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
14 using namespace llvm;
15
16 namespace {
17
TEST(AllocatorTest,Basics)18 TEST(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.
TEST(AllocatorTest,ThreeSlabs)35 TEST(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.
TEST(AllocatorTest,TestReset)47 TEST(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.
TEST(AllocatorTest,TestAlignment)62 TEST(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.
TEST(AllocatorTest,TestOverflow)83 TEST(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.
TEST(AllocatorTest,TestSmallSlabSize)96 TEST(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.
105 class MockSlabAllocator : public SlabAllocator {
106 MemSlab *LastSlab;
107
108 public:
~MockSlabAllocator()109 virtual ~MockSlabAllocator() { }
110
Allocate(size_t Size)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
Deallocate(MemSlab * Slab)130 virtual void Deallocate(MemSlab *Slab) {
131 free(((void**)Slab)[-1]);
132 }
133
GetLastSlab()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.
TEST(AllocatorTest,TestBigAlignment)142 TEST(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