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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
127 lines
2.9 KiB
C++
127 lines
2.9 KiB
C++
//===-- Use.cpp - Implement the Use class ---------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/IR/Use.h"
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#include "llvm/IR/User.h"
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#include "llvm/IR/Value.h"
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#include <new>
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namespace llvm {
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void Use::swap(Use &RHS) {
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if (Val == RHS.Val)
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return;
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if (Val)
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removeFromList();
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Value *OldVal = Val;
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if (RHS.Val) {
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RHS.removeFromList();
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Val = RHS.Val;
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Val->addUse(*this);
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} else {
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Val = nullptr;
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}
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if (OldVal) {
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RHS.Val = OldVal;
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RHS.Val->addUse(RHS);
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} else {
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RHS.Val = nullptr;
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}
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}
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User *Use::getUser() const {
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const Use *End = getImpliedUser();
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const UserRef *ref = reinterpret_cast<const UserRef *>(End);
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return ref->getInt() ? ref->getPointer()
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: reinterpret_cast<User *>(const_cast<Use *>(End));
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}
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unsigned Use::getOperandNo() const {
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return this - getUser()->op_begin();
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}
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// Sets up the waymarking algorithm's tags for a series of Uses. See the
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// algorithm details here:
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//
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// http://www.llvm.org/docs/ProgrammersManual.html#the-waymarking-algorithm
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//
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Use *Use::initTags(Use *const Start, Use *Stop) {
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ptrdiff_t Done = 0;
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while (Done < 20) {
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if (Start == Stop--)
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return Start;
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static const PrevPtrTag tags[20] = {
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fullStopTag, oneDigitTag, stopTag, oneDigitTag, oneDigitTag,
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stopTag, zeroDigitTag, oneDigitTag, oneDigitTag, stopTag,
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zeroDigitTag, oneDigitTag, zeroDigitTag, oneDigitTag, stopTag,
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oneDigitTag, oneDigitTag, oneDigitTag, oneDigitTag, stopTag};
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new (Stop) Use(tags[Done++]);
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}
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ptrdiff_t Count = Done;
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while (Start != Stop) {
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--Stop;
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if (!Count) {
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new (Stop) Use(stopTag);
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++Done;
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Count = Done;
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} else {
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new (Stop) Use(PrevPtrTag(Count & 1));
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Count >>= 1;
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++Done;
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}
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}
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return Start;
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}
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void Use::zap(Use *Start, const Use *Stop, bool del) {
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while (Start != Stop)
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(--Stop)->~Use();
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if (del)
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::operator delete(Start);
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}
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const Use *Use::getImpliedUser() const {
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const Use *Current = this;
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while (true) {
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unsigned Tag = (Current++)->Prev.getInt();
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switch (Tag) {
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case zeroDigitTag:
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case oneDigitTag:
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continue;
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case stopTag: {
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++Current;
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ptrdiff_t Offset = 1;
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while (true) {
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unsigned Tag = Current->Prev.getInt();
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switch (Tag) {
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case zeroDigitTag:
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case oneDigitTag:
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++Current;
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Offset = (Offset << 1) + Tag;
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continue;
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default:
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return Current + Offset;
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}
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}
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}
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case fullStopTag:
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return Current;
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}
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}
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}
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} // End llvm namespace
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