You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 

312 lines
9.2 KiB

/*
* Copyright 2011-2016 Formal Methods and Tools, University of Twente
* Copyright 2016-2017 Tom van Dijk, Johannes Kepler University Linz
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <sylvan_int.h>
#include <errno.h> // for errno
#include <string.h> // for strerror
#include <sys/mman.h> // for mmap
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
#ifndef CACHE_MASK
#define CACHE_MASK 1
#endif
#ifndef compiler_barrier
#define compiler_barrier() { asm volatile("" ::: "memory"); }
#endif
#ifndef cas
#define cas(ptr, old, new) (__sync_bool_compare_and_swap((ptr),(old),(new)))
#endif
/**
* This cache is designed to store a,b,c->res, with a,b,c,res 64-bit integers.
*
* Each cache bucket takes 32 bytes, 2 per cache line.
* Each cache status bucket takes 4 bytes, 16 per cache line.
* Therefore, size 2^N = 36*(2^N) bytes.
*/
struct __attribute__((packed)) cache6_entry {
uint64_t a;
uint64_t b;
uint64_t c;
uint64_t res;
uint64_t d;
uint64_t e;
uint64_t f;
uint64_t res2;
};
typedef struct cache6_entry *cache6_entry_t;
struct __attribute__((packed)) cache_entry {
uint64_t a;
uint64_t b;
uint64_t c;
uint64_t res;
};
static size_t cache_size; // power of 2
static size_t cache_max; // power of 2
#if CACHE_MASK
static size_t cache_mask; // cache_size-1
#endif
static cache_entry_t cache_table;
static uint32_t* cache_status;
static uint64_t next_opid;
uint64_t
cache_next_opid()
{
return __sync_fetch_and_add(&next_opid, 1LL<<40);
}
// status: 0x80000000 - bitlock
// 0x7fff0000 - hash (part of the 64-bit hash not used to position)
// 0x0000ffff - tag (every put increases tag field)
/* Rotating 64-bit FNV-1a hash */
static uint64_t
cache_hash(uint64_t a, uint64_t b, uint64_t c)
{
const uint64_t prime = 1099511628211;
uint64_t hash = 14695981039346656037LLU;
hash = (hash ^ (a>>32));
hash = (hash ^ a) * prime;
hash = (hash ^ b) * prime;
hash = (hash ^ c) * prime;
return hash;
}
static uint64_t
cache_hash6(uint64_t a, uint64_t b, uint64_t c, uint64_t d, uint64_t e, uint64_t f)
{
const uint64_t prime = 1099511628211;
uint64_t hash = 14695981039346656037LLU;
hash = (hash ^ (a>>32));
hash = (hash ^ a) * prime;
hash = (hash ^ b) * prime;
hash = (hash ^ c) * prime;
hash = (hash ^ d) * prime;
hash = (hash ^ e) * prime;
hash = (hash ^ f) * prime;
return hash;
}
int
cache_get6(uint64_t a, uint64_t b, uint64_t c, uint64_t d, uint64_t e, uint64_t f, uint64_t *res1, uint64_t *res2)
{
const uint64_t hash = cache_hash6(a, b, c, d, e, f);
#if CACHE_MASK
volatile uint64_t *s_bucket = (uint64_t*)cache_status + (hash & cache_mask)/2;
cache6_entry_t bucket = (cache6_entry_t)cache_table + (hash & cache_mask)/2;
#else
volatile uint64_t *s_bucket = (uint64_t*)cache_status + (hash % cache_size)/2;
cache6_entry_t bucket = (cache6_entry_t)cache_table + (hash % cache_size)/2;
#endif
const uint64_t s = *s_bucket;
compiler_barrier();
// abort if locked or second part of 2-part entry or if different hash
uint64_t x = ((hash>>32) & 0x7fff0000) | 0x04000000;
x = x | (x<<32);
if ((s & 0xffff0000ffff0000) != x) return 0;
// abort if key different
if (bucket->a != a || bucket->b != b || bucket->c != c) return 0;
if (bucket->d != d || bucket->e != e || bucket->f != f) return 0;
*res1 = bucket->res;
if (res2) *res2 = bucket->res2;
compiler_barrier();
// abort if status field changed after compiler_barrier()
return *s_bucket == s ? 1 : 0;
}
int
cache_put6(uint64_t a, uint64_t b, uint64_t c, uint64_t d, uint64_t e, uint64_t f, uint64_t res1, uint64_t res2)
{
const uint64_t hash = cache_hash6(a, b, c, d, e, f);
#if CACHE_MASK
volatile uint64_t *s_bucket = (uint64_t*)cache_status + (hash & cache_mask)/2;
cache6_entry_t bucket = (cache6_entry_t)cache_table + (hash & cache_mask)/2;
#else
volatile uint64_t *s_bucket = (uint64_t*)cache_status + (hash % cache_size)/2;
cache6_entry_t bucket = (cache6_entry_t)cache_table + (hash % cache_size)/2;
#endif
const uint64_t s = *s_bucket;
// abort if locked
