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
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
//===--- PtrState.cpp -----------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "objc-arc-ptr-state"
#include "llvm/Support/Debug.h"
#include "PtrState.h"
using namespace llvm;
using namespace llvm::objcarc;
raw_ostream &llvm::objcarc::operator<<(raw_ostream &OS, const Sequence S) {
switch (S) {
case S_None:
return OS << "S_None";
case S_Retain:
return OS << "S_Retain";
case S_CanRelease:
return OS << "S_CanRelease";
case S_Use:
return OS << "S_Use";
case S_Release:
return OS << "S_Release";
case S_MovableRelease:
return OS << "S_MovableRelease";
case S_Stop:
return OS << "S_Stop";
}
llvm_unreachable("Unknown sequence type.");
}
static Sequence MergeSeqs(Sequence A, Sequence B, bool TopDown) {
// The easy cases.
if (A == B)
return A;
if (A == S_None || B == S_None)
return S_None;
if (A > B)
std::swap(A, B);
if (TopDown) {
// Choose the side which is further along in the sequence.
if ((A == S_Retain || A == S_CanRelease) &&
(B == S_CanRelease || B == S_Use))
return B;
} else {
// Choose the side which is further along in the sequence.
if ((A == S_Use || A == S_CanRelease) &&
(B == S_Use || B == S_Release || B == S_Stop || B == S_MovableRelease))
return A;
// If both sides are releases, choose the more conservative one.
if (A == S_Stop && (B == S_Release || B == S_MovableRelease))
return A;
if (A == S_Release && B == S_MovableRelease)
return A;
}
return S_None;
}
void RRInfo::clear() {
KnownSafe = false;
IsTailCallRelease = false;
ReleaseMetadata = nullptr;
Calls.clear();
ReverseInsertPts.clear();
CFGHazardAfflicted = false;
}
bool RRInfo::Merge(const RRInfo &Other) {
// Conservatively merge the ReleaseMetadata information.
if (ReleaseMetadata != Other.ReleaseMetadata)
ReleaseMetadata = nullptr;
// Conservatively merge the boolean state.
KnownSafe &= Other.KnownSafe;
IsTailCallRelease &= Other.IsTailCallRelease;
CFGHazardAfflicted |= Other.CFGHazardAfflicted;
// Merge the call sets.
Calls.insert(Other.Calls.begin(), Other.Calls.end());
// Merge the insert point sets. If there are any differences,
// that makes this a partial merge.
bool Partial = ReverseInsertPts.size() != Other.ReverseInsertPts.size();
for (Instruction *Inst : Other.ReverseInsertPts)
Partial |= ReverseInsertPts.insert(Inst).second;
return Partial;
}
void PtrState::SetKnownPositiveRefCount() {
DEBUG(dbgs() << "Setting Known Positive.\n");
KnownPositiveRefCount = true;
}
void PtrState::ClearKnownPositiveRefCount() {
DEBUG(dbgs() << "Clearing Known Positive.\n");
KnownPositiveRefCount = false;
}
void PtrState::SetSeq(Sequence NewSeq) {
DEBUG(dbgs() << "Old: " << Seq << "; New: " << NewSeq << "\n");
Seq = NewSeq;
}
void PtrState::ResetSequenceProgress(Sequence NewSeq) {
DEBUG(dbgs() << "Resetting sequence progress.\n");
SetSeq(NewSeq);
Partial = false;
RRI.clear();
}
void PtrState::Merge(const PtrState &Other, bool TopDown) {
Seq = MergeSeqs(GetSeq(), Other.GetSeq(), TopDown);
KnownPositiveRefCount &= Other.KnownPositiveRefCount;
// If we're not in a sequence (anymore), drop all associated state.
if (Seq == S_None) {
Partial = false;
RRI.clear();
} else if (Partial || Other.Partial) {
// If we're doing a merge on a path that's previously seen a partial
// merge, conservatively drop the sequence, to avoid doing partial
// RR elimination. If the branch predicates for the two merge differ,
// mixing them is unsafe.
ClearSequenceProgress();
} else {
// Otherwise merge the other PtrState's RRInfo into our RRInfo. At this
// point, we know that currently we are not partial. Stash whether or not
// the merge operation caused us to undergo a partial merging of reverse
// insertion points.
Partial = RRI.Merge(Other.RRI);
}
}
|
