SmallVector and SmallPtrSet allocations now power-of-two aligned.

This time tested on both OSX and Linux.

llvm-svn: 178377

include/llvm/ADT/SmallPtrSet.h

@@ -54,8 +54,6 @@ protected:
   /// then the set is in 'small mode'.
   const void **CurArray;
   /// CurArraySize - The allocated size of CurArray, always a power of two.
-  /// Note that CurArray points to an array that has CurArraySize+1 elements in
-  /// it, so that the end iterator actually points to valid memory.
   unsigned CurArraySize;
 
   // If small, this is # elts allocated consecutively
@@ -68,9 +66,6 @@ protected:
     SmallArray(SmallStorage), CurArray(SmallStorage), CurArraySize(SmallSize) {
     assert(SmallSize && (SmallSize & (SmallSize-1)) == 0 &&
            "Initial size must be a power of two!");
-    // The end pointer, always valid, is set to a valid element to help the
-    // iterator.
-    CurArray[SmallSize] = 0;
     clear();
   }
   ~SmallPtrSetImpl();
@@ -147,9 +142,11 @@ protected:
 class SmallPtrSetIteratorImpl {
 protected:
   const void *const *Bucket;
+  const void *const *End;
 public:
-  explicit SmallPtrSetIteratorImpl(const void *const *BP) : Bucket(BP) {
-    AdvanceIfNotValid();
+  explicit SmallPtrSetIteratorImpl(const void *const *BP, const void*const *E)
+    : Bucket(BP), End(E) {
+      AdvanceIfNotValid();
   }
 
   bool operator==(const SmallPtrSetIteratorImpl &RHS) const {
@@ -164,8 +161,10 @@ protected:
   /// that is.   This is guaranteed to stop because the end() bucket is marked
   /// valid.
   void AdvanceIfNotValid() {
-    while (*Bucket == SmallPtrSetImpl::getEmptyMarker() ||
-           *Bucket == SmallPtrSetImpl::getTombstoneMarker())
+    assert(Bucket <= End);
+    while (Bucket != End &&
+           (*Bucket == SmallPtrSetImpl::getEmptyMarker() ||
+            *Bucket == SmallPtrSetImpl::getTombstoneMarker()))
       ++Bucket;
   }
 };
@@ -182,12 +181,13 @@ public:
   typedef std::ptrdiff_t            difference_type;
   typedef std::forward_iterator_tag iterator_category;
   
-  explicit SmallPtrSetIterator(const void *const *BP)
-    : SmallPtrSetIteratorImpl(BP) {}
+  explicit SmallPtrSetIterator(const void *const *BP, const void *const *E)
+    : SmallPtrSetIteratorImpl(BP, E) {}
 
   // Most methods provided by baseclass.
 
   const PtrTy operator*() const {
+    assert(Bucket < End);
     return PtrTraits::getFromVoidPointer(const_cast<void*>(*Bucket));
   }
 
@@ -236,9 +236,8 @@ template<class PtrType, unsigned SmallSize>
 class SmallPtrSet : public SmallPtrSetImpl {
   // Make sure that SmallSize is a power of two, round up if not.
   enum { SmallSizePowTwo = RoundUpToPowerOfTwo<SmallSize>::Val };
-  /// SmallStorage - Fixed size storage used in 'small mode'.  The extra element
-  /// ensures that the end iterator actually points to valid memory.
-  const void *SmallStorage[SmallSizePowTwo+1];
+  /// SmallStorage - Fixed size storage used in 'small mode'.
+  const void *SmallStorage[SmallSizePowTwo];
   typedef PointerLikeTypeTraits<PtrType> PtrTraits;
 public:
   SmallPtrSet() : SmallPtrSetImpl(SmallStorage, SmallSizePowTwo) {}
@@ -275,10 +274,10 @@ public:
   typedef SmallPtrSetIterator<PtrType> iterator;
   typedef SmallPtrSetIterator<PtrType> const_iterator;
   inline iterator begin() const {
-    return iterator(CurArray);
+    return iterator(CurArray, CurArray+CurArraySize);
   }
   inline iterator end() const {
-    return iterator(CurArray+CurArraySize);
+    return iterator(CurArray+CurArraySize, CurArray+CurArraySize);
   }
 
   // Allow assignment from any smallptrset with the same element type even if it

include/llvm/ADT/SmallVector.h

@@ -16,6 +16,7 @@
 
 #include "llvm/Support/AlignOf.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/type_traits.h"
 #include <algorithm>
 #include <cassert>
@@ -267,7 +268,8 @@ template <typename T, bool isPodLike>
 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
   size_t CurCapacity = this->capacity();
   size_t CurSize = this->size();
-  size_t NewCapacity = 2*CurCapacity + 1; // Always grow, even from zero.
+  // Always grow, even from zero.  
+  size_t NewCapacity = size_t(NextPowerOf2(CurCapacity+2));
   if (NewCapacity < MinSize)
     NewCapacity = MinSize;
   T *NewElts = static_cast<T*>(malloc(NewCapacity*sizeof(T)));

lib/Support/SmallPtrSet.cpp

@@ -29,13 +29,9 @@ void SmallPtrSetImpl::shrink_and_clear() {
   NumElements = NumTombstones = 0;
 
   // Install the new array.  Clear all the buckets to empty.
-  CurArray = (const void**)malloc(sizeof(void*) * (CurArraySize+1));
+  CurArray = (const void**)malloc(sizeof(void*) * CurArraySize);
   assert(CurArray && "Failed to allocate memory?");
   memset(CurArray, -1, CurArraySize*sizeof(void*));
-  
-  // The end pointer, always valid, is set to a valid element to help the
-  // iterator.
-  CurArray[CurArraySize] = 0;
 }
 
 bool SmallPtrSetImpl::insert_imp(const void * Ptr) {
@@ -139,15 +135,11 @@ void SmallPtrSetImpl::Grow(unsigned NewSize) {
   bool WasSmall = isSmall();
   
