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llvm-project/lldb/source/DataFormatters/FormatterBytecode.cpp
Adrian Prantl 87659a17d0 Reland: [lldb] Implement a formatter bytecode interpreter in C++ 
Compared to the python version, this also does type checking and error
handling, so it's slightly longer, however, it's still comfortably
under 500 lines.

Relanding with more explicit type conversions.
2024-12-10 16:37:53 -08:00

576 lines
18 KiB
C++
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//===-- FormatterBytecode.cpp ---------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "FormatterBytecode.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/ValueObject/ValueObject.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/FormatProviders.h"
#include "llvm/Support/FormatVariadicDetails.h"
using namespace lldb;
namespace lldb_private {
std::string toString(FormatterBytecode::OpCodes op) {
switch (op) {
#define DEFINE_OPCODE(OP, MNEMONIC, NAME) \
case OP: { \
const char *s = MNEMONIC; \
return s ? s : #NAME; \
}
#include "FormatterBytecode.def"
#undef DEFINE_SIGNATURE
}
return llvm::utostr(op);
}
std::string toString(FormatterBytecode::Selectors sel) {
switch (sel) {
#define DEFINE_SELECTOR(ID, NAME) \
case ID: \
return "@" #NAME;
#include "FormatterBytecode.def"
#undef DEFINE_SIGNATURE
}
return "@" + llvm::utostr(sel);
}
std::string toString(FormatterBytecode::Signatures sig) {
switch (sig) {
#define DEFINE_SIGNATURE(ID, NAME) \
case ID: \
return "@" #NAME;
#include "FormatterBytecode.def"
#undef DEFINE_SIGNATURE
}
return llvm::utostr(sig);
}
std::string toString(const FormatterBytecode::DataStack &data) {
std::string s;
llvm::raw_string_ostream os(s);
os << "[ ";
for (auto &d : data) {
if (auto s = std::get_if<std::string>(&d))
os << '"' << *s << '"';
else if (auto u = std::get_if<uint64_t>(&d))
os << *u << 'u';
else if (auto i = std::get_if<int64_t>(&d))
os << *i;
else if (auto valobj = std::get_if<ValueObjectSP>(&d)) {
if (!valobj->get())
os << "null";
else
os << "object(" << valobj->get()->GetValueAsCString() << ')';
} else if (auto type = std::get_if<CompilerType>(&d)) {
os << '(' << type->GetTypeName(true) << ')';
} else if (auto sel = std::get_if<FormatterBytecode::Selectors>(&d)) {
os << toString(*sel);
}
os << ' ';
}
os << ']';
return s;
}
namespace FormatterBytecode {
/// Implement the @format function.
static llvm::Error FormatImpl(DataStack &data) {
auto fmt = data.Pop<std::string>();
auto replacements =
llvm::formatv_object_base::parseFormatString(fmt, 0, false);
std::string s;
llvm::raw_string_ostream os(s);
unsigned num_args = 0;
for (const auto &r : replacements)
if (r.Type == llvm::ReplacementType::Format)
num_args = std::max(num_args, r.Index + 1);
if (data.size() < num_args)
return llvm::createStringError("not enough arguments");
for (const auto &r : replacements) {
if (r.Type == llvm::ReplacementType::Literal) {
os << r.Spec;
continue;
}
using namespace llvm::support::detail;
auto arg = data[data.size() - num_args + r.Index];
auto format = [&](format_adapter &&adapter) {
llvm::FmtAlign Align(adapter, r.Where, r.Width, r.Pad);
Align.format(os, r.Options);
};
if (auto s = std::get_if<std::string>(&arg))
format(build_format_adapter(s->c_str()));
else if (auto u = std::get_if<uint64_t>(&arg))
format(build_format_adapter(u));
else if (auto i = std::get_if<int64_t>(&arg))
format(build_format_adapter(i));
else if (auto valobj = std::get_if<ValueObjectSP>(&arg)) {
if (!valobj->get())
format(build_format_adapter("null object"));
else
format(build_format_adapter(valobj->get()->GetValueAsCString()));
} else if (auto type = std::get_if<CompilerType>(&arg))
format(build_format_adapter(type->GetDisplayTypeName()));
else if (auto sel = std::get_if<FormatterBytecode::Selectors>(&arg))
