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97 lines
4.0 KiB
C++
97 lines
4.0 KiB
C++
//===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the SmallVector class.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/SmallVector.h"
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#include <cstdint>
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using namespace llvm;
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// Check that no bytes are wasted and everything is well-aligned.
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namespace {
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struct Struct16B {
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alignas(16) void *X;
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};
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struct Struct32B {
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alignas(32) void *X;
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};
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}
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static_assert(sizeof(SmallVector<void *, 0>) ==
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sizeof(unsigned) * 2 + sizeof(void *),
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"wasted space in SmallVector size 0");
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static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
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"wrong alignment for 16-byte aligned T");
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static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
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"wrong alignment for 32-byte aligned T");
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static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
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"missing padding for 16-byte aligned T");
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static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
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"missing padding for 32-byte aligned T");
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static_assert(sizeof(SmallVector<void *, 1>) ==
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sizeof(unsigned) * 2 + sizeof(void *) * 2,
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"wasted space in SmallVector size 1");
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static_assert(sizeof(SmallVector<char, 0>) ==
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sizeof(void *) * 2 + sizeof(void *),
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"1 byte elements have word-sized type for size and capacity");
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// Note: Moving this function into the header may cause performance regression.
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template <class Size_T>
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void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinCapacity,
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size_t TSize) {
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// Ensure we can fit the new capacity.
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// This is only going to be applicable when the capacity is 32 bit.
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if (MinCapacity > SizeTypeMax())
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report_bad_alloc_error("SmallVector capacity overflow during allocation");
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// Ensure we can meet the guarantee of space for at least one more element.
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// The above check alone will not catch the case where grow is called with a
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// default MinCapacity of 0, but the current capacity cannot be increased.
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// This is only going to be applicable when the capacity is 32 bit.
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if (capacity() == SizeTypeMax())
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report_bad_alloc_error("SmallVector capacity unable to grow");
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// In theory 2*capacity can overflow if the capacity is 64 bit, but the
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// original capacity would never be large enough for this to be a problem.
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size_t NewCapacity = 2 * capacity() + 1; // Always grow.
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NewCapacity = std::min(std::max(NewCapacity, MinCapacity), SizeTypeMax());
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void *NewElts;
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if (BeginX == FirstEl) {
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NewElts = safe_malloc(NewCapacity * TSize);
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// Copy the elements over. No need to run dtors on PODs.
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memcpy(NewElts, this->BeginX, size() * TSize);
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} else {
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// If this wasn't grown from the inline copy, grow the allocated space.
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NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
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}
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this->BeginX = NewElts;
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this->Capacity = NewCapacity;
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}
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template class llvm::SmallVectorBase<uint32_t>;
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// Disable the uint64_t instantiation for 32-bit builds.
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// Both uint32_t and uint64_t instantations are needed for 64-bit builds.
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// This instantiation will never be used in 32-bit builds, and will cause
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// warnings when sizeof(Size_T) > sizeof(size_t).
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#if SIZE_MAX > UINT32_MAX
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template class llvm::SmallVectorBase<uint64_t>;
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// Assertions to ensure this #if stays in sync with SmallVectorSizeType.
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static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
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"Expected SmallVectorBase<uint64_t> variant to be in use.");
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#else
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static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t),
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"Expected SmallVectorBase<uint32_t> variant to be in use.");
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#endif
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