[trace][intel pt] Fix per-psb packet decoding

[wallace]

Summary

The per-PSB packet decoding logic was wrong because it was assuming that pt_insn_get_sync_offset was being udpated after every PSB. Silly me, that is not true. It returns the offset of the PSB packet after invoking pt_insn_sync_forward regardless of how many PSBs are visited later. Instead, I'm now following the approach described in https://github.com/intel/libipt/blob/master/doc/howto_libipt.md#parallel-decode for parallel decoding, which is basically what we need.

A nasty error that happened because of this is that when we had two PSBs (A and B), the following was happening

1. PSB A was processed all the way up to the end of the trace, which includes PSB B.
2. PSB B was then processed until the end of the trace.

The instructions emitted by step 2. were also emitted as part of step 1. so our trace had duplicated chunks. This problem becomes worse when you many PSBs.

As part of making sure this diff is correct, I added some other features that are very useful.

• Added a "synchronization point" event to the TraceCursor, so we can inspect when PSBs are emitted.
• Removed the single-thread decoder. Now the per-cpu decoder and single-thread decoder use the same code paths.
• Use the query decoder to fetch PSBs and timestamps. It turns out that the pt_insn_sync_forward of the instruction decoder can move past several PSBs (this means that we could skip some TSCs). On the other hand, the pt_query_sync_forward method doesn't skip PSBs, so we can get more accurate sync events and timing information.
• Turned LibiptDecoder into PSBBlockDecoder, which decodes single PSB blocks. It is the fundamental processing unit for decoding.
• Added many comments, asserts and improved error handling for clarity.
• Improved DecodeSystemWideTraceForThread so that a TSC is emitted always before a cpu change event. This was a bug that was annoying me before.
• SplitTraceInContinuousExecutions and FindLowestTSCInTrace are now using the query decoder, which can identify precisely each PSB along with their TSCs.
• Added an "only-events" option to the trace dumper to inspect only events.

I did extensive testing and I think we should have an in-house testing CI. The LLVM buildbots are not capable of supporting testing post-mortem traces of hundreds of megabytes. I'll leave that for later, but at least for now the current tests were able to catch most of the issues I encountered when doing this task.

A sample output of a program that I was single stepping is the following. You can see that only one PSB is emitted even though stepping happened!

thread #1: tid = 3578223
    0: (event) trace synchronization point [offset = 0x0xef0]
  a.out`main + 20 at main.cpp:29:20
    1: 0x0000000000402479    leaq   -0x1210(%rbp), %rax
    2: (event) software disabled tracing
    3: 0x0000000000402480    movq   %rax, %rdi
    4: (event) software disabled tracing
    5: (event) software disabled tracing
    6: 0x0000000000402483    callq  0x403bd4                  ; std::vector<int, std::allocator<int>>::vector at stl_vector.h:391:7
    7: (event) software disabled tracing
  a.out`std::vector<int, std::allocator<int>>::vector() at stl_vector.h:391:7
    8: 0x0000000000403bd4    pushq  %rbp
    9: (event) software disabled tracing
    10: 0x0000000000403bd5    movq   %rsp, %rbp
    11: (event) software disabled tracing

This is another trace of a long program with a few PSBs.

(lldb) thread trace dump instructions -E -f                                                                                                         thread #1: tid = 3603082
    0: (event) trace synchronization point [offset = 0x0x80]
    47417: (event) software disabled tracing
    129231: (event) trace synchronization point [offset = 0x0x800]
    146747: (event) software disabled tracing
    246076: (event) software disabled tracing
    259068: (event) trace synchronization point [offset = 0x0xf78]
    259276: (event) software disabled tracing
    259278: (event) software disabled tracing
    no more data

[wallace]

nit

[wallace]

improve documentation

[jj10306]

lldb/source/Plugins/Trace/intel-pt/LibiptDecoder.cpp

156–193

should this be trace_intel_pt?

477–479

so is this inner loop what's actually doing the work of getting to the next PSB? is the assumption that if an event has a tsc then it's a PSB?
Can you explain what the two different while loops are doing?

lldb/source/Plugins/Trace/intel-pt/LibiptDecoder.h

106–107

should we rename now that we are using PSBBlock everywhere?

lldb/source/Plugins/Trace/intel-pt/TraceIntelPTMultiCpuDecoder.cpp

93

rename?

[wallace]

lldb/source/Plugins/Trace/intel-pt/LibiptDecoder.cpp

477–479

discussed offline. Every invocation to pt_qry_event will get a new PSB. the event loop is just for getting the first TSC.

[jj10306]

lldb/source/Plugins/Trace/intel-pt/LibiptDecoder.cpp

439–440

consider renaming?

[wallace]

update

lldb/include/lldb/Target/TraceCursor.h

public:
   /// Get the approximate wall clock time in nanoseconds at which the current
   /// trace item was executed. Each trace plug-in has a different definition for
   /// what time 0 means.
   ///
   /// \return
   ///     The approximate wall clock time for the trace item, or \a llvm::None
   ///     if not available.
   virtual llvm::Optional<double> GetWallClockTime() const = 0;
+
+  /// Get some metadata associated with a synchronization point event. As
+  /// different trace technologies might have different values for this,
+  /// we return a string for flexibility.
+  ///
+  /// \return
+  ///     A string representing some metadata associated with a
+  ///     \a eTraceEventSyncPoint event. \b None if no metadata is available.
+  virtual llvm::Optional<std::string> GetSyncPointMetadata() const = 0;
   /// \}
 
 protected:
   ExecutionContextRef m_exe_ctx_ref;
   bool m_forwards = false;
 };
 } // namespace lldb_private
 
 #endif // LLDB_TARGET_TRACE_CURSOR_H

lldb/include/lldb/Target/TraceDumper.h

struct TraceDumperOptions {
   bool json = false;
   /// When dumping in JSON format, pretty print the output.
   bool pretty_print_json = false;
   /// For each trace item, print the corresponding timestamp in nanoseconds if
   /// available.
   bool show_timestamps = false;
   /// Dump the events that happened between instructions.
   bool show_events = false;
+  /// Dump events and none of the instructions.
+  bool only_events = false;
   /// For each instruction, print the instruction kind.
   bool show_control_flow_kind = false;
   /// Optional custom id to start traversing from.
   llvm::Optional<uint64_t> id = llvm::None;
   /// Optional number of instructions to skip from the starting position
   /// of the cursor.
   llvm::Optional<size_t> skip = llvm::None;
 };
public:
   };
 
   /// Helper struct that holds all the information we know about a trace item
   struct TraceItem {
     lldb::user_id_t id;
     lldb::addr_t load_address;
     llvm::Optional<double> timestamp;
     llvm::Optional<uint64_t> hw_clock;
+    llvm::Optional<std::string> sync_point_metadata;
     llvm::Optional<llvm::StringRef> error;
     llvm::Optional<lldb::TraceEvent> event;
     llvm::Optional<SymbolInfo> symbol_info;
     llvm::Optional<SymbolInfo> prev_symbol_info;
     llvm::Optional<lldb::cpu_id_t> cpu_id;
   };
 
   /// Interface used to abstract away the format in which the instruction

lldb/include/lldb/lldb-enumerations.h

enum SaveCoreStyle {
   eSaveCoreUnspecified = 0,
   eSaveCoreFull = 1,
   eSaveCoreDirtyOnly = 2,
   eSaveCoreStackOnly = 3,
 };
 
 /// Events that might happen during a trace session.
 enum TraceEvent {
-  /// Tracing was disabled for some time due to a software trigger
+  /// Tracing was disabled for some time due to a software trigger.
   eTraceEventDisabledSW,
-  /// Tracing was disable for some time due to a hardware trigger
+  /// Tracing was disable for some time due to a hardware trigger.
   eTraceEventDisabledHW,
   /// Event due to CPU change for a thread. This event is also fired when
   /// suddenly it's not possible to identify the cpu of a given thread.
   eTraceEventCPUChanged,
-  /// Event due to a CPU HW clock tick
+  /// Event due to a CPU HW clock tick.
   eTraceEventHWClockTick,
+  /// The underlying tracing technology emitted a synchronization event used by
+  /// trace processors.
+  eTraceEventSyncPoint,
 };
 
 // Enum used to identify which kind of item a \a TraceCursor is pointing at
 enum TraceItemKind {
   eTraceItemKindError = 0,
   eTraceItemKindEvent,
   eTraceItemKindInstruction,
 };

lldb/source/Commands/CommandObjectThread.cpp

Status SetOptionValue(uint32_t option_idx, llvm::StringRef option_arg,
         m_dumper_options.json = true;
         break;
       }
       case 'J': {
         m_dumper_options.pretty_print_json = true;
         m_dumper_options.json = true;
         break;
       }
+      case 'E': {
+        m_dumper_options.only_events = true;
+        m_dumper_options.show_events = true;
+        break;
+      }
       case 'C': {
         m_continue = true;
         break;
       }
       default:
         llvm_unreachable("Unimplemented option");
       }
       return error;

lldb/source/Commands/Options.td

def thread_trace_dump_instructions_show_kind : Option<"kind", "k">, Group<1>,
     "calls to and from kernel.">;
   def thread_trace_dump_instructions_show_timestamps: Option<"time", "t">,
     Group<1>,
     Desc<"For each trace item, print the corresponding wall clock timestamp "
     "if available.">;
   def thread_trace_dump_instructions_show_events : Option<"events", "e">,
     Group<1>,
     Desc<"Dump the events that happened during the execution of the target.">;
+  def thread_trace_dump_instruction_only_events : Option<"only-events", "E">,
+    Group<1>,
+    Desc<"Dump only the events that happened during the execution of the "
+    "target. No instrutions are dumped.">;
   def thread_trace_dump_instructions_continue: Option<"continue", "C">,
     Group<1>,
     Desc<"Continue dumping instructions right where the previous invocation of "
     "this command was left, or from the beginning if this is the first "
     "invocation. The --skip argument is discarded and the other arguments are "
     "preserved from the previous invocation when possible.">;
 }
 

lldb/source/Plugins/Trace/intel-pt/DecodedThread.h

 #include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
 #include <utility>
 #include <vector>
 
 namespace lldb_private {
 namespace trace_intel_pt {
 
-/// libipt status utils
-/// \{
-bool IsLibiptError(int libipt_status);
-
-bool IsEndOfStream(int libipt_status);
-
-bool IsTscUnavailable(int libipt_status);
-/// \}
-
 /// Class for representing a libipt decoding error.
 class IntelPTError : public llvm::ErrorInfo<IntelPTError> {
 public:
   static char ID;
 
   /// \param[in] libipt_error_code
   ///     Negative number returned by libipt when decoding the trace and
   ///     signaling errors.
public:
   ///
   /// \param[in] item_index
   ///   The trace item index to compare with.
   ///
   /// \return
   ///   The requested cpu id, or \a LLDB_INVALID_CPU_ID if not available.
   lldb::cpu_id_t GetCPUByIndex(uint64_t item_index) const;
 
+  /// \return
+  ///   The PSB offset associated with the given item index.
+  lldb::addr_t GetSyncPointOffsetByIndex(uint64_t item_index) const;
+
   /// Get a maximal range of trace items that include the given \p item_index
   /// that have the same TSC value.
   ///
   /// \param[in] item_index
   ///   The trace item index to compare with.
   ///
   /// \return
   ///   The requested TSC range, or \a llvm::None if not available.
public:
   ///   The requested nanoseconds range, or \a llvm::None if not available.
   llvm::Optional<DecodedThread::NanosecondsRange>
   GetNanosecondsRangeByIndex(uint64_t item_index);
 
   /// \return
   ///     The load address of the instruction at the given index.
   lldb::addr_t GetInstructionLoadAddress(uint64_t item_index) const;
 
-  /// Return an object with statistics of the TSC decoding errors that happened.
-  /// A TSC error is not a fatal error and doesn't create gaps in the trace.
-  /// Instead we only keep track of them as statistics.
-  ///
-  /// \return
-  ///   An object with the statistics of TSC decoding errors.
-  const LibiptErrorsStats &GetTscErrorsStats() const;
-
   /// Return an object with statistics of the trace events that happened.
   ///
   /// \return
   ///   The stats object of all the events.
   const EventsStats &GetEventsStats() const;
 
-  /// Record an error decoding a TSC timestamp.
-  ///
-  /// See \a GetTscErrors() for more documentation.
-  ///
-  /// \param[in] libipt_error_code
-  ///   An error returned by the libipt library.
-  void RecordTscError(int libipt_error_code);
-
   /// The approximate size in bytes used by this instance,
   /// including all the already decoded instructions.
   size_t CalculateApproximateMemoryUsage() const;
 
   lldb::ThreadSP GetThread();
 
   /// Notify this object that a new tsc has been seen.
   /// If this a new TSC, an event will be created.
   void NotifyTsc(TSC tsc);
 
   /// Notify this object that a CPU has been seen.
   /// If this a new CPU, an event will be created.
   void NotifyCPU(lldb::cpu_id_t cpu_id);
 
+  /// Notify this object that a new PSB has been seen.
+  void NotifySyncPoint(lldb::addr_t psb_offset);
+
   /// Append a decoding error.
   void AppendError(const IntelPTError &error);
 
   /// Append a custom decoding.
   void AppendCustomError(llvm::StringRef error);
 
   /// Append an event.
   void AppendEvent(lldb::TraceEvent);
private:
   /// decoded trace items. It maps `item index -> nanoseconds`, where `item
   /// index` is the first index at which the mapped nanoseconds first appears.
   /// We use this representation because timestamps are sporadic and we think of
   /// them as ranges.
   std::map<uint64_t, NanosecondsRange> m_nanoseconds;
   llvm::Optional<std::map<uint64_t, NanosecondsRange>::iterator>
       m_last_nanoseconds = llvm::None;
 
-  // The cpu information is stored as a map. It maps `instruction index -> CPU`
+  // The cpu information is stored as a map. It maps `item index -> CPU`.
   // A CPU is associated with the next instructions that follow until the next
   // cpu is seen.
   std::map<uint64_t, lldb::cpu_id_t> m_cpus;
   /// This is the chronologically last CPU ID.
   llvm::Optional<uint64_t> m_last_cpu = llvm::None;
 
+  // The PSB offsets are stored as a map. It maps `item index -> psb offset`.
+  llvm::DenseMap<uint64_t, lldb::addr_t> m_psb_offsets;
+
   /// TSC -> nanos conversion utility.
   llvm::Optional<LinuxPerfZeroTscConversion> m_tsc_conversion;
 
   /// Statistics of all tracing events.
   EventsStats m_events_stats;
-  /// Statistics of libipt errors when decoding TSCs.
-  LibiptErrorsStats m_tsc_errors_stats;
   /// Total amount of time spent decoding.
   std::chrono::milliseconds m_total_decoding_time{0};
 };
 
 using DecodedThreadSP = std::shared_ptr<DecodedThread>;
 
 } // namespace trace_intel_pt
 } // namespace lldb_private
 
 #endif // LLDB_SOURCE_PLUGINS_TRACE_INTEL_PT_DECODEDTHREAD_H

lldb/source/Plugins/Trace/intel-pt/DecodedThread.cpp

 #include <intel-pt.h>
 #include <memory>
 
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::trace_intel_pt;
 using namespace llvm;
 
-bool lldb_private::trace_intel_pt::IsLibiptError(int libipt_status) {
-  return libipt_status < 0;
-}
-
-bool lldb_private::trace_intel_pt::IsEndOfStream(int libipt_status) {
-  return libipt_status == -pte_eos;
-}
-
-bool lldb_private::trace_intel_pt::IsTscUnavailable(int libipt_status) {
-  return libipt_status == -pte_no_time;
-}
-
 char IntelPTError::ID;
 
 IntelPTError::IntelPTError(int libipt_error_code, lldb::addr_t address)
     : m_libipt_error_code(libipt_error_code), m_address(address) {
   assert(libipt_error_code < 0);
 }
 
 void IntelPTError::log(llvm::raw_ostream &OS) const {

 
 uint64_t DecodedThread::GetItemsCount() const { return m_item_kinds.size(); }
 
 lldb::addr_t
 DecodedThread::GetInstructionLoadAddress(uint64_t item_index) const {
   return m_item_data[item_index].load_address;
 }
 
