[clang-repl] Reimplement value printing using MemoryAccess to support in-process and out-of-process #156649
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… in-process and out-of-process
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@vgvassilev This is still a draft — some parts are not implemented yet (e.g. record and function types), but I shared it so you can see the idea and check if the approach looks feasible. |
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And also I need a way to detect whether the interpreter is running in-process or out-of-process. |
| return Str; | ||
| case clang::BuiltinType::Short: | ||
| SS << V.getShort(); | ||
| SS << B.as<short>(); |
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Why we have to cast the data when we know its type? If that's needed for out-of-process where the host and target architectures do not match, we should probably somehow do it in a separate facility because getX is much faster on matching architectures.
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Since I’m not using our existing Value, I introduced a universal buffer for built-in types (including strings).
class BuiltinValueBuffer : public ValueBuffer {
public:
std::vector<uint8_t> raw;
BuiltinValueBuffer(QualType _Ty) : ValueBuffer(K_Builtin) { Ty = _Ty; }
template <typename T> T as() const {
T v{};
// assert(raw.size() >= sizeof(T) && "Buffer too small for type!");
memcpy(&v, raw.data(), sizeof(T));
return v;
}
static bool classof(const ValueBuffer *B) { return B->isBuiltin(); }
};I use ValueBuffer to read memory directly into a buffer sized for the type, and at print time we cast the raw data back to the correct type.
If we use a Value-kind structure, we need to read memory, cast it, and set the value at read time.
Reimplement value printing on top of ORC MemoryAccess. The previous
implementation only supported in-process evaluation; with this new
design it now works in both in-process and out-of-process modes.
The implementation introduces a ValueBuffer hierarchy (Builtin, Array,
Pointer) for capturing evaluated values, a ReaderDispatcher for reading
values from MemoryAccess, and a ValueToString printer for converting
buffers back to strings.