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[lldb] Refactor ReadRegisterValueAsScalar to return an llvm::Error (NFC) #94556

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merged 1 commit into from
Jun 6, 2024
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[lldb] Refactor ReadRegisterValueAsScalar to return an llvm::Error (NFC) #94556

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130 changes: 56 additions & 74 deletions lldb/source/Expression/DWARFExpression.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -94,51 +94,38 @@ void DWARFExpression::SetRegisterKind(RegisterKind reg_kind) {
m_reg_kind = reg_kind;
}


static bool ReadRegisterValueAsScalar(RegisterContext *reg_ctx,
lldb::RegisterKind reg_kind,
uint32_t reg_num, Status *error_ptr,
Value &value) {
if (reg_ctx == nullptr) {
if (error_ptr)
error_ptr->SetErrorString("No register context in frame.\n");
} else {
uint32_t native_reg =
reg_ctx->ConvertRegisterKindToRegisterNumber(reg_kind, reg_num);
if (native_reg == LLDB_INVALID_REGNUM) {
if (error_ptr)
error_ptr->SetErrorStringWithFormat("Unable to convert register "
"kind=%u reg_num=%u to a native "
"register number.\n",
reg_kind, reg_num);
} else {
const RegisterInfo *reg_info =
reg_ctx->GetRegisterInfoAtIndex(native_reg);
RegisterValue reg_value;
if (reg_ctx->ReadRegister(reg_info, reg_value)) {
if (reg_value.GetScalarValue(value.GetScalar())) {
value.SetValueType(Value::ValueType::Scalar);
value.SetContext(Value::ContextType::RegisterInfo,
const_cast<RegisterInfo *>(reg_info));
if (error_ptr)
error_ptr->Clear();
return true;
} else {
// If we get this error, then we need to implement a value buffer in
// the dwarf expression evaluation function...
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"register %s can't be converted to a scalar value",
reg_info->name);
}
} else {
if (error_ptr)
error_ptr->SetErrorStringWithFormat("register %s is not available",
reg_info->name);
}
static llvm::Error ReadRegisterValueAsScalar(RegisterContext *reg_ctx,
lldb::RegisterKind reg_kind,
uint32_t reg_num, Value &value) {
if (reg_ctx == nullptr)
return llvm::createStringError("no register context in frame");

const uint32_t native_reg =
reg_ctx->ConvertRegisterKindToRegisterNumber(reg_kind, reg_num);
if (native_reg == LLDB_INVALID_REGNUM)
return llvm::createStringError(
"unable to convert register kind=%u reg_num=%u to a native "
"register number",
reg_kind, reg_num);

const RegisterInfo *reg_info = reg_ctx->GetRegisterInfoAtIndex(native_reg);
RegisterValue reg_value;
if (reg_ctx->ReadRegister(reg_info, reg_value)) {
if (reg_value.GetScalarValue(value.GetScalar())) {
value.SetValueType(Value::ValueType::Scalar);
value.SetContext(Value::ContextType::RegisterInfo,
const_cast<RegisterInfo *>(reg_info));
return llvm::Error::success();
}

// If we get this error, then we need to implement a value buffer in
// the dwarf expression evaluation function...
return llvm::createStringError(
"register %s can't be converted to a scalar value", reg_info->name);
}
return false;

return llvm::createStringError("register %s is not available",
reg_info->name);
}

/// Return the length in bytes of the set of operands for \p op. No guarantees
Expand Down Expand Up @@ -1839,11 +1826,10 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
dwarf4_location_description_kind = Register;
reg_num = op - DW_OP_reg0;

Status read_err;
if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, &read_err, tmp))
stack.push_back(tmp);
else
return read_err.ToError();
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
stack.push_back(tmp);
} break;
// OPCODE: DW_OP_regx
// OPERANDS:
Expand All @@ -1853,10 +1839,10 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
dwarf4_location_description_kind = Register;
reg_num = opcodes.GetULEB128(&offset);
Status read_err;
if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, &read_err, tmp))
stack.push_back(tmp);
else
return read_err.ToError();
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
stack.push_back(tmp);
} break;

// OPCODE: DW_OP_bregN
Expand Down Expand Up @@ -1897,17 +1883,15 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_breg30:
case DW_OP_breg31: {
reg_num = op - DW_OP_breg0;

Status read_err;
if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, &read_err,
tmp)) {
int64_t breg_offset = opcodes.GetSLEB128(&offset);
tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else
return read_err.ToError();
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;

int64_t breg_offset = opcodes.GetSLEB128(&offset);
tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
// OPCODE: DW_OP_bregx
// OPERANDS: 2
Expand All @@ -1917,17 +1901,15 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
// N plus an offset.
case DW_OP_bregx: {
reg_num = opcodes.GetULEB128(&offset);

Status read_err;
if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, &read_err,
tmp)) {
int64_t breg_offset = opcodes.GetSLEB128(&offset);
tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else
return read_err.ToError();
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;

int64_t breg_offset = opcodes.GetSLEB128(&offset);
tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;

case DW_OP_fbreg:
Expand Down
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