llvm-6502/include/llvm/ADT/SmallVector.h
Owen Anderson 747972914a Fix for PR3946, in which SmallVector could behave strangely in corner cases.
Patch by Peter Johnson.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69785 91177308-0d34-0410-b5e6-96231b3b80d8
2009-04-22 07:16:54 +00:00

610 lines
17 KiB
C++

//===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the SmallVector class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_SMALLVECTOR_H
#define LLVM_ADT_SMALLVECTOR_H
#include "llvm/ADT/iterator.h"
#include "llvm/Support/type_traits.h"
#include <algorithm>
#include <cassert>
#include <cstring>
#include <memory>
#ifdef _MSC_VER
namespace std {
#if _MSC_VER <= 1310
// Work around flawed VC++ implementation of std::uninitialized_copy. Define
// additional overloads so that elements with pointer types are recognized as
// scalars and not objects, causing bizarre type conversion errors.
template<class T1, class T2>
inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
_Scalar_ptr_iterator_tag _Cat;
return _Cat;
}
template<class T1, class T2>
inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
_Scalar_ptr_iterator_tag _Cat;
return _Cat;
}
#else
// FIXME: It is not clear if the problem is fixed in VS 2005. What is clear
// is that the above hack won't work if it wasn't fixed.
#endif
}
#endif
namespace llvm {
/// SmallVectorImpl - This class consists of common code factored out of the
/// SmallVector class to reduce code duplication based on the SmallVector 'N'
/// template parameter.
template <typename T>
class SmallVectorImpl {
protected:
T *Begin, *End, *Capacity;
// Allocate raw space for N elements of type T. If T has a ctor or dtor, we
// don't want it to be automatically run, so we need to represent the space as
// something else. An array of char would work great, but might not be
// aligned sufficiently. Instead, we either use GCC extensions, or some
// number of union instances for the space, which guarantee maximal alignment.
protected:
#ifdef __GNUC__
typedef char U;
U FirstEl __attribute__((aligned));
#else
union U {
double D;
long double LD;
long long L;
void *P;
} FirstEl;
#endif
// Space after 'FirstEl' is clobbered, do not add any instance vars after it.
public:
// Default ctor - Initialize to empty.
explicit SmallVectorImpl(unsigned N)
: Begin(reinterpret_cast<T*>(&FirstEl)),
End(reinterpret_cast<T*>(&FirstEl)),
Capacity(reinterpret_cast<T*>(&FirstEl)+N) {
}
~SmallVectorImpl() {
// Destroy the constructed elements in the vector.
destroy_range(Begin, End);
// If this wasn't grown from the inline copy, deallocate the old space.
if (!isSmall())
operator delete(Begin);
}
typedef size_t size_type;
typedef ptrdiff_t difference_type;
typedef T value_type;
typedef T* iterator;
typedef const T* const_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef T& reference;
typedef const T& const_reference;
typedef T* pointer;
typedef const T* const_pointer;
bool empty() const { return Begin == End; }
size_type size() const { return End-Begin; }
size_type max_size() const { return size_type(-1) / sizeof(T); }
// forward iterator creation methods.
iterator begin() { return Begin; }
const_iterator begin() const { return Begin; }
iterator end() { return End; }
const_iterator end() const { return End; }
// reverse iterator creation methods.