format(build_format_adapter(toString(*sel)));
}
data.Push(s);
return llvm::Error::success();
}
static llvm::Error TypeCheck(llvm::ArrayRef<DataStackElement> data,
DataType type) {
if (data.size() < 1)
return llvm::createStringError("not enough elements on data stack");
auto &elem = data.back();
switch (type) {
case Any:
break;
case String:
if (!std::holds_alternative<std::string>(elem))
return llvm::createStringError("expected String");
break;
case UInt:
if (!std::holds_alternative<uint64_t>(elem))
return llvm::createStringError("expected UInt");
break;
case Int:
if (!std::holds_alternative<int64_t>(elem))
return llvm::createStringError("expected Int");
break;
case Object:
if (!std::holds_alternative<ValueObjectSP>(elem))
return llvm::createStringError("expected Object");
break;
case Type:
if (!std::holds_alternative<CompilerType>(elem))
return llvm::createStringError("expected Type");
break;
case Selector:
if (!std::holds_alternative<Selectors>(elem))
return llvm::createStringError("expected Selector");
break;
}
return llvm::Error::success();
}
static llvm::Error TypeCheck(llvm::ArrayRef<DataStackElement> data,
DataType type1, DataType type2) {
if (auto error = TypeCheck(data, type2))
return error;
return TypeCheck(data.drop_back(), type1);
}
static llvm::Error TypeCheck(llvm::ArrayRef<DataStackElement> data,
DataType type1, DataType type2, DataType type3) {
if (auto error = TypeCheck(data, type3))
return error;
return TypeCheck(data.drop_back(1), type2, type1);
}
llvm::Error Interpret(std::vector<ControlStackElement> &control,
DataStack &data, Selectors sel) {
if (control.empty())
return llvm::Error::success();
// Since the only data types are single endian and ULEBs, the
// endianness should not matter.
llvm::DataExtractor cur_block(control.back(), true, 64);
llvm::DataExtractor::Cursor pc(0);
while (!control.empty()) {
/// Activate the top most block from the control stack.
auto activate_block = [&]() {
// Save the return address.
if (control.size() > 1)
control[control.size() - 2] = cur_block.getData().drop_front(pc.tell());
cur_block = llvm::DataExtractor(control.back(), true, 64);
if (pc)
pc = llvm::DataExtractor::Cursor(0);
};
/// Fetch the next byte in the instruction stream.
auto next_byte = [&]() -> uint8_t {
// At the end of the current block?
while (pc.tell() >= cur_block.size() && !control.empty()) {
if (control.size() == 1) {
control.pop_back();
return 0;
}
control.pop_back();
activate_block();
}
// Fetch the next instruction.
return cur_block.getU8(pc);
};
// Fetch the next opcode.
OpCodes opcode = (OpCodes)next_byte();
if (control.empty() || !pc)
return pc.takeError();
LLDB_LOGV(GetLog(LLDBLog::DataFormatters),
"[eval {0}] opcode={1}, control={2}, data={3}", toString(sel),
toString(opcode), control.size(), toString(data));
// Various shorthands to improve the readability of error handling.
#define TYPE_CHECK(...) \
if (auto error = TypeCheck(data, __VA_ARGS__)) \
return error;
auto error = [&](llvm::Twine msg) {
return llvm::createStringError(msg + "(opcode=" + toString(opcode) + ")");
};
switch (opcode) {
// Data stack manipulation.
case op_dup:
TYPE_CHECK(Any);
data.Push(data.back());
continue;
case op_drop:
TYPE_CHECK(Any);
data.pop_back();
continue;
case op_pick: {
TYPE_CHECK(UInt);
uint64_t idx = data.Pop<uint64_t>();
if (idx >= data.size())
return error("index out of bounds");
data.Push(data[idx]);
continue;
}
case op_over:
TYPE_CHECK(Any, Any);
data.Push(data[data.size() - 2]);
continue;
case op_swap: {
TYPE_CHECK(Any, Any);
auto x = data.PopAny();
auto y = data.PopAny();
data.Push(x);
data.Push(y);
continue;
}
case op_rot: {
TYPE_CHECK(Any, Any, Any);
auto z = data.PopAny();
auto y = data.PopAny();
auto x = data.PopAny();
data.Push(z);
data.Push(x);
data.Push(y);
continue;
}
// Control stack manipulation.
