[llvm] [offload] Document and assert allocation alignment guarantee (PR #223381)

[Łukasz Plewa via llvm-commits]

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@@ -35,6 +35,21 @@ TEST_P(olMemAllocAllocTypesTest, Success) {
   olMemFree(Alloc);
 }
 
+TEST_P(olMemAllocAllocTypesTest, SuccessSmallSizesWordSizeAlignment) {
+  const size_t Sizes[] = {1, 2, 3, 4, 5, 6, 7, 8, 14};
+  for (size_t Size : Sizes) {
+    SCOPED_TRACE("size: " + std::to_string(Size));
+    void *Alloc = nullptr;
+    ASSERT_SUCCESS(allocateDeviceOrHost(Size, &Alloc));
+    ASSERT_NE(Alloc, nullptr);
+
+    // Check word-size alignment without requesting explicit alignment.
+    EXPECT_EQ(reinterpret_cast<uintptr_t>(Alloc) % alignof(uintptr_t), 0U);
+
+    ASSERT_SUCCESS(olMemFree(Alloc));
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lplewa wrote:

please do free in separate loop after all allocations. 
In this implementation we are probably getting the same ptr after each allocation (as it is cached in memory manager).

https://github.com/llvm/llvm-project/pull/223381