C++ CodeGenFunction::CreateTempAlloca方法代码示例

DominatingValue<RValue>::saved_type
DominatingValue<RValue>::saved_type::save(CodeGenFunction &CGF, RValue rv) {
  if (rv.isScalar()) {
    llvm::Value *V = rv.getScalarVal();

    // These automatically dominate and don't need to be saved.
    if (!DominatingLLVMValue::needsSaving(V))
      return saved_type(V, ScalarLiteral);

    // Everything else needs an alloca.
    llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue");
    CGF.Builder.CreateStore(V, addr);
    return saved_type(addr, ScalarAddress);
  }

  if (rv.isComplex()) {
    CodeGenFunction::ComplexPairTy V = rv.getComplexVal();
    llvm::Type *ComplexTy =
      llvm::StructType::get(V.first->getType(), V.second->getType(),
                            (void*) nullptr);
    llvm::Value *addr = CGF.CreateTempAlloca(ComplexTy, "saved-complex");
    CGF.Builder.CreateStore(V.first, CGF.Builder.CreateStructGEP(addr, 0));
    CGF.Builder.CreateStore(V.second, CGF.Builder.CreateStructGEP(addr, 1));
    return saved_type(addr, ComplexAddress);
  }

  assert(rv.isAggregate());
  llvm::Value *V = rv.getAggregateAddr(); // TODO: volatile?
  if (!DominatingLLVMValue::needsSaving(V))
    return saved_type(V, AggregateLiteral);

  llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue");
  CGF.Builder.CreateStore(V, addr);
  return saved_type(addr, AggregateAddress);  
}

/// The given cleanup block is changing activation state.  Configure a
/// cleanup variable if necessary.
///
/// It would be good if we had some way of determining if there were
/// extra uses *after* the change-over point.
static void SetupCleanupBlockActivation(CodeGenFunction &CGF,
                                        EHScopeStack::stable_iterator C,
                                        ForActivation_t kind,
                                        llvm::Instruction *dominatingIP) {
  EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));

  // We always need the flag if we're activating the cleanup in a
  // conditional context, because we have to assume that the current
  // location doesn't necessarily dominate the cleanup's code.
  bool isActivatedInConditional =
    (kind == ForActivation && CGF.isInConditionalBranch());

  bool needFlag = false;

  // Calculate whether the cleanup was used:

  //   - as a normal cleanup
  if (Scope.isNormalCleanup() &&
      (isActivatedInConditional || IsUsedAsNormalCleanup(CGF.EHStack, C))) {
    Scope.setTestFlagInNormalCleanup();
    needFlag = true;
  }

  //  - as an EH cleanup
  if (Scope.isEHCleanup() &&
      (isActivatedInConditional || IsUsedAsEHCleanup(CGF.EHStack, C))) {
    Scope.setTestFlagInEHCleanup();
    needFlag = true;
  }

  // If it hasn't yet been used as either, we're done.
  if (!needFlag) return;

  Address var = Scope.getActiveFlag();
  if (!var.isValid()) {
    var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), CharUnits::One(),
                               "cleanup.isactive");
    Scope.setActiveFlag(var);

    assert(dominatingIP && "no existing variable and no dominating IP!");

    // Initialize to true or false depending on whether it was
    // active up to this point.
    llvm::Constant *value = CGF.Builder.getInt1(kind == ForDeactivation);

    // If we're in a conditional block, ignore the dominating IP and
    // use the outermost conditional branch.
    if (CGF.isInConditionalBranch()) {
      CGF.setBeforeOutermostConditional(value, var);
    } else {
      createStoreInstBefore(value, var, dominatingIP);
    }
  }