+lldb::addr_t
+DecodedThread::GetSyncPointOffsetByIndex(uint64_t item_index) const {
+  return m_psb_offsets.find(item_index)->second;
+}
+
 ThreadSP DecodedThread::GetThread() { return m_thread_sp; }
 
 DecodedThread::TraceItemStorage &
 DecodedThread::CreateNewTraceItem(lldb::TraceItemKind kind) {
   m_item_kinds.push_back(kind);
   m_item_data.emplace_back();
   if (m_last_tsc)
     (*m_last_tsc)->second.items_count++;
   if (m_last_nanoseconds)
     (*m_last_nanoseconds)->second.items_count++;
   return m_item_data.back();
 }
 
+void DecodedThread::NotifySyncPoint(lldb::addr_t psb_offset) {
+  m_psb_offsets.try_emplace(GetItemsCount(), psb_offset);
+  AppendEvent(lldb::eTraceEventSyncPoint);
+}
+
 void DecodedThread::NotifyTsc(TSC tsc) {
   if (m_last_tsc && (*m_last_tsc)->second.tsc == tsc)
     return;
+  if (m_last_tsc)
+    assert(tsc >= (*m_last_tsc)->second.tsc &&
+           "We can't have decreasing times");
 
   m_last_tsc =
       m_tscs.emplace(GetItemsCount(), TSCRange{tsc, 0, GetItemsCount()}).first;
 
   if (m_tsc_conversion) {
     uint64_t nanos = m_tsc_conversion->ToNanos(tsc);
     if (!m_last_nanoseconds || (*m_last_nanoseconds)->second.nanos != nanos) {
       m_last_nanoseconds =
void DecodedThread::AppendEvent(lldb::TraceEvent event) {
   m_events_stats.RecordEvent(event);
 }
 
 void DecodedThread::AppendInstruction(const pt_insn &insn) {
   CreateNewTraceItem(lldb::eTraceItemKindInstruction).load_address = insn.ip;
 }
 
 void DecodedThread::AppendError(const IntelPTError &error) {
-  // End of stream shouldn't be a public error
-  if (IsEndOfStream(error.GetLibiptErrorCode()))
-    return;
   CreateNewTraceItem(lldb::eTraceItemKindError).error =
       ConstString(error.message()).AsCString();
 }
 
 void DecodedThread::AppendCustomError(StringRef err) {
   CreateNewTraceItem(lldb::eTraceItemKindError).error =
       ConstString(err).AsCString();
 }
 
 lldb::TraceEvent DecodedThread::GetEventByIndex(int item_index) const {
   return m_item_data[item_index].event;
 }
 
 void DecodedThread::LibiptErrorsStats::RecordError(int libipt_error_code) {
   libipt_errors_counts[pt_errstr(pt_errcode(libipt_error_code))]++;
   total_count++;
 }
 
-void DecodedThread::RecordTscError(int libipt_error_code) {
-  m_tsc_errors_stats.RecordError(libipt_error_code);
-}
-
-const DecodedThread::LibiptErrorsStats &
-DecodedThread::GetTscErrorsStats() const {
-  return m_tsc_errors_stats;
-}
-
 const DecodedThread::EventsStats &DecodedThread::GetEventsStats() const {
   return m_events_stats;
 }
 
 void DecodedThread::EventsStats::RecordEvent(lldb::TraceEvent event) {
   events_counts[event]++;
   total_count++;
 }

lldb/source/Plugins/Trace/intel-pt/LibiptDecoder.h

 #include "DecodedThread.h"
 #include "PerfContextSwitchDecoder.h"
 #include "forward-declarations.h"
 #include "intel-pt.h"
 
 namespace lldb_private {
 namespace trace_intel_pt {
 
-/// This struct represents a point in the intel pt trace that the decoder can
-/// start decoding from without errors.
-struct IntelPTThreadSubtrace {
+/// This struct represents a contiguous section of a trace that starts at a PSB
+/// and ends right before the next PSB or the end of the trace.
+struct PSBBlock {
   /// The memory offset of a PSB packet that is a synchronization point for the
   /// decoder. A decoder normally looks first for a PSB packet and then it
   /// starts decoding.
   uint64_t psb_offset;
   /// The timestamp associated with the PSB packet above.
-  uint64_t tsc;
+  llvm::Optional<uint64_t> tsc;
+  /// Size in bytes of this block
+  uint64_t size;
+  /// The first ip for this PSB block.
+  /// This is \a None if tracing was disabled when the PSB block was emitted.
+  /// This means that eventually there's be an enablement event that will come
+  /// with an ip.
+  llvm::Optional<lldb::addr_t> starting_ip;
 };
 
 /// This struct represents a continuous execution of a thread in a cpu,
 /// delimited by a context switch in and out, and a list of Intel PT subtraces
 /// that belong to this execution.
 struct IntelPTThreadContinousExecution {
   ThreadContinuousExecution thread_execution;
-  std::vector<IntelPTThreadSubtrace> intelpt_subtraces;
+  std::vector<PSBBlock> psb_blocks;
 
   IntelPTThreadContinousExecution(
       const ThreadContinuousExecution &thread_execution)
       : thread_execution(thread_execution) {}
 
   /// Comparator by time
   bool operator<(const IntelPTThreadContinousExecution &o) const;
 };

 /// \param[in] trace_intel_pt
 ///   The main Trace object that contains all the information related to the
 ///   trace session.
 ///
 /// \param[in] buffer
 ///   The intel pt buffer that belongs to a single thread or to a single cpu
 ///   core.
 ///
+/// \param[in] expect_tscs
+///   If \b true, an error is return if a packet without TSC is found.
+///
 /// \return
 ///   A list of continuous executions sorted by time, or an \a llvm::Error in
 ///   case of failures.
-llvm::Expected<std::vector<IntelPTThreadSubtrace>>
-SplitTraceInContinuousExecutions(TraceIntelPT &trace_intel_pt,
-                                 llvm::ArrayRef<uint8_t> buffer);
+llvm::Expected<std::vector<PSBBlock>>
+SplitTraceIntoPSBBlock(TraceIntelPT &trace_intel_pt,
+                       llvm::ArrayRef<uint8_t> buffer, bool expect_tscs);
 
 /// Find the lowest TSC in the given trace.
 ///
 /// \return
 ///     The lowest TSC value in this trace if available, \a llvm::None if the
 ///     trace is empty or the trace contains no timing information, or an \a
 ///     llvm::Error if it was not possible to set up the decoder.
 llvm::Expected<llvm::Optional<uint64_t>>
 FindLowestTSCInTrace(TraceIntelPT &trace_intel_pt,
                      llvm::ArrayRef<uint8_t> buffer);
 
 } // namespace trace_intel_pt
 } // namespace lldb_private
 
 #endif // LLDB_SOURCE_PLUGINS_TRACE_LIBIPT_DECODER_H

lldb/source/Plugins/Trace/intel-pt/LibiptDecoder.cpp

 //===-- LibiptDecoder.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 "LibiptDecoder.h"
 #include "TraceIntelPT.h"
 #include "lldb/Target/Process.h"
 
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::trace_intel_pt;
 using namespace llvm;
 
-/// Class that decodes a raw buffer for a single thread using the low level
-/// libipt library.
+bool IsLibiptError(int status) { return status < 0; }
+
+bool IsEndOfStream(int status) {
+  assert(status >= 0 && "We can't check if we reached the end of the stream if "
+                        "we got a failed status");
+  return status & pts_eos;
+}
+
+bool HasEvents(int status) {
+  assert(status >= 0 && "We can't check for events if we got a failed status");
+  return status & pts_event_pending;
+}
+
+// RAII deleter for libipt's decoders
+auto InsnDecoderDeleter = [](pt_insn_decoder *decoder) {
+  pt_insn_free_decoder(decoder);
+};
+
+auto QueryDecoderDeleter = [](pt_query_decoder *decoder) {
+  pt_qry_free_decoder(decoder);
+};
+
+using PtInsnDecoderUP =
+    std::unique_ptr<pt_insn_decoder, decltype(InsnDecoderDeleter)>;
+
+using PtQueryDecoderUP =
+    std::unique_ptr<pt_query_decoder, decltype(QueryDecoderDeleter)>;
+
+/// Create a basic configuration object limited to a given buffer that can be
+/// used for many different decoders.
+static Expected<pt_config> CreateBasicLibiptConfig(TraceIntelPT &trace_intel_pt,
+                                                   ArrayRef<uint8_t> buffer) {
+  Expected<pt_cpu> cpu_info = trace_intel_pt.GetCPUInfo();
+  if (!cpu_info)
+    return cpu_info.takeError();
+
+  pt_config config;
+  pt_config_init(&config);
+  config.cpu = *cpu_info;
+
+  int status = pt_cpu_errata(&config.errata, &config.cpu);
+  if (IsLibiptError(status))
+    return make_error<IntelPTError>(status);
+
+  // The libipt library does not modify the trace buffer, hence the
+  // following casts are safe.
+  config.begin = const_cast<uint8_t *>(buffer.data());
+  config.end = const_cast<uint8_t *>(buffer.data() + buffer.size());
+  return config;
+}
+
+/// Callback used by libipt for reading the process memory.
+///
+/// More information can be found in
+/// https://github.com/intel/libipt/blob/master/doc/man/pt_image_set_callback.3.md
+static int ReadProcessMemory(uint8_t *buffer, size_t size,
+                             const pt_asid * /* unused */, uint64_t pc,
+                             void *context) {
+  Process *process = static_cast<Process *>(context);
+
+  Status error;
+  int bytes_read = process->ReadMemory(pc, buffer, size, error);
+  if (error.Fail())
+    return -pte_nomap;
+  return bytes_read;
+}
+
+/// Set up the memory image callback for the given decoder.
+static Error SetupMemoryImage(pt_insn_decoder *decoder, Process &process) {
+  pt_image *image = pt_insn_get_image(decoder);
+
+  int status = pt_image_set_callback(image, ReadProcessMemory, &process);
+  if (IsLibiptError(status))
+    return make_error<IntelPTError>(status);
+  return Error::success();
+}
+
+/// Create an instruction decoder for the given buffer and the given process.
+static Expected<PtInsnDecoderUP>
+CreateInstructionDecoder(TraceIntelPT &trace_intel_pt, ArrayRef<uint8_t> buffer,
+                         Process &process) {
+  Expected<pt_config> config = CreateBasicLibiptConfig(trace_intel_pt, buffer);
+  if (!config)
+    return config.takeError();
+
+  pt_insn_decoder *decoder_ptr = pt_insn_alloc_decoder(&*config);
+  if (!decoder_ptr)
+    return make_error<IntelPTError>(-pte_nomem);
+
+  PtInsnDecoderUP decoder_up(decoder_ptr, InsnDecoderDeleter);
+
+  if (Error err = SetupMemoryImage(decoder_ptr, process))
+    return std::move(err);
+
+  return decoder_up;
+}
+
+/// Create a query decoder for the given buffer. The query decoder is the
+/// highest level decoder that operates directly on packets and doesn't perform
+/// actual instruction decoding. That's why it can be useful for inspecting a
+/// raw trace without pinning it to a particular process.
+static Expected<PtQueryDecoderUP>
+CreateQueryDecoder(TraceIntelPT &trace_intel_pt, ArrayRef<uint8_t> buffer) {
+  Expected<pt_config> config = CreateBasicLibiptConfig(trace_intel_pt, buffer);
+  if (!config)
+    return config.takeError();
+
+  pt_query_decoder *decoder_ptr = pt_qry_alloc_decoder(&*config);
+  if (!decoder_ptr)
+    return make_error<IntelPTError>(-pte_nomem);
+
+  return PtQueryDecoderUP(decoder_ptr, QueryDecoderDeleter);
+}
+
+/// Class that decodes a raw buffer for a single PSB block using the low level
+/// libipt library. It assumes that kernel and user mode instructions are not
+/// mixed in the same PSB block.
 ///
 /// Throughout this code, the status of the decoder will be used to identify
 /// events needed to be processed or errors in the decoder. The values can be
 /// - negative: actual errors
 /// - positive or zero: not an error, but a list of bits signaling the status
 /// of the decoder, e.g. whether there are events that need to be decoded or
 /// not.
-class LibiptDecoder {
+class PSBBlockDecoder {
 public:
   /// \param[in] decoder
-  ///     A well configured decoder. Using the current state of that decoder,
-  ///     decoding will start at its next valid PSB. It's not assumed that the
-  ///     decoder is already pointing at a valid PSB.
+  ///     A decoder configured to start and end within the boundaries of the
+  ///     given \p psb_block.
+  ///
+  /// \param[in] psb_block
+  ///     The PSB block to decode.
+  ///
+  /// \param[in] next_block_ip
+  ///     The starting ip at the next PSB block of the same thread if available.
   ///
   /// \param[in] decoded_thread
   ///     A \a DecodedThread object where the decoded instructions will be
   ///     appended to. It might have already some instructions.
-  LibiptDecoder(pt_insn_decoder &decoder, DecodedThread &decoded_thread)
-      : m_decoder(decoder), m_decoded_thread(decoded_thread) {}
+  PSBBlockDecoder(PtInsnDecoderUP &&decoder_up, const PSBBlock &psb_block,
+                  Optional<lldb::addr_t> next_block_ip,
+                  DecodedThread &decoded_thread)
+      : m_decoder_up(std::move(decoder_up)), m_psb_block(psb_block),
+        m_next_block_ip(next_block_ip), m_decoded_thread(decoded_thread) {}
 
-  /// Decode all the instructions until the end of the trace.
-  /// The decoding flow is based on
-  /// https://github.com/intel/libipt/blob/master/doc/howto_libipt.md#the-instruction-flow-decode-loop.
-  void DecodeUntilEndOfTrace() {
-    // Multiple loops indicate gaps in the trace, which are found by the inner
-    // call to DecodeInstructionsAndEvents.
-    while (true) {
-      int status = pt_insn_sync_forward(&m_decoder);
+  /// \param[in] trace_intel_pt
+  ///     The main Trace object that own the PSB block.
+  ///
+  /// \param[in] decoder
+  ///     A decoder configured to start and end within the boundaries of the
+  ///     given \p psb_block.
+  ///
+  /// \param[in] psb_block
+  ///     The PSB block to decode.
+  ///
+  /// \param[in] buffer
+  ///     The raw intel pt trace for this block.
+  ///
+  /// \param[in] process
+  ///     The process to decode. It provides the memory image to use for
+  ///     decoding.
+  ///
+  /// \param[in] next_block_ip
+  ///     The starting ip at the next PSB block of the same thread if available.
+  ///
+  /// \param[in] decoded_thread
+  ///     A \a DecodedThread object where the decoded instructions will be
+  ///     appended to. It might have already some instructions.
+  static Expected<PSBBlockDecoder>
+  Create(TraceIntelPT &trace_intel_pt, const PSBBlock &psb_block,
+         ArrayRef<uint8_t> buffer, Process &process,
+         Optional<lldb::addr_t> next_block_ip, DecodedThread &decoded_thread) {
+    Expected<PtInsnDecoderUP> decoder_up =
+        CreateInstructionDecoder(trace_intel_pt, buffer, process);
+    if (!decoder_up)
+      return decoder_up.takeError();
 
-      if (IsLibiptError(status)) {
-        m_decoded_thread.AppendError(IntelPTError(status));
-        break;
-      }
+    return PSBBlockDecoder(std::move(*decoder_up), psb_block, next_block_ip,
+                           decoded_thread);
 
-      DecodeInstructionsAndEvents(status);
-    }
-  }
+  void DecodePSBBlock() {
+    int status = pt_insn_sync_forward(m_decoder_up.get());
+    assert(status >= 0 &&
+           "Synchronization shouldn't fail because this PSB was previously "
+           "decoded correctly.");
+
+    // We emit a TSC before a sync event to more easily associate a timestamp to
+    // the sync event. If present, the current block's TSC would be the first
+    // TSC we'll see when processing events.
+    if (m_psb_block.tsc)
+      m_decoded_thread.NotifyTsc(*m_psb_block.tsc);
 
