private static LLVMValueRef BuildLoadFieldPointer(
LLVMBuilderRef Builder,
LLVMValueRef Delegate,
uint FieldIndex,
string FieldName)
{
return(AtAddressEmitVariable.BuildConstantLoad(
Builder,
BuildStructGEP(
Builder,
Delegate,
FieldIndex,
FieldName + "_ptr"),
FieldName));
}
/// <summary>
/// Creates a sequence of instructions that computes the type ID
/// for the given VTable pointer.
/// </summary>
/// <param name="Builder">The builder to create the instructions in.</param>
/// <param name="VTablePtr">A pointer to a VTable.</param>
/// <returns>A type ID.</returns>
public static LLVMValueRef BuildTypeid(
LLVMBuilderRef Builder,
LLVMValueRef VTablePtr)
{
return(AtAddressEmitVariable.BuildConstantLoad(
Builder,
BuildStructGEP(
Builder,
BuildBitCast(
Builder,
VTablePtr,
PointerType(LLVMType.VTableType, 0),
"vtable_tmp"),
0,
"typeid_ptr_tmp"),
"typeid_tmp"));
}
public override BlockCodegen Emit(BasicBlockBuilder BasicBlock)
{
var delegateAndBlock = Delegate.Emit(BasicBlock);
BasicBlock = delegateAndBlock.BasicBlock;
var methodTypeAllocBlock = (CodeBlock)codeGen.Allocate(
new StaticCastExpression(
LLVMCodeGenerator.ToExpression(
new ConstantBlock(codeGen, PrimitiveTypes.UInt64, SizeOf(DelegateBlock.MethodTypeLayout))),
PrimitiveTypes.UInt64),
Type).Emit(codeGen);
var methodTypeAllocCodegen = methodTypeAllocBlock.Emit(BasicBlock);
BasicBlock = methodTypeAllocCodegen.BasicBlock;
BuildStore(
BasicBlock.Builder,
AtAddressEmitVariable.BuildConstantLoad(
BasicBlock.Builder,
BuildBitCast(
BasicBlock.Builder,
delegateAndBlock.Value,
PointerType(DelegateBlock.MethodTypeLayout, 0),
"delegate_ptr"),
"delegate_data"),
methodTypeAllocCodegen.Value);
BuildStore(
BasicBlock.Builder,
TypeVTableBlock.BuildTypeVTable(BasicBlock, Type),
BuildStructGEP(BasicBlock.Builder, methodTypeAllocCodegen.Value, 0, "vtable_ptr_ptr"));
return(new BlockCodegen(BasicBlock, methodTypeAllocCodegen.Value));
}
/// <summary>
/// Generates code that computes the address of the given callee function's
/// implementation.
/// </summary>
/// <param name="BasicBlock">The basic block to generate code in.</param>
/// <param name="Target">The object that receives the call.</param>
/// <param name="Callee">The callee method.</param>
/// <param name="Op">The call operator.</param>
/// <returns>A function pointer.</returns>
public static BlockCodegen EmitCallee(
BasicBlockBuilder BasicBlock,
LLVMValueRef Target,
IMethod Callee,
Operator Op)
{
var module = BasicBlock.FunctionBody.Module;
if (Op.Equals(Operator.GetDelegate) ||
Op.Equals(Operator.GetCurriedDelegate))
{
return(new BlockCodegen(BasicBlock, module.Declare(Callee)));
}
else if (Op.Equals(Operator.GetVirtualDelegate))
{
var method = (LLVMMethod)Callee;
if (method.DeclaringType.GetIsValueType() ||
!method.GetIsVirtual() ||
Target.Pointer == IntPtr.Zero)
{
return(EmitCallee(BasicBlock, Target, Callee, Operator.GetDelegate));
}
var vtablePtr = BuildBitCast(
BasicBlock.Builder,
Target,
PointerType(PointerType(LLVMType.VTableType, 0), 0),
"vtable_ptr_tmp");
var vtable = AtAddressEmitVariable.BuildConstantLoad(
BasicBlock.Builder,
vtablePtr,
"vtable_tmp");
if (method.DeclaringType.GetIsInterface())
{
// Resolve interface method implementations by calling a stub.
var typeIndexPtr = BuildStructGEP(
BasicBlock.Builder,
vtable,
1,
"type_index_ptr");
var typeIndex = AtAddressEmitVariable.BuildConstantLoad(
BasicBlock.Builder,
typeIndexPtr,
"type_ptr");
var stub = module.GetInterfaceStub(method);
var methodImpl = BuildCall(
BasicBlock.Builder,
stub.Function,
new LLVMValueRef[] { typeIndex },
"iface_method_ptr");
return(new BlockCodegen(BasicBlock, methodImpl));
}
else
{
// Resolve virtual/abstract method implementations by performing
// a table lookup.
