LLVM 20.0.0git
CodeLayout.h
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1//===- CodeLayout.h - Code layout/placement algorithms ---------*- 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/// \file
10/// Declares methods and data structures for code layout algorithms.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_TRANSFORMS_UTILS_CODELAYOUT_H
15#define LLVM_TRANSFORMS_UTILS_CODELAYOUT_H
16
17#include "llvm/ADT/ArrayRef.h"
18
19#include <utility>
20#include <vector>
21
23
24using EdgeT = std::pair<uint64_t, uint64_t>;
25
26struct EdgeCount {
30};
31
32/// Find a layout of nodes (basic blocks) of a given CFG optimizing jump
33/// locality and thus processor I-cache utilization. This is achieved via
34/// increasing the number of fall-through jumps and co-locating frequently
35/// executed nodes together.
36/// The nodes are assumed to be indexed by integers from [0, |V|) so that the
37/// current order is the identity permutation.
38/// \p NodeSizes: The sizes of the nodes (in bytes).
39/// \p NodeCounts: The execution counts of the nodes in the profile.
40/// \p EdgeCounts: The execution counts of every edge (jump) in the profile. The
41/// map also defines the edges in CFG and should include 0-count edges.
42/// \returns The best block order found.
43std::vector<uint64_t> computeExtTspLayout(ArrayRef<uint64_t> NodeSizes,
44 ArrayRef<uint64_t> NodeCounts,
45 ArrayRef<EdgeCount> EdgeCounts);
46
47/// Estimate the "quality" of a given node order in CFG. The higher the score,
48/// the better the order is. The score is designed to reflect the locality of
49/// the given order, which is anti-correlated with the number of I-cache misses
50/// in a typical execution of the function.
52 ArrayRef<uint64_t> NodeCounts,
53 ArrayRef<EdgeCount> EdgeCounts);
54
55/// Estimate the "quality" of the current node order in CFG.
56double calcExtTspScore(ArrayRef<uint64_t> NodeSizes,
57 ArrayRef<uint64_t> NodeCounts,
58 ArrayRef<EdgeCount> EdgeCounts);
59
60/// Algorithm-specific params for Cache-Directed Sort. The values are tuned for
61/// the best performance of large-scale front-end bound binaries.
63 /// The size of the cache.
64 unsigned CacheEntries = 16;
65 /// The size of a line in the cache.
66 unsigned CacheSize = 2048;
67 /// The maximum size of a chain to create.
68 unsigned MaxChainSize = 128;
69 /// The power exponent for the distance-based locality.
70 double DistancePower = 0.25;
71 /// The scale factor for the frequency-based locality.
72 double FrequencyScale = 0.25;
73};
74
75/// Apply a Cache-Directed Sort for functions represented by a call graph.
76/// The placement is done by optimizing the call locality by co-locating
77/// frequently executed functions.
78/// \p FuncSizes: The sizes of the nodes (in bytes).
79/// \p FuncCounts: The execution counts of the nodes in the profile.
80/// \p CallCounts: The execution counts of every edge (jump) in the profile. The
81/// map also defines the edges in CFG and should include 0-count edges.
82/// \p CallOffsets: The offsets of the calls from their source nodes.
83/// \returns The best function order found.
84std::vector<uint64_t> computeCacheDirectedLayout(
85 ArrayRef<uint64_t> FuncSizes, ArrayRef<uint64_t> FuncCounts,
86 ArrayRef<EdgeCount> CallCounts, ArrayRef<uint64_t> CallOffsets);
87
88/// Apply a Cache-Directed Sort with a custom config.
89std::vector<uint64_t> computeCacheDirectedLayout(
90 const CDSortConfig &Config, ArrayRef<uint64_t> FuncSizes,
91 ArrayRef<uint64_t> FuncCounts, ArrayRef<EdgeCount> CallCounts,
92 ArrayRef<uint64_t> CallOffsets);
93
94} // namespace llvm::codelayout
95
96#endif // LLVM_TRANSFORMS_UTILS_CODELAYOUT_H
RelaxConfig Config
Definition: ELF_riscv.cpp:506
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: ArrayRef.h:41
std::vector< uint64_t > computeCacheDirectedLayout(ArrayRef< uint64_t > FuncSizes, ArrayRef< uint64_t > FuncCounts, ArrayRef< EdgeCount > CallCounts, ArrayRef< uint64_t > CallOffsets)
Apply a Cache-Directed Sort for functions represented by a call graph.
double calcExtTspScore(ArrayRef< uint64_t > Order, ArrayRef< uint64_t > NodeSizes, ArrayRef< uint64_t > NodeCounts, ArrayRef< EdgeCount > EdgeCounts)
Estimate the "quality" of a given node order in CFG.
std::pair< uint64_t, uint64_t > EdgeT
Definition: CodeLayout.h:24
std::vector< uint64_t > computeExtTspLayout(ArrayRef< uint64_t > NodeSizes, ArrayRef< uint64_t > NodeCounts, ArrayRef< EdgeCount > EdgeCounts)
Find a layout of nodes (basic blocks) of a given CFG optimizing jump locality and thus processor I-ca...
Algorithm-specific params for Cache-Directed Sort.
Definition: CodeLayout.h:62
unsigned MaxChainSize
The maximum size of a chain to create.
Definition: CodeLayout.h:68
unsigned CacheSize
The size of a line in the cache.
Definition: CodeLayout.h:66
double DistancePower
The power exponent for the distance-based locality.
Definition: CodeLayout.h:70
double FrequencyScale
The scale factor for the frequency-based locality.
Definition: CodeLayout.h:72
unsigned CacheEntries
The size of the cache.
Definition: CodeLayout.h:64