LLVM 20.0.0git
Discriminator.h
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1//===---- llvm/Support/Discriminator.h -- Discriminator Utils ---*- 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// This file defines the constants and utility functions for discriminators.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_SUPPORT_DISCRIMINATOR_H
14#define LLVM_SUPPORT_DISCRIMINATOR_H
15
16#include "llvm/Support/Error.h"
17#include <assert.h>
18
19// Utility functions for encoding / decoding discriminators.
20/// With a given unsigned int \p U, use up to 13 bits to represent it.
21/// old_bit 1~5 --> new_bit 1~5
22/// old_bit 6~12 --> new_bit 7~13
23/// new_bit_6 is 0 if higher bits (7~13) are all 0
24static inline unsigned getPrefixEncodingFromUnsigned(unsigned U) {
25 U &= 0xfff;
26 return U > 0x1f ? (((U & 0xfe0) << 1) | (U & 0x1f) | 0x20) : U;
27}
28
29/// Reverse transformation as getPrefixEncodingFromUnsigned.
30static inline unsigned getUnsignedFromPrefixEncoding(unsigned U) {
31 if (U & 1)
32 return 0;
33 U >>= 1;
34 return (U & 0x20) ? (((U >> 1) & 0xfe0) | (U & 0x1f)) : (U & 0x1f);
35}
36
37/// Returns the next component stored in discriminator.
38static inline unsigned getNextComponentInDiscriminator(unsigned D) {
39 if ((D & 1) == 0)
40 return D >> ((D & 0x40) ? 14 : 7);
41 else
42 return D >> 1;
43}
44
45static inline unsigned encodeComponent(unsigned C) {
46 return (C == 0) ? 1U : (getPrefixEncodingFromUnsigned(C) << 1);
47}
48
49static inline unsigned encodingBits(unsigned C) {
50 return (C == 0) ? 1 : (C > 0x1f ? 14 : 7);
51}
52
53// Some constants used in FS Discriminators.
54//
55namespace llvm {
56namespace sampleprof {
58 Base = 0,
59 Pass0 = 0,
60 Pass1 = 1,
61 Pass2 = 2,
62 Pass3 = 3,
63 Pass4 = 4,
65};
66} // namespace sampleprof
67
68// The number of bits reserved for the base discrimininator. The base
69// discriminaitor starts from bit 0.
70static const unsigned BaseDiscriminatorBitWidth = 8;
71
72// The number of bits reserved for each FS discriminator pass.
73static const unsigned FSDiscriminatorBitWidth = 6;
74
75// Return the number of FS passes, excluding the pass adding the base
76// discriminators.
77// The number of passes for FS discriminators. Note that the total
78// number of discriminaitor bits, i.e.
79// BaseDiscriminatorBitWidth
80// + FSDiscriminatorBitWidth * getNumFSPasses()
81// needs to fit in an unsigned int type.
82static inline unsigned getNumFSPasses() {
83 return static_cast<unsigned>(sampleprof::FSDiscriminatorPass::PassLast);
84}
85
86// Return the ending bit for FSPass P.
88 unsigned I = static_cast<unsigned>(P);
89 assert(I <= getNumFSPasses() && "Invalid FS discriminator pass number.");
91}
92
93// Return the begining bit for FSPass P.
96 return 0;
97 unsigned I = static_cast<unsigned>(P);
98 assert(I <= getNumFSPasses() && "Invalid FS discriminator pass number.");
99 return getFSPassBitEnd(static_cast<sampleprof::FSDiscriminatorPass>(I - 1)) +
100 1;
101}
102
103// Return the beginning bit for the last FSPass.
104static inline int getLastFSPassBitBegin() {
105 return getFSPassBitBegin(
107}
108
109// Return the ending bit for the last FSPass.
110static inline unsigned getLastFSPassBitEnd() {
111 return getFSPassBitEnd(
113}
114
115// Return the beginning bit for the base (first) FSPass.
116static inline unsigned getBaseFSBitBegin() { return 0; }
117
118// Return the ending bit for the base (first) FSPass.
119static inline unsigned getBaseFSBitEnd() {
120 return BaseDiscriminatorBitWidth - 1;
121}
122
123// Set bits in range of [0 .. n] to 1. Used in FS Discriminators.
124static inline unsigned getN1Bits(int N) {
125 // Work around the g++ bug that folding "(1U << (N + 1)) - 1" to 0.
126 if (N == 31)
127 return 0xFFFFFFFF;
128 assert((N < 32) && "N is invalid");
129 return (1U << (N + 1)) - 1;
130}
131
132} // namespace llvm
133
134#endif /* LLVM_SUPPORT_DISCRIMINATOR_H */
static GCRegistry::Add< ShadowStackGC > C("shadow-stack", "Very portable GC for uncooperative code generators")
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
static unsigned getPrefixEncodingFromUnsigned(unsigned U)
With a given unsigned int U, use up to 13 bits to represent it.
Definition: Discriminator.h:24
static unsigned encodingBits(unsigned C)
Definition: Discriminator.h:49
static unsigned encodeComponent(unsigned C)
Definition: Discriminator.h:45
static unsigned getNextComponentInDiscriminator(unsigned D)
Returns the next component stored in discriminator.
Definition: Discriminator.h:38
static unsigned getUnsignedFromPrefixEncoding(unsigned U)
Reverse transformation as getPrefixEncodingFromUnsigned.
Definition: Discriminator.h:30
#define I(x, y, z)
Definition: MD5.cpp:58
#define P(N)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
static int getLastFSPassBitBegin()
static unsigned getFSPassBitBegin(sampleprof::FSDiscriminatorPass P)
Definition: Discriminator.h:94
static unsigned getNumFSPasses()
Definition: Discriminator.h:82
static unsigned getBaseFSBitBegin()
static unsigned getFSPassBitEnd(sampleprof::FSDiscriminatorPass P)
Definition: Discriminator.h:87
static unsigned getBaseFSBitEnd()
static unsigned getN1Bits(int N)
static unsigned getLastFSPassBitEnd()
static const unsigned FSDiscriminatorBitWidth
Definition: Discriminator.h:73
static const unsigned BaseDiscriminatorBitWidth
Definition: Discriminator.h:70
#define N