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/*
* Copyright © 2018 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include "snek.h"
#ifdef SNEK_DYNAMIC
uint8_t *snek_pool __attribute__((aligned(SNEK_ALLOC_ROUND)));
uint32_t snek_pool_size;
#else
uint8_t snek_pool[SNEK_POOL] __attribute__((aligned(SNEK_ALLOC_ROUND)));
#endif
struct snek_root {
const snek_mem_t *type;
void **addr;
};
#ifndef SNEK_ROOT_DECLARE
#define SNEK_ROOT_DECLARE(n) n
#define SNEK_ROOT_TYPE(n) ((n)->type)
#define SNEK_ROOT_ADDR(n) ((n)->addr)
#endif
static const struct snek_root SNEK_ROOT_DECLARE(snek_root)[] = {
{
.type = &snek_name_mem,
.addr = (void **) (void *) &snek_names,
},
{
.type = &snek_frame_mem,
.addr = (void **) (void *) &snek_globals,
},
{
.type = &snek_frame_mem,
.addr = (void **) (void *) &snek_frame,
},
{
.type = &snek_code_mem,
.addr = (void **) (void *) &snek_stash_code,
},
{
.type = &snek_code_mem,
.addr = (void **) (void *) &snek_code,
},
{
.type = &_snek_mems[snek_list - 1],
.addr = (void **) (void *) &snek_empty_tuple,
},
{
.type = NULL,
.addr = (void **) (void *) &snek_a,
},
{
.type = &snek_compile_mem,
.addr = (void **) (void *) &snek_compile,
},
};
#ifdef SNEK_MEM_CACHE_NUM
static const void ** const snek_mem_cache[] = {
(const void **) &SNEK_MEM_CACHE_0,
#if SNEK_MEM_CACHE_NUM > 1
(const void **) &SNEK_MEM_CACHE_1,
#endif
};
#endif
#define SNEK_ROOT (sizeof (snek_root) / sizeof (snek_root[0]))
#define SNEK_BUSY_SIZE ((SNEK_POOL + 31) / 32)
#define SNEK_NCHUNK_EST(pool) ((pool) / 64)
struct snek_chunk {
snek_offset_t old_offset;
union {
snek_offset_t size;
snek_offset_t new_offset;
};
};
#ifdef SNEK_DYNAMIC
static uint8_t *snek_busy;
static struct snek_chunk *snek_chunk;
static snek_offset_t SNEK_NCHUNK;
typedef snek_offset_t snek_chunk_t;
bool
snek_mem_alloc(snek_poly_t pool_size)
{
snek_poly_t busy_size = (pool_size + 31) / 32;
snek_pool = malloc(pool_size +
busy_size +
busy_size +
busy_size +
SNEK_NCHUNK_EST(pool_size) * sizeof (struct snek_chunk));
if (!snek_pool)
return false;
snek_busy = snek_pool + pool_size;
snek_chunk = (struct snek_chunk *) (((uintptr_t)(snek_busy + busy_size) + 7) & ~7);
snek_pool_size = pool_size;
SNEK_NCHUNK = SNEK_NCHUNK_EST(pool_size);
return true;
}
#else
#define SNEK_NCHUNK SNEK_NCHUNK_EST(SNEK_POOL)
static uint8_t snek_busy[SNEK_BUSY_SIZE];
static struct snek_chunk snek_chunk[SNEK_NCHUNK];
#if SNEK_NCHUNK < 255
typedef uint8_t snek_chunk_t;
#else
typedef snek_offset_t snek_chunk_t;
#endif
#endif
static snek_offset_t snek_note_list = SNEK_OFFSET_NONE;
static snek_offset_t snek_top;
/* Offset of an address within the pool. */
static snek_offset_t pool_offset(const void *addr) {
#if SNEK_DEBUG
if (addr == NULL)
snek_panic("null in pool_offset");
if ((uint8_t *) addr < snek_pool || &snek_pool[SNEK_POOL] <= (uint8_t *) addr)
snek_panic("out of bounds in pool_offset");
if (((uintptr_t) addr & (SNEK_ALLOC_ROUND-1)) != 0)
snek_panic("unaligned addr in pool_offset");
#endif
return ((uint8_t *) addr) - snek_pool;