  CGF.Builder.CreateStore(CGF.Builder.getInt1(kind == ForActivation), var);
}

// CopyObject - Utility to copy an object.  Calls copy constructor as necessary.
// N is casted to the right type.
static void CopyObject(CodeGenFunction &CGF, QualType ObjectType,
                       bool WasPointer, bool WasPointerReference,
                       llvm::Value *E, llvm::Value *N) {
  // Store the throw exception in the exception object.
  if (WasPointer || !CGF.hasAggregateLLVMType(ObjectType)) {
    llvm::Value *Value = E;
    if (!WasPointer)
      Value = CGF.Builder.CreateLoad(Value);
    const llvm::Type *ValuePtrTy = Value->getType()->getPointerTo(0);
    if (WasPointerReference) {
      llvm::Value *Tmp = CGF.CreateTempAlloca(Value->getType(), "catch.param");
      CGF.Builder.CreateStore(Value, Tmp);
      Value = Tmp;
      ValuePtrTy = Value->getType()->getPointerTo(0);
    }
    N = CGF.Builder.CreateBitCast(N, ValuePtrTy);
    CGF.Builder.CreateStore(Value, N);
  } else {
    const llvm::Type *Ty = CGF.ConvertType(ObjectType)->getPointerTo(0);
    const CXXRecordDecl *RD;
    RD = cast<CXXRecordDecl>(ObjectType->getAs<RecordType>()->getDecl());
    llvm::Value *This = CGF.Builder.CreateBitCast(N, Ty);
    if (RD->hasTrivialCopyConstructor()) {
      CGF.EmitAggregateCopy(This, E, ObjectType);
    } else if (CXXConstructorDecl *CopyCtor
               = RD->getCopyConstructor(CGF.getContext(), 0)) {
      llvm::Value *Src = E;

      // Stolen from EmitClassAggrMemberwiseCopy
      llvm::Value *Callee = CGF.CGM.GetAddrOfCXXConstructor(CopyCtor,
                                                            Ctor_Complete);
      CallArgList CallArgs;
      CallArgs.push_back(std::make_pair(RValue::get(This),
                                      CopyCtor->getThisType(CGF.getContext())));

      // Push the Src ptr.
      CallArgs.push_back(std::make_pair(RValue::get(Src),
                                        CopyCtor->getParamDecl(0)->getType()));

      const FunctionProtoType *FPT
        = CopyCtor->getType()->getAs<FunctionProtoType>();
      CGF.EmitCall(CGF.CGM.getTypes().getFunctionInfo(CallArgs, FPT),
                   Callee, ReturnValueSlot(), CallArgs, CopyCtor);
    } else
      llvm_unreachable("uncopyable object");
  }
}

DominatingValue<RValue>::saved_type
DominatingValue<RValue>::saved_type::save(CodeGenFunction &CGF, RValue rv) {
  if (rv.isScalar()) {
    llvm::Value *V = rv.getScalarVal();

    // These automatically dominate and don't need to be saved.
    if (!DominatingLLVMValue::needsSaving(V))
      return saved_type(V, ScalarLiteral);

    // Everything else needs an alloca.
    Address addr =
      CGF.CreateDefaultAlignTempAlloca(V->getType(), "saved-rvalue");
    CGF.Builder.CreateStore(V, addr);
    return saved_type(addr.getPointer(), ScalarAddress);
  }

  if (rv.isComplex()) {
    CodeGenFunction::ComplexPairTy V = rv.getComplexVal();
    llvm::Type *ComplexTy =
      llvm::StructType::get(V.first->getType(), V.second->getType(),
                            (void*) nullptr);
    Address addr = CGF.CreateDefaultAlignTempAlloca(ComplexTy, "saved-complex");
    CGF.Builder.CreateStore(V.first,
                            CGF.Builder.CreateStructGEP(addr, 0, CharUnits()));
    CharUnits offset = CharUnits::fromQuantity(
               CGF.CGM.getDataLayout().getTypeAllocSize(V.first->getType()));
    CGF.Builder.CreateStore(V.second,
                            CGF.Builder.CreateStructGEP(addr, 1, offset));
    return saved_type(addr.getPointer(), ComplexAddress);
  }

  assert(rv.isAggregate());
  Address V = rv.getAggregateAddress(); // TODO: volatile?
  if (!DominatingLLVMValue::needsSaving(V.getPointer()))
    return saved_type(V.getPointer(), AggregateLiteral,
                      V.getAlignment().getQuantity());