-  /// Decode all the instructions that belong to the same PSB packet given its
-  /// offset.
-  void DecodePSB(uint64_t psb_offset) {
-    int status = pt_insn_sync_set(&m_decoder, psb_offset);
-    if (IsLibiptError(status)) {
-      m_decoded_thread.AppendError(IntelPTError(status));
-      return;
-    }
-    DecodeInstructionsAndEvents(status, /*stop_on_psb_change=*/true);
+    m_decoded_thread.NotifySyncPoint(m_psb_block.psb_offset);
+
+    DecodeInstructionsAndEvents(status);
   }
 
 private:
-  /// Decode all the instructions and events until an error is found, the end
-  /// of the trace is reached, or optionally a new PSB is reached.
+  /// Decode all the instructions and events of the given PSB block.
   ///
   /// \param[in] status
   ///   The status that was result of synchronizing to the most recent PSB.
-  ///
-  /// \param[in] stop_on_psb_change
-  ///   If \b true, decoding stops if a different PSB is reached.
-  void DecodeInstructionsAndEvents(int status,
-                                   bool stop_on_psb_change = false) {
-    uint64_t psb_offset;
-    pt_insn_get_sync_offset(&m_decoder,
-                            &psb_offset); // this can't fail because we got here
+  void DecodeInstructionsAndEvents(int status) {
+    pt_insn insn;
+    while (true) {
+      status = ProcessPTEvents(status);
 
-    while (ProcessPTEvents(status)) {
-      if (stop_on_psb_change) {
-        uint64_t cur_psb_offset;
-        // this can't fail because we got here
-        pt_insn_get_sync_offset(&m_decoder, &cur_psb_offset);
-        if (cur_psb_offset != psb_offset)
-          break;
-      }
+      if (IsLibiptError(status))
+        return;
+      else if (IsEndOfStream(status))
 
       // The status returned by pt_insn_next will need to be processed
       // by ProcessPTEvents in the next loop if it is not an error.
-      pt_insn insn;
       std::memset(&insn, 0, sizeof insn);
-      if (IsLibiptError(status =
-                            pt_insn_next(&m_decoder, &insn, sizeof(insn)))) {
+      status = pt_insn_next(m_decoder_up.get(), &insn, sizeof(insn));
+
+      if (IsLibiptError(status)) {
         m_decoded_thread.AppendError(IntelPTError(status, insn.ip));
+        return;
+      } else if (IsEndOfStream(status)) {
         break;
       }
       m_decoded_thread.AppendInstruction(insn);
     }
-  }
 
-  /// Move the decoder forward to the next synchronization point (i.e. next PSB
-  /// packet).
-  ///
-  /// Once the decoder is at that synchronization point, it can start decoding
-  /// instructions.
-  ///
-  /// If errors are found, they will be appended to the trace.
-  ///
-  /// \return
-  ///   The libipt decoder status after moving to the next PSB. Negative if
-  ///   no PSB was found.
-  int FindNextSynchronizationPoint() {
-    // Try to sync the decoder. If it fails, then get the decoder_offset and
-    // try to sync again from the next synchronization point. If the
-    // new_decoder_offset is same as decoder_offset then we can't move to the
-    // next synchronization point. Otherwise, keep resyncing until either end
-    // of trace stream (eos) is reached or pt_insn_sync_forward() passes.
-    int status = pt_insn_sync_forward(&m_decoder);
+    // We need to keep querying non-branching instructions until we hit the
+    // starting point of the next PSB. We won't see events at this point. This
+    // is based on
+    // https://github.com/intel/libipt/blob/master/doc/howto_libipt.md#parallel-decode
+    if (m_next_block_ip && insn.ip != 0) {
+      while (insn.ip != *m_next_block_ip) {
+        m_decoded_thread.AppendInstruction(insn);
 
-    // We make this call to record any synchronization errors.
-    if (IsLibiptError(status))
-      m_decoded_thread.AppendError(IntelPTError(status));
+        status = pt_insn_next(m_decoder_up.get(), &insn, sizeof(insn));
 
-    return status;
+        if (IsLibiptError(status)) {
+          m_decoded_thread.AppendError(IntelPTError(status, insn.ip));
+          return;
+        }
+      }
+    }
   }
 
-  /// Before querying instructions, we need to query the events associated that
-  /// instruction e.g. timing events like ptev_tick, or paging events like
-  /// ptev_paging.
+  /// Before querying instructions, we need to query the events associated with
+  /// that instruction, e.g. timing and trace disablement events.
   ///
   /// \param[in] status
   ///   The status gotten from the previous instruction decoding or PSB
   ///   synchronization.
   ///
   /// \return
-  ///   \b true if no errors were found processing the events.
-  bool ProcessPTEvents(int status) {
-    while (status & pts_event_pending) {
+  ///     The pte_status after decoding events.
+  int ProcessPTEvents(int status) {
+    while (HasEvents(status)) {
       pt_event event;
-      status = pt_insn_event(&m_decoder, &event, sizeof(event));
+      std::memset(&event, 0, sizeof event);
+      status = pt_insn_event(m_decoder_up.get(), &event, sizeof(event));
+
       if (IsLibiptError(status)) {
         m_decoded_thread.AppendError(IntelPTError(status));
-        return false;
+        return status;
       }
 
       if (event.has_tsc)
         m_decoded_thread.NotifyTsc(event.tsc);
 
       switch (event.type) {
-      case ptev_enabled:
-        // The kernel started or resumed tracing the program.
-        break;
       case ptev_disabled:
         // The CPU paused tracing the program, e.g. due to ip filtering.
         m_decoded_thread.AppendEvent(lldb::eTraceEventDisabledHW);
         break;
       case ptev_async_disabled:
         // The kernel or user code paused tracing the program, e.g.
         // a breakpoint or a ioctl invocation pausing the trace, or a
         // context switch happened.
         m_decoded_thread.AppendEvent(lldb::eTraceEventDisabledSW);
         break;
       case ptev_overflow:
         // The CPU internal buffer had an overflow error and some instructions
         // were lost.
         m_decoded_thread.AppendError(IntelPTError(-pte_overflow));
         break;
       default:
         break;
       }
     }
 
-    return true;
+    return status;
   }
 
 private:
-  pt_insn_decoder &m_decoder;
+  PtInsnDecoderUP m_decoder_up;
+  PSBBlock m_psb_block;
+  Optional<lldb::addr_t> m_next_block_ip;
   DecodedThread &m_decoded_thread;
 };
 
-/// Callback used by libipt for reading the process memory.
-///
-/// More information can be found in
-/// https://github.com/intel/libipt/blob/master/doc/man/pt_image_set_callback.3.md
-static int ReadProcessMemory(uint8_t *buffer, size_t size,
-                             const pt_asid * /* unused */, uint64_t pc,
-                             void *context) {
-  Process *process = static_cast<Process *>(context);
-
-  Status error;
-  int bytes_read = process->ReadMemory(pc, buffer, size, error);
-  if (error.Fail())
-    return -pte_nomap;
-  return bytes_read;
-}
-
-// RAII deleter for libipt's decoder
-auto DecoderDeleter = [](pt_insn_decoder *decoder) {
-  pt_insn_free_decoder(decoder);
-};
-
-using PtInsnDecoderUP =
-    std::unique_ptr<pt_insn_decoder, decltype(DecoderDeleter)>;
-
-static Expected<PtInsnDecoderUP>
-CreateInstructionDecoder(TraceIntelPT &trace_intel_pt,
-                         ArrayRef<uint8_t> buffer) {
-  Expected<pt_cpu> cpu_info = trace_intel_pt.GetCPUInfo();
-  if (!cpu_info)
-    return cpu_info.takeError();
-
-  pt_config config;
-  pt_config_init(&config);
-  config.cpu = *cpu_info;
-  int status = pte_ok;
-
-  if (IsLibiptError(status = pt_cpu_errata(&config.errata, &config.cpu)))
-    return make_error<IntelPTError>(status);
-
-  // The libipt library does not modify the trace buffer, hence the
-  // following casts are safe.
-  config.begin = const_cast<uint8_t *>(buffer.data());
-  config.end = const_cast<uint8_t *>(buffer.data() + buffer.size());
-
-  pt_insn_decoder *decoder_ptr = pt_insn_alloc_decoder(&config);
-  if (!decoder_ptr)
-    return make_error<IntelPTError>(-pte_nomem);
-
-  return PtInsnDecoderUP(decoder_ptr, DecoderDeleter);
-}
-
-static Error SetupMemoryImage(PtInsnDecoderUP &decoder_up, Process &process) {
-  pt_image *image = pt_insn_get_image(decoder_up.get());
-
-  int status = pte_ok;
-  if (IsLibiptError(
-          status = pt_image_set_callback(image, ReadProcessMemory, &process)))
-    return make_error<IntelPTError>(status);
-  return Error::success();
-}
-
 Error lldb_private::trace_intel_pt::DecodeSingleTraceForThread(
     DecodedThread &decoded_thread, TraceIntelPT &trace_intel_pt,
     ArrayRef<uint8_t> buffer) {
-  Expected<PtInsnDecoderUP> decoder_up =
-      CreateInstructionDecoder(trace_intel_pt, buffer);
-  if (!decoder_up)
-    return decoder_up.takeError();
+  Expected<std::vector<PSBBlock>> blocks =
+      SplitTraceIntoPSBBlock(trace_intel_pt, buffer, /*expect_tscs=*/false);
+  if (!blocks)
+    return blocks.takeError();
+
+  for (size_t i = 0; i < blocks->size(); i++) {
+    PSBBlock &block = blocks->at(i);
+
+    Expected<PSBBlockDecoder> decoder = PSBBlockDecoder::Create(
+        trace_intel_pt, block, buffer.slice(block.psb_offset, block.size),
+        *decoded_thread.GetThread()->GetProcess(),
+        i + 1 < blocks->size() ? blocks->at(i + 1).starting_ip : None,
+        decoded_thread);
+    if (!decoder)
+      return decoder.takeError();
 
-  if (Error err = SetupMemoryImage(*decoder_up,
-                                   *decoded_thread.GetThread()->GetProcess()))
-    return err;
+    decoder->DecodePSBBlock();
+  }
 
-  LibiptDecoder libipt_decoder(*decoder_up.get(), decoded_thread);
-  libipt_decoder.DecodeUntilEndOfTrace();
   return Error::success();
 }
 
 Error lldb_private::trace_intel_pt::DecodeSystemWideTraceForThread(
     DecodedThread &decoded_thread, TraceIntelPT &trace_intel_pt,
     const DenseMap<lldb::cpu_id_t, llvm::ArrayRef<uint8_t>> &buffers,
     const std::vector<IntelPTThreadContinousExecution> &executions) {
-  DenseMap<lldb::cpu_id_t, LibiptDecoder> decoders;
-  for (auto &cpu_id_buffer : buffers) {
-    Expected<PtInsnDecoderUP> decoder_up =
-        CreateInstructionDecoder(trace_intel_pt, cpu_id_buffer.second);
-    if (!decoder_up)
-      return decoder_up.takeError();
-
-    if (Error err = SetupMemoryImage(*decoder_up,
-                                     *decoded_thread.GetThread()->GetProcess()))
-      return err;
-
-    decoders.try_emplace(cpu_id_buffer.first,
-                         LibiptDecoder(*decoder_up->release(), decoded_thread));
-  }
-
   bool has_seen_psbs = false;
   for (size_t i = 0; i < executions.size(); i++) {
     const IntelPTThreadContinousExecution &execution = executions[i];
 
     auto variant = execution.thread_execution.variant;
-    // We report the TSCs we are sure of
-    switch (variant) {
-    case ThreadContinuousExecution::Variant::Complete:
-      decoded_thread.NotifyTsc(execution.thread_execution.tscs.complete.start);
-      break;
-    case ThreadContinuousExecution::Variant::OnlyStart:
+
+    // We emit the first valid tsc
+    if (execution.psb_blocks.empty()) {
+      decoded_thread.NotifyTsc(execution.thread_execution.GetLowestKnownTSC());
+    } else {
+      assert(execution.psb_blocks.front().tsc &&
+             "per cpu decoding expects TSCs");
       decoded_thread.NotifyTsc(
-          execution.thread_execution.tscs.only_start.start);
-      break;
-    default:
-      break;
+          std::min(execution.thread_execution.GetLowestKnownTSC(),
+                   *execution.psb_blocks.front().tsc));
     }
 
+    // We then emit the CPU, which will be correctly associated with a tsc.
     decoded_thread.NotifyCPU(execution.thread_execution.cpu_id);
 
     // If we haven't seen a PSB yet, then it's fine not to show errors
     if (has_seen_psbs) {
-      if (execution.intelpt_subtraces.empty()) {
+      if (execution.psb_blocks.empty()) {
         decoded_thread.AppendCustomError(
-            formatv("Unable to find intel pt data for thread "
+            formatv("Unable to find intel pt data a thread "
                     "execution on cpu id = {0}",
                     execution.thread_execution.cpu_id)
                 .str());
       }
 
-      // If the first execution is incomplete because it doesn't have a previous
-      // context switch in its cpu, all good, otherwise we report the error.
-      if (variant == ThreadContinuousExecution::Variant::OnlyEnd ||
-          variant == ThreadContinuousExecution::Variant::HintedStart) {
+      // A hinted start is a non-initial execution that doesn't have a switch
+      // in. An only end is an initial execution that doesn't have a switch in.
+      // Any of those cases represent a gap because we have seen a PSB before.
+      if (variant == ThreadContinuousExecution::Variant::HintedStart ||
+          variant == ThreadContinuousExecution::Variant::OnlyEnd) {
         decoded_thread.AppendCustomError(
-            formatv("Unable to find the context switch in for the thread "
-                    "execution starting on cpu id = {0}",
+            formatv("Unable to find the context switch in for a thread "
+                    "execution on cpu id = {0}",
                     execution.thread_execution.cpu_id)
                 .str());
       }
     }
 
-    LibiptDecoder &decoder =
-        decoders.find(execution.thread_execution.cpu_id)->second;
-    for (const IntelPTThreadSubtrace &intel_pt_execution :
-         execution.intelpt_subtraces) {
-      has_seen_psbs = true;
-      decoder.DecodePSB(intel_pt_execution.psb_offset);
-    }
+    for (size_t j = 0; j < execution.psb_blocks.size(); j++) {
+      const PSBBlock &psb_block = execution.psb_blocks[j];
 
-    // We report the TSCs we are sure of
-    switch (variant) {
-    case ThreadContinuousExecution::Variant::Complete:
-      decoded_thread.NotifyTsc(execution.thread_execution.tscs.complete.end);
-      break;
-    case ThreadContinuousExecution::Variant::OnlyEnd:
-      decoded_thread.NotifyTsc(execution.thread_execution.tscs.only_end.end);
-      break;
-    default:
-      break;
+      Expected<PSBBlockDecoder> decoder = PSBBlockDecoder::Create(
+          trace_intel_pt, psb_block,
+          buffers.lookup(executions[i].thread_execution.cpu_id)
+              .slice(psb_block.psb_offset, psb_block.size),
+          *decoded_thread.GetThread()->GetProcess(),
+          j + 1 < execution.psb_blocks.size()
+              ? execution.psb_blocks[j + 1].starting_ip
+              : None,
+          decoded_thread);
+      if (!decoder)
+        return decoder.takeError();
+
+      has_seen_psbs = true;
+      decoder->DecodePSBBlock();
     }
 
