[llvm-commits] [llvm] r171581 - in /llvm/trunk: include/llvm/Support/ArrayRecycler.h unittests/Support/ArrayRecylerTest.cpp unittests/Support/CMakeLists.txt
Jakob Stoklund Olesen
stoklund at 2pi.dk
Fri Jan 4 16:57:12 PST 2013
Author: stoklund
Date: Fri Jan 4 18:57:11 2013
New Revision: 171581
URL: http://llvm.org/viewvc/llvm-project?rev=171581&view=rev
Log:
Add an ArrayRecycler class.
This is similar to the existing Recycler allocator, but instead of
recycling individual objects from a BumpPtrAllocator, arrays of
different sizes can be allocated.
Added:
llvm/trunk/include/llvm/Support/ArrayRecycler.h
llvm/trunk/unittests/Support/ArrayRecylerTest.cpp
Modified:
llvm/trunk/unittests/Support/CMakeLists.txt
Added: llvm/trunk/include/llvm/Support/ArrayRecycler.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/ArrayRecycler.h?rev=171581&view=auto
==============================================================================
--- llvm/trunk/include/llvm/Support/ArrayRecycler.h (added)
+++ llvm/trunk/include/llvm/Support/ArrayRecycler.h Fri Jan 4 18:57:11 2013
@@ -0,0 +1,143 @@
+//==- llvm/Support/ArrayRecycler.h - Recycling of Arrays ---------*- C++ -*-==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the ArrayRecycler class template which can recycle small
+// arrays allocated from one of the allocators in Allocator.h
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_ARRAY_RECYCLER_H
+#define LLVM_SUPPORT_ARRAY_RECYCLER_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/MathExtras.h"
+
+namespace llvm {
+
+class BumpPtrAllocator;
+
+/// Recycle small arrays allocated from a BumpPtrAllocator.
+///
+/// Arrays are allocated in a small number of fixed sizes. For each supported
+/// array size, the ArrayRecycler keeps a free list of available arrays.
+///
+template<class T, size_t Align = AlignOf<T>::Alignment>
+class ArrayRecycler {
+ // The free list for a given array size is a simple singly linked list.
+ // We can't use iplist or Recycler here since those classes can't be copied.
+ struct FreeList {
+ FreeList *Next;
+ };
+
+ // Keep a free list for each array size.
+ SmallVector<FreeList*, 8> Bucket;
+
+ // Remove an entry from the free list in Bucket[Idx] and return it.
+ // Return NULL if no entries are available.
+ T *pop(unsigned Idx) {
+ if (Idx >= Bucket.size())
+ return 0;
+ FreeList *Entry = Bucket[Idx];
+ if (!Entry)
+ return 0;
+ Bucket[Idx] = Entry->Next;
+ return reinterpret_cast<T*>(Entry);
+ }
+
+ // Add an entry to the free list at Bucket[Idx].
+ void push(unsigned Idx, T *Ptr) {
+ assert(Ptr && "Cannot recycle NULL pointer");
+ assert(sizeof(T) >= sizeof(FreeList) && "Objects are too small");
+ assert(Align >= AlignOf<FreeList>::Alignment && "Object underaligned");
+ FreeList *Entry = reinterpret_cast<FreeList*>(Ptr);
+ if (Idx >= Bucket.size())
+ Bucket.resize(size_t(Idx) + 1);
+ Entry->Next = Bucket[Idx];
+ Bucket[Idx] = Entry;
+ }
+
+public:
+ /// The size of an allocated array is represented by a Capacity instance.
+ ///
+ /// This class is much smaller than a size_t, and it provides methods to work
+ /// with the set of legal array capacities.
+ class Capacity {
+ uint8_t Index;
+ explicit Capacity(uint8_t idx) : Index(idx) {}
+
+ public:
+ Capacity() : Index(0) {}
+
+ /// Get the capacity of an array that can hold at least N elements.
+ static Capacity get(size_t N) {
+ return Capacity(N ? Log2_64_Ceil(N) : 0);
+ }
+
+ /// Get the number of elements in an array with this capacity.
+ size_t getSize() const { return size_t(1u) << Index; }
+
+ /// Get the bucket number for this capacity.
+ unsigned getBucket() const { return Index; }
+
+ /// Get the next larger capacity. Large capacities grow exponentially, so
+ /// this function can be used to reallocate incrementally growing vectors
+ /// in amortized linear time.
+ Capacity getNext() const { return Capacity(Index + 1); }
+ };
+
+ ~ArrayRecycler() {
+ // The client should always call clear() so recycled arrays can be returned
+ // to the allocator.
+ assert(Bucket.empty() && "Non-empty ArrayRecycler deleted!");
+ }
+
+ /// Release all the tracked allocations to the allocator. The recycler must
+ /// be free of any tracked allocations before being deleted.
+ template<class AllocatorType>
+ void clear(AllocatorType &Allocator) {
+ for (; !Bucket.empty(); Bucket.pop_back())
+ while (T *Ptr = pop(Bucket.size() - 1))
+ Allocator.Deallocate(Ptr);
+ }
+
+ /// Special case for BumpPtrAllocator which has an empty Deallocate()
+ /// function.
+ ///
+ /// There is no need to traverse the free lists, pulling all the objects into
+ /// cache.
+ void clear(BumpPtrAllocator&) {
+ Bucket.clear();
+ }
+
+ /// Allocate an array of at least the requested capacity.
+ ///
+ /// Return an existing recycled array, or allocate one from Allocator if
+ /// none are available for recycling.
