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access each with a fixed negative index from op_end(). This has two important implications: - getUser() will work faster, because there are less iterations for the waymarking algorithm to perform. This is important when running various analyses that want to determine callers of basic blocks. - getSuccessor() now runs faster, because the indirection via OperandList is not necessary: Uses corresponding to the successors are at fixed offset to "this". The price we pay is the slightly more complicated logic in the operator User::delete, as it has to pick up the information whether it has to free the memory of an original unconditional BranchInst or a BranchInst that was originally conditional, but has been shortened to unconditional. I was not able to come up with a nicer solution to this problem. (And rest assured, I tried *a lot*). Similar reorderings will follow for InvokeInst and CallInst. After that some optimizations to pred_iterator and CallSite will fall out naturally. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66815 91177308-0d34-0410-b5e6-96231b3b80d8
234 lines
7.0 KiB
C++
234 lines
7.0 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/User.h"
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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, ptrdiff_t Done) {
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ptrdiff_t Count = Done;
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while (Start != Stop) {
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--Stop;
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Stop->Val = 0;
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if (!Count) {
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Stop->Prev.setFromOpaqueValue(reinterpret_cast<Use**>(Done == 0
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? fullStopTag
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: stopTag));
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++Done;
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Count = Done;
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} else {
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Stop->Prev.setFromOpaqueValue(reinterpret_cast<Use**>(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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if (del) {
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while (Start != Stop) {
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(--Stop)->~Use();
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}
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::operator delete(Start);
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return;
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}
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while (Start != Stop) {
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(Start++)->set(0);
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}
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}
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//===----------------------------------------------------------------------===//
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// AugmentedUse layout struct
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//===----------------------------------------------------------------------===//
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struct AugmentedUse : Use {
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PointerIntPair<User*, 1, Tag> ref;
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AugmentedUse(); // not implemented
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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 PointerIntPair<User*, 1, Tag>& ref(
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static_cast<const AugmentedUse*>(End - 1)->ref);
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User *She = ref.getPointer();
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return ref.getInt()
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? She
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: (User*)End;
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}
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//===----------------------------------------------------------------------===//
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// User allocHungoffUses Implementation
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//===----------------------------------------------------------------------===//
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Use *User::allocHungoffUses(unsigned N) const {
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Use *Begin = static_cast<Use*>(::operator new(sizeof(Use) * N
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+ sizeof(AugmentedUse)
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- sizeof(Use)));
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Use *End = Begin + N;
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PointerIntPair<User*, 1, Tag>& ref(static_cast<AugmentedUse&>(End[-1]).ref);
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ref.setPointer(const_cast<User*>(this));
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ref.setInt(tagOne);
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return Use::initTags(Begin, End);
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}
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//===----------------------------------------------------------------------===//
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// User operator new Implementations
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//===----------------------------------------------------------------------===//
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void *User::operator new(size_t s, unsigned Us) {
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void *Storage = ::operator new(s + sizeof(Use) * Us);
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Use *Start = static_cast<Use*>(Storage);
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Use *End = Start + Us;
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User *Obj = reinterpret_cast<User*>(End);
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Obj->OperandList = Start;
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Obj->NumOperands = Us;
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Use::initTags(Start, End);
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return Obj;
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}
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/// Prefixed allocation - just before the first Use, allocate a NULL pointer.
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/// The destructor can detect its presence and readjust the OperandList
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/// for deletition.
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///
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void *User::operator new(size_t s, unsigned Us, bool Prefix) {
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// currently prefixed allocation only admissible for
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// unconditional branch instructions
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if (!Prefix)
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return operator new(s, Us);
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assert(Us == 1 && "Other than one Use allocated?");
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typedef PointerIntPair<void*, 2, Use::PrevPtrTag> TaggedPrefix;
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void *Raw = ::operator new(s + sizeof(TaggedPrefix) + sizeof(Use) * Us);
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TaggedPrefix *Pre = static_cast<TaggedPrefix*>(Raw);
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Pre->setFromOpaqueValue(0);
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void *Storage = Pre + 1; // skip over prefix
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Use *Start = static_cast<Use*>(Storage);
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Use *End = Start + Us;
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User *Obj = reinterpret_cast<User*>(End);
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Obj->OperandList = Start;
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Obj->NumOperands = Us;
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Use::initTags(Start, End);
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return Obj;
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}
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//===----------------------------------------------------------------------===//
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// User operator delete Implementation
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//===----------------------------------------------------------------------===//
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void User::operator delete(void *Usr) {
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User *Start = static_cast<User*>(Usr);
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Use *Storage = static_cast<Use*>(Usr) - Start->NumOperands;
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//
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// look for a variadic User
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if (Storage == Start->OperandList) {
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::operator delete(Storage);
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return;
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}
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//
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// check for the flag whether the destructor has detected a prefixed
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// allocation, in which case we remove the flag and delete starting
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// at OperandList
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if (reinterpret_cast<intptr_t>(Start->OperandList) & 1) {
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::operator delete(reinterpret_cast<char*>(Start->OperandList) - 1);
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return;
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}
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//
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// in all other cases just delete the nullary User (covers hung-off
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// uses also
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::operator delete(Usr);
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}
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} // End llvm namespace
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