diff -r 000000000000 -r 6474c204b198 js/jsd/jshash.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/jsd/jshash.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,453 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * PR hash table package.
+ */
+
+#include "jshash.h"
+
+#include "mozilla/MathAlgorithms.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "jstypes.h"
+
+#include "js/Utility.h"
+
+using namespace js;
+
+using mozilla::CeilingLog2Size;
+using mozilla::RotateLeft;
+
+/* Compute the number of buckets in ht */
+#define NBUCKETS(ht)    JS_BIT(JS_HASH_BITS - (ht)->shift)
+
+/* The smallest table has 16 buckets */
+#define MINBUCKETSLOG2  4
+#define MINBUCKETS      JS_BIT(MINBUCKETSLOG2)
+
+/* Compute the maximum entries given n buckets that we will tolerate, ~90% */
+#define OVERLOADED(n)   ((n) - ((n) >> 3))
+
+/* Compute the number of entries below which we shrink the table by half */
+#define UNDERLOADED(n)  (((n) > MINBUCKETS) ? ((n) >> 2) : 0)
+
+/*
+** Stubs for default hash allocator ops.
+*/
+static void *
+DefaultAllocTable(void *pool, size_t size)
+{
+    return js_malloc(size);
+}
+
+static void
+DefaultFreeTable(void *pool, void *item, size_t size)
+{
+    js_free(item);
+}
+
+static JSHashEntry *
+DefaultAllocEntry(void *pool, const void *key)
+{
+    return (JSHashEntry*) js_malloc(sizeof(JSHashEntry));
+}
+
+static void
+DefaultFreeEntry(void *pool, JSHashEntry *he, unsigned flag)
+{
+    if (flag == HT_FREE_ENTRY)
+        js_free(he);
+}
+
+static const JSHashAllocOps defaultHashAllocOps = {
+    DefaultAllocTable, DefaultFreeTable,
+    DefaultAllocEntry, DefaultFreeEntry
+};
+
+JSHashTable *
+JS_NewHashTable(uint32_t n, JSHashFunction keyHash,
+                JSHashComparator keyCompare, JSHashComparator valueCompare,
+                const JSHashAllocOps *allocOps, void *allocPriv)
+{
+    JSHashTable *ht;
+    size_t nb;
+
+    if (n <= MINBUCKETS) {
+        n = MINBUCKETSLOG2;
+    } else {
+        n = CeilingLog2Size(n);
+        if (int32_t(n) < 0)
+            return nullptr;
+    }
+
+    if (!allocOps) allocOps = &defaultHashAllocOps;
+
+    ht = (JSHashTable*) allocOps->allocTable(allocPriv, sizeof *ht);
+    if (!ht)
+        return nullptr;
+    memset(ht, 0, sizeof *ht);
+    ht->shift = JS_HASH_BITS - n;
+    n = JS_BIT(n);
+    nb = n * sizeof(JSHashEntry *);
+    ht->buckets = (JSHashEntry**) allocOps->allocTable(allocPriv, nb);
+    if (!ht->buckets) {
+        allocOps->freeTable(allocPriv, ht, nb);
+        return nullptr;
+    }
+    memset(ht->buckets, 0, nb);
+
+    ht->keyHash = keyHash;
+    ht->keyCompare = keyCompare;
+    ht->valueCompare = valueCompare;
+    ht->allocOps = allocOps;
+    ht->allocPriv = allocPriv;
+    return ht;
+}
+
+void
+JS_HashTableDestroy(JSHashTable *ht)
+{
+    uint32_t i, n;
+    JSHashEntry *he, **hep;
+    const JSHashAllocOps *allocOps = ht->allocOps;
+    void *allocPriv = ht->allocPriv;
+
+    n = NBUCKETS(ht);
+    for (i = 0; i < n; i++) {
+        hep = &ht->buckets[i];
+        while ((he = *hep) != nullptr) {
+            *hep = he->next;
+            allocOps->freeEntry(allocPriv, he, HT_FREE_ENTRY);
+        }
+    }
+#ifdef DEBUG
+    memset(ht->buckets, 0xDB, n * sizeof ht->buckets[0]);
+#endif
+    allocOps->freeTable(allocPriv, ht->buckets, n * sizeof ht->buckets[0]);
+#ifdef DEBUG
+    memset(ht, 0xDB, sizeof *ht);
+#endif
+    allocOps->freeTable(allocPriv, ht, sizeof *ht);
+}
+
+/*
+ * Multiplicative hash, from Knuth 6.4.
