContinueBB, StoreExpectedBB);
CGF.Builder.SetInsertPoint(StoreExpectedBB);
// Update the memory at Expected with Old's value.
llvm::StoreInst *StoreExpected = CGF.Builder.CreateStore(Old, Val1);
StoreExpected->setAlignment(Align);
// Finally, branch to the exit point.
CGF.Builder.CreateBr(ContinueBB);
CGF.Builder.SetInsertPoint(ContinueBB);
// Update the memory at Dest with Cmp's value.
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;
}
static void
AddDirectArgument(CodeGenFunction &CGF, CallArgList &Args,
bool UseOptimizedLibcall, llvm::Value *Val, QualType ValTy,
SourceLocation Loc) {
if (UseOptimizedLibcall) {
// Load value and pass it to the function directly.
unsigned Align = CGF.getContext().getTypeAlignInChars(ValTy).getQuantity();
Val = CGF.EmitLoadOfScalar(Val, false, Align, ValTy, Loc);
Args.add(RValue::get(Val), ValTy);
} else {
// Non-optimized functions always take a reference.
Args.add(RValue::get(CGF.EmitCastToVoidPtr(Val)),
CGF.getContext().VoidPtrTy);
}
}
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 =
getTarget().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 lvalue = LValue::MakeAddr(Ptr, AtomicTy, alignChars, getContext());
EmitAtomicInit(E->getVal1(), lvalue);
return RValue::get(0);
}
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) {
bool UseOptimizedLibcall = false;
switch (E->getOp()) {
case AtomicExpr::AO__c11_atomic_fetch_add:
case AtomicExpr::AO__atomic_fetch_add:
case AtomicExpr::AO__c11_atomic_fetch_and:
case AtomicExpr::AO__atomic_fetch_and:
case AtomicExpr::AO__c11_atomic_fetch_or:
case AtomicExpr::AO__atomic_fetch_or:
case AtomicExpr::AO__c11_atomic_fetch_sub:
case AtomicExpr::AO__atomic_fetch_sub:
case AtomicExpr::AO__c11_atomic_fetch_xor:
case AtomicExpr::AO__atomic_fetch_xor:
// For these, only library calls for certain sizes exist.
UseOptimizedLibcall = true;
break;
default:
// Only use optimized library calls for sizes for which they exist.
if (Size == 1 || Size == 2 || Size == 4 || Size == 8)
UseOptimizedLibcall = true;
break;
}
CallArgList Args;
if (!UseOptimizedLibcall) {
// For non-optimized library calls, the size is the first parameter
Args.add(RValue::get(llvm::ConstantInt::get(SizeTy, Size)),
getContext().getSizeType());
}
// Atomic address is the first or second parameter
Args.add(RValue::get(EmitCastToVoidPtr(Ptr)), getContext().VoidPtrTy);
std::string LibCallName;
QualType RetTy;
bool HaveRetTy = false;
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 *mem, void *expected,
// void *desired, int success, int failure)
// bool __atomic_compare_exchange_N(T *mem, T *expected, T 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;
HaveRetTy = true;
Args.add(RValue::get(EmitCastToVoidPtr(Val1)), getContext().VoidPtrTy);
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val2, MemTy,
E->getExprLoc());
Args.add(RValue::get(Order), getContext().IntTy);
Order = OrderFail;
break;
// void __atomic_exchange(size_t size, void *mem, void *val, void *return,
// int order)
// T __atomic_exchange_N(T *mem, T val, int order)
case AtomicExpr::AO__c11_atomic_exchange:
case AtomicExpr::AO__atomic_exchange_n:
case AtomicExpr::AO__atomic_exchange:
LibCallName = "__atomic_exchange";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1, MemTy,
E->getExprLoc());
break;
// void __atomic_store(size_t size, void *mem, void *val, int order)
// void __atomic_store_N(T *mem, T val, int order)
case AtomicExpr::AO__c11_atomic_store:
case AtomicExpr::AO__atomic_store:
case AtomicExpr::AO__atomic_store_n:
LibCallName = "__atomic_store";
RetTy = getContext().VoidTy;
HaveRetTy = true;
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1, MemTy,
E->getExprLoc());
break;
// void __atomic_load(size_t size, void *mem, void *return, int order)
// T __atomic_load_N(T *mem, int order)
case AtomicExpr::AO__c11_atomic_load:
case AtomicExpr::AO__atomic_load:
case AtomicExpr::AO__atomic_load_n:
LibCallName = "__atomic_load";
break;
// T __atomic_fetch_add_N(T *mem, T val, int order)
case AtomicExpr::AO__c11_atomic_fetch_add:
case AtomicExpr::AO__atomic_fetch_add:
LibCallName = "__atomic_fetch_add";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1, MemTy,
