SmallVector.cpp
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//===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
//
// 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 implements the SmallVector class.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallVector.h"
#include <cstdint>
using namespace llvm;
// Check that no bytes are wasted and everything is well-aligned.
namespace {
struct Struct16B {
alignas(16) void *X;
};
struct Struct32B {
alignas(32) void *X;
};
}
static_assert(sizeof(SmallVector<void *, 0>) ==
sizeof(unsigned) * 2 + sizeof(void *),
"wasted space in SmallVector size 0");
static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
"wrong alignment for 16-byte aligned T");
static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
"wrong alignment for 32-byte aligned T");
static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
"missing padding for 16-byte aligned T");
static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
"missing padding for 32-byte aligned T");
static_assert(sizeof(SmallVector<void *, 1>) ==
sizeof(unsigned) * 2 + sizeof(void *) * 2,
"wasted space in SmallVector size 1");
static_assert(sizeof(SmallVector<char, 0>) ==
sizeof(void *) * 2 + sizeof(void *),
"1 byte elements have word-sized type for size and capacity");
// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinCapacity,
size_t TSize) {
// Ensure we can fit the new capacity.
// This is only going to be applicable when the capacity is 32 bit.
if (MinCapacity > SizeTypeMax())
report_bad_alloc_error("SmallVector capacity overflow during allocation");
// Ensure we can meet the guarantee of space for at least one more element.
// The above check alone will not catch the case where grow is called with a
// default MinCapacity of 0, but the current capacity cannot be increased.
// This is only going to be applicable when the capacity is 32 bit.
if (capacity() == SizeTypeMax())
report_bad_alloc_error("SmallVector capacity unable to grow");
// In theory 2*capacity can overflow if the capacity is 64 bit, but the
// original capacity would never be large enough for this to be a problem.
size_t NewCapacity = 2 * capacity() + 1; // Always grow.
NewCapacity = std::min(std::max(NewCapacity, MinCapacity), SizeTypeMax());
void *NewElts;
if (BeginX == FirstEl) {
NewElts = safe_malloc(NewCapacity * TSize);
// Copy the elements over. No need to run dtors on PODs.
memcpy(NewElts, this->BeginX, size() * TSize);
} else {
// If this wasn't grown from the inline copy, grow the allocated space.
NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
}
this->BeginX = NewElts;
this->Capacity = NewCapacity;
}
template class llvm::SmallVectorBase<uint32_t>;
// Disable the uint64_t instantiation for 32-bit builds.
// Both uint32_t and uint64_t instantations are needed for 64-bit builds.
// This instantiation will never be used in 32-bit builds, and will cause
// warnings when sizeof(Size_T) > sizeof(size_t).
#if SIZE_MAX > UINT32_MAX
template class llvm::SmallVectorBase<uint64_t>;
// Assertions to ensure this #if stays in sync with SmallVectorSizeType.
static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
"Expected SmallVectorBase<uint64_t> variant to be in use.");
#else
static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t),
"Expected SmallVectorBase<uint32_t> variant to be in use.");
#endif