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 #ifdef LLVM_ENABLE_EXCEPTIONS 16 #include <stdexcept> 17 #endif 18 using namespace llvm; 19 20 // Check that no bytes are wasted and everything is well-aligned. 21 namespace { 22 struct Struct16B { 23 alignas(16) void *X; 24 }; 25 struct Struct32B { 26 alignas(32) void *X; 27 }; 28 } 29 static_assert(sizeof(SmallVector<void *, 0>) == 30 sizeof(unsigned) * 2 + sizeof(void *), 31 "wasted space in SmallVector size 0"); 32 static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B), 33 "wrong alignment for 16-byte aligned T"); 34 static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B), 35 "wrong alignment for 32-byte aligned T"); 36 static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B), 37 "missing padding for 16-byte aligned T"); 38 static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B), 39 "missing padding for 32-byte aligned T"); 40 static_assert(sizeof(SmallVector<void *, 1>) == 41 sizeof(unsigned) * 2 + sizeof(void *) * 2, 42 "wasted space in SmallVector size 1"); 43 44 static_assert(sizeof(SmallVector<char, 0>) == 45 sizeof(void *) * 2 + sizeof(void *), 46 "1 byte elements have word-sized type for size and capacity"); 47 48 /// Report that MinSize doesn't fit into this vector's size type. Throws 49 /// std::length_error or calls report_fatal_error. 50 LLVM_ATTRIBUTE_NORETURN 51 static void report_size_overflow(size_t MinSize, size_t MaxSize); 52 static void report_size_overflow(size_t MinSize, size_t MaxSize) { 53 std::string Reason = "SmallVector unable to grow. Requested capacity (" + 54 std::to_string(MinSize) + 55 ") is larger than maximum value for size type (" + 56 std::to_string(MaxSize) + ")"; 57 #ifdef LLVM_ENABLE_EXCEPTIONS 58 throw std::length_error(Reason); 59 #else 60 report_fatal_error(Reason); 61 #endif 62 } 63 64 /// Report that this vector is already at maximum capacity. Throws 65 /// std::length_error or calls report_fatal_error. 66 LLVM_ATTRIBUTE_NORETURN static void report_at_maximum_capacity(size_t MaxSize); 67 static void report_at_maximum_capacity(size_t MaxSize) { 68 std::string Reason = 69 "SmallVector capacity unable to grow. Already at maximum size " + 70 std::to_string(MaxSize); 71 #ifdef LLVM_ENABLE_EXCEPTIONS 72 throw std::length_error(Reason); 73 #else 74 report_fatal_error(Reason); 75 #endif 76 } 77 78 // Note: Moving this function into the header may cause performance regression. 79 template <class Size_T> 80 static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) { 81 constexpr size_t MaxSize = std::numeric_limits<Size_T>::max(); 82 83 // Ensure we can fit the new capacity. 84 // This is only going to be applicable when the capacity is 32 bit. 85 if (MinSize > MaxSize) 86 report_size_overflow(MinSize, MaxSize); 87 88 // Ensure we can meet the guarantee of space for at least one more element. 89 // The above check alone will not catch the case where grow is called with a 90 // default MinSize of 0, but the current capacity cannot be increased. 91 // This is only going to be applicable when the capacity is 32 bit. 92 if (OldCapacity == MaxSize) 93 report_at_maximum_capacity(MaxSize); 94 95 // In theory 2*capacity can overflow if the capacity is 64 bit, but the 96 // original capacity would never be large enough for this to be a problem. 97 size_t NewCapacity = 2 * OldCapacity + 1; // Always grow. 98 return std::min(std::max(NewCapacity, MinSize), MaxSize); 99 } 100 101 // Note: Moving this function into the header may cause performance regression. 102 template <class Size_T> 103 void *SmallVectorBase<Size_T>::mallocForGrow(size_t MinSize, size_t TSize, 104 size_t &NewCapacity) { 105 NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity()); 106 return llvm::safe_malloc(NewCapacity * TSize); 107 } 108 109 // Note: Moving this function into the header may cause performance regression. 110 template <class Size_T> 111 void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinSize, 112 size_t TSize) { 113 size_t NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity()); 114 void *NewElts; 115 if (BeginX == FirstEl) { 116 NewElts = safe_malloc(NewCapacity * TSize); 117 118 // Copy the elements over. No need to run dtors on PODs. 119 memcpy(NewElts, this->BeginX, size() * TSize); 120 } else { 121 // If this wasn't grown from the inline copy, grow the allocated space. 122 NewElts = safe_realloc(this->BeginX, NewCapacity * TSize); 123 } 124 125 this->BeginX = NewElts; 126 this->Capacity = NewCapacity; 127 } 128 129 template class llvm::SmallVectorBase<uint32_t>; 130 131 // Disable the uint64_t instantiation for 32-bit builds. 132 // Both uint32_t and uint64_t instantiations are needed for 64-bit builds. 133 // This instantiation will never be used in 32-bit builds, and will cause 134 // warnings when sizeof(Size_T) > sizeof(size_t). 135 #if SIZE_MAX > UINT32_MAX 136 template class llvm::SmallVectorBase<uint64_t>; 137 138 // Assertions to ensure this #if stays in sync with SmallVectorSizeType. 139 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t), 140 "Expected SmallVectorBase<uint64_t> variant to be in use."); 141 #else 142 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t), 143 "Expected SmallVectorBase<uint32_t> variant to be in use."); 144 #endif 145