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 static_assert(sizeof(SmallVector<char, 0>) ==
40                   sizeof(void *) * 2 + sizeof(void *),
41               "1 byte elements have word-sized type for size and capacity");
42