case op_begin: {
uint64_t length = cur_block.getULEB128(pc);
if (!pc)
return pc.takeError();
llvm::StringRef block = cur_block.getBytes(pc, length);
if (!pc)
return pc.takeError();
control.push_back(block);
continue;
}
case op_if:
TYPE_CHECK(UInt);
if (data.Pop<uint64_t>() != 0) {
if (!cur_block.size())
return error("empty control stack");
activate_block();
} else
control.pop_back();
continue;
case op_ifelse:
TYPE_CHECK(UInt);
if (cur_block.size() < 2)
return error("empty control stack");
if (data.Pop<uint64_t>() == 0)
control[control.size() - 2] = control.back();
control.pop_back();
activate_block();
continue;
// Literals.
case op_lit_uint:
data.Push(cur_block.getULEB128(pc));
continue;
case op_lit_int:
data.Push(cur_block.getSLEB128(pc));
continue;
case op_lit_selector:
data.Push(Selectors(cur_block.getU8(pc)));
continue;
case op_lit_string: {
uint64_t length = cur_block.getULEB128(pc);
llvm::StringRef bytes = cur_block.getBytes(pc, length);
data.Push(bytes.str());
continue;
}
case op_as_uint: {
TYPE_CHECK(Int);
uint64_t casted;
int64_t val = data.Pop<int64_t>();
memcpy(&casted, &val, sizeof(val));
data.Push(casted);
continue;
}
case op_as_int: {
TYPE_CHECK(UInt);
int64_t casted;
uint64_t val = data.Pop<uint64_t>();
memcpy(&casted, &val, sizeof(val));
data.Push(casted);
continue;
}
case op_is_null: {
TYPE_CHECK(Object);
data.Push(data.Pop<ValueObjectSP>() ? 0ULL : 1ULL);
continue;
}
// Arithmetic, logic, etc.
#define BINOP_IMPL(OP, CHECK_ZERO) \
{ \
TYPE_CHECK(Any, Any); \
auto y = data.PopAny(); \
if (std::holds_alternative<uint64_t>(y)) { \
if (CHECK_ZERO && !std::get<uint64_t>(y)) \
return error(#OP " by zero"); \
TYPE_CHECK(UInt); \
data.Push((uint64_t)(data.Pop<uint64_t>() OP std::get<uint64_t>(y))); \
} else if (std::holds_alternative<int64_t>(y)) { \
if (CHECK_ZERO && !std::get<int64_t>(y)) \
return error(#OP " by zero"); \
TYPE_CHECK(Int); \
data.Push((int64_t)(data.Pop<int64_t>() OP std::get<int64_t>(y))); \
} else \
return error("unsupported data types"); \
}
#define BINOP(OP) BINOP_IMPL(OP, false)
#define BINOP_CHECKZERO(OP) BINOP_IMPL(OP, true)
case op_plus:
BINOP(+);
continue;
case op_minus:
BINOP(-);
continue;
case op_mul:
BINOP(*);
continue;
case op_div:
BINOP_CHECKZERO(/);
continue;
case op_mod:
BINOP_CHECKZERO(%);
continue;
case op_shl:
#define SHIFTOP(OP) \
{ \
TYPE_CHECK(Any, UInt); \
uint64_t y = data.Pop<uint64_t>(); \
if (y > 64) \
return error("shift out of bounds"); \
if (std::holds_alternative<uint64_t>(data.back())) { \
uint64_t x = data.Pop<uint64_t>(); \
data.Push(x OP y); \
} else if (std::holds_alternative<int64_t>(data.back())) { \
int64_t x = data.Pop<int64_t>(); \
if (y > 64) \
return error("shift out of bounds"); \
if (y < 0) \
return error("shift out of bounds"); \
data.Push(x OP y); \
} else \
return error("unsupported data types"); \
}
SHIFTOP(<<);
continue;
case op_shr:
SHIFTOP(<<);
continue;
case op_and:
BINOP(&);
continue;
case op_or:
BINOP(|);
continue;
case op_xor:
BINOP(^);
continue;
case op_not:
TYPE_CHECK(UInt);
data.Push(~data.Pop<uint64_t>());
continue;
case op_eq:
BINOP(==);
continue;
case op_neq:
BINOP(!=);
continue;
case op_lt:
BINOP(<);
continue;
case op_gt:
BINOP(>);
continue;
case op_le:
BINOP(<=);
continue;
case op_ge:
BINOP(>=);
continue;
case op_call: {
TYPE_CHECK(Selector);
Selectors sel = data.Pop<Selectors>();
// Shorthand to improve readability.