var vtableSlot = module
.GetVTable(method.ParentType)
.GetAbsoluteSlot(method);
var vtableContentPtr = BuildBitCast(
BasicBlock.Builder,
BuildStructGEP(
BasicBlock.Builder,
vtable,
2,
"vtable_method_array_ptr"),
PointerType(PointerType(Int8Type(), 0), 0),
"vtable_methods_ptr");
var vtableSlotPtr = BuildGEP(
BasicBlock.Builder,
vtableContentPtr,
new LLVMValueRef[] { ConstInt(Int32Type(), (ulong)vtableSlot, false) },
"vtable_slot_ptr");
var methodImpl = AtAddressEmitVariable.BuildConstantLoad(
BasicBlock.Builder,
BuildBitCast(
BasicBlock.Builder,
vtableSlotPtr,
PointerType(PointerType(module.DeclarePrototype(method), 0), 0),
"method_ptr_field"
),
"method_ptr");
return(new BlockCodegen(BasicBlock, methodImpl));
}
}
else
{
throw new NotImplementedException(
string.Format("Unsupported call operator: {0}.", Op.Name));
}
}
public CatchHeader(IType ExceptionType, AtAddressEmitVariable ExceptionVariable)
{
this.ExceptionType = ExceptionType;
this.exceptionVar = ExceptionVariable;
}
/// <summary>
/// Populates the given 'catch' block.
/// </summary>
/// <param name="CatchBlock">The 'catch' block to populate.</param>
/// <param name="LeaveBlock">The 'leave' block to jump to when the 'catch' is done.</param>
private void PopulateCatchBlock(BasicBlockBuilder CatchBlock, BasicBlockBuilder LeaveBlock)
{
var catchBlockEntry = CatchBlock;
// Before we even get started on the catch block's body, we should first
// take the time to ensure that the '__cxa_begin_catch' environment set up
// by the catch block is properly terminated by a '__cxa_end_catch' call,
// even if an exception is thrown from the catch block itself. We can do
// so by creating a 'catch_end' block and a thunk landing pad.
var catchEndBlock = CatchBlock.CreateChildBlock("catch_end");
var catchExceptionBlock = CatchBlock.CreateChildBlock("catch_exception");
var catchEndLandingPadBlock = CatchBlock.CreateChildBlock("catch_end_landingpad");
ItaniumCxxFinallyBlock.PopulateThunkLandingPadBlock(
catchEndLandingPadBlock,
catchExceptionBlock.Block,
true);
CatchBlock = CatchBlock.WithUnwindTarget(catchEndLandingPadBlock, catchEndBlock);
// The catch block starts like this:
//
// catch:
// %exception_data = load { i8*, i32 }* %exception_data_alloca
// %exception_obj = extractvalue { i8*, i32 } %exception_data, 0
// %exception_ptr_opaque = call i8* @__cxa_begin_catch(i8* %exception_obj)
// %exception_ptr = bitcast i8* %exception_ptr_opaque to i8**
// %exception = load i8*, i8** %exception_ptr
// %exception_vtable_ptr_ptr = bitcast i8* %exception to i8**
// %exception_vtable_ptr = load i8*, i8** %exception_vtable_ptr_ptr
// %exception_typeid = <typeid> i64, i8* %exception_vtable_ptr
var exceptionData = BuildLoad(
CatchBlock.Builder,
CatchBlock.FunctionBody.ExceptionDataStorage.Value,
"exception_data");
var exceptionObj = BuildExtractValue(
CatchBlock.Builder,
exceptionData,
0,
"exception_obj");
var exceptionPtrOpaque = BuildCall(
CatchBlock.Builder,
CatchBlock.FunctionBody.Module.Declare(IntrinsicValue.CxaBeginCatch),
new LLVMValueRef[] { exceptionObj },
"exception_ptr_opaque");
var exceptionPtr = BuildBitCast(
CatchBlock.Builder,
exceptionPtrOpaque,
PointerType(PointerType(Int8Type(), 0), 0),
"exception_ptr");
var exception = BuildLoad(CatchBlock.Builder, exceptionPtr, "exception");
var exceptionVtablePtrPtr = BuildBitCast(
CatchBlock.Builder,
exception,
PointerType(PointerType(Int8Type(), 0), 0),
"exception_vtable_ptr_ptr");
var exceptionVtablePtr = AtAddressEmitVariable.BuildConstantLoad(
CatchBlock.Builder,
exceptionVtablePtrPtr,
"exception_vtable_ptr");
var exceptionTypeid = TypeIdBlock.BuildTypeid(
CatchBlock.Builder,
exceptionVtablePtr);
// Next, we need to figure out if we have a catch block that can handle the
// exception we've thrown. We do so by iterating over all catch blocks and
// testing if they're a match for the exception's type.