if (s & 0x8000000080000000LL) return 0;
// create new
uint64_t new_s = ((hash>>32) & 0x7fff0000) | 0x04000000;
new_s |= (new_s<<32);
new_s |= (((s>>32)+1)&0xffff)<<32;
new_s |= (s+1)&0xffff;
// use cas to claim bucket
if (!cas(s_bucket, s, new_s | 0x8000000080000000LL)) return 0;
// cas succesful: write data
bucket->a = a;
bucket->b = b;
bucket->c = c;
bucket->d = d;
bucket->e = e;
bucket->f = f;
bucket->res = res1;
bucket->res2 = res2;
compiler_barrier();
// after compiler_barrier(), unlock status field
*s_bucket = new_s;
return 1;
}
int
cache_get(uint64_t a, uint64_t b, uint64_t c, uint64_t *res)
{
const uint64_t hash = cache_hash(a, b, c);
#if CACHE_MASK
volatile uint32_t *s_bucket = cache_status + (hash & cache_mask);
cache_entry_t bucket = cache_table + (hash & cache_mask);
#else
volatile uint32_t *s_bucket = cache_status + (hash % cache_size);
cache_entry_t bucket = cache_table + (hash % cache_size);
#endif
const uint32_t s = *s_bucket;
compiler_barrier();
// abort if locked or if part of a 2-part cache entry
if (s & 0xc0000000) return 0;
// abort if different hash
if ((s ^ (hash>>32)) & 0x3fff0000) return 0;
// abort if key different
if (bucket->a != a || bucket->b != b || bucket->c != c) return 0;
*res = bucket->res;
compiler_barrier();
// abort if status field changed after compiler_barrier()
return *s_bucket == s ? 1 : 0;
}
int
cache_put(uint64_t a, uint64_t b, uint64_t c, uint64_t res)
{
const uint64_t hash = cache_hash(a, b, c);
#if CACHE_MASK
volatile uint32_t *s_bucket = cache_status + (hash & cache_mask);
cache_entry_t bucket = cache_table + (hash & cache_mask);
#else
volatile uint32_t *s_bucket = cache_status + (hash % cache_size);
cache_entry_t bucket = cache_table + (hash % cache_size);
#endif
const uint32_t s = *s_bucket;
// abort if locked
if (s & 0x80000000) return 0;
// abort if hash identical -> no: in iscasmc this occasionally causes timeouts?!
const uint32_t hash_mask = (hash>>32) & 0x3fff0000;
// if ((s & 0x7fff0000) == hash_mask) return 0;
// use cas to claim bucket
const uint32_t new_s = ((s+1) & 0x0000ffff) | hash_mask;
if (!cas(s_bucket, s, new_s | 0x80000000)) return 0;
// cas succesful: write data
bucket->a = a;
bucket->b = b;
bucket->c = c;
bucket->res = res;
compiler_barrier();
// after compiler_barrier(), unlock status field
*s_bucket = new_s;
return 1;
}
void
cache_create(size_t _cache_size, size_t _max_size)
{
#if CACHE_MASK
// Cache size must be a power of 2
if (__builtin_popcountll(_cache_size) != 1 || __builtin_popcountll(_max_size) != 1) {
fprintf(stderr, "cache_create: Table size must be a power of 2!\n");
exit(1);
}
#endif
cache_size = _cache_size;
cache_max = _max_size;
#if CACHE_MASK
cache_mask = cache_size - 1;
#endif
if (cache_size > cache_max) {
fprintf(stderr, "cache_create: Table size must be <= max size!\n");
exit(1);
}
cache_table = (cache_entry_t)mmap(0, cache_max * sizeof(struct cache_entry), PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
cache_status = (uint32_t*)mmap(0, cache_max * sizeof(uint32_t), PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (cache_table == (cache_entry_t)-1 || cache_status == (uint32_t*)-1) {
fprintf(stderr, "cache_create: Unable to allocate memory: %s!\n", strerror(errno));
exit(1);
}
next_opid = 512LL << 40;
}
void
cache_free()
{
munmap(cache_table, cache_max * sizeof(struct cache_entry));
munmap(cache_status, cache_max * sizeof(uint32_t));
}
void
cache_clear()
{
// a bit silly, but this works just fine, and does not require writing 0 everywhere...
cache_free();
cache_create(cache_size, cache_max);
}
void
cache_setsize(size_t size)
{
// easy solution
cache_free();
cache_create(size, cache_max);
}
size_t
cache_getsize()
{
return cache_size;
}
size_t
cache_getused()
{
size_t result = 0;
for (size_t i=0;i<cache_size;i++) {
uint32_t s = cache_status[i];
if (s & 0x80000000) fprintf(stderr, "cache_getuser: cache in use during cache_getused()\n");
if (s) result++;
}
return result;
}
size_t
cache_getmaxsize()
{
return cache_max;
}