     // If we haven't seen a PSB yet, then it's fine not to show errors
     if (has_seen_psbs) {
-      // If the last execution is incomplete because it doesn't have a following
-      // context switch in its cpu, all good.
-      if ((variant == ThreadContinuousExecution::Variant::OnlyStart &&
-           i + 1 != executions.size()) ||
-          variant == ThreadContinuousExecution::Variant::HintedEnd) {
+      // A hinted end is a non-ending execution that doesn't have a switch out.
+      // An only start is an ending execution that doesn't have a switch out.
+      // Any of those cases represent a gap if we still have executions to
+      // process and we have seen a PSB before.
+      if (i + 1 != executions.size() &&
+          (variant == ThreadContinuousExecution::Variant::OnlyStart ||
+           variant == ThreadContinuousExecution::Variant::HintedEnd)) {
         decoded_thread.AppendCustomError(
-            formatv("Unable to find the context switch out for the thread "
+            formatv("Unable to find the context switch out for a thread "
                     "execution on cpu id = {0}",
                     execution.thread_execution.cpu_id)
                 .str());
       }
     }
   }
   return Error::success();
 }
 
 bool IntelPTThreadContinousExecution::operator<(
     const IntelPTThreadContinousExecution &o) const {
   // As the context switch might be incomplete, we look first for the first real
   // PSB packet, which is a valid TSC. Otherwise, We query the thread execution
   // itself for some tsc.
   auto get_tsc = [](const IntelPTThreadContinousExecution &exec) {
-    return exec.intelpt_subtraces.empty()
-               ? exec.thread_execution.GetLowestKnownTSC()
-               : exec.intelpt_subtraces.front().tsc;
+    return exec.psb_blocks.empty() ? exec.thread_execution.GetLowestKnownTSC()
+                                   : exec.psb_blocks.front().tsc;
   };
 
   return get_tsc(*this) < get_tsc(o);
 }
 
-Expected<std::vector<IntelPTThreadSubtrace>>
-lldb_private::trace_intel_pt::SplitTraceInContinuousExecutions(
-    TraceIntelPT &trace_intel_pt, llvm::ArrayRef<uint8_t> buffer) {
-  Expected<PtInsnDecoderUP> decoder_up =
-      CreateInstructionDecoder(trace_intel_pt, buffer);
+Expected<std::vector<PSBBlock>>
+lldb_private::trace_intel_pt::SplitTraceIntoPSBBlock(
+    TraceIntelPT &trace_intel_pt, llvm::ArrayRef<uint8_t> buffer,
+    bool expect_tscs) {
+  // This follows
+  // https://github.com/intel/libipt/blob/master/doc/howto_libipt.md#parallel-decode
+
+  Expected<PtQueryDecoderUP> decoder_up =
+      CreateQueryDecoder(trace_intel_pt, buffer);
   if (!decoder_up)
     return decoder_up.takeError();
 
-  pt_insn_decoder *decoder = decoder_up.get().get();
+  pt_query_decoder *decoder = decoder_up.get().get();
 
-  std::vector<IntelPTThreadSubtrace> executions;
+  std::vector<PSBBlock> executions;
 
-  int status = pte_ok;
-  while (!IsLibiptError(status = pt_insn_sync_forward(decoder))) {
-    uint64_t tsc;
-    if (IsLibiptError(pt_insn_time(decoder, &tsc, nullptr, nullptr)))
-      return createStringError(inconvertibleErrorCode(),
-                               "intel pt trace doesn't have TSC timestamps");
+  while (true) {
+    uint64_t maybe_ip = LLDB_INVALID_ADDRESS;
+    int decoding_status = pt_qry_sync_forward(decoder, &maybe_ip);
+    if (IsLibiptError(decoding_status))
+      break;
 
     uint64_t psb_offset;
-    pt_insn_get_sync_offset(decoder,
-                            &psb_offset); // this can't fail because we got here
+    int offset_status = pt_qry_get_sync_offset(decoder, &psb_offset);
+    assert(offset_status >= 0 &&
+           "This can't fail because we were able to synchronize");
+
+    Optional<uint64_t> ip;
+    if (!(pts_ip_suppressed & decoding_status))
+      ip = maybe_ip;
+
+    Optional<uint64_t> tsc;
+    // Now we fetch the first TSC that comes after the PSB.
+    while (HasEvents(decoding_status)) {
+      pt_event event;
+      decoding_status = pt_qry_event(decoder, &event, sizeof(event));
+      if (IsLibiptError(decoding_status))
+        break;
+      if (event.has_tsc) {
+        tsc = event.tsc;
+        break;
+      }
+    }
+    if (IsLibiptError(decoding_status)) {
+      // We continue to the next PSB. This effectively merges this PSB with the
+      // previous one, and that should be fine because this PSB might be the
+      // direct continuation of the previous thread and it's better to show an
+      // error in the decoded thread than to hide it. If this is the first PSB,
+      // we are okay losing it. Besides that, an error at processing events
+      // means that we wouldn't be able to get any instruction out of it.
+      continue;
+    }
+
+    if (expect_tscs && !tsc)
+      return createStringError(inconvertibleErrorCode(),
+                               "Found a PSB without TSC.");
 
     executions.push_back({
         psb_offset,
         tsc,
+        0,
+        ip,
     });
   }
+  if (!executions.empty()) {
+    // We now adjust the sizes of each block
+    executions.back().size = buffer.size() - executions.back().psb_offset;
+    for (int i = (int)executions.size() - 2; i >= 0; i--) {
+      executions[i].size =
+          executions[i + 1].psb_offset - executions[i].psb_offset;
+    }
+  }
   return executions;
 }
 
 Expected<Optional<uint64_t>>
 lldb_private::trace_intel_pt::FindLowestTSCInTrace(TraceIntelPT &trace_intel_pt,
                                                    ArrayRef<uint8_t> buffer) {
-  Expected<PtInsnDecoderUP> decoder_up =
-      CreateInstructionDecoder(trace_intel_pt, buffer);
+  Expected<PtQueryDecoderUP> decoder_up =
+      CreateQueryDecoder(trace_intel_pt, buffer);
   if (!decoder_up)
     return decoder_up.takeError();
 
-  pt_insn_decoder *decoder = decoder_up.get().get();
-  int status = pte_ok;
-  if (IsLibiptError(status = pt_insn_sync_forward(decoder)))
+  pt_query_decoder *decoder = decoder_up.get().get();
+  uint64_t ip = LLDB_INVALID_ADDRESS;
+  int status = pt_qry_sync_forward(decoder, &ip);
+  if (IsLibiptError(status))
     return None;
 
-  uint64_t tsc;
-  if (IsLibiptError(pt_insn_time(decoder, &tsc, nullptr, nullptr)))
-    return None;
-  return tsc;
+  while (HasEvents(status)) {
+    pt_event event;
+    status = pt_qry_event(decoder, &event, sizeof(event));
+    if (IsLibiptError(status))
+      return None;
+    if (event.has_tsc)
+      return event.tsc;
+  }
 }

lldb/source/Plugins/Trace/intel-pt/TraceCursorIntelPT.h

public:
   bool GoToId(lldb::user_id_t id) override;
 
   lldb::user_id_t GetId() const override;
 
   bool HasId(lldb::user_id_t id) const override;
 
   llvm::Optional<double> GetWallClockTime() const override;
 
+  llvm::Optional<std::string> GetSyncPointMetadata() const override;
+
 private:
   /// Clear the current TSC and nanoseconds ranges if after moving they are not
   /// valid anymore.
   void ClearTimingRangesIfInvalid();
 
   /// Get or calculate the TSC range that includes the current trace item.
   const llvm::Optional<DecodedThread::TSCRange> &GetTSCRange() const;
 

lldb/source/Plugins/Trace/intel-pt/TraceCursorIntelPT.cpp

bool TraceCursorIntelPT::GoToId(user_id_t id) {
   return true;
 }
 
 bool TraceCursorIntelPT::HasId(lldb::user_id_t id) const {
   return id < m_decoded_thread_sp->GetItemsCount();
 }
 
 user_id_t TraceCursorIntelPT::GetId() const { return m_pos; }
+
+Optional<std::string> TraceCursorIntelPT::GetSyncPointMetadata() const {
+  return formatv("offset = 0x{0:x}",
+                 m_decoded_thread_sp->GetSyncPointOffsetByIndex(m_pos))
+      .str();
+}

lldb/source/Plugins/Trace/intel-pt/TraceIntelPT.cpp

s.Format(
         storage.multicpu_decoder->GetNumContinuousExecutionsForThread(tid));
     s.Format("    Total number of PSB blocks found: {0}\n",
              storage.multicpu_decoder->GetTotalPSBBlocksCount());
     s.Format("    Number of PSB blocks for this thread: {0}\n",
              storage.multicpu_decoder->GePSBBlocksCountForThread(tid));
     s.Format("    Total number of unattributed PSB blocks found: {0}\n",
              storage.multicpu_decoder->GetUnattributedPSBBlocksCount());
   }
-
-  // Errors
-  {
-    s << "\n  Errors:\n";
-    const DecodedThread::LibiptErrorsStats &tsc_errors_stats =
-        decoded_thread_sp->GetTscErrorsStats();
-    s.Format("    Number of TSC decoding errors: {0}\n",
-             tsc_errors_stats.total_count);
-    for (const auto &error_message_to_count :
-         tsc_errors_stats.libipt_errors_counts) {
-      s.Format("      {0}: {1}\n", error_message_to_count.first,
-               error_message_to_count.second);
-    }
-  }
 }
 
 void TraceIntelPT::DumpTraceInfoAsJson(Thread &thread, Stream &s,
                                        bool verbose) {
   Storage &storage = GetUpdatedStorage();
 
   lldb::tid_t tid = thread.GetID();
   json::OStream json_str(s.AsRawOstream(), 2);
json_str.attributeObject("threadStats", [&] {
       if (storage.multicpu_decoder) {
         json_str.attribute(
             "continuousExecutions",
             storage.multicpu_decoder->GetNumContinuousExecutionsForThread(tid));
         json_str.attribute(
             "PSBBlocks",
             storage.multicpu_decoder->GePSBBlocksCountForThread(tid));
       }
-
-      // Errors
-      const DecodedThread::LibiptErrorsStats &tsc_errors_stats =
-          decoded_thread_sp->GetTscErrorsStats();
-      json_str.attributeObject("errorItems", [&] {
-        json_str.attribute("total", tsc_errors_stats.total_count);
-        json_str.attributeObject("individualErrors", [&] {
-          for (const auto &error_message_to_count :
-               tsc_errors_stats.libipt_errors_counts) {
-            json_str.attribute(error_message_to_count.first,
-                               error_message_to_count.second);
-          }
-        });
-      });
     });
+
     json_str.attributeObject("globalStats", [&] {
       json_str.attributeObject("timingInSeconds", [&] {
         GetTimer().ForGlobal().ForEachTimedTask(
             [&](const std::string &name, std::chrono::milliseconds duration) {
               json_str.attribute(name, duration.count() / 1000.0);
             });
       });
       if (storage.multicpu_decoder) {

lldb/source/Plugins/Trace/intel-pt/TraceIntelPTMultiCpuDecoder.cpp

return trace_sp->GetThreadTimer(thread.GetID())
         if (err)
           return std::move(err);
 
         m_decoded_threads.try_emplace(thread.GetID(), decoded_thread_sp);
         return decoded_thread_sp;
       });
 }
 
-static Expected<std::vector<IntelPTThreadSubtrace>>
-GetIntelPTSubtracesForCpu(TraceIntelPT &trace, cpu_id_t cpu_id) {
-  std::vector<IntelPTThreadSubtrace> intel_pt_subtraces;
+static Expected<std::vector<PSBBlock>> GetPSBBlocksForCPU(TraceIntelPT &trace,
+                                                          cpu_id_t cpu_id) {
+  std::vector<PSBBlock> psb_blocks;
   Error err = trace.OnCpuBinaryDataRead(
       cpu_id, IntelPTDataKinds::kIptTrace,
       [&](ArrayRef<uint8_t> data) -> Error {
-        Expected<std::vector<IntelPTThreadSubtrace>> split_trace =
-            SplitTraceInContinuousExecutions(trace, data);
+        Expected<std::vector<PSBBlock>> split_trace =
+            SplitTraceIntoPSBBlock(trace, data, /*expect_tscs=*/true);
         if (!split_trace)
           return split_trace.takeError();
 
-        intel_pt_subtraces = std::move(*split_trace);
+        psb_blocks = std::move(*split_trace);
         return Error::success();
       });
   if (err)
     return std::move(err);
-  return intel_pt_subtraces;
+  return psb_blocks;
 }
 
 Expected<DenseMap<lldb::tid_t, std::vector<IntelPTThreadContinousExecution>>>
 TraceIntelPTMultiCpuDecoder::DoCorrelateContextSwitchesAndIntelPtTraces() {
   DenseMap<lldb::tid_t, std::vector<IntelPTThreadContinousExecution>>
       continuous_executions_per_thread;
   TraceIntelPTSP trace_sp = GetTrace();
 
   Optional<LinuxPerfZeroTscConversion> conv_opt =
       trace_sp->GetPerfZeroTscConversion();
   if (!conv_opt)
     return createStringError(
         inconvertibleErrorCode(),
         "TSC to nanoseconds conversion values were not found");
 
   LinuxPerfZeroTscConversion tsc_conversion = *conv_opt;
 
   for (cpu_id_t cpu_id : trace_sp->GetTracedCpus()) {
-    Expected<std::vector<IntelPTThreadSubtrace>> intel_pt_subtraces =
-        GetIntelPTSubtracesForCpu(*trace_sp, cpu_id);
-    if (!intel_pt_subtraces)
-      return intel_pt_subtraces.takeError();
+    Expected<std::vector<PSBBlock>> psb_blocks =
+        GetPSBBlocksForCPU(*trace_sp, cpu_id);
+    if (!psb_blocks)
+      return psb_blocks.takeError();
 
-    m_total_psb_blocks += intel_pt_subtraces->size();
+    m_total_psb_blocks += psb_blocks->size();
     // We'll be iterating through the thread continuous executions and the intel
     // pt subtraces sorted by time.
-    auto it = intel_pt_subtraces->begin();
+    auto it = psb_blocks->begin();
     auto on_new_thread_execution =
         [&](const ThreadContinuousExecution &thread_execution) {
           IntelPTThreadContinousExecution execution(thread_execution);
 
-          for (; it != intel_pt_subtraces->end() &&
-                 it->tsc < thread_execution.GetEndTSC();
+          for (; it != psb_blocks->end() &&
+                 *it->tsc < thread_execution.GetEndTSC();
                it++) {
-            if (it->tsc > thread_execution.GetStartTSC()) {
-              execution.intelpt_subtraces.push_back(*it);
+            if (*it->tsc > thread_execution.GetStartTSC()) {
+              execution.psb_blocks.push_back(*it);
             } else {
               m_unattributed_psb_blocks++;
             }
           }
           continuous_executions_per_thread[thread_execution.tid].push_back(
               execution);
         };
     Error err = trace_sp->OnCpuBinaryDataRead(
         cpu_id, IntelPTDataKinds::kPerfContextSwitchTrace,
         [&](ArrayRef<uint8_t> data) -> Error {
           Expected<std::vector<ThreadContinuousExecution>> executions =
               DecodePerfContextSwitchTrace(data, cpu_id, tsc_conversion);
           if (!executions)
             return executions.takeError();
           for (const ThreadContinuousExecution &exec : *executions)
             on_new_thread_execution(exec);
           return Error::success();
         });
     if (err)
       return std::move(err);
 
