[trace][intelpt] Support system-wide tracing [12] - Support multi-core trace load and save

:q!
This diff is massive, but it's because it connects the client with lldb-server
and also ensures that the postmortem case works.

- Flatten the postmortem trace schema. The reason is that the schema has become quite complex due to the new multicore case, which defeats the original purpose of having a schema that could work for every trace plug-in. At this point, it's better that each trace plug-in defines it's own full schema. This means that the only common field is "type".
-- Because of this new approach, I merged the "common" trace load and saving functionalities into the IntelPT one. This simplified the code quite a bit. If we eventually implement another trace plug-in, we can see then what we could reuse.
-- The new schema, which is flattened, has now better comments and is parsed better. A change I did was to disallow hex addresses, because they are a bit error prone. I'm asking now to print the address in decimal.
-- Renamed "intel" to "GenuineIntel" in the schema because that's what you see in /proc/cpuinfo.
- Implemented reading the context switch trace data buffer. I had to do
some refactors to do that cleanly.
-- A major change that I did here was to simplify the perf_event circular buffer reading logic. It was too complex. Maybe the original Intel author had something different in mind.
- Implemented all the necessary bits to read trace.json files with per-core data.
- Implemented all the necessary bits to save to disk per-core trace session.
- Added a test that ensures that parsing and saving to disk works.

Differential Revision: https://reviews.llvm.org/D126015

1 files changed, 18 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Process/Linux/IntelPTThreadTraceCollection.cpp b/lldb/source/Plugins/Process/Linux/IntelPTThreadTraceCollection.cpp
index d7206b193e8f..bd06e033f160 100644
--- a/lldb/source/Plugins/Process/Linux/IntelPTThreadTraceCollection.cpp
+++ b/lldb/source/Plugins/Process/Linux/IntelPTThreadTraceCollection.cpp
@@ -71,3 +71,21 @@ void IntelPTThreadTraceCollection::Clear() {
 size_t IntelPTThreadTraceCollection::GetTracedThreadsCount() const {
   return m_thread_traces.size();
 }
+
+llvm::Expected<llvm::Optional<std::vector<uint8_t>>>
+IntelPTThreadTraceCollection::TryGetBinaryData(
+    const TraceGetBinaryDataRequest &request) {
+  if (!request.tid)
+    return None;
+  if (request.kind != IntelPTDataKinds::kTraceBuffer)
+    return None;
+
+  if (!TracesThread(*request.tid))
+    return None;
+
+  if (Expected<IntelPTSingleBufferTrace &> trace =
+          GetTracedThread(*request.tid))
+    return trace->GetTraceBuffer(request.offset, request.size);
+  else
+    return trace.takeError();
+}