[XRay] Add a test for allocator exhaustion

Use a more representative test of allocating small chunks for
oddly-sized (small) objects from an allocator that has a page's worth of
memory.

llvm-svn: 347286

1 files changed, 19 insertions, 1 deletions

diff --git a/compiler-rt/lib/xray/tests/unit/allocator_test.cc b/compiler-rt/lib/xray/tests/unit/allocator_test.cc
index be404160e41..0177798b069 100644
--- a/compiler-rt/lib/xray/tests/unit/allocator_test.cc
+++ b/compiler-rt/lib/xray/tests/unit/allocator_test.cc
@@ -33,10 +33,28 @@ TEST(AllocatorTest, Allocate) {
 TEST(AllocatorTest, OverAllocate) {
   Allocator<sizeof(TestData)> A(sizeof(TestData));
   auto B1 = A.Allocate();
-  (void)B1;
+  ASSERT_NE(B1.Data, nullptr);
   auto B2 = A.Allocate();
   ASSERT_EQ(B2.Data, nullptr);
 }
 
+struct OddSizedData {
+  s64 A;
+  s32 B;
+};
+
+TEST(AllocatorTest, AllocateBoundaries) {
+  Allocator<sizeof(OddSizedData)> A(GetPageSizeCached());
+
+  // Keep allocating until we hit a nullptr block.
+  unsigned C = 0;
+  auto Expected =
+      GetPageSizeCached() / RoundUpTo(sizeof(OddSizedData), kCacheLineSize);
+  for (auto B = A.Allocate(); B.Data != nullptr; B = A.Allocate(), ++C)
+    ;
+
+  ASSERT_EQ(C, Expected);
+}
+
 } // namespace
 } // namespace __xray