Coverage Report

Created: 2019-07-24 05:18

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/lib/Support/StringMap.cpp
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//===--- StringMap.cpp - String Hash table map implementation -------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the StringMap class.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/StringMap.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/DJB.h"
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#include "llvm/Support/MathExtras.h"
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#include <cassert>
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using namespace llvm;
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/// Returns the number of buckets to allocate to ensure that the DenseMap can
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/// accommodate \p NumEntries without need to grow().
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377k
static unsigned getMinBucketToReserveForEntries(unsigned NumEntries) {
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377k
  // Ensure that "NumEntries * 4 < NumBuckets * 3"
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377k
  if (NumEntries == 0)
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0
    return 0;
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377k
  // +1 is required because of the strict equality.
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  // For example if NumEntries is 48, we need to return 401.
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  return NextPowerOf2(NumEntries * 4 / 3 + 1);
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}
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2.24M
StringMapImpl::StringMapImpl(unsigned InitSize, unsigned itemSize) {
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2.24M
  ItemSize = itemSize;
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2.24M
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2.24M
  // If a size is specified, initialize the table with that many buckets.
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2.24M
  if (InitSize) {
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377k
    // The table will grow when the number of entries reach 3/4 of the number of
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    // buckets. To guarantee that "InitSize" number of entries can be inserted
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    // in the table without growing, we allocate just what is needed here.
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    init(getMinBucketToReserveForEntries(InitSize));
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    return;
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  }
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1.87M
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  // Otherwise, initialize it with zero buckets to avoid the allocation.
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  TheTable = nullptr;
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  NumBuckets = 0;
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  NumItems = 0;
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1.87M
  NumTombstones = 0;
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}
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void StringMapImpl::init(unsigned InitSize) {
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  assert((InitSize & (InitSize-1)) == 0 &&
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         "Init Size must be a power of 2 or zero!");
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  unsigned NewNumBuckets = InitSize ? 
InitSize4.64M
:
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;
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  NumItems = 0;
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  NumTombstones = 0;
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  TheTable = static_cast<StringMapEntryBase **>(
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      safe_calloc(NewNumBuckets+1,
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                  sizeof(StringMapEntryBase **) + sizeof(unsigned)));
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  // Set the member only if TheTable was successfully allocated
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  NumBuckets = NewNumBuckets;
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  // Allocate one extra bucket, set it to look filled so the iterators stop at
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  // end.
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  TheTable[NumBuckets] = (StringMapEntryBase*)2;
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}
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/// LookupBucketFor - Look up the bucket that the specified string should end
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/// up in.  If it already exists as a key in the map, the Item pointer for the
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/// specified bucket will be non-null.  Otherwise, it will be null.  In either
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/// case, the FullHashValue field of the bucket will be set to the hash value
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/// of the string.
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1.13G
unsigned StringMapImpl::LookupBucketFor(StringRef Name) {
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1.13G
  unsigned HTSize = NumBuckets;
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1.13G
  if (HTSize == 0) {  // Hash table unallocated so far?
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4.25M
    init(16);
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    HTSize = NumBuckets;
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  }
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1.13G
  unsigned FullHashValue = djbHash(Name, 0);
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  unsigned BucketNo = FullHashValue & (HTSize-1);
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  unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
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  unsigned ProbeAmt = 1;
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  int FirstTombstone = -1;
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  while (
true1.76G
) {
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    StringMapEntryBase *BucketItem = TheTable[BucketNo];
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    // If we found an empty bucket, this key isn't in the table yet, return it.
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    if (LLVM_LIKELY(!BucketItem)) {
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      // If we found a tombstone, we want to reuse the tombstone instead of an
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      // empty bucket.  This reduces probing.
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      if (FirstTombstone != -1) {
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        HashTable[FirstTombstone] = FullHashValue;
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        return FirstTombstone;
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      }
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      HashTable[BucketNo] = FullHashValue;
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      return BucketNo;
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    }
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    if (BucketItem == getTombstoneVal()) {
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      // Skip over tombstones.  However, remember the first one we see.
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      if (FirstTombstone == -1) 
FirstTombstone = BucketNo1.93M
;
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    } else if (LLVM_LIKELY(HashTable[BucketNo] == FullHashValue)) {
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      // If the full hash value matches, check deeply for a match.  The common
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      // case here is that we are only looking at the buckets (for item info
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      // being non-null and for the full hash value) not at the items.  This
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      // is important for cache locality.
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      // Do the comparison like this because Name isn't necessarily
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      // null-terminated!
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      char *ItemStr = (char*)BucketItem+ItemSize;
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      if (Name == StringRef(ItemStr, BucketItem->getKeyLength())) {
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        // We found a match!
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        return BucketNo;
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      }
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    }
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    // Okay, we didn't find the item.  Probe to the next bucket.
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    BucketNo = (BucketNo+ProbeAmt) & (HTSize-1);
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    // Use quadratic probing, it has fewer clumping artifacts than linear
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    // probing and has good cache behavior in the common case.
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    ++ProbeAmt;
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  }
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}
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/// FindKey - Look up the bucket that contains the specified key. If it exists
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/// in the map, return the bucket number of the key.  Otherwise return -1.
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/// This does not modify the map.
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127M
int StringMapImpl::FindKey(StringRef Key) const {
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  unsigned HTSize = NumBuckets;
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  if (HTSize == 0) 
return -18.03M
; // Really empty table?
