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

   1 //===-- TraceIntelPTMultiCpuDecoder.h ---------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLDB_SOURCE_PLUGINS_TRACE_INTEL_PT_TRACEINTELPTMULTICPUDECODER_H
  10 #define LLDB_SOURCE_PLUGINS_TRACE_INTEL_PT_TRACEINTELPTMULTICPUDECODER_H
  11
  12 #include "LibiptDecoder.h"
  13 #include "PerfContextSwitchDecoder.h"
  14 #include "ThreadDecoder.h"
  15 #include "forward-declarations.h"
  16 #include <optional>
  17
  18 namespace lldb_private {
  19 namespace trace_intel_pt {
  20
  21 /// Class used to decode a multi-cpu Intel PT trace. It assumes that each
  22 /// thread could have potentially been executed on different cpu cores. It uses
  23 /// a context switch trace per CPU with timestamps to identify which thread owns
  24 /// each Intel PT decoded instruction and in which order. It also assumes that
  25 /// the Intel PT data and context switches might have gaps in their traces due
  26 /// to contention or race conditions. Finally, it assumes that a tid is not
  27 /// repeated twice for two different threads because of the shortness of the
  28 /// intel pt trace.
  29 ///
  30 /// This object should be recreated after every stop in the case of live
  31 /// processes.
  32 class TraceIntelPTMultiCpuDecoder {
  33 public:
  34   /// \param[in] TraceIntelPT
  35   ///   The trace object to be decoded
  36   TraceIntelPTMultiCpuDecoder(TraceIntelPTSP trace_sp);
  37
  38   /// \return
  39   ///   A \a DecodedThread for the \p thread by decoding its instructions on all
  40   ///   CPUs, sorted by TSCs. An \a llvm::Error is returned if the decoder
  41   ///   couldn't be properly set up.
  42   llvm::Expected<DecodedThreadSP> Decode(Thread &thread);
  43
  44   /// \return
  45   ///   \b true if the given \p tid is managed by this decoder, regardless of
  46   ///   whether there's tracing data associated to it or not.
  47   bool TracesThread(lldb::tid_t tid) const;
  48
  49   /// \return
  50   ///   The number of continuous executions found for the given \p tid.
  51   size_t GetNumContinuousExecutionsForThread(lldb::tid_t tid) const;
  52
  53   /// \return
  54   ///   The number of PSB blocks for a given thread in all cores.
  55   size_t GePSBBlocksCountForThread(lldb::tid_t tid) const;
  56
  57   /// \return
  58   ///   The total number of continuous executions found across CPUs.
  59   size_t GetTotalContinuousExecutionsCount() const;
  60
  61   /// \return
  62   ///   The number of psb blocks in all cores that couldn't be matched with a
  63   ///   thread execution coming from context switch traces.
  64   size_t GetUnattributedPSBBlocksCount() const;
  65
  66   /// \return
  67   ///   The total number of PSB blocks in all cores.
  68   size_t GetTotalPSBBlocksCount() const;
  69
  70   /// \return
  71   ///     The lowest TSC value in this trace if available, \a std::nullopt if
  72   ///     the trace is empty or the trace contains no timing information, or an
  73   ///     \a llvm::Error if it was not possible to set up the decoder.
  74   llvm::Expected<std::optional<uint64_t>> FindLowestTSC();
  75
  76 private:
  77   /// Traverse the context switch traces and the basic intel pt continuous
  78   /// subtraces and produce a list of continuous executions for each process and
  79   /// thread.
  80   ///
  81   /// See \a DoCorrelateContextSwitchesAndIntelPtTraces.
  82   ///
  83   /// Any errors are stored in \a m_setup_error.
  84   llvm::Error CorrelateContextSwitchesAndIntelPtTraces();
  85
  86   /// Produce a mapping from thread ids to the list of continuos executions with
  87   /// their associated intel pt subtraces.
  88   llvm::Expected<
  89       llvm::DenseMap<lldb::tid_t, std::vector<IntelPTThreadContinousExecution>>>
  90   DoCorrelateContextSwitchesAndIntelPtTraces();
  91
  92   TraceIntelPTSP GetTrace();
  93
  94   std::weak_ptr<TraceIntelPT> m_trace_wp;
  95   std::set<lldb::tid_t> m_tids;
  96   std::optional<
  97       llvm::DenseMap<lldb::tid_t, std::vector<IntelPTThreadContinousExecution>>>
  98       m_continuous_executions_per_thread;
  99   llvm::DenseMap<lldb::tid_t, DecodedThreadSP> m_decoded_threads;
 100   /// This variable will not be std::nullopt if a severe error happened during
 101   /// the setup of the decoder and we don't want decoding to be reattempted.
 102   std::optional<std::string> m_setup_error;
 103   uint64_t m_unattributed_psb_blocks = 0;
 104   uint64_t m_total_psb_blocks = 0;
 105 };
 106
 107 } // namespace trace_intel_pt
 108 } // namespace lldb_private
 109
 110 #endif // LLDB_SOURCE_PLUGINS_TRACE_INTEL_PT_TRACEINTELPTMULTICPUDECODER_H