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 template <class Size_T> 49 void SmallVectorBase<Size_T>::report_size_overflow(size_t MinSize) { 50 std::string Reason = "SmallVector unable to grow. Requested capacity (" + 51 std::to_string(MinSize) + 52 ") is larger than maximum value for size type (" + 53 std::to_string(SizeTypeMax()) + ")"; 54 #ifdef LLVM_ENABLE_EXCEPTIONS 55 throw std::length_error(Reason); 56 #else 57 report_fatal_error(Reason); 58 #endif 59 } 60 61 template <class Size_T> void SmallVectorBase<Size_T>::report_at_maximum_capacity() { 62 std::string Reason = 63 "SmallVector capacity unable to grow. Already at maximum size " + 64 std::to_string(SizeTypeMax()); 65 #ifdef LLVM_ENABLE_EXCEPTIONS 66 throw std::length_error(Reason); 67 #else 68 report_fatal_error(Reason); 69 #endif 70 } 71 72 // Note: Moving this function into the header may cause performance regression. 73 template <class Size_T> 74 void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinSize, 75 size_t TSize) { 76 // Ensure we can fit the new capacity. 77 // This is only going to be applicable when the capacity is 32 bit. 78 if (MinSize > SizeTypeMax()) 79 report_size_overflow(MinSize); 80 81 // Ensure we can meet the guarantee of space for at least one more element. 82 // The above check alone will not catch the case where grow is called with a 83 // default MinSize of 0, but the current capacity cannot be increased. 84 // This is only going to be applicable when the capacity is 32 bit. 85 if (capacity() == SizeTypeMax()) 86 report_at_maximum_capacity(); 87 88 // In theory 2*capacity can overflow if the capacity is 64 bit, but the 89 // original capacity would never be large enough for this to be a problem. 90 size_t NewCapacity = 2 * capacity() + 1; // Always grow. 91 NewCapacity = std::min(std::max(NewCapacity, MinSize), SizeTypeMax()); 92 93 void *NewElts; 94 if (BeginX == FirstEl) { 95 NewElts = safe_malloc(NewCapacity * TSize); 96 97 // Copy the elements over. No need to run dtors on PODs. 98 memcpy(NewElts, this->BeginX, size() * TSize); 99 } else { 100 // If this wasn't grown from the inline copy, grow the allocated space. 101 NewElts = safe_realloc(this->BeginX, NewCapacity * TSize); 102 } 103 104 this->BeginX = NewElts; 105 this->Capacity = NewCapacity; 106 } 107 108 template class llvm::SmallVectorBase<uint32_t>; 109 110 // Disable the uint64_t instantiation for 32-bit builds. 111 // Both uint32_t and uint64_t instantiations are needed for 64-bit builds. 112 // This instantiation will never be used in 32-bit builds, and will cause 113 // warnings when sizeof(Size_T) > sizeof(size_t). 114 #if SIZE_MAX > UINT32_MAX 115 template class llvm::SmallVectorBase<uint64_t>; 116 117 // Assertions to ensure this #if stays in sync with SmallVectorSizeType. 118 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t), 119 "Expected SmallVectorBase<uint64_t> variant to be in use."); 120 #else 121 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t), 122 "Expected SmallVectorBase<uint32_t> variant to be in use."); 123 #endif 124