reverse_iterator rbegin() { return reverse_iterator(end()); }
const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
reverse_iterator rend() { return reverse_iterator(begin()); }
const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
/* These asserts could be "Begin + idx < End", but there are lots of places
in llvm where we use &v[v.size()] instead of v.end(). */
reference operator[](unsigned idx) {
assert (Begin + idx <= End);
return Begin[idx];
}
const_reference operator[](unsigned idx) const {
assert (Begin + idx <= End);
return Begin[idx];
}
reference front() {
return begin()[0];
}
const_reference front() const {
return begin()[0];
}
reference back() {
return end()[-1];
}
const_reference back() const {
return end()[-1];
}
void push_back(const_reference Elt) {
if (End < Capacity) {
Retry:
new (End) T(Elt);
++End;
return;
}
grow();
goto Retry;
}
void pop_back() {
--End;
End->~T();
}
T pop_back_val() {
T Result = back();
pop_back();
return Result;
}
void clear() {
destroy_range(Begin, End);
End = Begin;
}
void resize(unsigned N) {
if (N < size()) {
destroy_range(Begin+N, End);
End = Begin+N;
} else if (N > size()) {
if (unsigned(Capacity-Begin) < N)
grow(N);
construct_range(End, Begin+N, T());
End = Begin+N;
}
}
void resize(unsigned N, const T &NV) {
if (N < size()) {
destroy_range(Begin+N, End);
End = Begin+N;
} else if (N > size()) {
if (unsigned(Capacity-Begin) < N)
grow(N);
construct_range(End, Begin+N, NV);
End = Begin+N;
}
}
void reserve(unsigned N) {
if (unsigned(Capacity-Begin) < N)
grow(N);
}
void swap(SmallVectorImpl &RHS);
/// append - Add the specified range to the end of the SmallVector.
///
template<typename in_iter>
void append(in_iter in_start, in_iter in_end) {
size_type NumInputs = std::distance(in_start, in_end);
// Grow allocated space if needed.
if (NumInputs > size_type(Capacity-End))
grow(size()+NumInputs);
// Copy the new elements over.
std::uninitialized_copy(in_start, in_end, End);
End += NumInputs;
}
/// append - Add the specified range to the end of the SmallVector.
///
void append(size_type NumInputs, const T &Elt) {
// Grow allocated space if needed.
if (NumInputs > size_type(Capacity-End))
grow(size()+NumInputs);
// Copy the new elements over.
std::uninitialized_fill_n(End, NumInputs, Elt);
End += NumInputs;
}
void assign(unsigned NumElts, const T &Elt) {
clear();
if (unsigned(Capacity-Begin) < NumElts)
grow(NumElts);
End = Begin+NumElts;
construct_range(Begin, End, Elt);
}
iterator erase(iterator I) {
iterator N = I;
// Shift all elts down one.
std::copy(I+1, End, I);
// Drop the last elt.
pop_back();
return(N);
}
iterator erase(iterator S, iterator E) {
iterator N = S;
// Shift all elts down.
iterator I = std::copy(E, End, S);
// Drop the last elts.
destroy_range(I, End);
End = I;
return(N);
}
iterator insert(iterator I, const T &Elt) {
if (I == End) { // Important special case for empty vector.
push_back(Elt);
return end()-1;
}
if (End < Capacity) {
Retry:
new (End) T(back());
++End;
// Push everything else over.
std::copy_backward(I, End-1, End);
*I = Elt;
return I;
}
size_t EltNo = I-Begin;
grow();
I = Begin+EltNo;
goto Retry;
}
iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
if (I == End) { // Important special case for empty vector.
append(NumToInsert, Elt);
return end()-1;
}
// Convert iterator to elt# to avoid invalidating iterator when we reserve()
size_t InsertElt = I-begin();
// Ensure there is enough space.
reserve(static_cast<unsigned>(size() + NumToInsert));
// Uninvalidate the iterator.
I = begin()+InsertElt;
// If there are more elements between the insertion point and the end of the
// range than there are being inserted, we can use a simple approach to
// insertion. Since we already reserved space, we know that this won't
// reallocate the vector.
if (size_t(end()-I) >= NumToInsert) {
T *OldEnd = End;
append(End-NumToInsert, End);
// Copy the existing elements that get replaced.
std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
std::fill_n(I, NumToInsert, Elt);
return I;
}
// Otherwise, we're inserting more elements than exist already, and we're
// not inserting at the end.
// Copy over the elements that we're about to overwrite.