}
/* Address of an offset within the pool */
static void *pool_addr(snek_offset_t offset) {
#if SNEK_DEBUG
if (snek_offset_is_none(offset))
snek_panic("none in pool_addr");
if (offset >= SNEK_POOL)
snek_panic("out of bounds in pool_addr");
if ((offset & (SNEK_ALLOC_ROUND-1)) != 0)
snek_panic("unaligned offset in pool_addr");
#endif
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Warray-bounds"
return snek_pool + offset;
#pragma GCC diagnostic pop
}
static snek_offset_t tag_byte(snek_offset_t offset) {
return offset >> (SNEK_ALLOC_SHIFT + 3);
}
static uint8_t tag_bit(snek_offset_t offset) {
return (offset >> SNEK_ALLOC_SHIFT) & 7;
}
static void mark(snek_offset_t offset) {
snek_busy[tag_byte(offset)] |= (1 << tag_bit(offset));
}
static bool busy(snek_offset_t offset) {
return (snek_busy[tag_byte(offset)] >> tag_bit(offset)) & 1;
}
bool
snek_is_pool_addr(const void *addr)
{
const uint8_t *a = addr;
return (snek_pool <= a) && (a < snek_pool + SNEK_POOL);
}
static snek_offset_t
snek_size_round(snek_offset_t size)
{
return (size + (SNEK_ALLOC_ROUND - 1)) & ~(SNEK_ALLOC_ROUND - 1);
}
static snek_offset_t
snek_size(const snek_mem_t *mem, void *addr)
{
return snek_size_round(SNEK_MEM_SIZE(mem)(addr));
}
static void
note_list(snek_list_t *list_old, snek_list_t *list_new)
{
debug_memory("\tnote list %d -> %d\n", pool_offset(list_old), pool_offset(list_new));
snek_list_set_note_next(list_new, snek_note_list);
snek_note_list = pool_offset(list_old);
}
static snek_offset_t chunk_low, chunk_high;
static snek_chunk_t chunk_first, chunk_last;
static snek_chunk_t
find_chunk(snek_offset_t offset)
{
snek_chunk_t l, r;
/* Binary search for the location */
l = chunk_first;
r = chunk_last;
while (l < r) {
snek_chunk_t m = (l + r) >> 1;
if (snek_chunk[m].old_offset < offset)
l = m + 1;
else
r = m;
}
return l;
}
static void
note_chunk(snek_offset_t offset, snek_offset_t size)
{
snek_chunk_t chunk;
snek_offset_t end;
if (offset < chunk_low || chunk_high <= offset)
return;
chunk = find_chunk(offset);
#if SNEK_DEBUG
if (chunk >= SNEK_NCHUNK)
snek_error_0("note chunk failed");
#endif
/*
* The correct location is always in 'l', with r = l-1 being
* the entry before the right one
*/
/* Shuffle existing entries right */
end = chunk_last + 1;
if (end > SNEK_NCHUNK)
end = SNEK_NCHUNK;
memmove(&snek_chunk[chunk+1],
&snek_chunk[chunk],
(end - (chunk+1)) * sizeof (struct snek_chunk));
/* Add new entry */
snek_chunk[chunk].old_offset = offset;
snek_chunk[chunk].size = size;
/* Increment the number of elements up to the size of the array */
if (chunk_last < SNEK_NCHUNK)
chunk_last++;
debug_memory("add chunk %d offset %d size %d chunk_last %d\n", chunk, offset, size, chunk_last);
/* Set the top address if the array is full */
if (chunk_last == SNEK_NCHUNK) {
chunk_high = snek_chunk[SNEK_NCHUNK-1].old_offset +
snek_chunk[SNEK_NCHUNK-1].size;
debug_memory("reset chunk_high to %d\n", chunk_high);
}
}
static void
reset_chunks(void)
{
chunk_high = snek_top;