-    m_unattributed_psb_blocks += intel_pt_subtraces->end() - it;
+    m_unattributed_psb_blocks += psb_blocks->end() - it;
   }
   // We now sort the executions of each thread to have them ready for
   // instruction decoding
   for (auto &tid_executions : continuous_executions_per_thread)
     std::sort(tid_executions.second.begin(), tid_executions.second.end());
 
   return continuous_executions_per_thread;
 }

 TraceIntelPTMultiCpuDecoder::GePSBBlocksCountForThread(lldb::tid_t tid) const {
   if (!m_continuous_executions_per_thread)
     return 0;
   size_t count = 0;
   auto it = m_continuous_executions_per_thread->find(tid);
   if (it == m_continuous_executions_per_thread->end())
     return 0;
   for (const IntelPTThreadContinousExecution &execution : it->second)
-    count += execution.intelpt_subtraces.size();
+    count += execution.psb_blocks.size();
   return count;
 }
 
 size_t TraceIntelPTMultiCpuDecoder::GetUnattributedPSBBlocksCount() const {
   return m_unattributed_psb_blocks;
 }
 
 size_t TraceIntelPTMultiCpuDecoder::GetTotalPSBBlocksCount() const {
   return m_total_psb_blocks;
 }

lldb/source/Target/TraceCursor.cpp

const char *TraceCursor::EventKindToString(lldb::TraceEvent event_kind) {
   case lldb::eTraceEventDisabledHW:
     return "hardware disabled tracing";
   case lldb::eTraceEventDisabledSW:
     return "software disabled tracing";
   case lldb::eTraceEventCPUChanged:
     return "CPU core changed";
   case lldb::eTraceEventHWClockTick:
     return "HW clock tick";
+  case lldb::eTraceEventSyncPoint:
+    return "trace synchronization point";
   }
   llvm_unreachable("Fully covered switch above");
 }

lldb/source/Target/TraceDumper.cpp

if (item.event) {
         break;
       case eTraceEventHWClockTick:
         m_s.Format(" [{0}]", item.hw_clock ? std::to_string(*item.hw_clock)
                                            : "unavailable");
         break;
       case eTraceEventDisabledHW:
       case eTraceEventDisabledSW:
         break;
+      case eTraceEventSyncPoint:
+        m_s.Format(" [{0}]", item.sync_point_metadata);
+        break;
       }
     } else if (item.error) {
       m_s << "(error) " << *item.error;
     } else {
       m_s.Format("{0:x+16}", item.load_address);
       if (item.symbol_info && item.symbol_info->instruction) {
         m_s << "    ";
         item.symbol_info->instruction->Dump(
/* schema:
     } | {
       "error": string,
       "id": decimal,
       "tsc"?: string decimal,
     | {
       "loadAddress": string decimal,
       "id": decimal,
       "hwClock"?: string decimal,
+      "syncPointMetadata"?: string,
       "timestamp_ns"?: string decimal,
       "module"?: string,
       "symbol"?: string,
       "line"?: decimal,
       "column"?: decimal,
       "source"?: string,
       "mnemonic"?: string,
       "controlFlowKind"?: string,
case eTraceEventCPUChanged:
       m_j.attribute("cpuId", item.cpu_id);
       break;
     case eTraceEventHWClockTick:
       m_j.attribute("hwClock", item.hw_clock);
       break;
     case eTraceEventDisabledHW:
     case eTraceEventDisabledSW:
       break;
+    case eTraceEventSyncPoint:
+      m_j.attribute("syncPointMetadata", item.sync_point_metadata);
+      break;
     }
   }
 
   void DumpInstruction(const TraceDumper::TraceItem &item) {
     m_j.attribute("loadAddress", formatv("{0:x}", item.load_address));
     if (item.symbol_info) {
       m_j.attribute("module", ToOptionalString(GetModuleName(item)));
       m_j.attribute(
Optional<lldb::user_id_t> TraceDumper::DumpInstructions(size_t count) {
   thread_sp->GetProcess()->GetTarget().CalculateExecutionContext(exe_ctx);
 
   for (size_t insn_seen = 0; insn_seen < count && m_cursor_sp->HasValue();
        m_cursor_sp->Next()) {
 
     last_id = m_cursor_sp->GetId();
     TraceItem item = CreatRawTraceItem();
 
-    if (m_cursor_sp->IsEvent()) {
-      if (!m_options.show_events)
-        continue;
+    if (m_cursor_sp->IsEvent() && m_options.show_events) {
       item.event = m_cursor_sp->GetEventType();
       switch (*item.event) {
       case eTraceEventCPUChanged:
         item.cpu_id = m_cursor_sp->GetCPU();
         break;
       case eTraceEventHWClockTick:
         item.hw_clock = m_cursor_sp->GetHWClock();
         break;
       case eTraceEventDisabledHW:
       case eTraceEventDisabledSW:
         break;
+      case eTraceEventSyncPoint:
+        item.sync_point_metadata = m_cursor_sp->GetSyncPointMetadata();
+        break;
       }
+      m_writer_up->TraceItem(item);
     } else if (m_cursor_sp->IsError()) {
       item.error = m_cursor_sp->GetError();
-    } else {
+      m_writer_up->TraceItem(item);
+    } else if (m_cursor_sp->IsInstruction() && !m_options.only_events) {
       insn_seen++;
       item.load_address = m_cursor_sp->GetLoadAddress();
 
       if (!m_options.raw) {
         SymbolInfo symbol_info;
         symbol_info.exe_ctx = exe_ctx;
         symbol_info.address.SetLoadAddress(item.load_address,
                                            exe_ctx.GetTargetPtr());
         symbol_info.sc =
             CalculateSymbolContext(symbol_info.address, prev_symbol_info);
         std::tie(symbol_info.disassembler, symbol_info.instruction) =
             CalculateDisass(symbol_info, prev_symbol_info, exe_ctx);
         item.prev_symbol_info = prev_symbol_info;
         item.symbol_info = symbol_info;
         prev_symbol_info = symbol_info;
       }
-    }
       m_writer_up->TraceItem(item);
     }
+  }
   if (!m_cursor_sp->HasValue())
     m_writer_up->NoMoreData();
   return last_id;
 }

lldb/test/API/commands/trace/TestTraceDumpInfo.py

def testDumpRawTraceSize(self):
         os.path.join(self.getSourceDir(), "intelpt-trace", "trace.json"),
         substrs=["intel-pt"])
 
         self.expect("thread trace dump info",
             substrs=['''thread #1: tid = 3842849
 
   Trace technology: intel-pt
 
-  Total number of trace items: 23
+  Total number of trace items: 24
 
   Memory usage:
     Raw trace size: 4 KiB
-    Total approximate memory usage (excluding raw trace): 0.20 KiB
+    Total approximate memory usage (excluding raw trace): 0.21 KiB
     Average memory usage per item (excluding raw trace): 9.00 bytes
 
   Timing for this thread:
     Decoding instructions: ''', '''
 
   Events:
-    Number of individual events: 2
+    Number of individual events: 3
       software disabled tracing: 2
-
-  Errors:
-    Number of TSC decoding errors: 0'''],
+      trace synchronization point: 1'''],
             patterns=["Decoding instructions: \d.\d\ds"])
 
     def testDumpRawTraceSizeJSON(self):
         self.expect("trace load -v " +
         os.path.join(self.getSourceDir(), "intelpt-trace", "trace.json"),
         substrs=["intel-pt"])
 
         self.expect("thread trace dump info --json ",
             substrs=['''{
   "traceTechnology": "intel-pt",
   "threadStats": {
     "tid": 3842849,
-    "traceItemsCount": 23,
+    "traceItemsCount": 24,
     "memoryUsage": {
-      "totalInBytes": "207",
+      "totalInBytes": "216",
       "avgPerItemInBytes": 9
     },
     "timingInSeconds": {
       "Decoding instructions": 0''', '''
     },
     "events": {
-      "totalCount": 2,
+      "totalCount": 3,
       "individualCounts": {
-        "software disabled tracing": 2
+        "software disabled tracing": 2,
+        "trace synchronization point": 1
       }
-    },
-    "errorItems": {
-      "total": 0,
-      "individualErrors": {}
     }
   },
   "globalStats": {
     "timingInSeconds": {}
   }
 }'''])

lldb/test/API/commands/trace/TestTraceDumpInstructions.py

def testErrorMessages(self):
             error=True)
 
     def testRawDumpInstructionsInJSON(self):
         self.expect("trace load -v " +
             os.path.join(self.getSourceDir(), "intelpt-trace", "trace.json"),
             substrs=["intel-pt"])
 
         self.expect("thread trace dump instructions --raw --count 5 --forwards --json",
-            substrs=['''[{"id":0,"loadAddress":"0x400511"}''',
-                     '''{"id":2,"loadAddress":"0x400518"}''',
-                     '''{"id":3,"loadAddress":"0x40051f"}''',
-                     '''{"id":4,"loadAddress":"0x400529"}''',
-                     '''{"id":5,"loadAddress":"0x40052d"}'''])
+            substrs=['''[{"id":1,"loadAddress":"0x400511"}''',
+                     '''{"id":3,"loadAddress":"0x400518"}''',
+                     '''{"id":4,"loadAddress":"0x40051f"}''',
+                     '''{"id":5,"loadAddress":"0x400529"}''',
+                     '''{"id":6,"loadAddress":"0x40052d"}'''])
 
         self.expect("thread trace dump instructions --raw --count 5 --forwards --pretty-json",
             substrs=['''[
   {
-    "id": 0,
+    "id": 1,
     "loadAddress": "0x400511"
   },
   {
-    "id": 2,
+    "id": 3,
     "loadAddress": "0x400518"
   },
   {
-    "id": 3,
+    "id": 4,
     "loadAddress": "0x40051f"
   },
   {
-    "id": 4,
+    "id": 5,
     "loadAddress": "0x400529"
   },
   {
-    "id": 5,
+    "id": 6,
     "loadAddress": "0x40052d"
   }
 ]'''])
 
     def testRawDumpInstructionsInJSONToFile(self):
         self.expect("trace load -v " +
             os.path.join(self.getSourceDir(), "intelpt-trace", "trace.json"),
             substrs=["intel-pt"])
 
         outfile = os.path.join(self.getBuildDir(), "output.json")
 
         self.expect("thread trace dump instructions --raw --count 5 --forwards --pretty-json --file " + outfile)
 
         with open(outfile, "r") as out:
             self.assertEqual(out.read(), '''[
   {
-    "id": 0,
+    "id": 1,
     "loadAddress": "0x400511"
   },
   {
-    "id": 2,
+    "id": 3,
     "loadAddress": "0x400518"
   },
   {
-    "id": 3,
+    "id": 4,
     "loadAddress": "0x40051f"
   },
   {
-    "id": 4,
+    "id": 5,
     "loadAddress": "0x400529"
   },
   {
-    "id": 5,
+    "id": 6,
     "loadAddress": "0x40052d"
   }
 ]''')
 
     def testRawDumpInstructions(self):
         self.expect("trace load -v " +
             os.path.join(self.getSourceDir(), "intelpt-trace", "trace.json"),
             substrs=["intel-pt"])
 
         self.expect("thread trace dump instructions --raw --count 21 --forwards",
             substrs=['''thread #1: tid = 3842849
-    0: 0x0000000000400511
-    2: 0x0000000000400518
-    3: 0x000000000040051f
-    4: 0x0000000000400529
-    5: 0x000000000040052d
-    6: 0x0000000000400521
-    7: 0x0000000000400525
-    8: 0x0000000000400529
-    9: 0x000000000040052d
-    10: 0x0000000000400521
-    11: 0x0000000000400525
-    12: 0x0000000000400529
-    13: 0x000000000040052d
-    14: 0x0000000000400521
-    15: 0x0000000000400525
-    16: 0x0000000000400529
-    17: 0x000000000040052d
-    18: 0x0000000000400521
-    19: 0x0000000000400525
-    20: 0x0000000000400529
-    21: 0x000000000040052d'''])
+    1: 0x0000000000400511
+    3: 0x0000000000400518
+    4: 0x000000000040051f
+    5: 0x0000000000400529
+    6: 0x000000000040052d
+    7: 0x0000000000400521
+    8: 0x0000000000400525
+    9: 0x0000000000400529
+    10: 0x000000000040052d
+    11: 0x0000000000400521
+    12: 0x0000000000400525
+    13: 0x0000000000400529
+    14: 0x000000000040052d
+    15: 0x0000000000400521
+    16: 0x0000000000400525
+    17: 0x0000000000400529
+    18: 0x000000000040052d
+    19: 0x0000000000400521
+    20: 0x0000000000400525
+    21: 0x0000000000400529
+    22: 0x000000000040052d'''])
 
         # We check if we can pass count and skip
         self.expect("thread trace dump instructions --count 5 --skip 6 --raw --forwards",
             substrs=['''thread #1: tid = 3842849
-    6: 0x0000000000400521
-    7: 0x0000000000400525
-    8: 0x0000000000400529
-    9: 0x000000000040052d
-    10: 0x0000000000400521'''])
+    6: 0x000000000040052d
+    7: 0x0000000000400521
+    8: 0x0000000000400525
+    9: 0x0000000000400529
+    10: 0x000000000040052d'''])
 
         self.expect("thread trace dump instructions --count 5 --skip 6 --raw",
             substrs=['''thread #1: tid = 3842849
-    16: 0x0000000000400529
-    15: 0x0000000000400525
-    14: 0x0000000000400521
-    13: 0x000000000040052d
-    12: 0x0000000000400529'''])
+    17: 0x0000000000400529
+    16: 0x0000000000400525
+    15: 0x0000000000400521
+    14: 0x000000000040052d
+    13: 0x0000000000400529'''])
 
         # We check if we can pass count and skip and instruction id in hex
         self.expect("thread trace dump instructions --count 5 --skip 6 --raw --id 0xA",
             substrs=['''thread #1: tid = 3842849
-    4: 0x0000000000400529
-    3: 0x000000000040051f
-    2: 0x0000000000400518
-    0: 0x0000000000400511
+    4: 0x000000000040051f
+    3: 0x0000000000400518
+    1: 0x0000000000400511
     no more data'''])
 
         # We check if we can pass count and skip and instruction id in decimal
         self.expect("thread trace dump instructions --count 5 --skip 6 --raw --id 10",
             substrs=['''thread #1: tid = 3842849
-    4: 0x0000000000400529
-    3: 0x000000000040051f
-    2: 0x0000000000400518
-    0: 0x0000000000400511
+    4: 0x000000000040051f
+    3: 0x0000000000400518
+    1: 0x0000000000400511
     no more data'''])
 
         # We check if we can access the thread by index id
         self.expect("thread trace dump instructions 1 --raw",
             substrs=['''thread #1: tid = 3842849
-    21: 0x000000000040052d'''])
+    22: 0x000000000040052d'''])
 
         # We check that we get an error when using an invalid thread index id
         self.expect("thread trace dump instructions 10", error=True,
             substrs=['error: no thread with index: "10"'])
 
     def testDumpFullInstructionsWithMultipleThreads(self):
         # We load a trace with two threads
         self.expect("trace load -v " +
             os.path.join(self.getSourceDir(), "intelpt-trace", "trace_2threads.json"))
 
         # We print the instructions of a specific thread
         self.expect("thread trace dump instructions 2 --count 2",
             substrs=['''thread #2: tid = 3842850
   a.out`main + 32 at main.cpp:4
-    21: 0x000000000040052d    jle    0x400521                  ; <+20> at main.cpp:5
-    20: 0x0000000000400529    cmpl   $0x3, -0x8(%rbp)'''])
+    22: 0x000000000040052d    jle    0x400521                  ; <+20> at main.cpp:5
+    21: 0x0000000000400529    cmpl   $0x3, -0x8(%rbp)'''])
 
         # We use custom --count and --skip, saving the command to history for later
         self.expect("thread trace dump instructions 2 --count 2 --skip 2", inHistory=True,
             substrs=['''thread #2: tid = 3842850
   a.out`main + 28 at main.cpp:4
-    20: 0x0000000000400529    cmpl   $0x3, -0x8(%rbp)
-    19: 0x0000000000400525    addl   $0x1, -0x8(%rbp)'''])
+    21: 0x0000000000400529    cmpl   $0x3, -0x8(%rbp)
+    20: 0x0000000000400525    addl   $0x1, -0x8(%rbp)'''])
 
         # We use a repeat command twice and ensure the previous count is used and the
         # start position moves with each command.
         self.expect("", inHistory=True,
             substrs=['''thread #2: tid = 3842850
   a.out`main + 20 at main.cpp:5
-    18: 0x0000000000400521    xorl   $0x1, -0x4(%rbp)
+    19: 0x0000000000400521    xorl   $0x1, -0x4(%rbp)
   a.out`main + 32 at main.cpp:4
-    17: 0x000000000040052d    jle    0x400521                  ; <+20> at main.cpp:5'''])
+    18: 0x000000000040052d    jle    0x400521                  ; <+20> at main.cpp:5'''])
 
         self.expect("", inHistory=True,
             substrs=['''thread #2: tid = 3842850
   a.out`main + 28 at main.cpp:4
-    16: 0x0000000000400529    cmpl   $0x3, -0x8(%rbp)
-    15: 0x0000000000400525    addl   $0x1, -0x8(%rbp'''])
+    17: 0x0000000000400529    cmpl   $0x3, -0x8(%rbp)
+    16: 0x0000000000400525    addl   $0x1, -0x8(%rbp'''])
 
     def testInvalidBounds(self):
         self.expect("trace load -v " +
             os.path.join(self.getSourceDir(), "intelpt-trace", "trace.json"))
 
