1 //===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the SmallVector class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/ADT/SmallVector.h" 14 #include <cstdint> 15 using namespace llvm; 16 17 // Check that no bytes are wasted and everything is well-aligned. 18 namespace { 19 struct Struct16B { 20 alignas(16) void *X; 21 }; 22 struct Struct32B { 23 alignas(32) void *X; 24 }; 25 } 26 static_assert(sizeof(SmallVector<void *, 0>) == 27 sizeof(unsigned) * 2 + sizeof(void *), 28 "wasted space in SmallVector size 0"); 29 static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B), 30 "wrong alignment for 16-byte aligned T"); 31 static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B), 32 "wrong alignment for 32-byte aligned T"); 33 static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B), 34 "missing padding for 16-byte aligned T"); 35 static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B), 36 "missing padding for 32-byte aligned T"); 37 static_assert(sizeof(SmallVector<void *, 1>) == 38 sizeof(unsigned) * 2 + sizeof(void *) * 2, 39 "wasted space in SmallVector size 1"); 40 41 static_assert(sizeof(SmallVector<char, 0>) == 42 sizeof(void *) * 2 + sizeof(void *), 43 "1 byte elements have word-sized type for size and capacity"); 44 45 // Note: Moving this function into the header may cause performance regression. 46 template <class Size_T> 47 void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinCapacity, 48 size_t TSize) { 49 // Ensure we can fit the new capacity. 50 // This is only going to be applicable when the capacity is 32 bit. 51 if (MinCapacity > SizeTypeMax()) 52 report_bad_alloc_error("SmallVector capacity overflow during allocation"); 53 54 // Ensure we can meet the guarantee of space for at least one more element. 55 // The above check alone will not catch the case where grow is called with a 56 // default MinCapacity of 0, but the current capacity cannot be increased. 57 // This is only going to be applicable when the capacity is 32 bit. 58 if (capacity() == SizeTypeMax()) 59 report_bad_alloc_error("SmallVector capacity unable to grow"); 60 61 // In theory 2*capacity can overflow if the capacity is 64 bit, but the 62 // original capacity would never be large enough for this to be a problem. 63 size_t NewCapacity = 2 * capacity() + 1; // Always grow. 64 NewCapacity = std::min(std::max(NewCapacity, MinCapacity), SizeTypeMax()); 65 66 void *NewElts; 67 if (BeginX == FirstEl) { 68 NewElts = safe_malloc(NewCapacity * TSize); 69 70 // Copy the elements over. No need to run dtors on PODs. 71 memcpy(NewElts, this->BeginX, size() * TSize); 72 } else { 73 // If this wasn't grown from the inline copy, grow the allocated space. 74 NewElts = safe_realloc(this->BeginX, NewCapacity * TSize); 75 } 76 77 this->BeginX = NewElts; 78 this->Capacity = NewCapacity; 79 } 80 81 template class llvm::SmallVectorBase<uint32_t>; 82 83 // Disable the uint64_t instantiation for 32-bit builds. 84 // Both uint32_t and uint64_t instantations are needed for 64-bit builds. 85 // This instantiation will never be used in 32-bit builds, and will cause 86 // warnings when sizeof(Size_T) > sizeof(size_t). 87 #if SIZE_MAX > UINT32_MAX 88 template class llvm::SmallVectorBase<uint64_t>; 89 90 // Assertions to ensure this #if stays in sync with SmallVectorSizeType. 91 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t), 92 "Expected SmallVectorBase<uint64_t> variant to be in use."); 93 #else 94 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t), 95 "Expected SmallVectorBase<uint32_t> variant to be in use."); 96 #endif 97