unittests/Support/AllocatorTest.cpp

   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 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:
 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+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
 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