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
34// Allocate enough bytes to create three slabs.
35TEST(AllocatorTest, ThreeSlabs) {
36  BumpPtrAllocator Alloc(4096, 4096);
37  Alloc.Allocate(3000, 0);
38  EXPECT_EQ(1U, Alloc.GetNumSlabs());
39  Alloc.Allocate(3000, 0);
40  EXPECT_EQ(2U, Alloc.GetNumSlabs());
41  Alloc.Allocate(3000, 0);
42  EXPECT_EQ(3U, Alloc.GetNumSlabs());
43}
44
45// Allocate enough bytes to create two slabs, reset the allocator, and do it
46// again.
47TEST(AllocatorTest, TestReset) {
48  BumpPtrAllocator Alloc(4096, 4096);
49  Alloc.Allocate(3000, 0);
50  EXPECT_EQ(1U, Alloc.GetNumSlabs());
51  Alloc.Allocate(3000, 0);
52  EXPECT_EQ(2U, Alloc.GetNumSlabs());
53  Alloc.Reset();
54  EXPECT_EQ(1U, Alloc.GetNumSlabs());
55  Alloc.Allocate(3000, 0);
56  EXPECT_EQ(1U, Alloc.GetNumSlabs());
57  Alloc.Allocate(3000, 0);
58  EXPECT_EQ(2U, Alloc.GetNumSlabs());
59}
60
61// Test some allocations at varying alignments.
62TEST(AllocatorTest, TestAlignment) {
63  BumpPtrAllocator Alloc;
64  uintptr_t a;
65  a = (uintptr_t)Alloc.Allocate(1, 2);
66  EXPECT_EQ(0U, a & 1);
67  a = (uintptr_t)Alloc.Allocate(1, 4);
68  EXPECT_EQ(0U, a & 3);
69  a = (uintptr_t)Alloc.Allocate(1, 8);
70  EXPECT_EQ(0U, a & 7);
71  a = (uintptr_t)Alloc.Allocate(1, 16);
72  EXPECT_EQ(0U, a & 15);
73  a = (uintptr_t)Alloc.Allocate(1, 32);
74  EXPECT_EQ(0U, a & 31);
75  a = (uintptr_t)Alloc.Allocate(1, 64);
76  EXPECT_EQ(0U, a & 63);
77  a = (uintptr_t)Alloc.Allocate(1, 128);
78  EXPECT_EQ(0U, a & 127);
79}
80
81// Test allocating just over the slab size.  This tests a bug where before the
82// allocator incorrectly calculated the buffer end pointer.
83TEST(AllocatorTest, TestOverflow) {
84  BumpPtrAllocator Alloc(4096, 4096);
85
86  // Fill the slab right up until the end pointer.
87  Alloc.Allocate(4096 - sizeof(MemSlab), 0);
88  EXPECT_EQ(1U, Alloc.GetNumSlabs());
89
90  // If we don't allocate a new slab, then we will have overflowed.
91  Alloc.Allocate(1, 0);
92  EXPECT_EQ(2U, Alloc.GetNumSlabs());
93}
94
95// Test allocating with a size larger than the initial slab size.
96TEST(AllocatorTest, TestSmallSlabSize) {
97  BumpPtrAllocator Alloc(128);
98
99  Alloc.Allocate(200, 0);
100  EXPECT_EQ(2U, Alloc.GetNumSlabs());
101}
102
103// Mock slab allocator that returns slabs aligned on 4096 bytes.  There is no
104// easy portable way to do this, so this is kind of a hack.
105class MockSlabAllocator : public SlabAllocator {
106  MemSlab *LastSlab;
107
108public:
109  virtual ~MockSlabAllocator() { }
110
111  virtual MemSlab *Allocate(size_t Size) {
112    // Allocate space for the alignment, the slab, and a void* that goes right
113    // before the slab.
114    size_t Alignment = 4096;
115    void *MemBase = malloc(Size + Alignment - 1 + sizeof(void*));
116
117    // Make the slab.
118    MemSlab *Slab = (MemSlab*)(((uintptr_t)MemBase+sizeof(void*)+Alignment-1) &
119                               ~(uintptr_t)(Alignment - 1));
120    Slab->Size = Size;
121    Slab->NextPtr = 0;
122
123    // Hold a pointer to the base so we can free the whole malloced block.
124    ((void**)Slab)[-1] = MemBase;
125
126    LastSlab = Slab;
127    return Slab;
128  }
129
130  virtual void Deallocate(MemSlab *Slab) {
131    free(((void**)Slab)[-1]);
132  }
133
134  MemSlab *GetLastSlab() {
135    return LastSlab;
136  }
137};
138
139// Allocate a large-ish block with a really large alignment so that the
140// allocator will think that it has space, but after it does the alignment it
141// will not.
142TEST(AllocatorTest, TestBigAlignment) {
143  MockSlabAllocator SlabAlloc;
144  BumpPtrAllocator Alloc(4096, 4096, SlabAlloc);
145  uintptr_t Ptr = (uintptr_t)Alloc.Allocate(3000, 2048);
146  MemSlab *Slab = SlabAlloc.GetLastSlab();
147  EXPECT_LE(Ptr + 3000, ((uintptr_t)Slab) + Slab->Size);
148}
149
150}  // anonymous namespace
151