E->getExprLoc());
break;
// T __atomic_fetch_and_N(T *mem, T val, int order)
case AtomicExpr::AO__c11_atomic_fetch_and:
case AtomicExpr::AO__atomic_fetch_and:
LibCallName = "__atomic_fetch_and";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1, MemTy,
E->getExprLoc());
break;
// T __atomic_fetch_or_N(T *mem, T val, int order)
case AtomicExpr::AO__c11_atomic_fetch_or:
case AtomicExpr::AO__atomic_fetch_or:
LibCallName = "__atomic_fetch_or";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1, MemTy,
E->getExprLoc());
break;
// T __atomic_fetch_sub_N(T *mem, T val, int order)
case AtomicExpr::AO__c11_atomic_fetch_sub:
case AtomicExpr::AO__atomic_fetch_sub:
LibCallName = "__atomic_fetch_sub";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1, MemTy,
E->getExprLoc());
break;
// T __atomic_fetch_xor_N(T *mem, T val, int order)
case AtomicExpr::AO__c11_atomic_fetch_xor:
case AtomicExpr::AO__atomic_fetch_xor:
LibCallName = "__atomic_fetch_xor";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1, MemTy,
E->getExprLoc());
break;
default: return EmitUnsupportedRValue(E, "atomic library call");
}
// Optimized functions have the size in their name.
if (UseOptimizedLibcall)
LibCallName += "_" + llvm::utostr(Size);
// By default, assume we return a value of the atomic type.
if (!HaveRetTy) {
if (UseOptimizedLibcall) {
// Value is returned directly.
RetTy = MemTy;
} else {
// Value is returned through parameter before the order.
RetTy = getContext().VoidTy;
Args.add(RValue::get(EmitCastToVoidPtr(Dest)),
getContext().VoidPtrTy);
}
}
// 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 (!RetTy->isVoidType())
return Res;
if (E->getType()->isVoidType())
return RValue::get(0);
return convertTempToRValue(Dest, E->getType(), E->getExprLoc());
}
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 AO_ABI_memory_order_relaxed:
EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, Size, Align,
llvm::Monotonic);
break;
case AO_ABI_memory_order_consume:
case AO_ABI_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 AO_ABI_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 AO_ABI_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 AO_ABI_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(), E->getExprLoc());
}
// 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(), E->getExprLoc());
}
llvm::Value *AtomicInfo::emitCastToAtomicIntPointer(llvm::Value *addr) const {
unsigned addrspace =
cast<llvm::PointerType>(addr->getType())->getAddressSpace();
llvm::IntegerType *ty =
llvm::IntegerType::get(CGF.getLLVMContext(), AtomicSizeInBits);
return CGF.Builder.CreateBitCast(addr, ty->getPointerTo(addrspace));
}
RValue AtomicInfo::convertTempToRValue(llvm::Value *addr,
AggValueSlot resultSlot,
SourceLocation loc) const {
if (EvaluationKind == TEK_Aggregate)
return resultSlot.asRValue();
// Drill into the padding structure if we have one.
if (hasPadding())
addr = CGF.Builder.CreateStructGEP(addr, 0);
// Otherwise, just convert the temporary to an r-value using the
// normal conversion routine.
return CGF.convertTempToRValue(addr, getValueType(), loc);
}
/// Emit a load from an l-value of atomic type. Note that the r-value
/// we produce is an r-value of the atomic *value* type.
RValue CodeGenFunction::EmitAtomicLoad(LValue src, SourceLocation loc,
AggValueSlot resultSlot) {
AtomicInfo atomics(*this, src);
// Check whether we should use a library call.
if (atomics.shouldUseLibcall()) {
llvm::Value *tempAddr;
if (!resultSlot.isIgnored()) {
assert(atomics.getEvaluationKind() == TEK_Aggregate);
tempAddr = resultSlot.getAddr();
} else {
tempAddr = CreateMemTemp(atomics.getAtomicType(), "atomic-load-temp");
}
// void __atomic_load(size_t size, void *mem, void *return, int order);
CallArgList args;
args.add(RValue::get(atomics.getAtomicSizeValue()),
getContext().getSizeType());
args.add(RValue::get(EmitCastToVoidPtr(src.getAddress())),
getContext().VoidPtrTy);
args.add(RValue::get(EmitCastToVoidPtr(tempAddr)),
getContext().VoidPtrTy);
args.add(RValue::get(llvm::ConstantInt::get(IntTy,
AO_ABI_memory_order_seq_cst)),
getContext().IntTy);
emitAtomicLibcall(*this, "__atomic_load", getContext().VoidTy, args);
// Produce the r-value.