T *OldEnd = End;
End += NumToInsert;
size_t NumOverwritten = OldEnd-I;
std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
// Replace the overwritten part.
std::fill_n(I, NumOverwritten, Elt);
// Insert the non-overwritten middle part.
std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
return I;
}
template<typename ItTy>
iterator insert(iterator I, ItTy From, ItTy To) {
if (I == End) { // Important special case for empty vector.
append(From, To);
return end()-1;
}
size_t NumToInsert = std::distance(From, To);
// Convert iterator to elt# to avoid invalidating iterator when we reserve()
size_t InsertElt = I-begin();
// Ensure there is enough space.
reserve(static_cast<unsigned>(size() + NumToInsert));
// Uninvalidate the iterator.
I = begin()+InsertElt;
// If there are more elements between the insertion point and the end of the
// range than there are being inserted, we can use a simple approach to
// insertion. Since we already reserved space, we know that this won't
// reallocate the vector.
if (size_t(end()-I) >= NumToInsert) {
T *OldEnd = End;
append(End-NumToInsert, End);
// Copy the existing elements that get replaced.
std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
std::copy(From, To, I);
return I;
}
// Otherwise, we're inserting more elements than exist already, and we're
// not inserting at the end.
// Copy over the elements that we're about to overwrite.
T *OldEnd = End;
End += NumToInsert;
size_t NumOverwritten = OldEnd-I;
std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
// Replace the overwritten part.
std::copy(From, From+NumOverwritten, I);
// Insert the non-overwritten middle part.
std::uninitialized_copy(From+NumOverwritten, To, OldEnd);
return I;
}
const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
bool operator==(const SmallVectorImpl &RHS) const {
if (size() != RHS.size()) return false;
for (T *This = Begin, *That = RHS.Begin, *E = Begin+size();
This != E; ++This, ++That)
if (*This != *That)
return false;
return true;
}
bool operator!=(const SmallVectorImpl &RHS) const { return !(*this == RHS); }
bool operator<(const SmallVectorImpl &RHS) const {
return std::lexicographical_compare(begin(), end(),
RHS.begin(), RHS.end());
}
private:
/// isSmall - Return true if this is a smallvector which has not had dynamic
/// memory allocated for it.
bool isSmall() const {
return static_cast<const void*>(Begin) ==
static_cast<const void*>(&FirstEl);
}
/// grow - double the size of the allocated memory, guaranteeing space for at
/// least one more element or MinSize if specified.
void grow(size_type MinSize = 0);
void construct_range(T *S, T *E, const T &Elt) {
for (; S != E; ++S)
new (S) T(Elt);
}
void destroy_range(T *S, T *E) {
while (S != E) {
--E;
E->~T();
}
}
};
// Define this out-of-line to dissuade the C++ compiler from inlining it.
template <typename T>
void SmallVectorImpl<T>::grow(size_t MinSize) {
size_t CurCapacity = Capacity-Begin;
size_t CurSize = size();
size_t NewCapacity = 2*CurCapacity;
if (NewCapacity < MinSize)
NewCapacity = MinSize;
T *NewElts = static_cast<T*>(operator new(NewCapacity*sizeof(T)));
// Copy the elements over.
if (is_class<T>::value)
std::uninitialized_copy(Begin, End, NewElts);
else
// Use memcpy for PODs (std::uninitialized_copy optimizes to memmove).
memcpy(NewElts, Begin, CurSize * sizeof(T));
// Destroy the original elements.
destroy_range(Begin, End);
// If this wasn't grown from the inline copy, deallocate the old space.
if (!isSmall())
operator delete(Begin);
Begin = NewElts;
End = NewElts+CurSize;
Capacity = Begin+NewCapacity;
}
template <typename T>
void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
if (this == &RHS) return;
// We can only avoid copying elements if neither vector is small.
if (!isSmall() && !RHS.isSmall()) {
std::swap(Begin, RHS.Begin);
std::swap(End, RHS.End);
std::swap(Capacity, RHS.Capacity);
return;
}
if (RHS.size() > size_type(Capacity-Begin))
grow(RHS.size());
if (size() > size_type(RHS.Capacity-RHS.begin()))
RHS.grow(size());
// Swap the shared elements.
