2013-05-24 Richard Biener <rguenther@suse.de>
[official-gcc.git] / libgo / runtime / go-type-identity.c
blobed510f75a725fa5f58f4ee48d08f4b7128767052
1 /* go-type-identity.c -- hash and equality identity functions.
3 Copyright 2009 The Go Authors. All rights reserved.
4 Use of this source code is governed by a BSD-style
5 license that can be found in the LICENSE file. */
7 #include <stddef.h>
9 #include "runtime.h"
10 #include "go-type.h"
12 /* An identity hash function for a type. This is used for types where
13 we can simply use the type value itself as a hash code. This is
14 true of, e.g., integers and pointers. */
16 uintptr_t
17 __go_type_hash_identity (const void *key, uintptr_t key_size)
19 uintptr_t ret;
20 uintptr_t i;
21 const unsigned char *p;
23 if (key_size <= 8)
25 union
27 uint64 v;
28 unsigned char a[8];
29 } u;
30 u.v = 0;
31 #ifdef WORDS_BIGENDIAN
32 __builtin_memcpy (&u.a[8 - key_size], key, key_size);
33 #else
34 __builtin_memcpy (&u.a[0], key, key_size);
35 #endif
36 if (sizeof (uintptr_t) >= 8)
37 return (uintptr_t) u.v;
38 else
39 return (uintptr_t) ((u.v >> 32) ^ (u.v & 0xffffffff));
42 ret = 5381;
43 for (i = 0, p = (const unsigned char *) key; i < key_size; i++, p++)
44 ret = ret * 33 + *p;
45 return ret;
48 /* An identity equality function for a type. This is used for types
49 where we can check for equality by checking that the values have
50 the same bits. */
52 _Bool
53 __go_type_equal_identity (const void *k1, const void *k2, uintptr_t key_size)
55 return __builtin_memcmp (k1, k2, key_size) == 0;