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 void SmallVectorBase::grow_pod(void *FirstEl, size_t MinCapacity,
43                                size_t TSize) {
44   // Ensure we can fit the new capacity in 32 bits.
45   if (MinCapacity > UINT32_MAX)
46     report_bad_alloc_error("SmallVector capacity overflow during allocation");
47 
48   size_t NewCapacity = 2 * capacity() + 1; // Always grow.
49   NewCapacity =
50       std::min(std::max(NewCapacity, MinCapacity), size_t(UINT32_MAX));
51 
52   void *NewElts;
53   if (BeginX == FirstEl) {
54     NewElts = safe_malloc(NewCapacity * TSize);
55 
56     // Copy the elements over.  No need to run dtors on PODs.
57     memcpy(NewElts, this->BeginX, size() * TSize);
58   } else {
59     // If this wasn't grown from the inline copy, grow the allocated space.
60     NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
61   }
62 
63   this->BeginX = NewElts;
64   this->Capacity = NewCapacity;
65 }
66