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
140
141
142
143
| //===- CmpInstAnalysis.cpp - Utils to help fold compares ---------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file holds routines to help analyse compare instructions
// and fold them into constants or other compare instructions
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/CmpInstAnalysis.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/PatternMatch.h"
using namespace llvm;
unsigned llvm::getICmpCode(const ICmpInst *ICI, bool InvertPred) {
ICmpInst::Predicate Pred = InvertPred ? ICI->getInversePredicate()
: ICI->getPredicate();
switch (Pred) {
// False -> 0
case ICmpInst::ICMP_UGT: return 1; // 001
case ICmpInst::ICMP_SGT: return 1; // 001
case ICmpInst::ICMP_EQ: return 2; // 010
case ICmpInst::ICMP_UGE: return 3; // 011
case ICmpInst::ICMP_SGE: return 3; // 011
case ICmpInst::ICMP_ULT: return 4; // 100
case ICmpInst::ICMP_SLT: return 4; // 100
case ICmpInst::ICMP_NE: return 5; // 101
case ICmpInst::ICMP_ULE: return 6; // 110
case ICmpInst::ICMP_SLE: return 6; // 110
// True -> 7
default:
llvm_unreachable("Invalid ICmp predicate!");
}
}
Constant *llvm::getPredForICmpCode(unsigned Code, bool Sign, Type *OpTy,
CmpInst::Predicate &Pred) {
switch (Code) {
default: llvm_unreachable("Illegal ICmp code!");
case 0: // False.
return ConstantInt::get(CmpInst::makeCmpResultType(OpTy), 0);
case 1: Pred = Sign ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; break;
case 2: Pred = ICmpInst::ICMP_EQ; break;
case 3: Pred = Sign ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; break;
case 4: Pred = Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; break;
case 5: Pred = ICmpInst::ICMP_NE; break;
case 6: Pred = Sign ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; break;
case 7: // True.
return ConstantInt::get(CmpInst::makeCmpResultType(OpTy), 1);
}
return nullptr;
}
bool llvm::predicatesFoldable(ICmpInst::Predicate P1, ICmpInst::Predicate P2) {
return (CmpInst::isSigned(P1) == CmpInst::isSigned(P2)) ||
(CmpInst::isSigned(P1) && ICmpInst::isEquality(P2)) ||
(CmpInst::isSigned(P2) && ICmpInst::isEquality(P1));
}
bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
CmpInst::Predicate &Pred,
Value *&X, APInt &Mask, bool LookThruTrunc) {
using namespace PatternMatch;
const APInt *C;
if (!match(RHS, m_APInt(C)))
return false;
switch (Pred) {
default:
return false;
case ICmpInst::ICMP_SLT:
// X < 0 is equivalent to (X & SignMask) != 0.
if (!C->isNullValue())
return false;
Mask = APInt::getSignMask(C->getBitWidth());
Pred = ICmpInst::ICMP_NE;
break;
case ICmpInst::ICMP_SLE:
// X <= -1 is equivalent to (X & SignMask) != 0.
if (!C->isAllOnesValue())
return false;
Mask = APInt::getSignMask(C->getBitWidth());
Pred = ICmpInst::ICMP_NE;
break;
case ICmpInst::ICMP_SGT:
// X > -1 is equivalent to (X & SignMask) == 0.
if (!C->isAllOnesValue())
return false;
Mask = APInt::getSignMask(C->getBitWidth());
Pred = ICmpInst::ICMP_EQ;
break;
case ICmpInst::ICMP_SGE:
// X >= 0 is equivalent to (X & SignMask) == 0.
if (!C->isNullValue())
return false;
Mask = APInt::getSignMask(C->getBitWidth());
Pred = ICmpInst::ICMP_EQ;
break;
case ICmpInst::ICMP_ULT:
// X <u 2^n is equivalent to (X & ~(2^n-1)) == 0.
if (!C->isPowerOf2())
return false;
Mask = -*C;
Pred = ICmpInst::ICMP_EQ;
break;
case ICmpInst::ICMP_ULE:
// X <=u 2^n-1 is equivalent to (X & ~(2^n-1)) == 0.
if (!(*C + 1).isPowerOf2())
return false;
Mask = ~*C;
Pred = ICmpInst::ICMP_EQ;
break;
case ICmpInst::ICMP_UGT:
// X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
if (!(*C + 1).isPowerOf2())
return false;
Mask = ~*C;
Pred = ICmpInst::ICMP_NE;
break;
case ICmpInst::ICMP_UGE:
// X >=u 2^n is equivalent to (X & ~(2^n-1)) != 0.
if (!C->isPowerOf2())
return false;
Mask = -*C;
Pred = ICmpInst::ICMP_NE;
break;
}
if (LookThruTrunc && match(LHS, m_Trunc(m_Value(X)))) {
Mask = Mask.zext(X->getType()->getScalarSizeInBits());
} else {
X = LHS;
}
return true;
}
|