         # The output should be work when too many instructions are asked
         self.expect("thread trace dump instructions --count 20 --forwards",
             substrs=['''thread #1: tid = 3842849
   a.out`main + 4 at main.cpp:2
-    0: 0x0000000000400511    movl   $0x0, -0x4(%rbp)
+    1: 0x0000000000400511    movl   $0x0, -0x4(%rbp)
   a.out`main + 11 at main.cpp:4
-    2: 0x0000000000400518    movl   $0x0, -0x8(%rbp)
-    3: 0x000000000040051f    jmp    0x400529                  ; <+28> at main.cpp:4'''])
+    3: 0x0000000000400518    movl   $0x0, -0x8(%rbp)
+    4: 0x000000000040051f    jmp    0x400529                  ; <+28> at main.cpp:4'''])
 
         # Should print no instructions if the position is out of bounds
         self.expect("thread trace dump instructions --skip 23",
             endstr='no more data\n')
 
         # Should fail with negative bounds
         self.expect("thread trace dump instructions --skip -1", error=True)
         self.expect("thread trace dump instructions --count -1", error=True)
 
     def testWrongImage(self):
         self.expect("trace load " +
             os.path.join(self.getSourceDir(), "intelpt-trace", "trace_bad_image.json"))
         self.expect("thread trace dump instructions --forwards",
             substrs=['''thread #1: tid = 3842849
     ...missing instructions
-    0: (error) no memory mapped at this address: 0x0000000000400511
-    1: (error) no memory mapped at this address: 0x0000000000400518'''])
+    1: (error) no memory mapped at this address: 0x0000000000400511'''])
 
     def testWrongCPU(self):
         self.expect("trace load " +
             os.path.join(self.getSourceDir(), "intelpt-trace", "trace_wrong_cpu.json"))
         self.expect("thread trace dump instructions --forwards",
             substrs=["error: unknown cpu"], error=True)
 
     def testMultiFileTraceWithMissingModuleInJSON(self):
         self.expect("trace load " +
             os.path.join(self.getSourceDir(), "intelpt-trace-multi-file", "multi-file-no-ld.json"))
 
-        self.expect("thread trace dump instructions --count 4 --id 4 --forwards --pretty-json",
+        self.expect("thread trace dump instructions --count 4 --id 5 --forwards --pretty-json",
             substrs=['''[
   {
-    "id": 4,
+    "id": 5,
     "loadAddress": "0x40054b",
     "module": "a.out",
     "symbol": "foo()",
     "mnemonic": "jmp"
   },
   {
-    "id": 5,
+    "id": 6,
     "loadAddress": "0x400510",
     "module": "a.out",
     "symbol": null,
     "mnemonic": "pushq"
   },
   {
-    "id": 6,
+    "id": 7,
     "loadAddress": "0x400516",
     "module": "a.out",
     "symbol": null,
     "mnemonic": "jmpq"
   },
   {
-    "id": 7,
+    "id": 8,
     "error": "no memory mapped at this address: 0x00007ffff7df1950"
   },
   {
-    "id": 8,
+    "id": 10,
     "loadAddress": "0x400674",
     "module": "a.out",
     "symbol": "main",
     "mnemonic": "movl",
     "source": "/home/wallace/llvm-sand/external/llvm-project/lldb/test/API/commands/trace/intelpt-trace-multi-file/main.cpp",
     "line": 10,
     "column": 0
   }
 ]'''])
 
         self.expect("thread trace dump instructions --count 4 --id 20 --forwards --pretty-json",
                 substrs=['''[
   {
     "id": 20,
-    "loadAddress": "0x40069a",
+    "loadAddress": "0x400694",
     "module": "a.out",
-    "symbol": "main",
-    "mnemonic": "addl",
+    "symbol": "inline_function()",
+    "mnemonic": "movl",
     "source": "/home/wallace/llvm-sand/external/llvm-project/lldb/test/API/commands/trace/intelpt-trace-multi-file/main.cpp",
-    "line": 14,
+    "line": 6,
     "column": 0
   },
   {
     "id": 21,
-    "loadAddress": "0x40069c",
+    "loadAddress": "0x400697",
     "module": "a.out",
     "symbol": "main",
     "mnemonic": "movl",
     "source": "/home/wallace/llvm-sand/external/llvm-project/lldb/test/API/commands/trace/intelpt-trace-multi-file/main.cpp",
     "line": 14,
     "column": 0
   },
   {
-    "id": 23,
-    "loadAddress": "0x40069f",
+    "id": 22,
+    "loadAddress": "0x40069a",
     "module": "a.out",
     "symbol": "main",
-    "mnemonic": "callq",
+    "mnemonic": "addl",
     "source": "/home/wallace/llvm-sand/external/llvm-project/lldb/test/API/commands/trace/intelpt-trace-multi-file/main.cpp",
-    "line": 16,
+    "line": 14,
     "column": 0
   },
   {
-    "id": 24,
-    "loadAddress": "0x400540",
+    "id": 23,
+    "loadAddress": "0x40069c",
     "module": "a.out",
-    "symbol": "foo()",
-    "mnemonic": "jmpq"
+    "symbol": "main",
+    "mnemonic": "movl",
+    "source": "/home/wallace/llvm-sand/external/llvm-project/lldb/test/API/commands/trace/intelpt-trace-multi-file/main.cpp",
+    "line": 14,
+    "column": 0
   }
 ]'''])
 
     def testMultiFileTraceWithMissingModule(self):
         self.expect("trace load " +
             os.path.join(self.getSourceDir(), "intelpt-trace-multi-file", "multi-file-no-ld.json"))
 
         # This instructions in this test covers the following flow:
         #
         # - The trace starts with a call to libfoo, which triggers the dynamic
         #   linker, but the dynamic linker is not included in the JSON file,
         #   thus the trace reports a set of missing instructions after
         #   instruction [6].
         # - Then, the dump continues in the next synchronization point showing
         #   a call to an inlined function, which is displayed as [inlined].
         # - Finally, a call to libfoo is performed, which invokes libbar inside.
         #
         # Whenever there's a line or symbol change, including the inline case, a
         # line is printed showing the symbol context change.
         #
         # Finally, the instruction disassembly is included in the dump.
         self.expect("thread trace dump instructions --count 50 --forwards",
             substrs=['''thread #1: tid = 815455
   a.out`main + 15 at main.cpp:10
-    0: 0x000000000040066f    callq  0x400540                  ; symbol stub for: foo()
+    1: 0x000000000040066f    callq  0x400540                  ; symbol stub for: foo()
   a.out`symbol stub for: foo()
-    2: 0x0000000000400540    jmpq   *0x200ae2(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 40
-    3: 0x0000000000400546    pushq  $0x2
-    4: 0x000000000040054b    jmp    0x400510
+    3: 0x0000000000400540    jmpq   *0x200ae2(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 40
+    4: 0x0000000000400546    pushq  $0x2
+    5: 0x000000000040054b    jmp    0x400510
   a.out`(none)
-    5: 0x0000000000400510    pushq  0x200af2(%rip)            ; _GLOBAL_OFFSET_TABLE_ + 8
-    6: 0x0000000000400516    jmpq   *0x200af4(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 16
+    6: 0x0000000000400510    pushq  0x200af2(%rip)            ; _GLOBAL_OFFSET_TABLE_ + 8
+    7: 0x0000000000400516    jmpq   *0x200af4(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 16
     ...missing instructions
-    7: (error) no memory mapped at this address: 0x00007ffff7df1950
+    8: (error) no memory mapped at this address: 0x00007ffff7df1950
   a.out`main + 20 at main.cpp:10
-    8: 0x0000000000400674    movl   %eax, -0xc(%rbp)
+    10: 0x0000000000400674    movl   %eax, -0xc(%rbp)
   a.out`main + 23 at main.cpp:12
-    10: 0x0000000000400677    movl   -0xc(%rbp), %eax
-    11: 0x000000000040067a    addl   $0x1, %eax
-    12: 0x000000000040067f    movl   %eax, -0xc(%rbp)
+    12: 0x0000000000400677    movl   -0xc(%rbp), %eax
+    13: 0x000000000040067a    addl   $0x1, %eax
+    14: 0x000000000040067f    movl   %eax, -0xc(%rbp)
   a.out`main + 34 [inlined] inline_function() at main.cpp:4
-    14: 0x0000000000400682    movl   $0x0, -0x4(%rbp)
+    16: 0x0000000000400682    movl   $0x0, -0x4(%rbp)
   a.out`main + 41 [inlined] inline_function() + 7 at main.cpp:5
-    15: 0x0000000000400689    movl   -0x4(%rbp), %eax
-    16: 0x000000000040068c    addl   $0x1, %eax
-    17: 0x0000000000400691    movl   %eax, -0x4(%rbp)
+    17: 0x0000000000400689    movl   -0x4(%rbp), %eax
+    18: 0x000000000040068c    addl   $0x1, %eax
+    19: 0x0000000000400691    movl   %eax, -0x4(%rbp)
   a.out`main + 52 [inlined] inline_function() + 18 at main.cpp:6
-    18: 0x0000000000400694    movl   -0x4(%rbp), %eax
+    20: 0x0000000000400694    movl   -0x4(%rbp), %eax
   a.out`main + 55 at main.cpp:14
-    19: 0x0000000000400697    movl   -0xc(%rbp), %ecx
-    20: 0x000000000040069a    addl   %eax, %ecx
-    21: 0x000000000040069c    movl   %ecx, -0xc(%rbp)
+    21: 0x0000000000400697    movl   -0xc(%rbp), %ecx
+    22: 0x000000000040069a    addl   %eax, %ecx
+    23: 0x000000000040069c    movl   %ecx, -0xc(%rbp)
   a.out`main + 63 at main.cpp:16
-    23: 0x000000000040069f    callq  0x400540                  ; symbol stub for: foo()
+    25: 0x000000000040069f    callq  0x400540                  ; symbol stub for: foo()
   a.out`symbol stub for: foo()
-    24: 0x0000000000400540    jmpq   *0x200ae2(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 40
+    26: 0x0000000000400540    jmpq   *0x200ae2(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 40
   libfoo.so`foo() at foo.cpp:3
-    25: 0x00007ffff7bd96e0    pushq  %rbp
-    26: 0x00007ffff7bd96e1    movq   %rsp, %rbp
+    27: 0x00007ffff7bd96e0    pushq  %rbp
+    28: 0x00007ffff7bd96e1    movq   %rsp, %rbp
   libfoo.so`foo() + 4 at foo.cpp:4
-    27: 0x00007ffff7bd96e4    subq   $0x10, %rsp
-    28: 0x00007ffff7bd96e8    callq  0x7ffff7bd95d0            ; symbol stub for: bar()
+    29: 0x00007ffff7bd96e4    subq   $0x10, %rsp
+    30: 0x00007ffff7bd96e8    callq  0x7ffff7bd95d0            ; symbol stub for: bar()
   libfoo.so`symbol stub for: bar()
-    29: 0x00007ffff7bd95d0    jmpq   *0x200a4a(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 32
+    31: 0x00007ffff7bd95d0    jmpq   *0x200a4a(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 32
   libbar.so`bar() at bar.cpp:1
-    30: 0x00007ffff79d7690    pushq  %rbp
-    31: 0x00007ffff79d7691    movq   %rsp, %rbp
+    32: 0x00007ffff79d7690    pushq  %rbp
+    33: 0x00007ffff79d7691    movq   %rsp, %rbp
   libbar.so`bar() + 4 at bar.cpp:2
-    32: 0x00007ffff79d7694    movl   $0x1, -0x4(%rbp)
+    34: 0x00007ffff79d7694    movl   $0x1, -0x4(%rbp)
   libbar.so`bar() + 11 at bar.cpp:3
-    33: 0x00007ffff79d769b    movl   -0x4(%rbp), %eax
-    34: 0x00007ffff79d769e    addl   $0x1, %eax
-    35: 0x00007ffff79d76a3    movl   %eax, -0x4(%rbp)
+    35: 0x00007ffff79d769b    movl   -0x4(%rbp), %eax
+    36: 0x00007ffff79d769e    addl   $0x1, %eax
+    37: 0x00007ffff79d76a3    movl   %eax, -0x4(%rbp)
   libbar.so`bar() + 22 at bar.cpp:4
-    36: 0x00007ffff79d76a6    movl   -0x4(%rbp), %eax
-    37: 0x00007ffff79d76a9    popq   %rbp
-    38: 0x00007ffff79d76aa    retq''',
+    38: 0x00007ffff79d76a6    movl   -0x4(%rbp), %eax
+    39: 0x00007ffff79d76a9    popq   %rbp
+    40: 0x00007ffff79d76aa    retq''',
   '''libfoo.so`foo() + 13 at foo.cpp:4
-    39: 0x00007ffff7bd96ed    movl   %eax, -0x4(%rbp)
+    41: 0x00007ffff7bd96ed    movl   %eax, -0x4(%rbp)
   libfoo.so`foo() + 16 at foo.cpp:5
-    40: 0x00007ffff7bd96f0    movl   -0x4(%rbp), %eax
-    41: 0x00007ffff7bd96f3    addl   $0x1, %eax
-    42: 0x00007ffff7bd96f8    movl   %eax, -0x4(%rbp)
+    42: 0x00007ffff7bd96f0    movl   -0x4(%rbp), %eax
+    43: 0x00007ffff7bd96f3    addl   $0x1, %eax
+    44: 0x00007ffff7bd96f8    movl   %eax, -0x4(%rbp)
   libfoo.so`foo() + 27 at foo.cpp:6
-    43: 0x00007ffff7bd96fb    movl   -0x4(%rbp), %eax
-    44: 0x00007ffff7bd96fe    addq   $0x10, %rsp
-    45: 0x00007ffff7bd9702    popq   %rbp
-    46: 0x00007ffff7bd9703    retq''',
+    45: 0x00007ffff7bd96fb    movl   -0x4(%rbp), %eax
+    46: 0x00007ffff7bd96fe    addq   $0x10, %rsp
+    47: 0x00007ffff7bd9702    popq   %rbp
+    48: 0x00007ffff7bd9703    retq''',
   '''a.out`main + 68 at main.cpp:16
-    47: 0x00000000004006a4    movl   -0xc(%rbp), %ecx
-    48: 0x00000000004006a7    addl   %eax, %ecx
-    49: 0x00000000004006a9    movl   %ecx, -0xc(%rbp)
+    49: 0x00000000004006a4    movl   -0xc(%rbp), %ecx
+    50: 0x00000000004006a7    addl   %eax, %ecx
+    51: 0x00000000004006a9    movl   %ecx, -0xc(%rbp)
     no more data'''])
 
