1 files changed, 261 insertions, 0 deletions
diff --git a/llvm/lib/Support/StringMap.cpp b/llvm/lib/Support/StringMap.cpp
new file mode 100644
index 000000000000..6b5ea020dd46
--- /dev/null
+++ b/llvm/lib/Support/StringMap.cpp
@@ -0,0 +1,261 @@
+//===--- StringMap.cpp - String Hash table map implementation -------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the StringMap class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/DJB.h"
+#include "llvm/Support/MathExtras.h"
+#include <cassert>
+
+using namespace llvm;
+
+/// Returns the number of buckets to allocate to ensure that the DenseMap can
+/// accommodate \p NumEntries without need to grow().
+static unsigned getMinBucketToReserveForEntries(unsigned NumEntries) {
+  // Ensure that "NumEntries * 4 < NumBuckets * 3"
+  if (NumEntries == 0)
+    return 0;
+  // +1 is required because of the strict equality.
+  // For example if NumEntries is 48, we need to return 401.
+  return NextPowerOf2(NumEntries * 4 / 3 + 1);
+}
+
+StringMapImpl::StringMapImpl(unsigned InitSize, unsigned itemSize) {
+  ItemSize = itemSize;
+
+  // If a size is specified, initialize the table with that many buckets.
+  if (InitSize) {
+    // The table will grow when the number of entries reach 3/4 of the number of
+    // buckets. To guarantee that "InitSize" number of entries can be inserted
+    // in the table without growing, we allocate just what is needed here.
+    init(getMinBucketToReserveForEntries(InitSize));
+    return;
+  }
+
+  // Otherwise, initialize it with zero buckets to avoid the allocation.
+  TheTable = nullptr;
+  NumBuckets = 0;
+  NumItems = 0;
+  NumTombstones = 0;
+}
+
+void StringMapImpl::init(unsigned InitSize) {
+  assert((InitSize & (InitSize-1)) == 0 &&
+         "Init Size must be a power of 2 or zero!");
+
+  unsigned NewNumBuckets = InitSize ? InitSize : 16;
+  NumItems = 0;
+  NumTombstones = 0;
+
+  TheTable = static_cast<StringMapEntryBase **>(
+      safe_calloc(NewNumBuckets+1,
+                  sizeof(StringMapEntryBase **) + sizeof(unsigned)));
+
+  // Set the member only if TheTable was successfully allocated
+  NumBuckets = NewNumBuckets;
+
+  // Allocate one extra bucket, set it to look filled so the iterators stop at
+  // end.
+  TheTable[NumBuckets] = (StringMapEntryBase*)2;
+}
+
+/// LookupBucketFor - Look up the bucket that the specified string should end
+/// up in.  If it already exists as a key in the map, the Item pointer for the
+/// specified bucket will be non-null.  Otherwise, it will be null.  In either
+/// case, the FullHashValue field of the bucket will be set to the hash value
+/// of the string.
+unsigned StringMapImpl::LookupBucketFor(StringRef Name) {
+  unsigned HTSize = NumBuckets;
+  if (HTSize == 0) {  // Hash table unallocated so far?
+    init(16);
+    HTSize = NumBuckets;
+  }
+  unsigned FullHashValue = djbHash(Name, 0);
+  unsigned BucketNo = FullHashValue & (HTSize-1);
+  unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
+
+  unsigned ProbeAmt = 1;
+  int FirstTombstone = -1;
+  while (true) {
+    StringMapEntryBase *BucketItem = TheTable[BucketNo];
+    // If we found an empty bucket, this key isn't in the table yet, return it.
+    if (LLVM_LIKELY(!BucketItem)) {
+      // If we found a tombstone, we want to reuse the tombstone instead of an
+      // empty bucket.  This reduces probing.
+      if (FirstTombstone != -1) {
+        HashTable[FirstTombstone] = FullHashValue;
+        return FirstTombstone;
+      }
+
+      HashTable[BucketNo] = FullHashValue;
+      return BucketNo;
+    }
+
+    if (BucketItem == getTombstoneVal()) {
+      // Skip over tombstones.  However, remember the first one we see.
+      if (FirstTombstone == -1) FirstTombstone = BucketNo;
+    } else if (LLVM_LIKELY(HashTable[BucketNo] == FullHashValue)) {
+      // If the full hash value matches, check deeply for a match.  The common
+      // case here is that we are only looking at the buckets (for item info
+      // being non-null and for the full hash value) not at the items.  This
+      // is important for cache locality.
+
+      // Do the comparison like this because Name isn't necessarily
+      // null-terminated!
+      char *ItemStr = (char*)BucketItem+ItemSize;
+      if (Name == StringRef(ItemStr, BucketItem->getKeyLength())) {
+        // We found a match!
+        return BucketNo;
+      }
+    }
+
+    // Okay, we didn't find the item.  Probe to the next bucket.
+    BucketNo = (BucketNo+ProbeAmt) & (HTSize-1);
+
+    // Use quadratic probing, it has fewer clumping artifacts than linear
+    // probing and has good cache behavior in the common case.
+    ++ProbeAmt;
+  }
+}
+
+/// FindKey - Look up the bucket that contains the specified key. If it exists
+/// in the map, return the bucket number of the key.  Otherwise return -1.
+/// This does not modify the map.
