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+//===- BumpVector.h - Vector-like ADT that uses bump allocation -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides BumpVector, a vector-like ADT whose contents are
+// allocated from a BumpPtrAllocator.
+//
+//===----------------------------------------------------------------------===//
+
+// FIXME: Most of this is copy-and-paste from SmallVector.h. We can
+// refactor this core logic into something common that is shared between
+// the two. The main thing that is different is the allocation strategy.
+
+#ifndef LLVM_CLANG_ANALYSIS_SUPPORT_BUMPVECTOR_H
+#define LLVM_CLANG_ANALYSIS_SUPPORT_BUMPVECTOR_H
+
+#include "llvm/ADT/PointerIntPair.h"
+#include "llvm/Support/Allocator.h"
+#include <cassert>
+#include <cstddef>
+#include <cstring>
+#include <iterator>
+#include <memory>
+#include <type_traits>
+
+namespace clang {
+
+class BumpVectorContext {
+ llvm::PointerIntPair<llvm::BumpPtrAllocator*, 1> Alloc;
+
+public:
+ /// Construct a new BumpVectorContext that creates a new BumpPtrAllocator
+ /// and destroys it when the BumpVectorContext object is destroyed.
+ BumpVectorContext() : Alloc(new llvm::BumpPtrAllocator(), 1) {}
+
+ BumpVectorContext(BumpVectorContext &&Other) : Alloc(Other.Alloc) {
+ Other.Alloc.setInt(false);
+ Other.Alloc.setPointer(nullptr);
+ }
+
+ /// Construct a new BumpVectorContext that reuses an existing
+ /// BumpPtrAllocator. This BumpPtrAllocator is not destroyed when the
+ /// BumpVectorContext object is destroyed.
+ BumpVectorContext(llvm::BumpPtrAllocator &A) : Alloc(&A, 0) {}
+
+ ~BumpVectorContext() {
+ if (Alloc.getInt())
+ delete Alloc.getPointer();
+ }
+
+ llvm::BumpPtrAllocator &getAllocator() { return *Alloc.getPointer(); }
+};
+
+template<typename T>
+class BumpVector {
+ T *Begin = nullptr;
+ T *End = nullptr;
+ T *Capacity = nullptr;
+
+public:
+ // Default ctor - Initialize to empty.
+ explicit BumpVector(BumpVectorContext &C, unsigned N) {
+ reserve(C, N);
+ }
+
+ ~BumpVector() {
+ if (std::is_class<T>::value) {
+ // Destroy the constructed elements in the vector.
+ destroy_range(Begin, End);
+ }
+ }
+
+ using size_type = size_t;
+ using difference_type = ptrdiff_t;
+ using value_type = T;
+ using iterator = T *;
+ using const_iterator = const T *;
+
+ using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+ using reverse_iterator = std::reverse_iterator<iterator>;
+
+ using reference = T &;
+ using const_reference = const T &;
+ using pointer = T *;
+ using const_pointer = const 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());
+ }
+
+ bool empty() const { return Begin == End; }
+ size_type size() const { return End-Begin; }
+
+ 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 pop_back() {
+ --End;
+ End->~T();
+ }
+
+ T pop_back_val() {
+ T Result = back();
+ pop_back();
+ return Result;
+ }
+
+ void clear() {
+ if (std::is_class<T>::value) {
+ destroy_range(Begin, End);
+ }
+ End = Begin;
+ }
+
+ /// data - Return a pointer to the vector's buffer, even if empty().
+ pointer data() {
+ return pointer(Begin);
+ }
+
+ /// data - Return a pointer to the vector's buffer, even if empty().
+ const_pointer data() const {
+ return const_pointer(Begin);
+ }
+
+ void push_back(const_reference Elt, BumpVectorContext &C) {
+ if (End < Capacity) {
+ Retry:
+ new (End) T(Elt);
+ ++End;
+ return;
+ }
+ grow(C);
+ goto Retry;
+ }
+
+ /// insert - Insert some number of copies of element into a position. Return
+ /// iterator to position after last inserted copy.
+ iterator insert(iterator I, size_t Cnt, const_reference E,
+ BumpVectorContext &C) {
+ assert(I >= Begin && I <= End && "Iterator out of bounds.");
+ if (End + Cnt <= Capacity) {
+ Retry:
+ move_range_right(I, End, Cnt);
+ construct_range(I, I + Cnt, E);
+ End += Cnt;
+ return I + Cnt;
+ }
+ ptrdiff_t D = I - Begin;
+ grow(C, size() + Cnt);
+ I = Begin + D;
+ goto Retry;
+ }
+
+ void reserve(BumpVectorContext &C, unsigned N) {
+ if (unsigned(Capacity-Begin) < N)
+ grow(C, N);
+ }
+
+ /// capacity - Return the total number of elements in the currently allocated
+ /// buffer.
+ size_t capacity() const { return Capacity - Begin; }
+
+private:
+ /// grow - double the size of the allocated memory, guaranteeing space for at
+ /// least one more element or MinSize if specified.
+ void grow(BumpVectorContext &C, size_type MinSize = 1);
+
+ 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();
+ }
+ }
+
+ void move_range_right(T *S, T *E, size_t D) {
+ for (T *I = E + D - 1, *IL = S + D - 1; I != IL; --I) {
+ --E;
+ new (I) T(*E);
+ E->~T();
+ }
+ }
+};
+
+// Define this out-of-line to dissuade the C++ compiler from inlining it.
+template <typename T>
+void BumpVector<T>::grow(BumpVectorContext &C, size_t MinSize) {
+ size_t CurCapacity = Capacity-Begin;
+ size_t CurSize = size();
+ size_t NewCapacity = 2*CurCapacity;
+ if (NewCapacity < MinSize)
+ NewCapacity = MinSize;
+
+ // Allocate the memory from the BumpPtrAllocator.
+ T *NewElts = C.getAllocator().template Allocate<T>(NewCapacity);
+
+ // Copy the elements over.
+ if (Begin != End) {
+ if (std::is_class<T>::value) {
+ std::uninitialized_copy(Begin, End, NewElts);
+ // Destroy the original elements.
+ destroy_range(Begin, End);
+ } else {
+ // Use memcpy for PODs (std::uninitialized_copy optimizes to memmove).
+ memcpy(NewElts, Begin, CurSize * sizeof(T));
+ }
+ }
+
+ // For now, leak 'Begin'. We can add it back to a freelist in
+ // BumpVectorContext.
+ Begin = NewElts;
+ End = NewElts+CurSize;
+ Capacity = Begin+NewCapacity;
+}
+
+} // namespace clang
+
+#endif // LLVM_CLANG_ANALYSIS_SUPPORT_BUMPVECTOR_H