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 using namespace llvm; 15 16 // Check that no bytes are wasted and everything is well-aligned. 17 namespace { 18 struct Struct16B { 19 alignas(16) void *X; 20 }; 21 struct Struct32B { 22 alignas(32) void *X; 23 }; 24 } 25 static_assert(sizeof(SmallVector<void *, 0>) == 26 sizeof(unsigned) * 2 + sizeof(void *), 27 "wasted space in SmallVector size 0"); 28 static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B), 29 "wrong alignment for 16-byte aligned T"); 30 static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B), 31 "wrong alignment for 32-byte aligned T"); 32 static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B), 33 "missing padding for 16-byte aligned T"); 34 static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B), 35 "missing padding for 32-byte aligned T"); 36 static_assert(sizeof(SmallVector<void *, 1>) == 37 sizeof(unsigned) * 2 + sizeof(void *) * 2, 38 "wasted space in SmallVector size 1"); 39 40 /// grow_pod - This is an implementation of the grow() method which only works 41 /// on POD-like datatypes and is out of line to reduce code duplication. 42 /// This function will report a fatal error if it cannot increase capacity. 43 void SmallVectorBase::grow_pod(void *FirstEl, size_t MinCapacity, 44 size_t TSize) { 45 // Ensure we can fit the new capacity in 32 bits. 46 if (MinCapacity > UINT32_MAX) 47 report_bad_alloc_error("SmallVector capacity overflow during allocation"); 48 49 // Ensure we can meet the guarantee of space for at least one more element. 50 // The above check alone will not catch the case where grow is called with a 51 // default MinCapacity of 0, but the current capacity cannot be increased. 52 if (capacity() == size_t(UINT32_MAX)) 53 report_bad_alloc_error("SmallVector capacity unable to grow"); 54 55 size_t NewCapacity = 2 * capacity() + 1; // Always grow. 56 NewCapacity = 57 std::min(std::max(NewCapacity, MinCapacity), size_t(UINT32_MAX)); 58 59 void *NewElts; 60 if (BeginX == FirstEl) { 61 NewElts = safe_malloc(NewCapacity * TSize); 62 63 // Copy the elements over. No need to run dtors on PODs. 64 memcpy(NewElts, this->BeginX, size() * TSize); 65 } else { 66 // If this wasn't grown from the inline copy, grow the allocated space. 67 NewElts = safe_realloc(this->BeginX, NewCapacity * TSize); 68 } 69 70 this->BeginX = NewElts; 71 this->Capacity = NewCapacity; 72 } 73