 
         self.expect("thread trace dump instructions --count 50",
             substrs=['''thread #1: tid = 815455
   a.out`main + 73 at main.cpp:16
-    49: 0x00000000004006a9    movl   %ecx, -0xc(%rbp)
-    48: 0x00000000004006a7    addl   %eax, %ecx
-    47: 0x00000000004006a4    movl   -0xc(%rbp), %ecx
+    51: 0x00000000004006a9    movl   %ecx, -0xc(%rbp)
+    50: 0x00000000004006a7    addl   %eax, %ecx
+    49: 0x00000000004006a4    movl   -0xc(%rbp), %ecx
   libfoo.so`foo() + 35 at foo.cpp:6
-    46: 0x00007ffff7bd9703    retq''',
-    '''45: 0x00007ffff7bd9702    popq   %rbp
-    44: 0x00007ffff7bd96fe    addq   $0x10, %rsp
-    43: 0x00007ffff7bd96fb    movl   -0x4(%rbp), %eax
+    48: 0x00007ffff7bd9703    retq''',
+    '''47: 0x00007ffff7bd9702    popq   %rbp
+    46: 0x00007ffff7bd96fe    addq   $0x10, %rsp
+    45: 0x00007ffff7bd96fb    movl   -0x4(%rbp), %eax
   libfoo.so`foo() + 24 at foo.cpp:5
-    42: 0x00007ffff7bd96f8    movl   %eax, -0x4(%rbp)
-    41: 0x00007ffff7bd96f3    addl   $0x1, %eax
-    40: 0x00007ffff7bd96f0    movl   -0x4(%rbp), %eax
+    44: 0x00007ffff7bd96f8    movl   %eax, -0x4(%rbp)
+    43: 0x00007ffff7bd96f3    addl   $0x1, %eax
+    42: 0x00007ffff7bd96f0    movl   -0x4(%rbp), %eax
   libfoo.so`foo() + 13 at foo.cpp:4
-    39: 0x00007ffff7bd96ed    movl   %eax, -0x4(%rbp)
+    41: 0x00007ffff7bd96ed    movl   %eax, -0x4(%rbp)
   libbar.so`bar() + 26 at bar.cpp:4
-    38: 0x00007ffff79d76aa    retq''',
-    '''37: 0x00007ffff79d76a9    popq   %rbp
-    36: 0x00007ffff79d76a6    movl   -0x4(%rbp), %eax
+    40: 0x00007ffff79d76aa    retq''',
+    '''39: 0x00007ffff79d76a9    popq   %rbp
+    38: 0x00007ffff79d76a6    movl   -0x4(%rbp), %eax
   libbar.so`bar() + 19 at bar.cpp:3
-    35: 0x00007ffff79d76a3    movl   %eax, -0x4(%rbp)
-    34: 0x00007ffff79d769e    addl   $0x1, %eax
-    33: 0x00007ffff79d769b    movl   -0x4(%rbp), %eax
+    37: 0x00007ffff79d76a3    movl   %eax, -0x4(%rbp)
+    36: 0x00007ffff79d769e    addl   $0x1, %eax
+    35: 0x00007ffff79d769b    movl   -0x4(%rbp), %eax
   libbar.so`bar() + 4 at bar.cpp:2
-    32: 0x00007ffff79d7694    movl   $0x1, -0x4(%rbp)
+    34: 0x00007ffff79d7694    movl   $0x1, -0x4(%rbp)
   libbar.so`bar() + 1 at bar.cpp:1
-    31: 0x00007ffff79d7691    movq   %rsp, %rbp
-    30: 0x00007ffff79d7690    pushq  %rbp
+    33: 0x00007ffff79d7691    movq   %rsp, %rbp
+    32: 0x00007ffff79d7690    pushq  %rbp
   libfoo.so`symbol stub for: bar()
-    29: 0x00007ffff7bd95d0    jmpq   *0x200a4a(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 32
+    31: 0x00007ffff7bd95d0    jmpq   *0x200a4a(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 32
   libfoo.so`foo() + 8 at foo.cpp:4
-    28: 0x00007ffff7bd96e8    callq  0x7ffff7bd95d0            ; symbol stub for: bar()
-    27: 0x00007ffff7bd96e4    subq   $0x10, %rsp
+    30: 0x00007ffff7bd96e8    callq  0x7ffff7bd95d0            ; symbol stub for: bar()
+    29: 0x00007ffff7bd96e4    subq   $0x10, %rsp
   libfoo.so`foo() + 1 at foo.cpp:3
-    26: 0x00007ffff7bd96e1    movq   %rsp, %rbp
-    25: 0x00007ffff7bd96e0    pushq  %rbp
+    28: 0x00007ffff7bd96e1    movq   %rsp, %rbp
+    27: 0x00007ffff7bd96e0    pushq  %rbp
   a.out`symbol stub for: foo()
-    24: 0x0000000000400540    jmpq   *0x200ae2(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 40
+    26: 0x0000000000400540    jmpq   *0x200ae2(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 40
   a.out`main + 63 at main.cpp:16
-    23: 0x000000000040069f    callq  0x400540                  ; symbol stub for: foo()
+    25: 0x000000000040069f    callq  0x400540                  ; symbol stub for: foo()
   a.out`main + 60 at main.cpp:14
-    21: 0x000000000040069c    movl   %ecx, -0xc(%rbp)
-    20: 0x000000000040069a    addl   %eax, %ecx
-    19: 0x0000000000400697    movl   -0xc(%rbp), %ecx
+    23: 0x000000000040069c    movl   %ecx, -0xc(%rbp)
+    22: 0x000000000040069a    addl   %eax, %ecx
+    21: 0x0000000000400697    movl   -0xc(%rbp), %ecx
   a.out`main + 52 [inlined] inline_function() + 18 at main.cpp:6
-    18: 0x0000000000400694    movl   -0x4(%rbp), %eax
+    20: 0x0000000000400694    movl   -0x4(%rbp), %eax
   a.out`main + 49 [inlined] inline_function() + 15 at main.cpp:5
-    17: 0x0000000000400691    movl   %eax, -0x4(%rbp)
-    16: 0x000000000040068c    addl   $0x1, %eax
-    15: 0x0000000000400689    movl   -0x4(%rbp), %eax
+    19: 0x0000000000400691    movl   %eax, -0x4(%rbp)
+    18: 0x000000000040068c    addl   $0x1, %eax
+    17: 0x0000000000400689    movl   -0x4(%rbp), %eax
   a.out`main + 34 [inlined] inline_function() at main.cpp:4
-    14: 0x0000000000400682    movl   $0x0, -0x4(%rbp)
+    16: 0x0000000000400682    movl   $0x0, -0x4(%rbp)
   a.out`main + 31 at main.cpp:12
-    12: 0x000000000040067f    movl   %eax, -0xc(%rbp)
-    11: 0x000000000040067a    addl   $0x1, %eax
-    10: 0x0000000000400677    movl   -0xc(%rbp), %eax
+    14: 0x000000000040067f    movl   %eax, -0xc(%rbp)
+    13: 0x000000000040067a    addl   $0x1, %eax
+    12: 0x0000000000400677    movl   -0xc(%rbp), %eax
   a.out`main + 20 at main.cpp:10
-    8: 0x0000000000400674    movl   %eax, -0xc(%rbp)
+    10: 0x0000000000400674    movl   %eax, -0xc(%rbp)
     ...missing instructions
-    7: (error) no memory mapped at this address: 0x00007ffff7df1950
+    8: (error) no memory mapped at this address: 0x00007ffff7df1950
   a.out`(none)
-    6: 0x0000000000400516    jmpq   *0x200af4(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 16
-    5: 0x0000000000400510    pushq  0x200af2(%rip)            ; _GLOBAL_OFFSET_TABLE_ + 8
+    7: 0x0000000000400516    jmpq   *0x200af4(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 16
+    6: 0x0000000000400510    pushq  0x200af2(%rip)            ; _GLOBAL_OFFSET_TABLE_ + 8
   a.out`symbol stub for: foo() + 11
-    4: 0x000000000040054b    jmp    0x400510
-    3: 0x0000000000400546    pushq  $0x2
-    2: 0x0000000000400540    jmpq   *0x200ae2(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 40
+    5: 0x000000000040054b    jmp    0x400510
+    4: 0x0000000000400546    pushq  $0x2
+    3: 0x0000000000400540    jmpq   *0x200ae2(%rip)           ; _GLOBAL_OFFSET_TABLE_ + 40
   a.out`main + 15 at main.cpp:10
-    0: 0x000000000040066f    callq  0x400540                  ; symbol stub for: foo()
+    1: 0x000000000040066f    callq  0x400540                  ; symbol stub for: foo()
     no more data'''])
 
         self.expect("thread trace dump instructions --skip 100 --forwards", inHistory=True,
             substrs=['''thread #1: tid = 815455
     no more data'''])
 
         self.expect("", substrs=['''thread #1: tid = 815455
     no more data'''])
 
 
         self.expect("thread trace dump instructions --raw --all --forwards",
             substrs=['''thread #1: tid = 815455
-    0: 0x000000000040066f
-    2: 0x0000000000400540''',
-    '''6: 0x0000000000400516
+    1: 0x000000000040066f
+    3: 0x0000000000400540''',
+    '''7: 0x0000000000400516
     ...missing instructions
-    7: (error) no memory mapped at this address: 0x00007ffff7df1950
-    8: 0x0000000000400674''',
-    '''47: 0x00000000004006a4
-    48: 0x00000000004006a7
-    49: 0x00000000004006a9
+    8: (error) no memory mapped at this address: 0x00007ffff7df1950
+    10: 0x0000000000400674''',
+    '''49: 0x00000000004006a4
+    50: 0x00000000004006a7
+    51: 0x00000000004006a9
     no more data'''])

lldb/test/API/commands/trace/TestTraceEvents.py

def testCPUEvents(self):
       trace_description_file_path = os.path.join(self.getSourceDir(), "intelpt-multi-core-trace", "trace_missing_threads.json")
       self.traceLoad(traceDescriptionFilePath=trace_description_file_path, substrs=["intel-pt"])
 
       self.expect("thread trace dump instructions 3 -e --forward -c 5",
         substrs=['''thread #3: tid = 3497496
     0: (event) HW clock tick [40450075477621505]
     1: (event) CPU core changed [new CPU=51]
     2: (event) HW clock tick [40450075477657246]
+    3: (event) trace synchronization point [offset = 0x0x1331]
   m.out`foo() + 65 at multi_thread.cpp:12:21'''])
 
       self.expect("thread trace dump instructions 3 -e --forward -c 5 -J",
         substrs=['''{
     "id": 0,
     "event": "HW clock tick",
     "hwClock": 40450075477621505
   },
def testPauseEvents(self):
       self.expect("n")
       self.expect("n")
       self.expect("si")
       self.expect("si")
       self.expect("si")
       # We ensure that the paused events are printed correctly forward
       self.expect("thread trace dump instructions -e -f",
         patterns=[f'''thread #1: tid = .*
+    0: \(event\) trace synchronization point \[offset \= 0x0xec0\]
   a.out`main \+ 23 at main.cpp:12
-    0: {ADDRESS_REGEX}    movl .*
-    1: \(event\) software disabled tracing
-    2: {ADDRESS_REGEX}    addl .*
-    3: {ADDRESS_REGEX}    movl .*
-    4: \(event\) software disabled tracing
+    1: {ADDRESS_REGEX}    movl .*
+    2: \(event\) software disabled tracing
+    3: {ADDRESS_REGEX}    addl .*
+    4: {ADDRESS_REGEX}    movl .*
+    5: \(event\) software disabled tracing
   a.out`main \+ 34 \[inlined\] inline_function\(\) at main.cpp:4
-    5: {ADDRESS_REGEX}    movl .*
-  a.out`main \+ 41 \[inlined\] inline_function\(\) \+ 7 at main.cpp:5
     6: {ADDRESS_REGEX}    movl .*
-    7: {ADDRESS_REGEX}    addl .*
-    8: {ADDRESS_REGEX}    movl .*
-  a.out`main \+ 52 \[inlined\] inline_function\(\) \+ 18 at main.cpp:6
+  a.out`main \+ 41 \[inlined\] inline_function\(\) \+ 7 at main.cpp:5
+    7: {ADDRESS_REGEX}    movl .*
+    8: {ADDRESS_REGEX}    addl .*
     9: {ADDRESS_REGEX}    movl .*
-  a.out`main \+ 55 at main.cpp:14
+  a.out`main \+ 52 \[inlined\] inline_function\(\) \+ 18 at main.cpp:6
     10: {ADDRESS_REGEX}    movl .*
-    11: {ADDRESS_REGEX}    addl .*
-    12: {ADDRESS_REGEX}    movl .*
-    13: \(event\) software disabled tracing
+  a.out`main \+ 55 at main.cpp:14
+    11: {ADDRESS_REGEX}    movl .*
+    12: {ADDRESS_REGEX}    addl .*
+    13: {ADDRESS_REGEX}    movl .*
+    14: \(event\) software disabled tracing
   a.out`main \+ 63 at main.cpp:16
-    14: {ADDRESS_REGEX}    callq  .* ; symbol stub for: foo\(\)
-    15: \(event\) software disabled tracing
+    15: {ADDRESS_REGEX}    callq  .* ; symbol stub for: foo\(\)
+    16: \(event\) software disabled tracing
   a.out`symbol stub for: foo\(\)
-    16: {ADDRESS_REGEX}    jmpq'''])
+    17: {ADDRESS_REGEX}    jmpq'''])
 
       # We ensure that the paused events are printed correctly backward
-      self.expect("thread trace dump instructions -e --id 16",
+      self.expect("thread trace dump instructions -e --id 17",
         patterns=[f'''thread #1: tid = .*
   a.out`symbol stub for: foo\(\)
-    16: {ADDRESS_REGEX}    jmpq .*
-    15: \(event\) software disabled tracing
+    17: {ADDRESS_REGEX}    jmpq .*
+    16: \(event\) software disabled tracing
   a.out`main \+ 63 at main.cpp:16
-    14: {ADDRESS_REGEX}    callq  .* ; symbol stub for: foo\(\)
-    13: \(event\) software disabled tracing
+    15: {ADDRESS_REGEX}    callq  .* ; symbol stub for: foo\(\)
+    14: \(event\) software disabled tracing
   a.out`main \+ 60 at main.cpp:14
-    12: {ADDRESS_REGEX}    movl .*
-    11: {ADDRESS_REGEX}    addl .*
-    10: {ADDRESS_REGEX}    movl .*
+    13: {ADDRESS_REGEX}    movl .*
+    12: {ADDRESS_REGEX}    addl .*
+    11: {ADDRESS_REGEX}    movl .*
   a.out`main \+ 52 \[inlined\] inline_function\(\) \+ 18 at main.cpp:6
-    9: {ADDRESS_REGEX}    movl .*
+    10: {ADDRESS_REGEX}    movl .*
   a.out`main \+ 49 \[inlined\] inline_function\(\) \+ 15 at main.cpp:5
-    8: {ADDRESS_REGEX}    movl .*
-    7: {ADDRESS_REGEX}    addl .*
-    6: {ADDRESS_REGEX}    movl .*
+    9: {ADDRESS_REGEX}    movl .*
+    8: {ADDRESS_REGEX}    addl .*
+    7: {ADDRESS_REGEX}    movl .*
   a.out`main \+ 34 \[inlined\] inline_function\(\) at main.cpp:4
-    5: {ADDRESS_REGEX}    movl .*
-    4: \(event\) software disabled tracing
+    6: {ADDRESS_REGEX}    movl .*
+    5: \(event\) software disabled tracing
   a.out`main \+ 31 at main.cpp:12
-    3: {ADDRESS_REGEX}    movl .*
-    2: {ADDRESS_REGEX}    addl .*
-    1: \(event\) software disabled tracing
-    0: {ADDRESS_REGEX}    movl .*'''])
+    4: {ADDRESS_REGEX}    movl .*
+    3: {ADDRESS_REGEX}    addl .*
+    2: \(event\) software disabled tracing
+    1: {ADDRESS_REGEX}    movl .*
+    0: \(event\) trace synchronization point \[offset \= 0x0xec0\]'''])

lldb/test/API/commands/trace/TestTraceLoad.py

 import lldb
 from intelpt_testcase import *
 from lldbsuite.test.lldbtest import *
 from lldbsuite.test import lldbutil
 from lldbsuite.test.decorators import *
 
 class TestTraceLoad(TraceIntelPTTestCaseBase):
     NO_DEBUG_INFO_TESTCASE = True
 