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  unsigned FullHashValue = djbHash(Key, 0);
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  unsigned BucketNo = FullHashValue & (HTSize-1);
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  unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
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  unsigned ProbeAmt = 1;
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  while (
true256M
) {
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    StringMapEntryBase *BucketItem = TheTable[BucketNo];
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    // If we found an empty bucket, this key isn't in the table yet, return.
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    if (LLVM_LIKELY(!BucketItem))
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return -174.0M
;
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    if (BucketItem == getTombstoneVal()) {
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      // Ignore tombstones.
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    } else if (LLVM_LIKELY(HashTable[BucketNo] == FullHashValue)) {
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      // If the full hash value matches, check deeply for a match.  The common
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      // case here is that we are only looking at the buckets (for item info
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      // being non-null and for the full hash value) not at the items.  This
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      // is important for cache locality.
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      // Do the comparison like this because NameStart isn't necessarily
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      // null-terminated!
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      char *ItemStr = (char*)BucketItem+ItemSize;
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      if (Key == StringRef(ItemStr, BucketItem->getKeyLength())) {
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        // We found a match!
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        return BucketNo;
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      }
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    }
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    // Okay, we didn't find the item.  Probe to the next bucket.
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    BucketNo = (BucketNo+ProbeAmt) & (HTSize-1);
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    // Use quadratic probing, it has fewer clumping artifacts than linear
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    // probing and has good cache behavior in the common case.
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    ++ProbeAmt;
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  }
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}
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/// RemoveKey - Remove the specified StringMapEntry from the table, but do not
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/// delete it.  This aborts if the value isn't in the table.
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void StringMapImpl::RemoveKey(StringMapEntryBase *V) {
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  const char *VStr = (char*)V + ItemSize;
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  StringMapEntryBase *V2 = RemoveKey(StringRef(VStr, V->getKeyLength()));
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  (void)V2;
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  assert(V == V2 && "Didn't find key?");
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}
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/// RemoveKey - Remove the StringMapEntry for the specified key from the
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/// table, returning it.  If the key is not in the table, this returns null.
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StringMapEntryBase *StringMapImpl::RemoveKey(StringRef Key) {
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  int Bucket = FindKey(Key);
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  if (Bucket == -1) 
return nullptr0
;
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  StringMapEntryBase *Result = TheTable[Bucket];
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  TheTable[Bucket] = getTombstoneVal();
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  --NumItems;
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  ++NumTombstones;
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  assert(NumItems + NumTombstones <= NumBuckets);
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  return Result;
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}
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/// RehashTable - Grow the table, redistributing values into the buckets with
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/// the appropriate mod-of-hashtable-size.
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unsigned StringMapImpl::RehashTable(unsigned BucketNo) {
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  unsigned NewSize;
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  unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
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  // If the hash table is now more than 3/4 full, or if fewer than 1/8 of
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  // the buckets are empty (meaning that many are filled with tombstones),
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  // grow/rehash the table.
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  if (LLVM_UNLIKELY(NumItems * 4 > NumBuckets * 3)) {
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    NewSize = NumBuckets*2;
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  } else if (LLVM_UNLIKELY(NumBuckets - (NumItems + NumTombstones) <=
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                           NumBuckets / 8)) {
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    NewSize = NumBuckets;
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  } else {
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    return BucketNo;
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  }
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  unsigned NewBucketNo = BucketNo;
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  // Allocate one extra bucket which will always be non-empty.  This allows the
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  // iterators to stop at end.
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3.13M
  auto NewTableArray = static_cast<StringMapEntryBase **>(
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      safe_calloc(NewSize+1, sizeof(StringMapEntryBase *) + sizeof(unsigned)));
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  unsigned *NewHashArray = (unsigned *)(NewTableArray + NewSize + 1);
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  NewTableArray[NewSize] = (StringMapEntryBase*)2;
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  // Rehash all the items into their new buckets.  Luckily :) we already have
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  // the hash values available, so we don't have to rehash any strings.
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  for (unsigned I = 0, E = NumBuckets; I != E; 
++I466M
) {
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    StringMapEntryBase *Bucket = TheTable[I];
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    if (Bucket && 
Bucket != getTombstoneVal()352M
) {
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      // Fast case, bucket available.
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      unsigned FullHash = HashTable[I];
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      unsigned NewBucket = FullHash & (NewSize-1);
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      if (!NewTableArray[NewBucket]) {
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        NewTableArray[FullHash & (NewSize-1)] = Bucket;
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        NewHashArray[FullHash & (NewSize-1)] = FullHash;
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        if (I == BucketNo)
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2.38M
          NewBucketNo = NewBucket;
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285M
        continue;
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      }
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67.0M
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      // Otherwise probe for a spot.
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      unsigned ProbeSize = 1;
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      do {
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        NewBucket = (NewBucket + ProbeSize++) & (NewSize-1);
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      } while (NewTableArray[NewBucket]);
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67.0M
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      // Finally found a slot.  Fill it in.
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      NewTableArray[NewBucket] = Bucket;
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      NewHashArray[NewBucket] = FullHash;
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67.0M
      if (I == BucketNo)
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742k
        NewBucketNo = NewBucket;
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    }
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466M
  }
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3.13M
  free(TheTable);
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3.13M
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3.13M
  TheTable = NewTableArray;
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3.13M
  NumBuckets = NewSize;
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3.13M
  NumTombstones = 0;
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  return NewBucketNo;
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3.13M
}