Add a new SmallSet ADT specialized for pointers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33577 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/SmallPtrSet.cpp b/lib/Support/SmallPtrSet.cpp
new file mode 100644
index 0000000..0e6d334
--- /dev/null
+++ b/lib/Support/SmallPtrSet.cpp
@@ -0,0 +1,113 @@
+//===- llvm/ADT/SmallPtrSet.cpp - 'Normally small' pointer set ------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the SmallPtrSet class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallPtrSet.h"
+using namespace llvm;
+
+bool SmallPtrSetImpl::insert(void *Ptr) {
+ if (isSmall()) {
+ // Check to see if it is already in the set.
+ for (void **APtr = SmallArray, **E = SmallArray+NumElements;
+ APtr != E; ++APtr)
+ if (*APtr == Ptr)
+ return false;
+
+ // Nope, there isn't. If we stay small, just 'pushback' now.
+ if (NumElements < CurArraySize-1) {
+ SmallArray[NumElements++] = Ptr;
+ return true;
+ }
+ // Otherwise, hit the big set case, which will call grow.
+ }
+
+ // If more than 3/4 of the array is full, grow.
+ if (NumElements*4 >= CurArraySize*3)
+ Grow();
+
+ // Okay, we know we have space. Find a hash bucket.
+ void **Bucket = const_cast<void**>(FindBucketFor(Ptr));
+ if (*Bucket == Ptr) return false; // Already inserted, good.
+
+ // Otherwise, insert it!
+ *Bucket = Ptr;
+ ++NumElements; // Track density.
+ return true;
+}
+
+void * const *SmallPtrSetImpl::FindBucketFor(void *Ptr) const {
+ unsigned Bucket = Hash(Ptr);
+ unsigned ArraySize = CurArraySize;
+ unsigned ProbeAmt = 1;
+ void *const *Array = CurArray;
+ void *const *Tombstone = 0;
+ while (1) {
+ // Found Ptr's bucket?
+ if (Array[Bucket] == Ptr)
+ return Array+Bucket;
+
+ // If we found an empty bucket, the pointer doesn't exist in the set.
+ // Return a tombstone if we've seen one so far, or the empty bucket if
+ // not.
+ if (Array[Bucket] == getEmptyMarker())
+ return Tombstone ? Tombstone : Array+Bucket;
+
+ // If this is a tombstone, remember it. If Ptr ends up not in the set, we
+ // prefer to return it than something that would require more probing.
+ if (Array[Bucket] == getTombstoneMarker() && !Tombstone)
+ Tombstone = Array+Bucket; // Remember the first tombstone found.
+
+ // It's a hash collision or a tombstone. Reprobe.
+ Bucket = (Bucket + ProbeAmt++) & (ArraySize-1);
+ }
+}
+
+/// Grow - Allocate a larger backing store for the buckets and move it over.
+///
+void SmallPtrSetImpl::Grow() {
+ // Allocate at twice as many buckets, but at least 128.
+ unsigned OldSize = CurArraySize;
+ unsigned NewSize = OldSize < 64 ? 128 : OldSize*2;
+
+ void **OldBuckets = CurArray;
+ bool WasSmall = isSmall();
+
+ // Install the new array. Clear all the buckets to empty.
+ CurArray = new void*[NewSize+1];
+ 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.
+ for (void **BucketPtr = OldBuckets, **E = OldBuckets+NumElements;
+ BucketPtr != E; ++BucketPtr) {
+ void *Elt = *BucketPtr;
+ *const_cast<void**>(FindBucketFor(Elt)) = Elt;
+ }
+ } else {
+ // Copy over all valid entries.
+ for (void **BucketPtr = OldBuckets, **E = OldBuckets+OldSize;
+ BucketPtr != E; ++BucketPtr) {
+ // Copy over the element if it is valid.
+ void *Elt = *BucketPtr;
+ if (Elt != getTombstoneMarker() && Elt != getEmptyMarker())
+ *const_cast<void**>(FindBucketFor(Elt)) = Elt;
+ }
+
+ delete [] OldBuckets;
+ }
+}