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
12 #include "gtest/gtest.h"
13 #include <cstdlib>
14
15 using namespace llvm;
16
17 namespace {
18
TEST(AllocatorTest,Basics)19 TEST(AllocatorTest, Basics) {
20 BumpPtrAllocator Alloc;
21 int *a = (int*)Alloc.Allocate(sizeof(int), 0);
22 int *b = (int*)Alloc.Allocate(sizeof(int) * 10, 0);
23 int *c = (int*)Alloc.Allocate(sizeof(int), 0);
24 *a = 1;
25 b[0] = 2;
26 b[9] = 2;
27 *c = 3;
28 EXPECT_EQ(1, *a);
29 EXPECT_EQ(2, b[0]);
30 EXPECT_EQ(2, b[9]);
31 EXPECT_EQ(3, *c);
32 EXPECT_EQ(1U, Alloc.GetNumSlabs());
33 }
34
35 // Allocate enough bytes to create three slabs.
TEST(AllocatorTest,ThreeSlabs)36 TEST(AllocatorTest, ThreeSlabs) {
37 BumpPtrAllocator Alloc(4096, 4096);
38 Alloc.Allocate(3000, 0);
39 EXPECT_EQ(1U, Alloc.GetNumSlabs());
40 Alloc.Allocate(3000, 0);
41 EXPECT_EQ(2U, Alloc.GetNumSlabs());
42 Alloc.Allocate(3000, 0);
43 EXPECT_EQ(3U, Alloc.GetNumSlabs());
44 }
45
46 // Allocate enough bytes to create two slabs, reset the allocator, and do it
47 // again.
TEST(AllocatorTest,TestReset)48 TEST(AllocatorTest, TestReset) {
49 BumpPtrAllocator Alloc(4096, 4096);
50 Alloc.Allocate(3000, 0);
51 EXPECT_EQ(1U, Alloc.GetNumSlabs());
52 Alloc.Allocate(3000, 0);
53 EXPECT_EQ(2U, Alloc.GetNumSlabs());
54 Alloc.Reset();
55 EXPECT_EQ(1U, Alloc.GetNumSlabs());
56 Alloc.Allocate(3000, 0);
57 EXPECT_EQ(1U, Alloc.GetNumSlabs());
58 Alloc.Allocate(3000, 0);
59 EXPECT_EQ(2U, Alloc.GetNumSlabs());
60 }
61
62 // Test some allocations at varying alignments.
TEST(AllocatorTest,TestAlignment)63 TEST(AllocatorTest, TestAlignment) {
64 BumpPtrAllocator Alloc;
65 uintptr_t a;
66 a = (uintptr_t)Alloc.Allocate(1, 2);
67 EXPECT_EQ(0U, a & 1);
68 a = (uintptr_t)Alloc.Allocate(1, 4);
69 EXPECT_EQ(0U, a & 3);
70 a = (uintptr_t)Alloc.Allocate(1, 8);
71 EXPECT_EQ(0U, a & 7);
72 a = (uintptr_t)Alloc.Allocate(1, 16);
73 EXPECT_EQ(0U, a & 15);
74 a = (uintptr_t)Alloc.Allocate(1, 32);
75 EXPECT_EQ(0U, a & 31);
76 a = (uintptr_t)Alloc.Allocate(1, 64);
77 EXPECT_EQ(0U, a & 63);
78 a = (uintptr_t)Alloc.Allocate(1, 128);
79 EXPECT_EQ(0U, a & 127);
80 }
81
82 // Test allocating just over the slab size. This tests a bug where before the
83 // allocator incorrectly calculated the buffer end pointer.
TEST(AllocatorTest,TestOverflow)84 TEST(AllocatorTest, TestOverflow) {
85 BumpPtrAllocator Alloc(4096, 4096);
86
87 // Fill the slab right up until the end pointer.
88 Alloc.Allocate(4096 - sizeof(MemSlab), 0);
89 EXPECT_EQ(1U, Alloc.GetNumSlabs());
90
91 // If we don't allocate a new slab, then we will have overflowed.
92 Alloc.Allocate(1, 0);
93 EXPECT_EQ(2U, Alloc.GetNumSlabs());
94 }
95
96 // Mock slab allocator that returns slabs aligned on 4096 bytes. There is no
97 // easy portable way to do this, so this is kind of a hack.
98 class MockSlabAllocator : public SlabAllocator {
99 MemSlab *LastSlab;
100
101 public:
~MockSlabAllocator()102 virtual ~MockSlabAllocator() { }
103
Allocate(size_t Size)104 virtual MemSlab *Allocate(size_t Size) {
105 // Allocate space for the alignment, the slab, and a void* that goes right
106 // before the slab.
107 size_t Alignment = 4096;
108 void *MemBase = malloc(Size + Alignment - 1 + sizeof(void*));
109
110 // Make the slab.
111 MemSlab *Slab = (MemSlab*)(((uintptr_t)MemBase+sizeof(void*)+Alignment-1) &
112 ~(uintptr_t)(Alignment - 1));
113 Slab->Size = Size;
114 Slab->NextPtr = 0;
115
116 // Hold a pointer to the base so we can free the whole malloced block.
117 ((void**)Slab)[-1] = MemBase;
118
119 LastSlab = Slab;
120 return Slab;
121 }
122
Deallocate(MemSlab * Slab)123 virtual void Deallocate(MemSlab *Slab) {
124 free(((void**)Slab)[-1]);
125 }
126
GetLastSlab()127 MemSlab *GetLastSlab() {
128 return LastSlab;
129 }
130 };
131
132 // Allocate a large-ish block with a really large alignment so that the
133 // allocator will think that it has space, but after it does the alignment it
134 // will not.
TEST(AllocatorTest,TestBigAlignment)135 TEST(AllocatorTest, TestBigAlignment) {
136 MockSlabAllocator SlabAlloc;
137 BumpPtrAllocator Alloc(4096, 4096, SlabAlloc);
138 uintptr_t Ptr = (uintptr_t)Alloc.Allocate(3000, 2048);
139 MemSlab *Slab = SlabAlloc.GetLastSlab();
140 EXPECT_LE(Ptr + 3000, ((uintptr_t)Slab) + Slab->Size);
141 }
142
143 } // anonymous namespace
144