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
18namespace lldb_private {
19namespace 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.
32class TraceIntelPTMultiCpuDecoder {
33public:
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
76private:
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
111

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