chunk_last = 0;
chunk_first = 0;
}
/*
* Walk all referenced objects calling functions on each one
*/
static void
walk(bool (*visit_addr)(const struct snek_mem *type, void **addr),
bool (*visit_poly)(snek_poly_t *p))
{
snek_offset_t i;
memset(snek_busy, '\0', SNEK_BUSY_SIZE);
for (i = 0; i < snek_stackp; i++)
visit_poly(&snek_stack[i]);
for (i = 0; i < (snek_offset_t) SNEK_ROOT; i++) {
const snek_mem_t *mem = SNEK_ROOT_TYPE(&snek_root[i]);
if (mem) {
void **a = SNEK_ROOT_ADDR(&snek_root[i]), *v;
if (a == NULL || (v = *a) != NULL) {
visit_addr(mem, a);
}
} else {
snek_poly_t *a = (snek_poly_t *) SNEK_ROOT_ADDR(&snek_root[i]), p;
if (a && !snek_is_null(p = *a)) {
visit_poly(a);
}
}
}
while (!snek_offset_is_none(snek_note_list)) {
snek_offset_t note = snek_note_list;
snek_note_list = SNEK_OFFSET_NONE;
debug_memory("processing list %d\n", note);
while (!snek_offset_is_none(note)) {
snek_list_t *list = pool_addr(note);
debug_memory("\tprocess list %d\n", pool_offset(list));
visit_addr(snek_mems(snek_list), (void **) &list);
note = snek_list_note_next(list);
debug_memory("\t\tprocessed, list is now %d next now %d\n",
pool_offset(list), note);
snek_list_set_note_next(list, 0);
}
debug_memory("done procesing list\n");
}
}
static bool
snek_mark_ref(const struct snek_mem *type, void **ref)
{
return snek_mark_addr(type, *ref);
}
bool
snek_poly_mark_ref(snek_poly_t *p)
{
return snek_poly_mark(*p);
}
snek_offset_t snek_last_top;
uint8_t snek_collect_counts;
#ifdef DEBUG_MEMORY
static void dump_busy(void)
{
snek_offset_t i;
for (i = 0; i < snek_top; i += 4)
if (busy(i))
debug_memory("\tBusy %d\n", i);
}
#else
#define dump_busy()
#endif
snek_offset_t
snek_collect(uint8_t style)
{
snek_chunk_t c;
snek_offset_t top;
debug_memory("Collect...\n");
/* The first time through, we're doing a full collect */
if (snek_last_top == 0)
style = SNEK_COLLECT_FULL;
/* One in a while, just do a full collect */
if (snek_collect_counts >= 128)
style = SNEK_COLLECT_FULL;
if (style == SNEK_COLLECT_FULL)
snek_collect_counts = 0;
#if SNEK_MEM_CACHE_NUM
for (c = 0; c < SNEK_MEM_CACHE_NUM; c++)
*snek_mem_cache[c] = NULL;
#endif
if (style == SNEK_COLLECT_FULL) {
chunk_low = top = 0;
} else {
chunk_low = top = snek_last_top;
}
for (;;) {
/* Find the sizes of the first chunk of objects to move */
reset_chunks();
debug_memory("mark\n");
walk(snek_mark_ref, snek_poly_mark_ref);
dump_busy();
debug_memory("done\n");
debug_memory("chunk_last %d\n", chunk_last);
/* Find the first moving object */
for (c = 0; c < chunk_last; c++) {
snek_offset_t size = snek_chunk[c].size;
debug_memory("size %d old_offset %d top %d\n", size, snek_chunk[c].old_offset, top);
if (snek_chunk[c].old_offset > top)
break;
top += size;
}
/* Short-circuit the rest of the loop when all of the
* found objects aren't moving. This isn't strictly
* necessary as the rest of the loop is structured to
* work in this case, but GCC 7.2.0 with optimization
* greater than 2 generates incorrect code for this...