   // Install the new array.  Clear all the buckets to empty.
-  CurArray = (const void**)malloc(sizeof(void*) * (NewSize+1));
+  CurArray = (const void**)malloc(sizeof(void*) * NewSize);
   assert(CurArray && "Failed to allocate memory?");
   CurArraySize = NewSize;
   memset(CurArray, -1, NewSize*sizeof(void*));
   
-  // The end pointer, always valid, is set to a valid element to help the
-  // iterator.
-  CurArray[NewSize] = 0;
-  
   // Copy over all the elements.
   if (WasSmall) {
     // Small sets store their elements in order.
@@ -180,7 +172,7 @@ SmallPtrSetImpl::SmallPtrSetImpl(const void **SmallStorage,
     CurArray = SmallArray;
   // Otherwise, allocate new heap space (unless we were the same size)
   } else {
-    CurArray = (const void**)malloc(sizeof(void*) * (that.CurArraySize+1));
+    CurArray = (const void**)malloc(sizeof(void*) * that.CurArraySize);
     assert(CurArray && "Failed to allocate memory?");
   }
   
@@ -188,7 +180,7 @@ SmallPtrSetImpl::SmallPtrSetImpl(const void **SmallStorage,
   CurArraySize = that.CurArraySize;
 
   // Copy over the contents from the other set
-  memcpy(CurArray, that.CurArray, sizeof(void*)*(CurArraySize+1));
+  memcpy(CurArray, that.CurArray, sizeof(void*)*CurArraySize);
   
   NumElements = that.NumElements;
   NumTombstones = that.NumTombstones;
@@ -200,7 +192,7 @@ void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) {
   if (isSmall() && RHS.isSmall())
     assert(CurArraySize == RHS.CurArraySize &&
            "Cannot assign sets with different small sizes");
-           
+
   // If we're becoming small, prepare to insert into our stack space
   if (RHS.isSmall()) {
     if (!isSmall())
@@ -209,9 +201,9 @@ void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) {
   // Otherwise, allocate new heap space (unless we were the same size)
   } else if (CurArraySize != RHS.CurArraySize) {
     if (isSmall())
-      CurArray = (const void**)malloc(sizeof(void*) * (RHS.CurArraySize+1));
+      CurArray = (const void**)malloc(sizeof(void*) * RHS.CurArraySize);
     else
-      CurArray = (const void**)realloc(CurArray, sizeof(void*)*(RHS.CurArraySize+1));
+      CurArray = (const void**)realloc(CurArray, sizeof(void*)*RHS.CurArraySize);
     assert(CurArray && "Failed to allocate memory?");
   }
   
@@ -219,7 +211,7 @@ void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) {
   CurArraySize = RHS.CurArraySize;
 
   // Copy over the contents from the other set
-  memcpy(CurArray, RHS.CurArray, sizeof(void*)*(CurArraySize+1));
+  memcpy(CurArray, RHS.CurArray, sizeof(void*)*CurArraySize);
   
   NumElements = RHS.NumElements;
   NumTombstones = RHS.NumTombstones;

unittests/ADT/SmallPtrSetTest.cpp

@@ -17,6 +17,61 @@
 using namespace llvm;
 
 // SmallPtrSet swapping test.
+TEST(SmallPtrSetTest, GrowthTest) {
+  int i;
+  int buf[8];
+  for(i=0; i<8; ++i) buf[i]=0;
+
+
+  SmallPtrSet<int *, 4> s;
+  typedef SmallPtrSet<int *, 4>::iterator iter;
+  
+  s.insert(&buf[0]);
+  s.insert(&buf[1]);
+  s.insert(&buf[2]);
+  s.insert(&buf[3]);
+  EXPECT_EQ(4U, s.size());
+
+  i = 0;
+  for(iter I=s.begin(), E=s.end(); I!=E; ++I, ++i)
+      (**I)++;
+  EXPECT_EQ(4, i);
+  for(i=0; i<8; ++i)
+      EXPECT_EQ(i<4?1:0,buf[i]);
+
+  s.insert(&buf[4]);
+  s.insert(&buf[5]);
+  s.insert(&buf[6]);
+  s.insert(&buf[7]);
+
+  i = 0;
+  for(iter I=s.begin(), E=s.end(); I!=E; ++I, ++i)
+      (**I)++;
+  EXPECT_EQ(8, i);
+  s.erase(&buf[4]);
+  s.erase(&buf[5]);
+  s.erase(&buf[6]);
+  s.erase(&buf[7]);
+  EXPECT_EQ(4U, s.size());
+
+  i = 0;
+  for(iter I=s.begin(), E=s.end(); I!=E; ++I, ++i)
+      (**I)++;
+  EXPECT_EQ(4, i);
+  for(i=0; i<8; ++i)
+      EXPECT_EQ(i<4?3:1,buf[i]);
+
+  s.clear();
+  for(i=0; i<8; ++i) buf[i]=0;
+  for(i=0; i<128; ++i) s.insert(&buf[i%8]); // test repeated entires
+  EXPECT_EQ(8U, s.size());
+  for(iter I=s.begin(), E=s.end(); I!=E; ++I, ++i)
+      (**I)++;
+  for(i=0; i<8; ++i)
+      EXPECT_EQ(1,buf[i]);
+}
+
+
 TEST(SmallPtrSetTest, SwapTest) {
   int buf[10];