Move the atomics code into its own file.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176657 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 485 insertions, 0 deletions

diff --git a/lib/CodeGen/CGAtomic.cpp b/lib/CodeGen/CGAtomic.cpp
new file mode 100644
index 0000000000..f17e48d2f2
--- /dev/null
+++ b/lib/CodeGen/CGAtomic.cpp
@@ -0,0 +1,485 @@
+//===--- 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());
+}