1 //===- ValueLattice.cpp - Value constraint analysis -------------*- 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 #include "llvm/Analysis/ValueLattice.h"
10 #include "llvm/Analysis/ConstantFolding.h"
11
12 namespace llvm {
13 Constant *
getCompare(CmpInst::Predicate Pred,Type * Ty,const ValueLatticeElement & Other,const DataLayout & DL) const14 ValueLatticeElement::getCompare(CmpInst::Predicate Pred, Type *Ty,
15 const ValueLatticeElement &Other,
16 const DataLayout &DL) const {
17 // Not yet resolved.
18 if (isUnknown() || Other.isUnknown())
19 return nullptr;
20
21 // TODO: Can be made more precise, but always returning undef would be
22 // incorrect.
23 if (isUndef() || Other.isUndef())
24 return nullptr;
25
26 if (isConstant() && Other.isConstant())
27 return ConstantFoldCompareInstOperands(Pred, getConstant(),
28 Other.getConstant(), DL);
29
30 if (ICmpInst::isEquality(Pred)) {
31 // not(C) != C => true, not(C) == C => false.
32 if ((isNotConstant() && Other.isConstant() &&
33 getNotConstant() == Other.getConstant()) ||
34 (isConstant() && Other.isNotConstant() &&
35 getConstant() == Other.getNotConstant()))
36 return Pred == ICmpInst::ICMP_NE ? ConstantInt::getTrue(Ty)
37 : ConstantInt::getFalse(Ty);
38 }
39
40 // Integer constants are represented as ConstantRanges with single
41 // elements.
42 if (!isConstantRange() || !Other.isConstantRange())
43 return nullptr;
44
45 const auto &CR = getConstantRange();
46 const auto &OtherCR = Other.getConstantRange();
47 if (CR.icmp(Pred, OtherCR))
48 return ConstantInt::getTrue(Ty);
49 if (CR.icmp(CmpInst::getInversePredicate(Pred), OtherCR))
50 return ConstantInt::getFalse(Ty);
51
52 return nullptr;
53 }
54
operator <<(raw_ostream & OS,const ValueLatticeElement & Val)55 raw_ostream &operator<<(raw_ostream &OS, const ValueLatticeElement &Val) {
56 if (Val.isUnknown())
57 return OS << "unknown";
58 if (Val.isUndef())
59 return OS << "undef";
60 if (Val.isOverdefined())
61 return OS << "overdefined";
62
63 if (Val.isNotConstant())
64 return OS << "notconstant<" << *Val.getNotConstant() << ">";
65
66 if (Val.isConstantRangeIncludingUndef())
67 return OS << "constantrange incl. undef <"
68 << Val.getConstantRange(true).getLower() << ", "
69 << Val.getConstantRange(true).getUpper() << ">";
70
71 if (Val.isConstantRange())
72 return OS << "constantrange<" << Val.getConstantRange().getLower() << ", "
73 << Val.getConstantRange().getUpper() << ">";
74 return OS << "constant<" << *Val.getConstant() << ">";
75 }
76 } // end namespace llvm
77