+int StringMapImpl::FindKey(StringRef Key) const {
+  unsigned HTSize = NumBuckets;
+  if (HTSize == 0) return -1;  // Really empty table?
+  unsigned FullHashValue = djbHash(Key, 0);
+  unsigned BucketNo = FullHashValue & (HTSize-1);
+  unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
+
+  unsigned ProbeAmt = 1;
+  while (true) {
+    StringMapEntryBase *BucketItem = TheTable[BucketNo];
+    // If we found an empty bucket, this key isn't in the table yet, return.
+    if (LLVM_LIKELY(!BucketItem))
+      return -1;
+
+    if (BucketItem == getTombstoneVal()) {
+      // Ignore tombstones.
+    } else if (LLVM_LIKELY(HashTable[BucketNo] == FullHashValue)) {
+      // If the full hash value matches, check deeply for a match.  The common
+      // case here is that we are only looking at the buckets (for item info
+      // being non-null and for the full hash value) not at the items.  This
+      // is important for cache locality.
+
+      // Do the comparison like this because NameStart isn't necessarily
+      // null-terminated!
+      char *ItemStr = (char*)BucketItem+ItemSize;
+      if (Key == StringRef(ItemStr, BucketItem->getKeyLength())) {
+        // We found a match!
+        return BucketNo;
+      }
+    }
+
+    // Okay, we didn't find the item.  Probe to the next bucket.
+    BucketNo = (BucketNo+ProbeAmt) & (HTSize-1);
+
+    // Use quadratic probing, it has fewer clumping artifacts than linear
+    // probing and has good cache behavior in the common case.
+    ++ProbeAmt;
+  }
+}
+
+/// RemoveKey - Remove the specified StringMapEntry from the table, but do not
+/// delete it.  This aborts if the value isn't in the table.
+void StringMapImpl::RemoveKey(StringMapEntryBase *V) {
+  const char *VStr = (char*)V + ItemSize;
+  StringMapEntryBase *V2 = RemoveKey(StringRef(VStr, V->getKeyLength()));
+  (void)V2;
+  assert(V == V2 && "Didn't find key?");
+}
+
+/// RemoveKey - Remove the StringMapEntry for the specified key from the
+/// table, returning it.  If the key is not in the table, this returns null.
+StringMapEntryBase *StringMapImpl::RemoveKey(StringRef Key) {
+  int Bucket = FindKey(Key);
+  if (Bucket == -1) return nullptr;
+
+  StringMapEntryBase *Result = TheTable[Bucket];
+  TheTable[Bucket] = getTombstoneVal();
+  --NumItems;
+  ++NumTombstones;
+  assert(NumItems + NumTombstones <= NumBuckets);
+
+  return Result;
+}
+
+/// RehashTable - Grow the table, redistributing values into the buckets with
+/// the appropriate mod-of-hashtable-size.
+unsigned StringMapImpl::RehashTable(unsigned BucketNo) {
+  unsigned NewSize;
+  unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
+
+  // If the hash table is now more than 3/4 full, or if fewer than 1/8 of
+  // the buckets are empty (meaning that many are filled with tombstones),
+  // grow/rehash the table.
+  if (LLVM_UNLIKELY(NumItems * 4 > NumBuckets * 3)) {
+    NewSize = NumBuckets*2;
+  } else if (LLVM_UNLIKELY(NumBuckets - (NumItems + NumTombstones) <=
+                           NumBuckets / 8)) {
+    NewSize = NumBuckets;
+  } else {
+    return BucketNo;
+  }
+
+  unsigned NewBucketNo = BucketNo;
+  // Allocate one extra bucket which will always be non-empty.  This allows the
+  // iterators to stop at end.
+  auto NewTableArray = static_cast<StringMapEntryBase **>(
+      safe_calloc(NewSize+1, sizeof(StringMapEntryBase *) + sizeof(unsigned)));
+
+  unsigned *NewHashArray = (unsigned *)(NewTableArray + NewSize + 1);
+  NewTableArray[NewSize] = (StringMapEntryBase*)2;
+
+  // Rehash all the items into their new buckets.  Luckily :) we already have
+  // the hash values available, so we don't have to rehash any strings.
+  for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
+    StringMapEntryBase *Bucket = TheTable[I];
+    if (Bucket && Bucket != getTombstoneVal()) {
+      // Fast case, bucket available.
+      unsigned FullHash = HashTable[I];
+      unsigned NewBucket = FullHash & (NewSize-1);
+      if (!NewTableArray[NewBucket]) {
+        NewTableArray[FullHash & (NewSize-1)] = Bucket;
+        NewHashArray[FullHash & (NewSize-1)] = FullHash;
+        if (I == BucketNo)
+          NewBucketNo = NewBucket;
+        continue;
+      }
+
+      // Otherwise probe for a spot.
+      unsigned ProbeSize = 1;
+      do {
+        NewBucket = (NewBucket + ProbeSize++) & (NewSize-1);
+      } while (NewTableArray[NewBucket]);
+
+      // Finally found a slot.  Fill it in.
+      NewTableArray[NewBucket] = Bucket;
+      NewHashArray[NewBucket] = FullHash;
+      if (I == BucketNo)
+        NewBucketNo = NewBucket;
+    }
+  }
+
+  free(TheTable);
+
+  TheTable = NewTableArray;
+  NumBuckets = NewSize;
+  NumTombstones = 0;
+  return NewBucketNo;
+}