var fallthroughBlock = CatchBlock.CreateChildBlock("catch_test");
for (int i = 0; i < CatchClauses.Count; i++)
{
var clause = CatchClauses[i];
var catchBodyBlock = CatchBlock.CreateChildBlock("catch_body");
var catchBodyBlockTail = catchBodyBlock;
// First, emit the catch body. This is just a regular block that
// clears the exception value variable when it gets started and
// jumps to the 'catch_end' when it's done.
//
// catch_body:
// %exception_val = bitcast i8* %exception to <clause_type>
// store <clause_type> %exception_val, <clause_type>* %clause_exception_variable_alloca
// <catch clause body>
// br catch_end
var ehVarAddressAndBlock = clause.LLVMHeader
.AtAddressExceptionVariable.Address.Emit(catchBodyBlockTail);
catchBodyBlockTail = ehVarAddressAndBlock.BasicBlock;
BuildStore(
catchBodyBlockTail.Builder,
BuildBitCast(
catchBodyBlockTail.Builder,
exception,
catchBodyBlockTail.FunctionBody.Module.Declare(clause.ExceptionType),
"exception_val"),
ehVarAddressAndBlock.Value);
catchBodyBlockTail = clause.Body.Emit(catchBodyBlockTail).BasicBlock;
BuildBr(catchBodyBlockTail.Builder, catchEndBlock.Block);
// Each clause is implemented as:
//
// catch_clause:
// %clause_typeid = <typeid> i64, clause-exception-type
// %typeid_rem = urem i64 %exception_typeid_tmp, %clause_typeid
// %is_subtype = cmp eq i64 %typeid_rem, 0
// br i1 %is_subtype, label %catch_body, label %fallthrough
//
var clauseTypeid = CatchBlock.FunctionBody.Module.GetTypeId((LLVMType)clause.ExceptionType);
var typeIdRem = BuildURem(
CatchBlock.Builder,
exceptionTypeid,
ConstInt(exceptionTypeid.TypeOf(), clauseTypeid, false),
"typeid_rem");
var isSubtype = BuildICmp(
CatchBlock.Builder,
LLVMIntPredicate.LLVMIntEQ,
typeIdRem,
ConstInt(exceptionTypeid.TypeOf(), 0, false),
"is_subtype");
BuildCondBr(CatchBlock.Builder, isSubtype, catchBodyBlock.Block, fallthroughBlock.Block);
CatchBlock = fallthroughBlock;
fallthroughBlock = CatchBlock.CreateChildBlock("catch_test");
}
// If we didn't match any catch clauses, then we'll rethrow the exception and
// unwind to the end-catch landing pad.
//
// no_matching_clause:
// invoke void @__cxa_rethrow() to label %unreachable unwind label %catch_end_landingpad
//
// unreachable:
// unreachable
BuildInvoke(
CatchBlock.Builder,
CatchBlock.FunctionBody.Module.Declare(IntrinsicValue.CxaRethrow),
new LLVMValueRef[] { },
fallthroughBlock.Block,
catchEndLandingPadBlock.Block,
"");
BuildUnreachable(fallthroughBlock.Builder);
// The catch end block simply calls '__cxa_end_catch' and jumps to the 'leave'
// block. Like so:
//
// catch_end:
// call void @__cxa_end_catch()
// br label %leave
BuildCall(
catchEndBlock.Builder,
CatchBlock.FunctionBody.Module.Declare(IntrinsicValue.CxaEndCatch),
new LLVMValueRef[] { },
"");
BuildBr(catchEndBlock.Builder, LeaveBlock.Block);
// The 'catch exception' block is entered when an exception is thrown from
// the 'catch' block, or if the catch block is ill-equipped to handle the
// exception. Its responsibility is to end the catch block and jump to
// the manual unwind target.
//
// catch_exception:
// call void @__cxa_end_catch()
// br label %manual_unwind_target
BuildCall(
catchExceptionBlock.Builder,
catchExceptionBlock.FunctionBody.Module.Declare(IntrinsicValue.CxaEndCatch),
new LLVMValueRef[] { },
"");
BuildBr(catchExceptionBlock.Builder, ItaniumCxxFinallyBlock.GetManualUnwindTarget(catchBlockEntry));
}
