Add ADT/IntervalMap.

This is a sorted interval map data structure for small keys and values with
automatic coalescing and bidirectional iteration over coalesced intervals.

Except for coalescing intervals, it provides similar functionality to std::map.
It is however much more compact for small keys and values, and hopefully faster
too.

The container object itself can hold the first few intervals without any
allocations, then it switches to a cache conscious B+-tree representation. A
recycling allocator can be shared between many containers, even between
containers holding different types.

The IntervalMap is initially intended to be used with SlotIndex intervals for:

- Backing store for LiveIntervalUnion that is smaller and faster than std::set.

- Backing store for LiveInterval with less overhead than std::vector for typical
  intervals and O(N log N) merging of large intervals. 99% of virtual registers
  need 4 entries or less and would benefit from the small object optimization.

- Backing store for LiveDebugVariable which doesn't exist yet, but will track
  debug variables during register allocation.

This is a work in progress. Missing items are:

- Performance metrics.
- erase().
- insert() shrinkage.
- clear().
- More performance metrics.
- Simplification and detemplatization.

llvm-svn: 119772

llvm/lib/Support/CMakeLists.txt

@@ -19,6 +19,7 @@ add_llvm_library(LLVMSupport
   FoldingSet.cpp
   FormattedStream.cpp
   GraphWriter.cpp
+  IntervalMap.cpp
   IsInf.cpp
   IsNAN.cpp
   ManagedStatic.cpp

llvm/lib/Support/IntervalMap.cpp

@@ -0,0 +1,60 @@
+//===- lib/Support/IntervalMap.cpp - A sorted interval map ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the few non-templated functions in IntervalMap.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/IntervalMap.h"
+
+namespace llvm {
+namespace IntervalMapImpl {
+
+IdxPair distribute(unsigned Nodes, unsigned Elements, unsigned Capacity,
+                   const unsigned *CurSize, unsigned NewSize[],
+                   unsigned Position, bool Grow) {
+  assert(Elements + Grow <= Nodes * Capacity && "Not enough room for elements");
+  assert(Position <= Elements && "Invalid position");
+  if (!Nodes)
+    return IdxPair();
+
+  // Trivial algorithm: left-leaning even distribution.
+  const unsigned PerNode = (Elements + Grow) / Nodes;
+  const unsigned Extra = (Elements + Grow) % Nodes;
+  IdxPair PosPair = IdxPair(Nodes, 0);
+  unsigned Sum = 0;
+  for (unsigned n = 0; n != Nodes; ++n) {
+    Sum += NewSize[n] = PerNode + (n < Extra);
+    if (PosPair.first == Nodes && Sum > Position)
+      PosPair = IdxPair(n, Position - (Sum - NewSize[n]));
+  }
+  assert(Sum == Elements + Grow && "Bad distribution sum");
+
+  // Subtract the Grow element that was added.
+  if (Grow) {
+    assert(PosPair.first < Nodes && "Bad algebra");
+    assert(NewSize[PosPair.first] && "Too few elements to need Grow");
+    --NewSize[PosPair.first];
+  }
+
+#ifndef NDEBUG
+  Sum = 0;
+  for (unsigned n = 0; n != Nodes; ++n) {
+    assert(NewSize[n] <= Capacity && "Overallocated node");
+    Sum += NewSize[n];
+  }
+  assert(Sum == Elements && "Bad distribution sum");
+#endif
+
+  return PosPair;
+}
+
+} // namespace IntervalMapImpl
+} // namespace llvm 
+

