vsk added a comment. In D103588#2806512 <https://reviews.llvm.org/D103588#2806512>, @wallace wrote:
> Right now we haven't implemented lazy decoding; we are decoding the entire > trace. But that's just because so far we have been working with small traces. > As we progress in this work, we'll start working with larger traces and we'll > have to do implement the lazy decoding, for which the TraverseInstructions > API will come handy. This approach - of prototyping trace analyses on a vector<TraceInstruction> representation and then rewriting them later when scaling issues arise - doesn't sound good to me. Even for something simple, like finding a backtrace, the window of instructions needed for analysis can easily grow to a point where the full vector<TraceInstruction> can't be maintained in memory. To clarify: I think that's a perfectly reasonable way to prototype trace analyses, but I don't think that kind of prototyping should be done at the SB API level, as there are extra bincompat & portability concerns here. >> What alternatives to the vector<TraceInstruction> representation have you >> considered? One idea might be to implement your program analyses on top of a >> generic interface for navigating forward/backward through a trace and >> extracting info about the instruction via a set of API calls; this leaves >> the actual in-memory representation of "TraceInstruction" unspecified. > > That's exactly what I described as the TraverseInstructions method :) The > intel-pt plugin or any other trace plugin could have an internal > representation for traces, but we still need a generic TraceInstruction > object for consumers that want to be agnostic of the trace technology. It's not at all clear to me that lldb needs to surface a generic TraceInstruction object, with metadata like m_byte_size, m_inst_type, etc. stored inline. It seems more flexible to instead vend a cursor (just an integer) that indicates a position in the trace; a separate set of APIs could answer queries given a cursor, e.g. 'getInstTypeAtCursor(u64 cursor)'. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D103588/new/ https://reviews.llvm.org/D103588 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