size_t NumShared = size();
if (NumShared > RHS.size()) NumShared = RHS.size();
for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
std::swap(Begin[i], RHS[i]);
// Copy over the extra elts.
if (size() > RHS.size()) {
size_t EltDiff = size() - RHS.size();
std::uninitialized_copy(Begin+NumShared, End, RHS.End);
RHS.End += EltDiff;
destroy_range(Begin+NumShared, End);
End = Begin+NumShared;
} else if (RHS.size() > size()) {
size_t EltDiff = RHS.size() - size();
std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
End += EltDiff;
destroy_range(RHS.Begin+NumShared, RHS.End);
RHS.End = RHS.Begin+NumShared;
}
}
template <typename T>
const SmallVectorImpl<T> &
SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
// Avoid self-assignment.
if (this == &RHS) return *this;
// If we already have sufficient space, assign the common elements, then
// destroy any excess.
unsigned RHSSize = unsigned(RHS.size());
unsigned CurSize = unsigned(size());
if (CurSize >= RHSSize) {
// Assign common elements.
iterator NewEnd;
if (RHSSize)
NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
else
NewEnd = Begin;
// Destroy excess elements.
destroy_range(NewEnd, End);
// Trim.
End = NewEnd;
return *this;
}
// If we have to grow to have enough elements, destroy the current elements.
// This allows us to avoid copying them during the grow.
if (unsigned(Capacity-Begin) < RHSSize) {
// Destroy current elements.
destroy_range(Begin, End);
End = Begin;
CurSize = 0;
grow(RHSSize);
} else if (CurSize) {
// Otherwise, use assignment for the already-constructed elements.
std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
}
// Copy construct the new elements in place.
std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
// Set end.
End = Begin+RHSSize;
return *this;
}
/// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
/// for the case when the array is small. It contains some number of elements
/// in-place, which allows it to avoid heap allocation when the actual number of
/// elements is below that threshold. This allows normal "small" cases to be
/// fast without losing generality for large inputs.
///
/// Note that this does not attempt to be exception safe.
///
template <typename T, unsigned N>
class SmallVector : public SmallVectorImpl<T> {
/// InlineElts - These are 'N-1' elements that are stored inline in the body
/// of the vector. The extra '1' element is stored in SmallVectorImpl.
typedef typename SmallVectorImpl<T>::U U;
enum {
// MinUs - The number of U's require to cover N T's.
MinUs = (static_cast<unsigned int>(sizeof(T))*N +
static_cast<unsigned int>(sizeof(U)) - 1) /
static_cast<unsigned int>(sizeof(U)),
// NumInlineEltsElts - The number of elements actually in this array. There
// is already one in the parent class, and we have to round up to avoid
// having a zero-element array.
NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
// NumTsAvailable - The number of T's we actually have space for, which may
// be more than N due to rounding.
NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
static_cast<unsigned int>(sizeof(T))
};
U InlineElts[NumInlineEltsElts];
public:
SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
}
explicit SmallVector(unsigned Size, const T &Value = T())
: SmallVectorImpl<T>(NumTsAvailable) {
this->reserve(Size);
while (Size--)
this->push_back(Value);
}
template<typename ItTy>
SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
this->append(S, E);
}
SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
if (!RHS.empty())
SmallVectorImpl<T>::operator=(RHS);
}
const SmallVector &operator=(const SmallVector &RHS) {
SmallVectorImpl<T>::operator=(RHS);
return *this;
}
};
} // End llvm namespace
namespace std {
/// Implement std::swap in terms of SmallVector swap.
template<typename T>
inline void
swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
LHS.swap(RHS);
}
/// Implement std::swap in terms of SmallVector swap.
template<typename T, unsigned N>
inline void
swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {
LHS.swap(RHS);
}
}
#endif