llvm/unittests/ADT/IntervalMapTest.cpp

@@ -0,0 +1,357 @@
+//===---- ADT/IntervalMapTest.cpp - IntervalMap unit tests ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/IntervalMap.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+typedef IntervalMap<unsigned, unsigned> UUMap;
+
+// Empty map tests
+TEST(IntervalMapTest, EmptyMap) {
+  UUMap::Allocator allocator;
+  UUMap map(allocator);
+  EXPECT_TRUE(map.empty());
+
+  // Lookup on empty map.
+  EXPECT_EQ(0u, map.lookup(0));
+  EXPECT_EQ(7u, map.lookup(0, 7));
+  EXPECT_EQ(0u, map.lookup(~0u-1));
+  EXPECT_EQ(7u, map.lookup(~0u-1, 7));
+
+  // Iterators.
+  EXPECT_TRUE(map.begin() == map.begin());
+  EXPECT_TRUE(map.begin() == map.end());
+  EXPECT_TRUE(map.end() == map.end());
+  EXPECT_FALSE(map.begin() != map.begin());
+  EXPECT_FALSE(map.begin() != map.end());
+  EXPECT_FALSE(map.end() != map.end());
+  EXPECT_FALSE(map.begin().valid());
+  EXPECT_FALSE(map.end().valid());
+  UUMap::iterator I = map.begin();
+  EXPECT_FALSE(I.valid());
+  EXPECT_TRUE(I == map.end());
+}
+
+// Single entry map tests
+TEST(IntervalMapTest, SingleEntryMap) {
+  UUMap::Allocator allocator;
+  UUMap map(allocator);
+  map.insert(100, 150, 1);
+  EXPECT_FALSE(map.empty());
+
+  // Lookup around interval.
+  EXPECT_EQ(0u, map.lookup(0));
+  EXPECT_EQ(0u, map.lookup(99));
+  EXPECT_EQ(1u, map.lookup(100));
+  EXPECT_EQ(1u, map.lookup(101));
+  EXPECT_EQ(1u, map.lookup(125));
+  EXPECT_EQ(1u, map.lookup(149));
+  EXPECT_EQ(1u, map.lookup(150));
+  EXPECT_EQ(0u, map.lookup(151));
+  EXPECT_EQ(0u, map.lookup(200));
+  EXPECT_EQ(0u, map.lookup(~0u-1));
+
+  // Iterators.
+  EXPECT_TRUE(map.begin() == map.begin());
+  EXPECT_FALSE(map.begin() == map.end());
+  EXPECT_TRUE(map.end() == map.end());
+  EXPECT_TRUE(map.begin().valid());
+  EXPECT_FALSE(map.end().valid());
+
+  // Iter deref.
+  UUMap::iterator I = map.begin();
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(100u, I.start());
+  EXPECT_EQ(150u, I.stop());
+  EXPECT_EQ(1u, I.value());
+
+  // Preincrement.
+  ++I;
+  EXPECT_FALSE(I.valid());
+  EXPECT_FALSE(I == map.begin());
+  EXPECT_TRUE(I == map.end());
+
+  // PreDecrement.
+  --I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(100u, I.start());
+  EXPECT_EQ(150u, I.stop());
+  EXPECT_EQ(1u, I.value());
+  EXPECT_TRUE(I == map.begin());
+  EXPECT_FALSE(I == map.end());
+}
+
+// Flat coalescing tests.
+TEST(IntervalMapTest, RootCoalescing) {
+  UUMap::Allocator allocator;
+  UUMap map(allocator);
+  map.insert(100, 150, 1);
+
+  // Coalesce from the left.
+  map.insert(90, 99, 1);
+  EXPECT_EQ(1, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(90u, map.start());
+  EXPECT_EQ(150u, map.stop());
+
+  // Overlap left.
+  map.insert(80, 100, 1);
+  EXPECT_EQ(1, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(80u, map.start());
+  EXPECT_EQ(150u, map.stop());
+
+  // Inside.
+  map.insert(100, 130, 1);
+  EXPECT_EQ(1, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(80u, map.start());
+  EXPECT_EQ(150u, map.stop());
+
+  // Overlap both.
+  map.insert(70, 160, 1);
+  EXPECT_EQ(1, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(70u, map.start());
