146 lines
4.0 KiB
C++
146 lines
4.0 KiB
C++
//===-- Use.cpp - Implement the Use class ---------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the algorithm for finding the User of a Use.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Value.h"
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#include <new>
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namespace llvm {
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//===----------------------------------------------------------------------===//
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// Use swap Implementation
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//===----------------------------------------------------------------------===//
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void Use::swap(Use &RHS) {
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Value *V1(Val);
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Value *V2(RHS.Val);
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if (V1 != V2) {
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if (V1) {
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removeFromList();
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}
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if (V2) {
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RHS.removeFromList();
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Val = V2;
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V2->addUse(*this);
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} else {
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Val = 0;
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}
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if (V1) {
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RHS.Val = V1;
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V1->addUse(RHS);
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} else {
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RHS.Val = 0;
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}
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}
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}
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//===----------------------------------------------------------------------===//
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// Use getImpliedUser Implementation
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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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//===----------------------------------------------------------------------===//
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// Use initTags Implementation
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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] = { fullStopTag, oneDigitTag, stopTag,
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oneDigitTag, oneDigitTag, stopTag,
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zeroDigitTag, oneDigitTag, oneDigitTag,
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stopTag, zeroDigitTag, oneDigitTag,
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zeroDigitTag, oneDigitTag, stopTag,
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oneDigitTag, oneDigitTag, oneDigitTag,
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oneDigitTag, stopTag
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};
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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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//===----------------------------------------------------------------------===//
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// Use zap Implementation
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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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//===----------------------------------------------------------------------===//
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// Use getUser Implementation
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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()
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? ref->getPointer()
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: (User*)End;
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}
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} // End llvm namespace
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