  Address addr =
    CGF.CreateTempAlloca(V.getType(), CGF.getPointerAlign(), "saved-rvalue");
  CGF.Builder.CreateStore(V.getPointer(), addr);
  return saved_type(addr.getPointer(), AggregateAddress,
                    V.getAlignment().getQuantity());
}

/// CreateCoercedStore - Create a store to \arg DstPtr from \arg Src,
/// where the source and destination may have different types.
///
/// This safely handles the case when the src type is larger than the
/// destination type; the upper bits of the src will be lost.
static void CreateCoercedStore(llvm::Value *Src,
                               llvm::Value *DstPtr,
                               bool DstIsVolatile,
                               CodeGenFunction &CGF) {
  const llvm::Type *SrcTy = Src->getType();
  const llvm::Type *DstTy =
    cast<llvm::PointerType>(DstPtr->getType())->getElementType();

  uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
  uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(DstTy);

  // If store is legal, just bitcast the src pointer.
  if (SrcSize <= DstSize) {
    llvm::Value *Casted =
      CGF.Builder.CreateBitCast(DstPtr, llvm::PointerType::getUnqual(SrcTy));
    // FIXME: Use better alignment / avoid requiring aligned store.
    CGF.Builder.CreateStore(Src, Casted, DstIsVolatile)->setAlignment(1);
  } else {
    // Otherwise do coercion through memory. This is stupid, but
    // simple.

    // Generally SrcSize is never greater than DstSize, since this means we are
    // losing bits. However, this can happen in cases where the structure has
    // additional padding, for example due to a user specified alignment.
    //
    // FIXME: Assert that we aren't truncating non-padding bits when have access
    // to that information.
    llvm::Value *Tmp = CGF.CreateTempAlloca(SrcTy);
    CGF.Builder.CreateStore(Src, Tmp);
    llvm::Value *Casted =
      CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(DstTy));
    llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
    // FIXME: Use better alignment / avoid requiring aligned load.
    Load->setAlignment(1);
    CGF.Builder.CreateStore(Load, DstPtr, DstIsVolatile);
  }
}

// CUDA 9.0+ uses new way to launch kernels. Parameters are packed in a local
// array and kernels are launched using cudaLaunchKernel().
void CGNVCUDARuntime::emitDeviceStubBodyNew(CodeGenFunction &CGF,
                                            FunctionArgList &Args) {
  // Build the shadow stack entry at the very start of the function.

  // Calculate amount of space we will need for all arguments.  If we have no
  // args, allocate a single pointer so we still have a valid pointer to the
  // argument array that we can pass to runtime, even if it will be unused.
  Address KernelArgs = CGF.CreateTempAlloca(
      VoidPtrTy, CharUnits::fromQuantity(16), "kernel_args",
      llvm::ConstantInt::get(SizeTy, std::max<size_t>(1, Args.size())));
  // Store pointers to the arguments in a locally allocated launch_args.
  for (unsigned i = 0; i < Args.size(); ++i) {
    llvm::Value* VarPtr = CGF.GetAddrOfLocalVar(Args[i]).getPointer();
    llvm::Value *VoidVarPtr = CGF.Builder.CreatePointerCast(VarPtr, VoidPtrTy);
    CGF.Builder.CreateDefaultAlignedStore(
        VoidVarPtr, CGF.Builder.CreateConstGEP1_32(KernelArgs.getPointer(), i));
  }

  llvm::BasicBlock *EndBlock = CGF.createBasicBlock("setup.end");