*/
if (c == SNEK_NCHUNK) {
chunk_low = chunk_high;
continue;
}
/*
* Limit amount of chunk array used in mapping moves
* to the active region
*/
chunk_first = c;
chunk_low = snek_chunk[c].old_offset;
/* Copy all of the objects */
for (; c < chunk_last; c++) {
snek_offset_t size = snek_chunk[c].size;
debug_memory(" moving %d -> %d (%d)\n",
snek_chunk[c].old_offset, top, size);
snek_chunk[c].new_offset = top;
memmove(&snek_pool[top],
&snek_pool[snek_chunk[c].old_offset],
size);
top += size;
}
if (chunk_first < chunk_last) {
/* Relocate all references to the objects */
debug_memory("move\n");
walk(snek_move_addr, snek_poly_move);
debug_memory("done\n");
}
/* If we ran into the end of the heap, then
* there's no need to keep walking
*/
if (chunk_last != SNEK_NCHUNK)
break;
/* Next loop starts right above this loop */
chunk_low = chunk_high;
}
snek_top = top;
if (style == SNEK_COLLECT_FULL)
snek_last_top = top;
debug_memory("%d free\n", SNEK_POOL - snek_top);
return SNEK_POOL - snek_top;
}
/*
* Mark interfaces for objects
*/
/*
* Note a reference to memory and collect information about a few
* object sizes at a time
*/
bool
snek_mark_blob(void *addr, snek_offset_t size)
{
snek_offset_t offset;
#if SNEK_DEBUG
if (!snek_is_pool_addr(addr))
return true;
#endif
offset = pool_offset(addr);
if (busy(offset))
return true;
debug_memory("\tmark %d size %d\n", offset, size);
mark(offset);
note_chunk(offset, size);
return false;
}
#ifdef DEBUG_MEMORY
static const char *
type_name(const struct snek_mem *type)
{
if (type == &snek_code_mem)
return "code";
if (type == &snek_compile_mem)
return "compile";
if (type == &snek_frame_mem)
return "frame";
if (type == &snek_name_mem)
return "name";
snek_type_t t = (type - _snek_mems) + 1;
switch (t) {
case snek_list:
return "list";
case snek_string:
return "string";
case snek_func:
return "func";
default:
snek_panic("invalid mem type\n");
return NULL;
}
}
#endif
bool
snek_mark_block_addr(const struct snek_mem *type, void *addr)
{
bool ret;
ret = snek_mark_blob(addr, snek_size(type, addr));
if (!ret) {
debug_memory("\tmark %s %d %d\n", type_name(type), pool_offset(addr), snek_size(type, addr));
}
return ret;
}
/*
* Mark an object and all that it refereces
*/
bool
snek_mark_addr(const struct snek_mem *type, void *addr)
{
bool ret;
ret = snek_mark_block_addr(type, addr);
if (!ret)
SNEK_MEM_MARK(type)(addr);
return ret;
}
bool
snek_mark_offset(const struct snek_mem *type, snek_offset_t offset)
{
if (snek_offset_is_none(offset))
return true;
return snek_mark_addr(type, pool_addr(offset));
}
const struct snek_mem SNEK_MEMS_DECLARE(_snek_mems)[] = {
[snek_list-1] = {
.size = snek_list_size,
.mark = snek_list_mark,
.move = snek_list_move,
},
[snek_string-1] = {
.size = snek_string_size,
.mark = snek_string_mark_move,
.move = snek_string_mark_move,
},
[snek_func-1] = {
.size = snek_func_size,
.mark = snek_func_mark,
.move = snek_func_move,
},
};
/*
* Mark an object, unless it is a list. In that case, just set a bit
* in the list note array; those will be marked in a separate pass to