return atomics.convertTempToRValue(tempAddr, resultSlot, loc);
}
// Okay, we're doing this natively.
llvm::Value *addr = atomics.emitCastToAtomicIntPointer(src.getAddress());
llvm::LoadInst *load = Builder.CreateLoad(addr, "atomic-load");
load->setAtomic(llvm::SequentiallyConsistent);
// Other decoration.
load->setAlignment(src.getAlignment().getQuantity());
if (src.isVolatileQualified())
load->setVolatile(true);
if (src.getTBAAInfo())
CGM.DecorateInstruction(load, src.getTBAAInfo());
// Okay, turn that back into the original value type.
QualType valueType = atomics.getValueType();
llvm::Value *result = load;
// If we're ignoring an aggregate return, don't do anything.
if (atomics.getEvaluationKind() == TEK_Aggregate && resultSlot.isIgnored())
return RValue::getAggregate(0, false);
// The easiest way to do this this is to go through memory, but we
// try not to in some easy cases.
if (atomics.getEvaluationKind() == TEK_Scalar && !atomics.hasPadding()) {
llvm::Type *resultTy = CGM.getTypes().ConvertTypeForMem(valueType);
if (isa<llvm::IntegerType>(resultTy)) {
assert(result->getType() == resultTy);
result = EmitFromMemory(result, valueType);
} else if (isa<llvm::PointerType>(resultTy)) {
result = Builder.CreateIntToPtr(result, resultTy);
} else {
result = Builder.CreateBitCast(result, resultTy);
}
return RValue::get(result);
}
// Create a temporary. This needs to be big enough to hold the
// atomic integer.
llvm::Value *temp;
bool tempIsVolatile = false;
CharUnits tempAlignment;
if (atomics.getEvaluationKind() == TEK_Aggregate) {
assert(!resultSlot.isIgnored());
temp = resultSlot.getAddr();
tempAlignment = atomics.getValueAlignment();
tempIsVolatile = resultSlot.isVolatile();
} else {
temp = CreateMemTemp(atomics.getAtomicType(), "atomic-load-temp");
tempAlignment = atomics.getAtomicAlignment();
}
// Slam the integer into the temporary.
llvm::Value *castTemp = atomics.emitCastToAtomicIntPointer(temp);
Builder.CreateAlignedStore(result, castTemp, tempAlignment.getQuantity())
->setVolatile(tempIsVolatile);
return atomics.convertTempToRValue(temp, resultSlot, loc);
}
/// Copy an r-value into memory as part of storing to an atomic type.
/// This needs to create a bit-pattern suitable for atomic operations.
void AtomicInfo::emitCopyIntoMemory(RValue rvalue, LValue dest) const {
// If we have an r-value, the rvalue should be of the atomic type,
// which means that the caller is responsible for having zeroed
// any padding. Just do an aggregate copy of that type.
if (rvalue.isAggregate()) {
CGF.EmitAggregateCopy(dest.getAddress(),
rvalue.getAggregateAddr(),
getAtomicType(),
(rvalue.isVolatileQualified()
|| dest.isVolatileQualified()),
dest.getAlignment());
return;
}
// Okay, otherwise we're copying stuff.
// Zero out the buffer if necessary.
emitMemSetZeroIfNecessary(dest);
// Drill past the padding if present.
dest = projectValue(dest);
// Okay, store the rvalue in.
if (rvalue.isScalar()) {
CGF.EmitStoreOfScalar(rvalue.getScalarVal(), dest, /*init*/ true);
} else {
CGF.EmitStoreOfComplex(rvalue.getComplexVal(), dest, /*init*/ true);
}
}
/// Materialize an r-value into memory for the purposes of storing it
/// to an atomic type.
llvm::Value *AtomicInfo::materializeRValue(RValue rvalue) const {
// Aggregate r-values are already in memory, and EmitAtomicStore
// requires them to be values of the atomic type.
if (rvalue.isAggregate())
return rvalue.getAggregateAddr();
// Otherwise, make a temporary and materialize into it.
llvm::Value *temp = CGF.CreateMemTemp(getAtomicType(), "atomic-store-temp");
LValue tempLV = CGF.MakeAddrLValue(temp, getAtomicType(), getAtomicAlignment());
emitCopyIntoMemory(rvalue, tempLV);
return temp;
}
/// Emit a store to an l-value of atomic type.