+ */
+#define BUCKET_HEAD(ht, keyHash)                                              \
+    (&(ht)->buckets[((keyHash) * JS_GOLDEN_RATIO) >> (ht)->shift])
+
+JSHashEntry **
+JS_HashTableRawLookup(JSHashTable *ht, JSHashNumber keyHash, const void *key)
+{
+    JSHashEntry *he, **hep, **hep0;
+
+#ifdef JS_HASHMETER
+    ht->nlookups++;
+#endif
+    hep = hep0 = BUCKET_HEAD(ht, keyHash);
+    while ((he = *hep) != nullptr) {
+        if (he->keyHash == keyHash && ht->keyCompare(key, he->key)) {
+            /* Move to front of chain if not already there */
+            if (hep != hep0) {
+                *hep = he->next;
+                he->next = *hep0;
+                *hep0 = he;
+            }
+            return hep0;
+        }
+        hep = &he->next;
+#ifdef JS_HASHMETER
+        ht->nsteps++;
+#endif
+    }
+    return hep;
+}
+
+static bool
+Resize(JSHashTable *ht, uint32_t newshift)
+{
+    size_t nb, nentries, i;
+    JSHashEntry **oldbuckets, *he, *next, **hep;
+    size_t nold = NBUCKETS(ht);
+
+    MOZ_ASSERT(newshift < JS_HASH_BITS);
+
+    nb = (size_t)1 << (JS_HASH_BITS - newshift);
+
+    /* Integer overflow protection. */
+    if (nb > (size_t)-1 / sizeof(JSHashEntry*))
+        return false;
+    nb *= sizeof(JSHashEntry*);
+
+    oldbuckets = ht->buckets;
+    ht->buckets = (JSHashEntry**)ht->allocOps->allocTable(ht->allocPriv, nb);
+    if (!ht->buckets) {
+        ht->buckets = oldbuckets;
+        return false;
+    }
+    memset(ht->buckets, 0, nb);
+
+    ht->shift = newshift;
+    nentries = ht->nentries;
+
+    for (i = 0; nentries != 0; i++) {
+        for (he = oldbuckets[i]; he; he = next) {
+            MOZ_ASSERT(nentries != 0);
+            --nentries;
+            next = he->next;
+            hep = BUCKET_HEAD(ht, he->keyHash);
+
+            /*
+             * We do not require unique entries, instead appending he to the
+             * chain starting at hep.
+             */
+            while (*hep)
+                hep = &(*hep)->next;
+            he->next = nullptr;
+            *hep = he;
+        }
+    }
+#ifdef DEBUG
+    memset(oldbuckets, 0xDB, nold * sizeof oldbuckets[0]);
+#endif
+    ht->allocOps->freeTable(ht->allocPriv, oldbuckets,
+                            nold * sizeof oldbuckets[0]);
+    return true;
+}
+
+JSHashEntry *
+JS_HashTableRawAdd(JSHashTable *ht, JSHashEntry **&hep,
+                   JSHashNumber keyHash, const void *key, void *value)
+{
+    uint32_t n;
+    JSHashEntry *he;
+
+    /* Grow the table if it is overloaded */
+    n = NBUCKETS(ht);
+    if (ht->nentries >= OVERLOADED(n)) {
+        if (!Resize(ht, ht->shift - 1))
+            return nullptr;
+#ifdef JS_HASHMETER
+        ht->ngrows++;
+#endif
+        hep = JS_HashTableRawLookup(ht, keyHash, key);
+    }
+
+    /* Make a new key value entry */
+    he = ht->allocOps->allocEntry(ht->allocPriv, key);
+    if (!he)
+        return nullptr;
+    he->keyHash = keyHash;
+    he->key = key;
+    he->value = value;
+    he->next = *hep;
+    *hep = he;
+    ht->nentries++;
+    return he;
+}
+
+JSHashEntry *
+JS_HashTableAdd(JSHashTable *ht, const void *key, void *value)
+{
+    JSHashNumber keyHash;
+    JSHashEntry *he, **hep;
+
+    keyHash = ht->keyHash(key);
+    hep = JS_HashTableRawLookup(ht, keyHash, key);
+    if ((he = *hep) != nullptr) {
+        /* Hit; see if values match */
+        if (ht->valueCompare(he->value, value)) {
+            /* key,value pair is already present in table */
+            return he;
+        }
+        if (he->value)
+            ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_VALUE);
+        he->value = value;
+        return he;
+    }
+    return JS_HashTableRawAdd(ht, hep, keyHash, key, value);
+}
+
+void
+JS_HashTableRawRemove(JSHashTable *ht, JSHashEntry **hep, JSHashEntry *he)
+{
+    uint32_t n;
+
+    *hep = he->next;
+    ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
+
+    /* Shrink table if it's underloaded */
+    n = NBUCKETS(ht);
+    if (--ht->nentries < UNDERLOADED(n)) {
+        Resize(ht, ht->shift + 1);
+#ifdef JS_HASHMETER
+        ht->nshrinks++;
+#endif
+    }
+}
+
+bool
+JS_HashTableRemove(JSHashTable *ht, const void *key)
+{
+    JSHashNumber keyHash;
+    JSHashEntry *he, **hep;
+
+    keyHash = ht->keyHash(key);
+    hep = JS_HashTableRawLookup(ht, keyHash, key);
+    if ((he = *hep) == nullptr)
+        return false;
+
+    /* Hit; remove element */
+    JS_HashTableRawRemove(ht, hep, he);
+    return true;
+}
+
+void *
+JS_HashTableLookup(JSHashTable *ht, const void *key)
+{
+    JSHashNumber keyHash;
+    JSHashEntry *he, **hep;
+
+    keyHash = ht->keyHash(key);
+    hep = JS_HashTableRawLookup(ht, keyHash, key);
+    if ((he = *hep) != nullptr) {
+        return he->value;
+    }
+    return nullptr;
+}
+
+/*
+** Iterate over the entries in the hash table calling func for each
+** entry found. Stop if "f" says to (return value & JS_ENUMERATE_STOP).