     @testSBAPIAndCommands
     def testLoadMultiCoreTrace(self):
         src_dir = self.getSourceDir()
         trace_description_file_path = os.path.join(src_dir, "intelpt-multi-core-trace", "trace.json")
         self.traceLoad(traceDescriptionFilePath=trace_description_file_path, substrs=["intel-pt"])
         self.expect("thread trace dump instructions 2 -t",
-          substrs=["19531: [20456511.000 ns] (error) expected tracing enabled event",
+          substrs=["19532: [20456513.000 ns] (error) expected tracing enabled event",
                    "m.out`foo() + 65 at multi_thread.cpp:12:21",
-                   "19523: [19691630.216 ns] 0x0000000000400ba7    jg     0x400bb3"])
+                   "9524: [19691630.226 ns] 0x0000000000400ba7    jg     0x400bb3"])
         self.expect("thread trace dump instructions 3 -t",
-          substrs=["67919: [19736130.084 ns] 0x0000000000400bd7    addl   $0x1, -0x4(%rbp)",
+          substrs=["61831: [19736134.073 ns] 0x0000000000400bd7    addl   $0x1, -0x4(%rbp)",
                    "m.out`bar() + 26 at multi_thread.cpp:20:6"])
 
         self.expect("thread trace dump info --json",
           substrs=['''{
   "traceTechnology": "intel-pt",
   "threadStats": {
     "tid": 3497234,
     "traceItemsCount": 0,
     "memoryUsage": {
       "totalInBytes": "0",
       "avgPerItemInBytes": null
     },
     "timingInSeconds": {
       "Decoding instructions": ''', '''
     },
     "events": {
       "totalCount": 0,
       "individualCounts": {}
     },
     "continuousExecutions": 0,
-    "PSBBlocks": 0,
-    "errorItems": {
-      "total": 0,
-      "individualErrors": {}
-    }
+    "PSBBlocks": 0
   },
   "globalStats": {
     "timingInSeconds": {
       "Context switch and Intel PT traces correlation": 0
     },
     "totalUnattributedPSBBlocks": 0,
     "totalCountinuosExecutions": 153,
     "totalPSBBlocks": 5,
     "totalContinuousExecutions": 153
   }
 }'''])
 
         self.expect("thread trace dump info 2 --json",
           substrs=['''{
   "traceTechnology": "intel-pt",
   "threadStats": {
     "tid": 3497496,
     "traceItemsCount": 19533,
     "memoryUsage": {
-      "totalInBytes": "176097",
+      "totalInBytes": "176065",
       "avgPerItemInBytes": 9.''', '''},
     "timingInSeconds": {
       "Decoding instructions": ''', '''
     },
     "events": {
       "totalCount": 11,
       "individualCounts": {
         "software disabled tracing": 1,
-        "HW clock tick": 9,
+        "trace synchronization point": 1,
+        "HW clock tick": 8,
         "CPU core changed": 1
       }
     },
     "continuousExecutions": 1,
-    "PSBBlocks": 1,
-    "errorItems": {
-      "total": 0,
-      "individualErrors": {}
-    }
+    "PSBBlocks": 1
   },
   "globalStats": {
     "timingInSeconds": {
       "Context switch and Intel PT traces correlation": 0''', '''},
     "totalUnattributedPSBBlocks": 0,
     "totalCountinuosExecutions": 153,
     "totalPSBBlocks": 5,
     "totalContinuousExecutions": 153
def testLoadCompactMultiCoreTrace(self):
 
         # we'll delete the previous target and make sure it's trace object is deleted
         self.dbg.DeleteTarget(self.dbg.GetTargetAtIndex(0))
         self.expect("thread trace dump instructions 2 -t", substrs=["error: invalid target"], error=True)
 
         # we'll load the compact trace and make sure it works
         self.traceLoad(os.path.join(compact_trace_bundle_dir, "trace.json"), substrs=["intel-pt"])
         self.expect("thread trace dump instructions 2 -t",
-          substrs=["19531: [20456511.000 ns] (error) expected tracing enabled event",
+          substrs=["19532: [20456513.000 ns] (error) expected tracing enabled event",
                    "m.out`foo() + 65 at multi_thread.cpp:12:21",
-                   "19523: [19691630.216 ns] 0x0000000000400ba7    jg     0x400bb3"])
+                   "19524: [19691630.226 ns] 0x0000000000400ba7    jg     0x400bb3"])
         self.expect("thread trace dump instructions 3 -t",
-          substrs=["67919: [19736130.084 ns] 0x0000000000400bd7    addl   $0x1, -0x4(%rbp)",
+          substrs=["61831: [19736134.073 ns] 0x0000000000400bd7    addl   $0x1, -0x4(%rbp)",
                    "m.out`bar() + 26 at multi_thread.cpp:20:6"])
 
         # This reduced the number of continuous executions to look at
         self.expect("thread trace dump info 2", substrs=["Total number of continuous executions found: 3"])
 
         # We clean up for the next run of this test
         self.dbg.DeleteTarget(self.dbg.GetTargetAtIndex(0))
 
     @testSBAPIAndCommands
     def testLoadMultiCoreTraceWithStringNumbers(self):
         src_dir = self.getSourceDir()
         trace_description_file_path = os.path.join(src_dir, "intelpt-multi-core-trace", "trace_with_string_numbers.json")
         self.traceLoad(traceDescriptionFilePath=trace_description_file_path, substrs=["intel-pt"])
         self.expect("thread trace dump instructions 2 -t",
-          substrs=["19531: [20456511.000 ns] (error) expected tracing enabled event",
+          substrs=["19532: [20456513.000 ns] (error) expected tracing enabled event",
                    "m.out`foo() + 65 at multi_thread.cpp:12:21",
-                   "19523: [19691630.216 ns] 0x0000000000400ba7    jg     0x400bb3"])
+                   "19524: [19691630.226 ns] 0x0000000000400ba7    jg     0x400bb3"])
         self.expect("thread trace dump instructions 3 -t",
-          substrs=["67919: [19736130.084 ns] 0x0000000000400bd7    addl   $0x1, -0x4(%rbp)",
+          substrs=["61831: [19736134.073 ns] 0x0000000000400bd7    addl   $0x1, -0x4(%rbp)",
                    "m.out`bar() + 26 at multi_thread.cpp:20:6"])
 
     @testSBAPIAndCommands
     def testLoadMultiCoreTraceWithMissingThreads(self):
         src_dir = self.getSourceDir()
         trace_description_file_path = os.path.join(src_dir, "intelpt-multi-core-trace", "trace_missing_threads.json")
         self.traceLoad(traceDescriptionFilePath=trace_description_file_path, substrs=["intel-pt"])
         self.expect("thread trace dump instructions 3 -t",
-          substrs=["19531: [20456511.000 ns] (error) expected tracing enabled event",
+          substrs=["19532: [20456513.000 ns] (error) expected tracing enabled event",
                    "m.out`foo() + 65 at multi_thread.cpp:12:21",
-                   "19523: [19691630.216 ns] 0x0000000000400ba7    jg     0x400bb3"])
+                   "19524: [19691630.226 ns] 0x0000000000400ba7    jg     0x400bb3"])
         self.expect("thread trace dump instructions 2 -t",
-          substrs=["67919: [19736130.084 ns] 0x0000000000400bd7    addl   $0x1, -0x4(%rbp)",
+          substrs=["61831: [19736134.073 ns] 0x0000000000400bd7    addl   $0x1, -0x4(%rbp)",
                    "m.out`bar() + 26 at multi_thread.cpp:20:6"])
 
     @testSBAPIAndCommands
     def testLoadTrace(self):
         src_dir = self.getSourceDir()
         trace_description_file_path = os.path.join(src_dir, "intelpt-trace", "trace.json")
         self.traceLoad(traceDescriptionFilePath=trace_description_file_path, substrs=["intel-pt"])
 
def testLoadTrace(self):
 
         # check that the Process and Thread objects were created correctly
         self.expect("thread info", substrs=["tid = 3842849"])
         self.expect("thread list", substrs=["Process 1234 stopped", "tid = 3842849"])
         self.expect("thread trace dump info", substrs=['''thread #1: tid = 3842849
 
   Trace technology: intel-pt
 
-  Total number of trace items: 23
+  Total number of trace items: 24
 
   Memory usage:
     Raw trace size: 4 KiB
-    Total approximate memory usage (excluding raw trace): 0.20 KiB
+    Total approximate memory usage (excluding raw trace): 0.21 KiB
     Average memory usage per item (excluding raw trace): 9.00 bytes
 
   Timing for this thread:
     Decoding instructions: ''', '''
 
   Events:
-    Number of individual events: 2
+    Number of individual events: 3
       software disabled tracing: 2
-
-  Errors:
-    Number of TSC decoding errors: 0'''])
+      trace synchronization point: 1'''])
 
     @testSBAPIAndCommands
     def testLoadInvalidTraces(self):
         src_dir = self.getSourceDir()
 
         # We test first an invalid type
         trace_description_file_path = os.path.join(src_dir, "intelpt-trace", "trace_bad.json")
         expected_substrs = ['''error: expected object at traceBundle.processes[0]
def testLoadTraceCursor(self):
         self.assertSBError(error)
 
         target = self.dbg.GetSelectedTarget()
         process = target.process
 
 
         # 1. Test some expected items of thread 1's trace cursor.
         thread1 = process.threads[1]
-        cursor = trace.CreateNewCursor(error, thread1) 
+        cursor = trace.CreateNewCursor(error, thread1)
         self.assertTrue(cursor)
         self.assertTrue(cursor.HasValue())
         cursor.Seek(0, lldb.eTraceCursorSeekTypeBeginning)
         cursor.SetForwards(True)
 
         self.assertTrue(cursor.IsEvent())
         self.assertEqual(cursor.GetEventTypeAsString(), "HW clock tick")
         self.assertEqual(cursor.GetCPU(), lldb.LLDB_INVALID_CPU_ID)
 
         cursor.Next()
 
         self.assertTrue(cursor.IsEvent())
         self.assertEqual(cursor.GetEventTypeAsString(), "CPU core changed")
         self.assertEqual(cursor.GetCPU(), 51)
 
-        cursor.GoToId(19531)
+        cursor.GoToId(19532)
 
         self.assertTrue(cursor.IsError())
         self.assertEqual(cursor.GetError(), "expected tracing enabled event")
 
-        cursor.GoToId(19523)
+        cursor.GoToId(19524)
 
         self.assertTrue(cursor.IsInstruction())
-        self.assertEqual(cursor.GetLoadAddress(), 4197287)
+        self.assertEqual(cursor.GetLoadAddress(), 0x400BA7)
 
 
 
         # Helper function to check equality of the current item of two trace cursors.
         def assertCurrentTraceCursorItemEqual(lhs, rhs):
             self.assertTrue(lhs.HasValue() and rhs.HasValue())
 
             self.assertEqual(lhs.GetId(), rhs.GetId())
             self.assertEqual(lhs.GetItemKind(), rhs.GetItemKind())
             if lhs.IsError():
                 self.assertEqual(lhs.GetError(), rhs.GetError())
             elif lhs.IsEvent():
                 self.assertEqual(lhs.GetEventType(), rhs.GetEventType())
                 self.assertEqual(lhs.GetEventTypeAsString(), rhs.GetEventTypeAsString())
             elif lhs.IsInstruction():
                 self.assertEqual(lhs.GetLoadAddress(), rhs.GetLoadAddress())
             else:
                 self.fail("Unknown trace item kind")
 
         for thread in process.threads:
-            sequentialTraversalCursor = trace.CreateNewCursor(error, thread) 
+            sequentialTraversalCursor = trace.CreateNewCursor(error, thread)
             self.assertSBError(error)
             # Skip threads with no trace items
             if not sequentialTraversalCursor.HasValue():
                 continue
 
-            # 2. Test "End" boundary of the trace by advancing past the trace's last item. 
+            # 2. Test "End" boundary of the trace by advancing past the trace's last item.
             sequentialTraversalCursor.Seek(0, lldb.eTraceCursorSeekTypeEnd)
             self.assertTrue(sequentialTraversalCursor.HasValue())
             sequentialTraversalCursor.SetForwards(True)
             sequentialTraversalCursor.Next()
             self.assertFalse(sequentialTraversalCursor.HasValue())
 
 
 
             # 3. Test sequential traversal using sequential access API (ie Next())
             # and random access API (ie GoToId()) simultaneously.
-            randomAccessCursor = trace.CreateNewCursor(error, thread) 
+            randomAccessCursor = trace.CreateNewCursor(error, thread)
             self.assertSBError(error)
-            # Reset the sequential cursor 
+            # Reset the sequential cursor
             sequentialTraversalCursor.Seek(0, lldb.eTraceCursorSeekTypeBeginning)
             sequentialTraversalCursor.SetForwards(True)
             self.assertTrue(sequentialTraversalCursor.IsForwards())
 
             while sequentialTraversalCursor.HasValue():
                 itemId = sequentialTraversalCursor.GetId()
                 randomAccessCursor.GoToId(itemId)
                 assertCurrentTraceCursorItemEqual(sequentialTraversalCursor, randomAccessCursor)
                 sequentialTraversalCursor.Next()
 
 
 
             # 4. Test a random access with random access API (ie Seek()) and
             # sequential access API (ie consecutive calls to Next()).
             TEST_SEEK_ID = 3
             randomAccessCursor.GoToId(TEST_SEEK_ID )
-            # Reset the sequential cursor 
+            # Reset the sequential cursor
             sequentialTraversalCursor.Seek(0, lldb.eTraceCursorSeekTypeBeginning)
             sequentialTraversalCursor.SetForwards(True)
             for _ in range(TEST_SEEK_ID): sequentialTraversalCursor.Next()
             assertCurrentTraceCursorItemEqual(sequentialTraversalCursor, randomAccessCursor)
 
     @testSBAPIAndCommands
     def testLoadKernelTrace(self):
         # kernel section without loadAddress (using default loadAddress).

lldb/test/API/commands/trace/TestTraceStartStop.py

def testStartStopLiveThreads(self):
         self.expect("thread trace start", error=True,
             substrs=["error: Thread ", "already traced"])
 
         # We can reconstruct the single instruction executed in the first line
         self.expect("n")
         self.expect("thread trace dump instructions -f",
             patterns=[f'''thread #1: tid = .*
   a.out`main \+ 4 at main.cpp:2
-    0: {ADDRESS_REGEX}    movl'''])
+    1: {ADDRESS_REGEX}    movl'''])
 
         # We can reconstruct the instructions up to the second line
         self.expect("n")
         self.expect("thread trace dump instructions -f",
             patterns=[f'''thread #1: tid = .*
   a.out`main \+ 4 at main.cpp:2
-    0: {ADDRESS_REGEX}    movl .*
+    1: {ADDRESS_REGEX}    movl .*
   a.out`main \+ 11 at main.cpp:4
-    2: {ADDRESS_REGEX}    movl .*
-    4: {ADDRESS_REGEX}    jmp  .* ; <\+28> at main.cpp:4
-    6: {ADDRESS_REGEX}    cmpl .*
-    8: {ADDRESS_REGEX}    jle  .* ; <\+20> at main.cpp:5'''])
+    3: {ADDRESS_REGEX}    movl .*
+    5: {ADDRESS_REGEX}    jmp  .* ; <\+28> at main.cpp:4
+    7: {ADDRESS_REGEX}    cmpl .*
+    9: {ADDRESS_REGEX}    jle  .* ; <\+20> at main.cpp:5'''])
 
         self.expect("thread trace dump instructions",
             patterns=[f'''thread #1: tid = .*
   a.out`main \+ 32 at main.cpp:4
-    8: {ADDRESS_REGEX}    jle  .* ; <\+20> at main.cpp:5
-    6: {ADDRESS_REGEX}    cmpl .*
-    4: {ADDRESS_REGEX}    jmp  .* ; <\+28> at main.cpp:4
-    2: {ADDRESS_REGEX}    movl .*
+    9: {ADDRESS_REGEX}    jle  .* ; <\+20> at main.cpp:5
+    7: {ADDRESS_REGEX}    cmpl .*
+    5: {ADDRESS_REGEX}    jmp  .* ; <\+28> at main.cpp:4
+    3: {ADDRESS_REGEX}    movl .*
   a.out`main \+ 4 at main.cpp:2
-    0: {ADDRESS_REGEX}    movl .* '''])
+    1: {ADDRESS_REGEX}    movl .* '''])
 
         # We stop tracing
         self.expect("thread trace stop")
 
         # We can't stop twice
         self.expect("thread trace stop", error=True,
             substrs=["error: Thread ", "not currently traced"])
 
         # We trace again from scratch, this time letting LLDB to pick the current
         # thread
         self.expect("thread trace start")
         self.expect("n")
         self.expect("thread trace dump instructions -f",
             patterns=[f'''thread #1: tid = .*
   a.out`main \+ 20 at main.cpp:5
-    0: {ADDRESS_REGEX}    xorl'''])
+    1: {ADDRESS_REGEX}    xorl'''])
 
         self.expect("thread trace dump instructions",
             patterns=[f'''thread #1: tid = .*
   a.out`main \+ 20 at main.cpp:5
-    0: {ADDRESS_REGEX}    xorl'''])
+    1: {ADDRESS_REGEX}    xorl'''])
 
         self.expect("c")
         # Now the process has finished, so the commands should fail
         self.expect("thread trace start", error=True,
             substrs=["error: Process must be launched"])
 
         self.expect("thread trace stop", error=True,
             substrs=["error: Process must be launched"])