+  EXPECT_EQ(160u, map.stop());
+
+  // Overlap right.
+  map.insert(80, 170, 1);
+  EXPECT_EQ(1, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(70u, map.start());
+  EXPECT_EQ(170u, map.stop());
+
+  // Coalesce from the right.
+  map.insert(170, 200, 1);
+  EXPECT_EQ(1, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(70u, map.start());
+  EXPECT_EQ(200u, map.stop());
+
+  // Non-coalesce from the left.
+  map.insert(60, 69, 2);
+  EXPECT_EQ(2, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(60u, map.start());
+  EXPECT_EQ(200u, map.stop());
+  EXPECT_EQ(2u, map.lookup(69));
+  EXPECT_EQ(1u, map.lookup(70));
+
+  UUMap::iterator I = map.begin();
+  EXPECT_EQ(60u, I.start());
+  EXPECT_EQ(69u, I.stop());
+  EXPECT_EQ(2u, I.value());
+  ++I;
+  EXPECT_EQ(70u, I.start());
+  EXPECT_EQ(200u, I.stop());
+  EXPECT_EQ(1u, I.value());
+  ++I;
+  EXPECT_FALSE(I.valid());
+
+  // Non-coalesce from the right.
+  map.insert(201, 210, 2);
+  EXPECT_EQ(3, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(60u, map.start());
+  EXPECT_EQ(210u, map.stop());
+  EXPECT_EQ(2u, map.lookup(201));
+  EXPECT_EQ(1u, map.lookup(200));
+}
+
+// Flat multi-coalescing tests.
+TEST(IntervalMapTest, RootMultiCoalescing) {
+  UUMap::Allocator allocator;
+  UUMap map(allocator);
+  map.insert(140, 150, 1);
+  map.insert(160, 170, 1);
+  map.insert(100, 110, 1);
+  map.insert(120, 130, 1);
+  EXPECT_EQ(4, std::distance(map.begin(), map.end()));
+  EXPECT_EQ(100u, map.start());
+  EXPECT_EQ(170u, map.stop());
+
+  // Verify inserts.
+  UUMap::iterator I = map.begin();
+  EXPECT_EQ(100u, I.start());
+  EXPECT_EQ(110u, I.stop());
+  ++I;
+  EXPECT_EQ(120u, I.start());
+  EXPECT_EQ(130u, I.stop());
+  ++I;
+  EXPECT_EQ(140u, I.start());
+  EXPECT_EQ(150u, I.stop());
+  ++I;
+  EXPECT_EQ(160u, I.start());
+  EXPECT_EQ(170u, I.stop());
+  ++I;
+  EXPECT_FALSE(I.valid());
+
+
+  // Coalesce left with followers.
+  // [100;110] [120;130] [140;150] [160;170]
+  map.insert(111, 115, 1);
+  I = map.begin();
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(100u, I.start());
+  EXPECT_EQ(115u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(120u, I.start());
+  EXPECT_EQ(130u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(140u, I.start());
+  EXPECT_EQ(150u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(160u, I.start());
+  EXPECT_EQ(170u, I.stop());
+  ++I;
+  EXPECT_FALSE(I.valid());
+
+  // Coalesce right with followers.
+  // [100;115] [120;130] [140;150] [160;170]
+  map.insert(135, 139, 1);
+  I = map.begin();
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(100u, I.start());
+  EXPECT_EQ(115u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(120u, I.start());
+  EXPECT_EQ(130u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(135u, I.start());
+  EXPECT_EQ(150u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(160u, I.start());
+  EXPECT_EQ(170u, I.stop());
+  ++I;
+  EXPECT_FALSE(I.valid());
+
+  // Coalesce left and right with followers.
+  // [100;115] [120;130] [135;150] [160;170]
+  map.insert(131, 134, 1);
+  I = map.begin();