///
/// Note that the r-value is expected to be an r-value *of the atomic
/// type*; this means that for aggregate r-values, it should include
/// storage for any padding that was necessary.
void CodeGenFunction::EmitAtomicStore(RValue rvalue, LValue dest, bool isInit) {
// If this is an aggregate r-value, it should agree in type except
// maybe for address-space qualification.
assert(!rvalue.isAggregate() ||
rvalue.getAggregateAddr()->getType()->getPointerElementType()
== dest.getAddress()->getType()->getPointerElementType());
AtomicInfo atomics(*this, dest);
// If this is an initialization, just put the value there normally.
if (isInit) {
atomics.emitCopyIntoMemory(rvalue, dest);
return;
}
// Check whether we should use a library call.
if (atomics.shouldUseLibcall()) {
// Produce a source address.
llvm::Value *srcAddr = atomics.materializeRValue(rvalue);
// void __atomic_store(size_t size, void *mem, void *val, int order)
CallArgList args;
args.add(RValue::get(atomics.getAtomicSizeValue()),
getContext().getSizeType());
args.add(RValue::get(EmitCastToVoidPtr(dest.getAddress())),
getContext().VoidPtrTy);
args.add(RValue::get(EmitCastToVoidPtr(srcAddr)),
getContext().VoidPtrTy);
args.add(RValue::get(llvm::ConstantInt::get(IntTy,
AO_ABI_memory_order_seq_cst)),
getContext().IntTy);
emitAtomicLibcall(*this, "__atomic_store", getContext().VoidTy, args);
return;
}
// Okay, we're doing this natively.
llvm::Value *intValue;
// If we've got a scalar value of the right size, try to avoid going
// through memory.
if (rvalue.isScalar() && !atomics.hasPadding()) {
llvm::Value *value = rvalue.getScalarVal();
if (isa<llvm::IntegerType>(value->getType())) {
intValue = value;
} else {
llvm::IntegerType *inputIntTy =
llvm::IntegerType::get(getLLVMContext(), atomics.getValueSizeInBits());
if (isa<llvm::PointerType>(value->getType())) {
intValue = Builder.CreatePtrToInt(value, inputIntTy);
} else {
intValue = Builder.CreateBitCast(value, inputIntTy);
}
}
// Otherwise, we need to go through memory.
} else {
// Put the r-value in memory.
llvm::Value *addr = atomics.materializeRValue(rvalue);
// Cast the temporary to the atomic int type and pull a value out.
addr = atomics.emitCastToAtomicIntPointer(addr);
intValue = Builder.CreateAlignedLoad(addr,
atomics.getAtomicAlignment().getQuantity());
}
// Do the atomic store.
llvm::Value *addr = atomics.emitCastToAtomicIntPointer(dest.getAddress());
llvm::StoreInst *store = Builder.CreateStore(intValue, addr);
// Initializations don't need to be atomic.
if (!isInit) store->setAtomic(llvm::SequentiallyConsistent);
// Other decoration.
store->setAlignment(dest.getAlignment().getQuantity());
if (dest.isVolatileQualified())
store->setVolatile(true);
if (dest.getTBAAInfo())
CGM.DecorateInstruction(store, dest.getTBAAInfo());
}
void CodeGenFunction::EmitAtomicInit(Expr *init, LValue dest) {
AtomicInfo atomics(*this, dest);
switch (atomics.getEvaluationKind()) {
case TEK_Scalar: {
llvm::Value *value = EmitScalarExpr(init);
atomics.emitCopyIntoMemory(RValue::get(value), dest);
return;
}
case TEK_Complex: {
ComplexPairTy value = EmitComplexExpr(init);
atomics.emitCopyIntoMemory(RValue::getComplex(value), dest);
return;
}
case TEK_Aggregate: {
// Fix up the destination if the initializer isn't an expression
// of atomic type.
bool Zeroed = false;
if (!init->getType()->isAtomicType()) {
Zeroed = atomics.emitMemSetZeroIfNecessary(dest);
dest = atomics.projectValue(dest);
}
// Evaluate the expression directly into the destination.
AggValueSlot slot = AggValueSlot::forLValue(dest,
AggValueSlot::IsNotDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased,
Zeroed ? AggValueSlot::IsZeroed :
AggValueSlot::IsNotZeroed);
EmitAggExpr(init, slot);
return;
}
}
llvm_unreachable("bad evaluation kind");
}
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