[llvm] [Support] Recycler: Enforce minimum allocation size (PR #121425)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,46 @@
+//===--- unittest/Support/RecyclerTest.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Recycler.h"
+#include "llvm/Support/AllocatorBase.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+struct Object1 {
+  char Data[1];
+};
+
+class DecoratedMallocAllocator : public MallocAllocator {
+public:
+  int DeallocCount = 0;
+
+  template <typename T> void Deallocate(T *Ptr) {
+    DeallocCount++;
+    MallocAllocator::Deallocate(Ptr);
+  }
+};
+
+TEST(RecyclerTest, RecycleAllocation) {
+  DecoratedMallocAllocator Allocator;
+  // Recycler needs size to be atleast 8 bytes.
+  Recycler<Object1, 8, 8> R;
+  Object1 *A1 = R.Allocate(Allocator);
+  Object1 *A2 = R.Allocate(Allocator);
+  R.Deallocate(Allocator, A2);
+  Object1 *A3 = R.Allocate(Allocator);
+  EXPECT_EQ(A2, A3); // reuse the deallocated object.
+  R.Deallocate(Allocator, A1);
+  R.Deallocate(Allocator, A3);
+  R.clear(Allocator); // Should deallocate A1 and A3.
+  EXPECT_EQ(Allocator.DeallocCount, 2);
+}
+
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arsenm wrote:

Is there a way to test the static_assert fails in the < 8 case? 

https://github.com/llvm/llvm-project/pull/121425