1 //===-- Use.cpp - Implement the Use class ---------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 #include "llvm/IR/Use.h"
10 #include "llvm/IR/User.h"
11 #include "llvm/IR/Value.h"
16 void Use::swap(Use &RHS) {
40 User *Use::getUser() const {
41 const Use *End = getImpliedUser();
42 const UserRef *ref = reinterpret_cast<const UserRef *>(End);
43 return ref->getInt() ? ref->getPointer()
44 : reinterpret_cast<User *>(const_cast<Use *>(End));
47 unsigned Use::getOperandNo() const {
48 return this - getUser()->op_begin();
51 // Sets up the waymarking algorithm's tags for a series of Uses. See the
52 // algorithm details here:
54 // http://www.llvm.org/docs/ProgrammersManual.html#the-waymarking-algorithm
56 Use *Use::initTags(Use *const Start, Use *Stop) {
61 static const PrevPtrTag tags[20] = {
62 fullStopTag, oneDigitTag, stopTag, oneDigitTag, oneDigitTag,
63 stopTag, zeroDigitTag, oneDigitTag, oneDigitTag, stopTag,
64 zeroDigitTag, oneDigitTag, zeroDigitTag, oneDigitTag, stopTag,
65 oneDigitTag, oneDigitTag, oneDigitTag, oneDigitTag, stopTag};
66 new (Stop) Use(tags[Done++]);
69 ptrdiff_t Count = Done;
70 while (Start != Stop) {
73 new (Stop) Use(stopTag);
77 new (Stop) Use(PrevPtrTag(Count & 1));
86 void Use::zap(Use *Start, const Use *Stop, bool del) {
90 ::operator delete(Start);
93 const Use *Use::getImpliedUser() const {
94 const Use *Current = this;
97 unsigned Tag = (Current++)->Prev.getInt();
105 ptrdiff_t Offset = 1;
107 unsigned Tag = Current->Prev.getInt();
112 Offset = (Offset << 1) + Tag;
115 return Current + Offset;
126 } // End llvm namespace