* avoid deep recursion in the collector
*/
bool
snek_poly_mark(snek_poly_t p)
{
snek_type_t type;
void *addr;
bool ret;
if (snek_is_null(p))
return true;
type = snek_poly_type(p);
if (type == snek_float || type == snek_builtin)
return true;
addr = snek_ref(p);
if (type == snek_list) {
debug_memory("\tmark list %d\n", pool_offset(addr));
}
#if SNEK_DEBUG
if (!snek_is_pool_addr(addr))
snek_panic("non-pool addr in heap");
#endif
ret = snek_mark_addr(snek_mems(type), addr);
if (!ret && type == snek_list)
note_list(addr, addr);
return ret;
}
/*
* Find the current location of an object
* based on the original location. For unmoved
* objects, this is simple. For moved objects,
* go search for it
*/
static snek_offset_t
move_map(snek_offset_t offset)
{
snek_chunk_t chunk;
if (offset < chunk_low || chunk_high <= offset)
return offset;
chunk = find_chunk(offset);
return snek_chunk[chunk].new_offset;
}
bool
snek_move_block_offset(void *ref)
{
snek_offset_t offset;
memcpy(&offset, ref, sizeof (snek_offset_t));
if (snek_offset_is_none(offset))
return true;
offset = move_map(offset);
memcpy(ref, &offset, sizeof (snek_offset_t));
if (busy(offset))
return true;
mark(offset);
return false;
}
bool
snek_move_block_addr(void **ref)
{
void *addr = *ref;
snek_offset_t offset;
bool ret;
#if SNEK_DEBUG
if (!snek_is_pool_addr(addr))
snek_panic("non-pool address");
#endif
offset = pool_offset(addr);
ret = snek_move_block_offset(&offset);
*ref = pool_addr(offset);
return ret;
}
bool
snek_move_addr(const struct snek_mem *type, void **ref)
{
bool ret;
ret = snek_move_block_addr(ref);
if (!ret)
SNEK_MEM_MOVE(type)(*ref);
return ret;
}
bool
snek_move_offset(const struct snek_mem *type, snek_offset_t *ref)
{
bool ret;
ret = snek_move_block_offset(ref);
if (!ret)
SNEK_MEM_MOVE(type)(pool_addr(*ref));
return ret;
}
bool
snek_poly_move(snek_poly_t *ref)
{
snek_poly_t p = *ref;
snek_type_t type = snek_poly_type(p);
void *orig_addr, *addr;
if (type == snek_float || type == snek_builtin)
return true;
orig_addr = addr = snek_ref(p);
if (type == snek_list) {
debug_memory("\tmove list %d\n", pool_offset(addr));
}
#if SNEK_DEBUG
if (!snek_is_pool_addr(addr))
snek_panic("non-pool address");
#endif
bool ret = snek_move_addr(snek_mems(type), &addr);
if (!ret && type == snek_list)
note_list(orig_addr, addr);
/* Re-write the poly value */
*ref = snek_poly(addr, snek_poly_type(p));
return ret;
}
void *
snek_alloc(snek_offset_t size)
{
void *addr;
size = snek_size_round(size);
if (SNEK_POOL - snek_top < size &&
snek_collect(SNEK_COLLECT_INCREMENTAL) < size &&
snek_collect(SNEK_COLLECT_FULL) < size)
{
snek_error_0("out of memory");
return NULL;
}
addr = pool_addr(snek_top);
memset(addr, '\0', size);
debug_memory("Alloc %d size %d\n", snek_top, size);
snek_top += size;
return addr;
}
void *
snek_pool_addr(snek_offset_t offset)
{
if (snek_offset_is_none(offset))
return NULL;
return pool_addr(offset);
}
snek_offset_t
snek_pool_offset(const void *addr)
{
if (addr == NULL)
return SNEK_OFFSET_NONE;
return pool_offset(addr);
}
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