1//===- llvm/unittest/Support/AllocatorTest.cpp - BumpPtrAllocator tests ---===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "llvm/Support/Allocator.h"
11#include "gtest/gtest.h"
12#include <cstdlib>
13
14using namespace llvm;
15
16namespace {
17
18TEST(AllocatorTest, Basics) {
19  BumpPtrAllocator Alloc;
20  int *a = (int*)Alloc.Allocate(sizeof(int), 0);
21  int *b = (int*)Alloc.Allocate(sizeof(int) * 10, 0);
22  int *c = (int*)Alloc.Allocate(sizeof(int), 0);
23  *a = 1;
24  b[0] = 2;
25  b[9] = 2;
26  *c = 3;
27  EXPECT_EQ(1, *a);
28  EXPECT_EQ(2, b[0]);
29  EXPECT_EQ(2, b[9]);
30  EXPECT_EQ(3, *c);
31  EXPECT_EQ(1U, Alloc.GetNumSlabs());
32
33  BumpPtrAllocator Alloc2 = std::move(Alloc);
34  EXPECT_EQ(0U, Alloc.GetNumSlabs());
35  EXPECT_EQ(1U, Alloc2.GetNumSlabs());
36
37  // Make sure the old pointers still work. These are especially interesting
38  // under ASan or Valgrind.
39  EXPECT_EQ(1, *a);
40  EXPECT_EQ(2, b[0]);
41  EXPECT_EQ(2, b[9]);
42  EXPECT_EQ(3, *c);
43
44  Alloc = std::move(Alloc2);
45  EXPECT_EQ(0U, Alloc2.GetNumSlabs());
46  EXPECT_EQ(1U, Alloc.GetNumSlabs());
47}
48
49// Allocate enough bytes to create three slabs.
50TEST(AllocatorTest, ThreeSlabs) {
51  BumpPtrAllocator Alloc;
52  Alloc.Allocate(3000, 0);
53  EXPECT_EQ(1U, Alloc.GetNumSlabs());
54  Alloc.Allocate(3000, 0);
55  EXPECT_EQ(2U, Alloc.GetNumSlabs());
56  Alloc.Allocate(3000, 0);
57  EXPECT_EQ(3U, Alloc.GetNumSlabs());
58}
59
60// Allocate enough bytes to create two slabs, reset the allocator, and do it
61// again.
62TEST(AllocatorTest, TestReset) {
63  BumpPtrAllocator Alloc;
64  Alloc.Allocate(3000, 0);
65  EXPECT_EQ(1U, Alloc.GetNumSlabs());
66  Alloc.Allocate(3000, 0);
67  EXPECT_EQ(2U, Alloc.GetNumSlabs());
68  Alloc.Reset();
69  EXPECT_EQ(1U, Alloc.GetNumSlabs());
70  Alloc.Allocate(3000, 0);
71  EXPECT_EQ(1U, Alloc.GetNumSlabs());
72  Alloc.Allocate(3000, 0);
73  EXPECT_EQ(2U, Alloc.GetNumSlabs());
74}
75
76// Test some allocations at varying alignments.
77TEST(AllocatorTest, TestAlignment) {
78  BumpPtrAllocator Alloc;
79  uintptr_t a;
80  a = (uintptr_t)Alloc.Allocate(1, 2);
81  EXPECT_EQ(0U, a & 1);
82  a = (uintptr_t)Alloc.Allocate(1, 4);
83  EXPECT_EQ(0U, a & 3);
84  a = (uintptr_t)Alloc.Allocate(1, 8);
85  EXPECT_EQ(0U, a & 7);
86  a = (uintptr_t)Alloc.Allocate(1, 16);
87  EXPECT_EQ(0U, a & 15);
88  a = (uintptr_t)Alloc.Allocate(1, 32);
89  EXPECT_EQ(0U, a & 31);
90  a = (uintptr_t)Alloc.Allocate(1, 64);
91  EXPECT_EQ(0U, a & 63);
92  a = (uintptr_t)Alloc.Allocate(1, 128);
93  EXPECT_EQ(0U, a & 127);
94}
95
96// Test allocating just over the slab size.  This tests a bug where before the
97// allocator incorrectly calculated the buffer end pointer.
98TEST(AllocatorTest, TestOverflow) {
99  BumpPtrAllocator Alloc;
100
101  // Fill the slab right up until the end pointer.
102  Alloc.Allocate(4096, 0);
103  EXPECT_EQ(1U, Alloc.GetNumSlabs());
104
105  // If we don't allocate a new slab, then we will have overflowed.
106  Alloc.Allocate(1, 0);
107  EXPECT_EQ(2U, Alloc.GetNumSlabs());
108}
109
110// Test allocating with a size larger than the initial slab size.
111TEST(AllocatorTest, TestSmallSlabSize) {
112  BumpPtrAllocator Alloc;
113
114  Alloc.Allocate(8000, 0);
115  EXPECT_EQ(2U, Alloc.GetNumSlabs());
116}
117
118// Mock slab allocator that returns slabs aligned on 4096 bytes.  There is no
119// easy portable way to do this, so this is kind of a hack.
120class MockSlabAllocator {
121  static size_t LastSlabSize;
122
123public:
124  ~MockSlabAllocator() { }
125
126  void *Allocate(size_t Size, size_t /*Alignment*/) {
127    // Allocate space for the alignment, the slab, and a void* that goes right
128    // before the slab.
129    size_t Alignment = 4096;
130    void *MemBase = malloc(Size + Alignment - 1 + sizeof(void*));
131
132    // Find the slab start.
133    void *Slab = alignPtr((char *)MemBase + sizeof(void *), Alignment);
134
135    // Hold a pointer to the base so we can free the whole malloced block.
136    ((void**)Slab)[-1] = MemBase;
137
138    LastSlabSize = Size;
139    return Slab;
140  }
141
142  void Deallocate(void *Slab, size_t Size) {
143    free(((void**)Slab)[-1]);
144  }
145
146  static size_t GetLastSlabSize() { return LastSlabSize; }
147};
148
149size_t MockSlabAllocator::LastSlabSize = 0;
150
151// Allocate a large-ish block with a really large alignment so that the
152// allocator will think that it has space, but after it does the alignment it
153// will not.
154TEST(AllocatorTest, TestBigAlignment) {
155  BumpPtrAllocatorImpl<MockSlabAllocator> Alloc;
156
157  // First allocate a tiny bit to ensure we have to re-align things.
158  (void)Alloc.Allocate(1, 0);
159
160  // Now the big chunk with a big alignment.
161  (void)Alloc.Allocate(3000, 2048);
162
163  // We test that the last slab size is not the default 4096 byte slab, but
164  // rather a custom sized slab that is larger.
165  EXPECT_GT(MockSlabAllocator::GetLastSlabSize(), 4096u);
166}
167
168}  // anonymous namespace
169