  // Lookup cudaLaunchKernel function.
  // cudaError_t cudaLaunchKernel(const void *func, dim3 gridDim, dim3 blockDim,
  //                              void **args, size_t sharedMem,
  //                              cudaStream_t stream);
  TranslationUnitDecl *TUDecl = CGM.getContext().getTranslationUnitDecl();
  DeclContext *DC = TranslationUnitDecl::castToDeclContext(TUDecl);
  IdentifierInfo &cudaLaunchKernelII =
      CGM.getContext().Idents.get("cudaLaunchKernel");
  FunctionDecl *cudaLaunchKernelFD = nullptr;
  for (const auto &Result : DC->lookup(&cudaLaunchKernelII)) {
    if (FunctionDecl *FD = dyn_cast<FunctionDecl>(Result))
      cudaLaunchKernelFD = FD;
  }

  if (cudaLaunchKernelFD == nullptr) {
    CGM.Error(CGF.CurFuncDecl->getLocation(),
              "Can't find declaration for cudaLaunchKernel()");
    return;
  }
  // Create temporary dim3 grid_dim, block_dim.
  ParmVarDecl *GridDimParam = cudaLaunchKernelFD->getParamDecl(1);
  QualType Dim3Ty = GridDimParam->getType();
  Address GridDim =
      CGF.CreateMemTemp(Dim3Ty, CharUnits::fromQuantity(8), "grid_dim");
  Address BlockDim =
      CGF.CreateMemTemp(Dim3Ty, CharUnits::fromQuantity(8), "block_dim");
  Address ShmemSize =
      CGF.CreateTempAlloca(SizeTy, CGM.getSizeAlign(), "shmem_size");
  Address Stream =
      CGF.CreateTempAlloca(VoidPtrTy, CGM.getPointerAlign(), "stream");
  llvm::FunctionCallee cudaPopConfigFn = CGM.CreateRuntimeFunction(
      llvm::FunctionType::get(IntTy,
                              {/*gridDim=*/GridDim.getType(),
                               /*blockDim=*/BlockDim.getType(),
                               /*ShmemSize=*/ShmemSize.getType(),
                               /*Stream=*/Stream.getType()},
                              /*isVarArg=*/false),
      "__cudaPopCallConfiguration");

  CGF.EmitRuntimeCallOrInvoke(cudaPopConfigFn,
                              {GridDim.getPointer(), BlockDim.getPointer(),
                               ShmemSize.getPointer(), Stream.getPointer()});

  // Emit the call to cudaLaunch
  llvm::Value *Kernel = CGF.Builder.CreatePointerCast(CGF.CurFn, VoidPtrTy);
  CallArgList LaunchKernelArgs;
  LaunchKernelArgs.add(RValue::get(Kernel),
                       cudaLaunchKernelFD->getParamDecl(0)->getType());
  LaunchKernelArgs.add(RValue::getAggregate(GridDim), Dim3Ty);
  LaunchKernelArgs.add(RValue::getAggregate(BlockDim), Dim3Ty);
  LaunchKernelArgs.add(RValue::get(KernelArgs.getPointer()),
                       cudaLaunchKernelFD->getParamDecl(3)->getType());
  LaunchKernelArgs.add(RValue::get(CGF.Builder.CreateLoad(ShmemSize)),
                       cudaLaunchKernelFD->getParamDecl(4)->getType());
  LaunchKernelArgs.add(RValue::get(CGF.Builder.CreateLoad(Stream)),
                       cudaLaunchKernelFD->getParamDecl(5)->getType());

  QualType QT = cudaLaunchKernelFD->getType();
  QualType CQT = QT.getCanonicalType();
  llvm::Type *Ty = CGM.getTypes().ConvertType(CQT);
  llvm::FunctionType *FTy = dyn_cast<llvm::FunctionType>(Ty);

  const CGFunctionInfo &FI =
      CGM.getTypes().arrangeFunctionDeclaration(cudaLaunchKernelFD);
  llvm::FunctionCallee cudaLaunchKernelFn =
      CGM.CreateRuntimeFunction(FTy, "cudaLaunchKernel");
  CGF.EmitCall(FI, CGCallee::forDirect(cudaLaunchKernelFn), ReturnValueSlot(),
               LaunchKernelArgs);
  CGF.EmitBranch(EndBlock);

  CGF.EmitBlock(EndBlock);
}