status_t
DwarfExpressionEvaluator::EvaluateLocation(const void* expression, size_t size,
ValueLocation& _location)
{
_location.Clear();
// the empty expression is a valid one
if (size == 0) {
ValuePieceLocation piece;
piece.SetToUnknown();
piece.SetSize(0);
return _location.AddPiece(piece) ? B_OK : B_NO_MEMORY;
}
fDataReader.SetTo(expression, size, fContext->AddressSize());
// parse the first (and maybe only) expression
try {
// push the object address, if any
target_addr_t objectAddress;
if (fContext->GetObjectAddress(objectAddress))
_Push(objectAddress);
ValuePieceLocation piece;
status_t error = _Evaluate(&piece);
if (error != B_OK)
return error;
// if that's all, it's only a simple expression without composition
if (fDataReader.BytesRemaining() == 0) {
if (!piece.IsValid())
piece.SetToMemory(_Pop());
piece.SetSize(0);
return _location.AddPiece(piece) ? B_OK : B_NO_MEMORY;
}
// there's more, so it must be a composition operator
uint8 opcode = fDataReader.Read<uint8>(0);
if (opcode == DW_OP_piece) {
piece.SetSize(fDataReader.ReadUnsignedLEB128(0));
} else if (opcode == DW_OP_bit_piece) {
uint64 bitSize = fDataReader.ReadUnsignedLEB128(0);
piece.SetSize(bitSize, fDataReader.ReadUnsignedLEB128(0));
} else
return B_BAD_DATA;
// If there's a composition operator, there must be at least two
// simple expressions, so this must not be the end.
if (fDataReader.BytesRemaining() == 0)
return B_BAD_DATA;
} catch (const EvaluationException& exception) {
WARNING("DwarfExpressionEvaluator::EvaluateLocation(): %s\n",
exception.message);
return B_BAD_VALUE;
} catch (const std::bad_alloc& exception) {
return B_NO_MEMORY;
}
// parse subsequent expressions (at least one)
while (fDataReader.BytesRemaining() > 0) {
// Restrict the data reader to the remaining bytes to prevent jumping
// back.
fDataReader.SetTo(fDataReader.Data(), fDataReader.BytesRemaining(),
fDataReader.AddressSize());
try {
// push the object address, if any
target_addr_t objectAddress;
if (fContext->GetObjectAddress(objectAddress))
_Push(objectAddress);
ValuePieceLocation piece;
status_t error = _Evaluate(&piece);
if (error != B_OK)
return error;
if (!piece.IsValid())
piece.SetToMemory(_Pop());
// each expression must be followed by a composition operator
if (fDataReader.BytesRemaining() == 0)
return B_BAD_DATA;
uint8 opcode = fDataReader.Read<uint8>(0);
if (opcode == DW_OP_piece) {
piece.SetSize(fDataReader.ReadUnsignedLEB128(0));
} else if (opcode == DW_OP_bit_piece) {
uint64 bitSize = fDataReader.ReadUnsignedLEB128(0);
piece.SetSize(bitSize, fDataReader.ReadUnsignedLEB128(0));
} else
return B_BAD_DATA;
} catch (const EvaluationException& exception) {
WARNING("DwarfExpressionEvaluator::EvaluateLocation(): %s\n",
exception.message);
return B_BAD_VALUE;
} catch (const std::bad_alloc& exception) {
return B_NO_MEMORY;
}
}
return B_OK;
}
status_t
DwarfType::ResolveLocation(DwarfTypeContext* typeContext,
const LocationDescription* description, target_addr_t objectAddress,
bool hasObjectAddress, ValueLocation& _location)
{
status_t error = typeContext->File()->ResolveLocation(
typeContext->GetCompilationUnit(), typeContext->AddressSize(),
typeContext->SubprogramEntry(), description,
typeContext->TargetInterface(), typeContext->InstructionPointer(),
objectAddress, hasObjectAddress, typeContext->FramePointer(),
typeContext->RelocationDelta(), _location);
if (error != B_OK)
return error;
// translate the DWARF register indices and the bit offset/size semantics
const Register* registers = typeContext->GetArchitecture()->Registers();
bool bigEndian = typeContext->GetArchitecture()->IsBigEndian();
int32 count = _location.CountPieces();
for (int32 i = 0; i < count; i++) {
ValuePieceLocation piece = _location.PieceAt(i);
if (piece.type == VALUE_PIECE_LOCATION_REGISTER) {
int32 reg = typeContext->FromDwarfRegisterMap()->MapRegisterIndex(
piece.reg);
if (reg >= 0) {
piece.reg = reg;
// The bit offset for registers is to the least
// significant bit, while we want the offset to the most
// significant bit.
if (registers[reg].BitSize() > piece.bitSize) {
piece.bitOffset = registers[reg].BitSize() - piece.bitSize
- piece.bitOffset;
}
} else
piece.SetToUnknown();
} else if (piece.type == VALUE_PIECE_LOCATION_MEMORY) {
// Whether the bit offset is to the least or most significant bit
// is target architecture and source language specific.
// TODO: Check whether this is correct!
// TODO: Source language!
if (!bigEndian && piece.size * 8 > piece.bitSize) {
piece.bitOffset = piece.size * 8 - piece.bitSize
- piece.bitOffset;
}
}
piece.Normalize(bigEndian);
_location.SetPieceAt(i, piece);
}
// If we only have one piece and that doesn't have a size, try to retrieve
// the size of the type.
if (count == 1) {
ValuePieceLocation piece = _location.PieceAt(0);
if (piece.IsValid() && piece.size == 0 && piece.bitSize == 0) {
piece.SetSize(ByteSize());
// TODO: Use bit size and bit offset, if specified!
_location.SetPieceAt(0, piece);
TRACE_LOCALS(" set single piece size to %" B_PRIu64 "\n",
ByteSize());
}
}
return B_OK;
}