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(100u, I.start());
+  EXPECT_EQ(115u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(120u, I.start());
+  EXPECT_EQ(150u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(160u, I.start());
+  EXPECT_EQ(170u, I.stop());
+  ++I;
+  EXPECT_FALSE(I.valid());
+
+  // Coalesce multiple with overlap right.
+  // [100;115] [120;150] [160;170]
+  map.insert(116, 165, 1);
+  I = map.begin();
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(100u, I.start());
+  EXPECT_EQ(170u, I.stop());
+  ++I;
+  EXPECT_FALSE(I.valid());
+
+  // Coalesce multiple with overlap left
+  // [100;170]
+  map.insert(180, 190, 1);
+  map.insert(200, 210, 1);
+  map.insert(220, 230, 1);
+  // [100;170] [180;190] [200;210] [220;230]
+  map.insert(160, 199, 1);
+  I = map.begin();
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(100u, I.start());
+  EXPECT_EQ(210u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(220u, I.start());
+  EXPECT_EQ(230u, I.stop());
+  ++I;
+  EXPECT_FALSE(I.valid());
+
+  // Overwrite 2 from gap to gap.
+  // [100;210] [220;230]
+  map.insert(50, 250, 1);
+  I = map.begin();
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(50u, I.start());
+  EXPECT_EQ(250u, I.stop());
+  ++I;
+  EXPECT_FALSE(I.valid());
+
+  // Coalesce at end of full root.
+  // [50;250]
+  map.insert(260, 270, 1);
+  map.insert(280, 290, 1);
+  map.insert(300, 310, 1);
+  // [50;250] [260;270] [280;290] [300;310]
+  map.insert(311, 320, 1);
+  I = map.begin();
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(50u, I.start());
+  EXPECT_EQ(250u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(260u, I.start());
+  EXPECT_EQ(270u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(280u, I.start());
+  EXPECT_EQ(290u, I.stop());
+  ++I;
+  ASSERT_TRUE(I.valid());
+  EXPECT_EQ(300u, I.start());
+  EXPECT_EQ(320u, I.stop());
+  ++I;
+  EXPECT_FALSE(I.valid());
+}
+
+// Branched, non-coalescing tests.
+TEST(IntervalMapTest, Branched) {
+  UUMap::Allocator allocator;
+  UUMap map(allocator);
+
+  // Insert enough intervals to force a branched tree.
+  // This creates 9 leaf nodes with 11 elements each, tree height = 1.
+  for (unsigned i = 1; i < 100; ++i)
+    map.insert(10*i, 10*i+5, i);
+
+  // Tree limits.
+  EXPECT_FALSE(map.empty());
+  EXPECT_EQ(10u, map.start());
+  EXPECT_EQ(995u, map.stop());
+
+  // Tree lookup.
+  for (unsigned i = 1; i < 100; ++i) {
+    EXPECT_EQ(0u, map.lookup(10*i-1));
+    EXPECT_EQ(i, map.lookup(10*i));
+    EXPECT_EQ(i, map.lookup(10*i+5));
+    EXPECT_EQ(0u, map.lookup(10*i+6));
+  }
+
+  // Forward iteration.
+  UUMap::iterator I = map.begin();
+  for (unsigned i = 1; i < 100; ++i) {
+    ASSERT_TRUE(I.valid());
+    EXPECT_EQ(10*i, I.start());
+    EXPECT_EQ(10*i+5, I.stop());
+    EXPECT_EQ(i, *I);
+    ++I;
+  }
+  EXPECT_FALSE(I.valid());
+  EXPECT_TRUE(I == map.end());
+
+}
+
+} // namespace

llvm/unittests/CMakeLists.txt

@@ -45,6 +45,7 @@ add_llvm_unittest(ADT
   ADT/DenseSetTest.cpp
   ADT/ilistTest.cpp
   ADT/ImmutableSetTest.cpp
+  ADT/IntervalMapTest.cpp
   ADT/SmallBitVectorTest.cpp
   ADT/SmallStringTest.cpp
   ADT/SmallVectorTest.cpp