Mercurial > hg > CbC > CbC_llvm

comparison llvm/lib/Analysis/CmpInstAnalysis.cpp @ 150:1d019706d866

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
LLVM10
author anatofuz
date Thu, 13 Feb 2020 15:10:13 +0900
parents
children c4bab56944e8
comparison
equal deleted inserted replaced
147:c2174574ed3a 150:1d019706d866
1 //===- CmpInstAnalysis.cpp - Utils to help fold compares ---------------===//
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 holds routines to help analyse compare instructions
10 // and fold them into constants or other compare instructions
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/Analysis/CmpInstAnalysis.h"
15 #include "llvm/IR/Constants.h"
16 #include "llvm/IR/Instructions.h"
17 #include "llvm/IR/PatternMatch.h"
18
19 using namespace llvm;
20
21 unsigned llvm::getICmpCode(const ICmpInst *ICI, bool InvertPred) {
22 ICmpInst::Predicate Pred = InvertPred ? ICI->getInversePredicate()
23 : ICI->getPredicate();
24 switch (Pred) {
25 // False -> 0
26 case ICmpInst::ICMP_UGT: return 1; // 001
27 case ICmpInst::ICMP_SGT: return 1; // 001
28 case ICmpInst::ICMP_EQ: return 2; // 010
29 case ICmpInst::ICMP_UGE: return 3; // 011
30 case ICmpInst::ICMP_SGE: return 3; // 011
31 case ICmpInst::ICMP_ULT: return 4; // 100
32 case ICmpInst::ICMP_SLT: return 4; // 100
33 case ICmpInst::ICMP_NE: return 5; // 101
34 case ICmpInst::ICMP_ULE: return 6; // 110
35 case ICmpInst::ICMP_SLE: return 6; // 110
36 // True -> 7
37 default:
38 llvm_unreachable("Invalid ICmp predicate!");
39 }
40 }
41
42 Constant *llvm::getPredForICmpCode(unsigned Code, bool Sign, Type *OpTy,
43 CmpInst::Predicate &Pred) {
44 switch (Code) {
45 default: llvm_unreachable("Illegal ICmp code!");
46 case 0: // False.
47 return ConstantInt::get(CmpInst::makeCmpResultType(OpTy), 0);
48 case 1: Pred = Sign ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; break;
49 case 2: Pred = ICmpInst::ICMP_EQ; break;
50 case 3: Pred = Sign ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; break;
51 case 4: Pred = Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; break;
52 case 5: Pred = ICmpInst::ICMP_NE; break;
53 case 6: Pred = Sign ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; break;
54 case 7: // True.
55 return ConstantInt::get(CmpInst::makeCmpResultType(OpTy), 1);
56 }
57 return nullptr;
58 }
59
60 bool llvm::predicatesFoldable(ICmpInst::Predicate P1, ICmpInst::Predicate P2) {
61 return (CmpInst::isSigned(P1) == CmpInst::isSigned(P2)) ||
62 (CmpInst::isSigned(P1) && ICmpInst::isEquality(P2)) ||
63 (CmpInst::isSigned(P2) && ICmpInst::isEquality(P1));
64 }
65
66 bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
67 CmpInst::Predicate &Pred,
68 Value *&X, APInt &Mask, bool LookThruTrunc) {
69 using namespace PatternMatch;
70
71 const APInt *C;
72 if (!match(RHS, m_APInt(C)))
73 return false;
74
75 switch (Pred) {
76 default:
77 return false;
78 case ICmpInst::ICMP_SLT:
79 // X < 0 is equivalent to (X & SignMask) != 0.
80 if (!C->isNullValue())
81 return false;
82 Mask = APInt::getSignMask(C->getBitWidth());
83 Pred = ICmpInst::ICMP_NE;
84 break;
85 case ICmpInst::ICMP_SLE:
86 // X <= -1 is equivalent to (X & SignMask) != 0.
87 if (!C->isAllOnesValue())
88 return false;
89 Mask = APInt::getSignMask(C->getBitWidth());
90 Pred = ICmpInst::ICMP_NE;
91 break;
92 case ICmpInst::ICMP_SGT:
93 // X > -1 is equivalent to (X & SignMask) == 0.
94 if (!C->isAllOnesValue())
95 return false;
96 Mask = APInt::getSignMask(C->getBitWidth());
97 Pred = ICmpInst::ICMP_EQ;
98 break;
99 case ICmpInst::ICMP_SGE:
100 // X >= 0 is equivalent to (X & SignMask) == 0.
101 if (!C->isNullValue())
102 return false;
103 Mask = APInt::getSignMask(C->getBitWidth());
104 Pred = ICmpInst::ICMP_EQ;
105 break;
106 case ICmpInst::ICMP_ULT:
107 // X <u 2^n is equivalent to (X & ~(2^n-1)) == 0.
108 if (!C->isPowerOf2())
109 return false;
110 Mask = -*C;
111 Pred = ICmpInst::ICMP_EQ;
112 break;
113 case ICmpInst::ICMP_ULE:
114 // X <=u 2^n-1 is equivalent to (X & ~(2^n-1)) == 0.
115 if (!(*C + 1).isPowerOf2())
116 return false;
117 Mask = ~*C;
118 Pred = ICmpInst::ICMP_EQ;
119 break;
120 case ICmpInst::ICMP_UGT:
121 // X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
122 if (!(*C + 1).isPowerOf2())
123 return false;
124 Mask = ~*C;
125 Pred = ICmpInst::ICMP_NE;
126 break;
127 case ICmpInst::ICMP_UGE:
128 // X >=u 2^n is equivalent to (X & ~(2^n-1)) != 0.
129 if (!C->isPowerOf2())
130 return false;
131 Mask = -*C;
132 Pred = ICmpInst::ICMP_NE;
133 break;
134 }
135
136 if (LookThruTrunc && match(LHS, m_Trunc(m_Value(X)))) {
137 Mask = Mask.zext(X->getType()->getScalarSizeInBits());
138 } else {
139 X = LHS;
140 }
141
142 return true;
143 }