blob: 129ffb3d163783925931c8e2b681784be2468411 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
|
//===--------------------- BottleneckAnalysis.h -----------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file implements the bottleneck analysis view.
///
/// This view internally observes backend pressure increase events in order to
/// identify potential sources of bottlenecks.
///
/// Example of bottleneck analysis report:
///
/// Cycles with backend pressure increase [ 33.40% ]
/// Throughput Bottlenecks:
/// Resource Pressure [ 0.52% ]
/// - JLAGU [ 0.52% ]
/// Data Dependencies: [ 32.88% ]
/// - Register Dependencies [ 32.88% ]
/// - Memory Dependencies [ 0.00% ]
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_MCA_BOTTLENECK_ANALYSIS_H
#define LLVM_TOOLS_LLVM_MCA_BOTTLENECK_ANALYSIS_H
#include "Views/View.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/MC/MCSchedule.h"
#include "llvm/Support/raw_ostream.h"
namespace llvm {
namespace mca {
/// A view that collects and prints a few performance numbers.
class BottleneckAnalysis : public View {
const llvm::MCSchedModel &SM;
unsigned TotalCycles;
struct BackPressureInfo {
// Cycles where backpressure increased.
unsigned PressureIncreaseCycles;
// Cycles where backpressure increased because of pipeline pressure.
unsigned ResourcePressureCycles;
// Cycles where backpressure increased because of data dependencies.
unsigned DataDependencyCycles;
// Cycles where backpressure increased because of register dependencies.
unsigned RegisterDependencyCycles;
// Cycles where backpressure increased because of memory dependencies.
unsigned MemoryDependencyCycles;
};
BackPressureInfo BPI;
// Resource pressure distribution. There is an element for every processor
// resource declared by the scheduling model. Quantities are number of cycles.
llvm::SmallVector<unsigned, 8> ResourcePressureDistribution;
// Each processor resource is associated with a so-called processor resource
// mask. This vector allows to correlate processor resource IDs with processor
// resource masks. There is exactly one element per each processor resource
// declared by the scheduling model.
llvm::SmallVector<uint64_t, 8> ProcResourceMasks;
// Used to map resource indices to actual processor resource IDs.
llvm::SmallVector<unsigned, 8> ResIdx2ProcResID;
// True if resource pressure events were notified during this cycle.
bool PressureIncreasedBecauseOfResources;
bool PressureIncreasedBecauseOfDataDependencies;
// True if throughput was affected by dispatch stalls.
bool SeenStallCycles;
// Prints a bottleneck message to OS.
void printBottleneckHints(llvm::raw_ostream &OS) const;
public:
BottleneckAnalysis(const llvm::MCSchedModel &Model);
void onCycleEnd() override {
++TotalCycles;
if (PressureIncreasedBecauseOfResources ||
PressureIncreasedBecauseOfDataDependencies) {
++BPI.PressureIncreaseCycles;
if (PressureIncreasedBecauseOfDataDependencies)
++BPI.DataDependencyCycles;
PressureIncreasedBecauseOfResources = false;
PressureIncreasedBecauseOfDataDependencies = false;
}
}
void onEvent(const HWStallEvent &Event) override { SeenStallCycles = true; }
void onEvent(const HWPressureEvent &Event) override;
void printView(llvm::raw_ostream &OS) const override;
};
} // namespace mca
} // namespace llvm
#endif
|