#define POP_VALOBJ(VALOBJ) \
auto VALOBJ = data.Pop<ValueObjectSP>(); \
if (!VALOBJ) \
return error("null object");
auto sel_error = [&](const char *msg) {
return llvm::createStringError("{0} (opcode={1}, selector={2})", msg,
toString(opcode).c_str(),
toString(sel).c_str());
};
switch (sel) {
case sel_summary: {
TYPE_CHECK(Object);
POP_VALOBJ(valobj);
const char *summary = valobj->GetSummaryAsCString();
data.Push(summary ? std::string(valobj->GetSummaryAsCString())
: std::string());
break;
}
case sel_get_num_children: {
TYPE_CHECK(Object);
POP_VALOBJ(valobj);
auto result = valobj->GetNumChildren();
if (!result)
return result.takeError();
data.Push((uint64_t)*result);
break;
}
case sel_get_child_at_index: {
TYPE_CHECK(Object, UInt);
auto index = data.Pop<uint64_t>();
POP_VALOBJ(valobj);
data.Push(valobj->GetChildAtIndex(index));
break;
}
case sel_get_child_with_name: {
TYPE_CHECK(Object, String);
auto name = data.Pop<std::string>();
POP_VALOBJ(valobj);
data.Push(valobj->GetChildMemberWithName(name));
break;
}
case sel_get_child_index: {
TYPE_CHECK(Object, String);
auto name = data.Pop<std::string>();
POP_VALOBJ(valobj);
data.Push((uint64_t)valobj->GetIndexOfChildWithName(name));
break;
}
case sel_get_type: {
TYPE_CHECK(Object);
POP_VALOBJ(valobj);
// FIXME: do we need to control dynamic type resolution?
data.Push(valobj->GetTypeImpl().GetCompilerType(false));
break;
}
case sel_get_template_argument_type: {
TYPE_CHECK(Type, UInt);
auto index = data.Pop<uint64_t>();
auto type = data.Pop<CompilerType>();
// FIXME: There is more code in SBType::GetTemplateArgumentType().
data.Push(type.GetTypeTemplateArgument(index, true));
break;
}
case sel_get_value: {
TYPE_CHECK(Object);
POP_VALOBJ(valobj);
data.Push(std::string(valobj->GetValueAsCString()));
break;
}
case sel_get_value_as_unsigned: {
TYPE_CHECK(Object);
POP_VALOBJ(valobj);
bool success;
uint64_t val = valobj->GetValueAsUnsigned(0, &success);
data.Push(val);
if (!success)
return sel_error("failed to get value");
break;
}
case sel_get_value_as_signed: {
TYPE_CHECK(Object);
POP_VALOBJ(valobj);
bool success;
int64_t val = valobj->GetValueAsSigned(0, &success);
data.Push(val);
if (!success)
return sel_error("failed to get value");
break;
}
case sel_get_value_as_address: {
TYPE_CHECK(Object);
POP_VALOBJ(valobj);
bool success;
uint64_t addr = valobj->GetValueAsUnsigned(0, &success);
if (!success)
return sel_error("failed to get value");
if (auto process_sp = valobj->GetProcessSP())
addr = process_sp->FixDataAddress(addr);
data.Push(addr);
break;
}
case sel_cast: {
TYPE_CHECK(Object, Type);
auto type = data.Pop<CompilerType>();
POP_VALOBJ(valobj);
data.Push(valobj->Cast(type));
break;
}
case sel_strlen: {
TYPE_CHECK(String);
data.Push((uint64_t)data.Pop<std::string>().size());
break;
}
case sel_fmt: {
TYPE_CHECK(String);
if (auto error = FormatImpl(data))
return error;
break;
}
default:
return sel_error("selector not implemented");
}
continue;
}
}
return error("opcode not implemented");
}
return pc.takeError();
}
} // namespace FormatterBytecode
} // namespace lldb_private
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