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 
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.
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.
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.
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.
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 dont'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:
102   virtual ~MockSlabAllocator() { }
103 
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 + 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 
123   virtual void Deallocate(MemSlab *Slab) {
124     free(((void**)Slab)[-1]);
125   }
126 
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.
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