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//===-- Use.cpp - Implement the Use class ---------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the algorithm for finding the User of a Use.
//
//===----------------------------------------------------------------------===//
#include "llvm/User.h"
namespace llvm {
//===----------------------------------------------------------------------===//
// Use swap Implementation
//===----------------------------------------------------------------------===//
void Use::swap(Use &RHS) {
Value *V1(Val);
Value *V2(RHS.Val);
if (V1 != V2) {
if (V1) {
removeFromList();
}
if (V2) {
RHS.removeFromList();
Val = V2;
V2->addUse(*this);
} else {
Val = 0;
}
if (V1) {
RHS.Val = V1;
V1->addUse(RHS);
} else {
RHS.Val = 0;
}
}
}
//===----------------------------------------------------------------------===//
// Use getImpliedUser Implementation
//===----------------------------------------------------------------------===//
const Use *Use::getImpliedUser() const {
const Use *Current = this;
while (true) {
unsigned Tag = (Current++)->Prev.getInt();
switch (Tag) {
case zeroDigitTag:
case oneDigitTag:
continue;
case stopTag: {
++Current;
ptrdiff_t Offset = 1;
while (true) {
unsigned Tag = Current->Prev.getInt();
switch (Tag) {
case zeroDigitTag:
case oneDigitTag:
++Current;
Offset = (Offset << 1) + Tag;
continue;
default:
return Current + Offset;
}
}
}
case fullStopTag:
return Current;
}
}
}
//===----------------------------------------------------------------------===//
// Use initTags Implementation
//===----------------------------------------------------------------------===//
Use *Use::initTags(Use * const Start, Use *Stop, ptrdiff_t Done) {
while (Done < 20) {
if (Start == Stop--)
return Start;
static const PrevPtrTag tags[20] = { fullStopTag, oneDigitTag, stopTag,
oneDigitTag, oneDigitTag, stopTag,
zeroDigitTag, oneDigitTag, oneDigitTag,
stopTag, zeroDigitTag, oneDigitTag,
zeroDigitTag, oneDigitTag, stopTag,
oneDigitTag, oneDigitTag, oneDigitTag,
oneDigitTag, stopTag
};
Stop->Prev.setFromOpaqueValue(reinterpret_cast<Use**>(tags[Done++]));
Stop->Val = 0;
}
ptrdiff_t Count = Done;
while (Start != Stop) {
--Stop;
Stop->Val = 0;
if (!Count) {
Stop->Prev.setFromOpaqueValue(reinterpret_cast<Use**>(stopTag));
++Done;
Count = Done;
} else {
Stop->Prev.setFromOpaqueValue(reinterpret_cast<Use**>(Count & 1));
Count >>= 1;
++Done;
}
}
return Start;
}
//===----------------------------------------------------------------------===//
// Use zap Implementation
//===----------------------------------------------------------------------===//
void Use::zap(Use *Start, const Use *Stop, bool del) {
if (del) {
while (Start != Stop) {
(--Stop)->~Use();
}
::operator delete(Start);
return;
}
while (Start != Stop) {
(Start++)->set(0);
}
}
//===----------------------------------------------------------------------===//
// AugmentedUse layout struct
//===----------------------------------------------------------------------===//
struct AugmentedUse : public Use {
PointerIntPair<User*, 1, Tag> ref;
AugmentedUse(); // not implemented
};
//===----------------------------------------------------------------------===//
// Use getUser Implementation
//===----------------------------------------------------------------------===//
User *Use::getUser() const {
const Use *End = getImpliedUser();
const PointerIntPair<User*, 1, Tag>& ref(
static_cast<const AugmentedUse*>(End - 1)->ref);
User *She = ref.getPointer();
return ref.getInt()
? She
: (User*)End;
}
//===----------------------------------------------------------------------===//
// User allocHungoffUses Implementation
//===----------------------------------------------------------------------===//
Use *User::allocHungoffUses(unsigned N) const {
Use *Begin = static_cast<Use*>(::operator new(sizeof(Use) * N
+ sizeof(AugmentedUse)
- sizeof(Use)));
Use *End = Begin + N;
PointerIntPair<User*, 1, Tag>& ref(static_cast<AugmentedUse&>(End[-1]).ref);
ref.setPointer(const_cast<User*>(this));
ref.setInt(tagOne);
return Use::initTags(Begin, End);
}
//===----------------------------------------------------------------------===//
// User operator new Implementations
//===----------------------------------------------------------------------===//
void *User::operator new(size_t s, unsigned Us) {
void *Storage = ::operator new(s + sizeof(Use) * Us);
Use *Start = static_cast<Use*>(Storage);
Use *End = Start + Us;
User *Obj = reinterpret_cast<User*>(End);
Obj->OperandList = Start;
Obj->NumOperands = Us;
Use::initTags(Start, End);
return Obj;
}
/// Prefixed allocation - just before the first Use, allocate a NULL pointer.
/// The destructor can detect its presence and readjust the OperandList
/// for deletition.
///
void *User::operator new(size_t s, unsigned Us, bool Prefix) {
// currently prefixed allocation only admissible for
// unconditional branch instructions
if (!Prefix)
return operator new(s, Us);
assert(Us == 1 && "Other than one Use allocated?");
typedef PointerIntPair<void*, 2, Use::PrevPtrTag> TaggedPrefix;
void *Raw = ::operator new(s + sizeof(TaggedPrefix) + sizeof(Use) * Us);
TaggedPrefix *Pre = static_cast<TaggedPrefix*>(Raw);
Pre->setFromOpaqueValue(0);
void *Storage = Pre + 1; // skip over prefix
Use *Start = static_cast<Use*>(Storage);
Use *End = Start + Us;
User *Obj = reinterpret_cast<User*>(End);
Obj->OperandList = Start;
Obj->NumOperands = Us;
Use::initTags(Start, End);
return Obj;
}
//===----------------------------------------------------------------------===//
// User operator delete Implementation
//===----------------------------------------------------------------------===//
void User::operator delete(void *Usr) {
User *Start = static_cast<User*>(Usr);
Use *Storage = static_cast<Use*>(Usr) - Start->NumOperands;
//
// look for a variadic User
if (Storage == Start->OperandList) {
::operator delete(Storage);
return;
}
//
// check for the flag whether the destructor has detected a prefixed
// allocation, in which case we remove the flag and delete starting
// at OperandList
if (reinterpret_cast<intptr_t>(Start->OperandList) & 1) {
::operator delete(reinterpret_cast<char*>(Start->OperandList) - 1);
return;
}
//
// in all other cases just delete the nullary User (covers hung-off
// uses also
::operator delete(Usr);
}
} // End llvm namespace
|