+** Return a count of the number of elements scanned.
+*/
+int
+JS_HashTableEnumerateEntries(JSHashTable *ht, JSHashEnumerator f, void *arg)
+{
+    JSHashEntry *he, **hep, **bucket;
+    uint32_t nlimit, n, nbuckets, newlog2;
+    int rv;
+
+    nlimit = ht->nentries;
+    n = 0;
+    for (bucket = ht->buckets; n != nlimit; ++bucket) {
+        hep = bucket;
+        while ((he = *hep) != nullptr) {
+            MOZ_ASSERT(n < nlimit);
+            rv = f(he, n, arg);
+            n++;
+            if (rv & HT_ENUMERATE_REMOVE) {
+                *hep = he->next;
+                ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
+                --ht->nentries;
+            } else {
+                hep = &he->next;
+            }
+            if (rv & HT_ENUMERATE_STOP) {
+                goto out;
+            }
+        }
+    }
+
+out:
+    /* Shrink table if removal of entries made it underloaded */
+    if (ht->nentries != nlimit) {
+        MOZ_ASSERT(ht->nentries < nlimit);
+        nbuckets = NBUCKETS(ht);
+        if (MINBUCKETS < nbuckets && ht->nentries < UNDERLOADED(nbuckets)) {
+            newlog2 = CeilingLog2Size(ht->nentries);
+            if (newlog2 < MINBUCKETSLOG2)
+                newlog2 = MINBUCKETSLOG2;
+
+            /*  Check that we really shrink the table. */
+            MOZ_ASSERT(JS_HASH_BITS - ht->shift > newlog2);
+            Resize(ht, JS_HASH_BITS - newlog2);
+        }
+    }
+    return (int)n;
+}
+
+#ifdef JS_HASHMETER
+#include <stdio.h>
+
+void
+JS_HashTableDumpMeter(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
+{
+    double sqsum, mean, sigma;
+    uint32_t nchains, nbuckets;
+    uint32_t i, n, maxChain, maxChainLen;
+    JSHashEntry *he;
+
+    sqsum = 0;
+    nchains = 0;
+    maxChain = maxChainLen = 0;
+    nbuckets = NBUCKETS(ht);
+    for (i = 0; i < nbuckets; i++) {
+        he = ht->buckets[i];
+        if (!he)
+            continue;
+        nchains++;
+        for (n = 0; he; he = he->next)
+            n++;
+        sqsum += n * n;
+        if (n > maxChainLen) {
+            maxChainLen = n;
+            maxChain = i;
+        }
+    }
+
+    mean = JS_MeanAndStdDev(nchains, ht->nentries, sqsum, &sigma);
+
+    fprintf(fp, "\nHash table statistics:\n");
+    fprintf(fp, "     number of lookups: %u\n", ht->nlookups);
+    fprintf(fp, "     number of entries: %u\n", ht->nentries);
+    fprintf(fp, "       number of grows: %u\n", ht->ngrows);
+    fprintf(fp, "     number of shrinks: %u\n", ht->nshrinks);
+    fprintf(fp, "   mean steps per hash: %g\n", (double)ht->nsteps
+                                                / ht->nlookups);
+    fprintf(fp, "mean hash chain length: %g\n", mean);
+    fprintf(fp, "    standard deviation: %g\n", sigma);
+    fprintf(fp, " max hash chain length: %u\n", maxChainLen);
+    fprintf(fp, "        max hash chain: [%u]\n", maxChain);
+
+    for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
+        if (dump(he, i, fp) != HT_ENUMERATE_NEXT)
+            break;
+}
+#endif /* JS_HASHMETER */
+
+int
+JS_HashTableDump(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
+{
+    int count;
+
+    count = JS_HashTableEnumerateEntries(ht, dump, fp);
+#ifdef JS_HASHMETER
+    JS_HashTableDumpMeter(ht, dump, fp);
+#endif
+    return count;
+}
+
+JSHashNumber
+JS_HashString(const void *key)
+{
+    JSHashNumber h;
+    const unsigned char *s;
+
+    h = 0;
+    for (s = (const unsigned char *)key; *s; s++)
+        h = RotateLeft(h, 4) ^ *s;
+    return h;
+}
+
+int
+JS_CompareValues(const void *v1, const void *v2)
+{
+    return v1 == v2;
+}