+ ///
+ template<class AllocatorType>
+ T *allocate(Capacity Cap, AllocatorType &Allocator) {
+ // Try to recycle an existing array.
+ if (T *Ptr = pop(Cap.getBucket()))
+ return Ptr;
+ // Nope, get more memory.
+ return static_cast<T*>(Allocator.Allocate(sizeof(T)*Cap.getSize(), Align));
+ }
+
+ /// Deallocate an array with the specified Capacity.
+ ///
+ /// Cap must be the same capacity that was given to allocate().
+ ///
+ void deallocate(Capacity Cap, T *Ptr) {
+ push(Cap.getBucket(), Ptr);
+ }
+};
+
+} // end llvm namespace
+
+#endif
Added: llvm/trunk/unittests/Support/ArrayRecylerTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/ArrayRecylerTest.cpp?rev=171581&view=auto
==============================================================================
--- llvm/trunk/unittests/Support/ArrayRecylerTest.cpp (added)
+++ llvm/trunk/unittests/Support/ArrayRecylerTest.cpp Fri Jan 4 18:57:11 2013
@@ -0,0 +1,109 @@
+//===--- unittest/Support/ArrayRecyclerTest.cpp ---------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/ArrayRecycler.h"
+#include "llvm/Support/Allocator.h"
+#include "gtest/gtest.h"
+#include <cstdlib>
+
+using namespace llvm;
+
+namespace {
+
+struct Object {
+ int Num;
+ Object *Other;
+};
+typedef ArrayRecycler<Object> ARO;
+
+TEST(ArrayRecyclerTest, Capacity) {
+ // Capacity size should never be 0.
+ ARO::Capacity Cap = ARO::Capacity::get(0);
+ EXPECT_LT(0u, Cap.getSize());
+
+ size_t PrevSize = Cap.getSize();
+ for (unsigned N = 1; N != 100; ++N) {
+ Cap = ARO::Capacity::get(N);
+ EXPECT_LE(N, Cap.getSize());
+ if (PrevSize >= N)
+ EXPECT_EQ(PrevSize, Cap.getSize());
+ else
+ EXPECT_LT(PrevSize, Cap.getSize());
+ PrevSize = Cap.getSize();
+ }
+
+ // Check that the buckets are monotonically increasing.
+ Cap = ARO::Capacity::get(0);
+ PrevSize = Cap.getSize();
+ for (unsigned N = 0; N != 20; ++N) {
+ Cap = Cap.getNext();
+ EXPECT_LT(PrevSize, Cap.getSize());
+ PrevSize = Cap.getSize();
+ }
+}
+
+TEST(ArrayRecyclerTest, Basics) {
+ BumpPtrAllocator Allocator;
+ ArrayRecycler<Object> DUT;
+
+ ARO::Capacity Cap = ARO::Capacity::get(8);
+ Object *A1 = DUT.allocate(Cap, Allocator);
+ A1[0].Num = 21;
+ A1[7].Num = 17;
+
+ Object *A2 = DUT.allocate(Cap, Allocator);
+ A2[0].Num = 121;
+ A2[7].Num = 117;
+
+ Object *A3 = DUT.allocate(Cap, Allocator);
+ A3[0].Num = 221;
+ A3[7].Num = 217;
+
+ EXPECT_EQ(21, A1[0].Num);
+ EXPECT_EQ(17, A1[7].Num);
+ EXPECT_EQ(121, A2[0].Num);
+ EXPECT_EQ(117, A2[7].Num);
+ EXPECT_EQ(221, A3[0].Num);
+ EXPECT_EQ(217, A3[7].Num);
+
+ DUT.deallocate(Cap, A2);
+
+ // Check that deallocation didn't clobber anything.
+ EXPECT_EQ(21, A1[0].Num);
+ EXPECT_EQ(17, A1[7].Num);
+ EXPECT_EQ(221, A3[0].Num);
+ EXPECT_EQ(217, A3[7].Num);
+
+ // Verify recycling.
+ Object *A2x = DUT.allocate(Cap, Allocator);
+ EXPECT_EQ(A2, A2x);
+
+ DUT.deallocate(Cap, A2x);
+ DUT.deallocate(Cap, A1);
+ DUT.deallocate(Cap, A3);
+
+ // Objects are not required to be recycled in reverse deallocation order, but
+ // that is what the current implementation does.
+ Object *A3x = DUT.allocate(Cap, Allocator);
+ EXPECT_EQ(A3, A3x);
+ Object *A1x = DUT.allocate(Cap, Allocator);
+ EXPECT_EQ(A1, A1x);
+ Object *A2y = DUT.allocate(Cap, Allocator);
+ EXPECT_EQ(A2, A2y);
+
+ // Back to allocation from the BumpPtrAllocator.
+ Object *A4 = DUT.allocate(Cap, Allocator);
+ EXPECT_NE(A1, A4);
+ EXPECT_NE(A2, A4);
+ EXPECT_NE(A3, A4);
+
+ DUT.clear(Allocator);
+}
+
+} // end anonymous namespace
Modified: llvm/trunk/unittests/Support/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/CMakeLists.txt?rev=171581&r1=171580&r2=171581&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/CMakeLists.txt (original)
+++ llvm/trunk/unittests/Support/CMakeLists.txt Fri Jan 4 18:57:11 2013
@@ -6,6 +6,7 @@
add_llvm_unittest(SupportTests
AlignOfTest.cpp
AllocatorTest.cpp
+ ArrayRecyclerTest.cpp
BlockFrequencyTest.cpp
Casting.cpp
CommandLineTest.cpp
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