124 lines
4.1 KiB
C
124 lines
4.1 KiB
C
/* A type-safe hash table template.
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Copyright (C) 2012-2019 Free Software Foundation, Inc.
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Contributed by Lawrence Crowl <crowl@google.com>
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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/* This file implements a typed hash table.
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The implementation borrows from libiberty's hashtab. */
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#ifdef GENERATOR_FILE
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#include "bconfig.h"
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#else
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#include "config.h"
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#endif
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#include "system.h"
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#include "coretypes.h"
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#include "hash-table.h"
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/* Table of primes and multiplicative inverses.
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Note that these are not minimally reduced inverses. Unlike when generating
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code to divide by a constant, we want to be able to use the same algorithm
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all the time. All of these inverses (are implied to) have bit 32 set.
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For the record, here's the function that computed the table; it's a
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vastly simplified version of the function of the same name from gcc. */
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struct prime_ent const prime_tab[] = {
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{ 7, 0x24924925, 0x9999999b, 2 },
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{ 13, 0x3b13b13c, 0x745d1747, 3 },
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{ 31, 0x08421085, 0x1a7b9612, 4 },
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{ 61, 0x0c9714fc, 0x15b1e5f8, 5 },
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{ 127, 0x02040811, 0x0624dd30, 6 },
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{ 251, 0x05197f7e, 0x073260a5, 7 },
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{ 509, 0x01824366, 0x02864fc8, 8 },
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{ 1021, 0x00c0906d, 0x014191f7, 9 },
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{ 2039, 0x0121456f, 0x0161e69e, 10 },
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{ 4093, 0x00300902, 0x00501908, 11 },
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{ 8191, 0x00080041, 0x00180241, 12 },
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{ 16381, 0x000c0091, 0x00140191, 13 },
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{ 32749, 0x002605a5, 0x002a06e6, 14 },
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{ 65521, 0x000f00e2, 0x00110122, 15 },
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{ 131071, 0x00008001, 0x00018003, 16 },
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{ 262139, 0x00014002, 0x0001c004, 17 },
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{ 524287, 0x00002001, 0x00006001, 18 },
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{ 1048573, 0x00003001, 0x00005001, 19 },
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{ 2097143, 0x00004801, 0x00005801, 20 },
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{ 4194301, 0x00000c01, 0x00001401, 21 },
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{ 8388593, 0x00001e01, 0x00002201, 22 },
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{ 16777213, 0x00000301, 0x00000501, 23 },
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{ 33554393, 0x00001381, 0x00001481, 24 },
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{ 67108859, 0x00000141, 0x000001c1, 25 },
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{ 134217689, 0x000004e1, 0x00000521, 26 },
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{ 268435399, 0x00000391, 0x000003b1, 27 },
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{ 536870909, 0x00000019, 0x00000029, 28 },
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{ 1073741789, 0x0000008d, 0x00000095, 29 },
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{ 2147483647, 0x00000003, 0x00000007, 30 },
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/* Avoid "decimal constant so large it is unsigned" for 4294967291. */
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{ 0xfffffffb, 0x00000006, 0x00000008, 31 }
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};
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/* The following function returns an index into the above table of the
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nearest prime number which is greater than N, and near a power of two. */
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unsigned int
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hash_table_higher_prime_index (unsigned long n)
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{
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unsigned int low = 0;
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unsigned int high = sizeof (prime_tab) / sizeof (prime_tab[0]);
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while (low != high)
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{
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unsigned int mid = low + (high - low) / 2;
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if (n > prime_tab[mid].prime)
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low = mid + 1;
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else
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high = mid;
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}
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/* If we've run out of primes, abort. */
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gcc_assert (n <= prime_tab[low].prime);
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return low;
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}
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/* Return a reference to the lazily initialized hash-table usage description.
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This needs to be a function rather than a simple global variable so that it
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is reliably initialized before hash table variables in other files such as
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sem_item::m_type_hash_cache. */
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mem_alloc_description<mem_usage>&
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hash_table_usage ()
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{
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static mem_alloc_description<mem_usage> usage;
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return usage;
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}
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/* Support function for statistics. */
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void dump_hash_table_loc_statistics (void)
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{
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if (!GATHER_STATISTICS)
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return;
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for (unsigned i = HASH_TABLE_ORIGIN; i <= HASH_SET_ORIGIN; i++)
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{
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mem_alloc_origin origin = (mem_alloc_origin) i;
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hash_table_usage ().dump (origin);
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}
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}
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