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Diffstat (limited to '')
| -rw-r--r-- | gc/nursery.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/gc/nursery.c b/gc/nursery.c new file mode 100644 index 0000000..8bbb101 --- /dev/null +++ b/gc/nursery.c @@ -0,0 +1,175 @@ +/* + * Copyright (c) 1999 by Silicon Graphics. All rights reserved. + * + * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED + * OR IMPLIED. ANY USE IS AT YOUR OWN RISK. + * + * Permission is hereby granted to use or copy this program + * for any purpose, provided the above notices are retained on all copies. + * Permission to modify the code and to distribute modified code is granted, + * provided the above notices are retained, and a notice that the code was + * modified is included with the above copyright notice. + */ + + +??? This implementation is incomplete. If you are trying to +??? compile this you are doing something wrong. + +#include "nursery.h" + +struct copy_obj { + ptr_t forward; /* Forwarding link for copied objects. */ + GC_copy_descriptor descr; /* Object descriptor */ + word data[1]; +} + +ptr_t GC_nursery_start; /* Start of nursery area. */ + /* Must be NURSERY_BLOCK_SIZE */ + /* aligned. */ +ptr_t GC_nursery_end; /* End of nursery area. */ +unsigned char * GC_nursery_map; + /* GC_nursery_map[i] != 0 if an object */ + /* starts on the ith 64-bit "word" of */ + /* nursery. This simple structure has */ + /* the advantage that */ + /* allocation is cheap. Lookup is */ + /* cheap for pointers to the head of */ + /* an object, which should be the */ + /* usual case. */ +# define NURSERY_MAP_NOT_START 0 /* Not start of object. */ +# define NURSERY_MAP_START 1 /* Start of object. */ +# define NURSERY_MAP_PINNED 2 /* Start of pinned obj. */ + +# ifdef ALIGN_DOUBLE +# define NURSERY_WORD_SIZE (2 * sizeof(word)) +# else +# define NURSERY_WORD_SIZE sizeof(word) +# endif + +# define NURSERY_BLOCK_SIZE (HBLKSIZE/2) + /* HBLKSIZE must be a multiple of NURSERY_BLOCK_SIZE */ +# define NURSERY_SIZE (1024 * NURSERY_BLOCK_SIZE) + +size_t GC_nursery_size = NURSERY_SIZE; + /* Must be multiple of NURSERY_BLOCK_SIZE */ + +size_t GC_nursery_blocks; /* Number of blocks in the nursery. */ + +unsigned GC_next_nursery_block; /* index of next block we will attempt */ + /* allocate from during this cycle. */ + /* If it is pinned, we won't actually */ + /* use it. */ + +unsigned short *GC_pinned; /* Number of pinned objects in ith */ + /* nursery block. */ + /* GC_pinned[i] != 0 if the ith nursery */ + /* block is pinned, and thus not used */ + /* for allocation. */ + +GC_copy_alloc_state global_alloc_state = (ptr_t)(-1); /* will overflow. */ + +/* Should be called with allocator lock held. */ +GC_nursery_init() { + GC_nursery_start = GET_MEM(GC_nursery_size); + GC_nursery_end = GC_nursery_start + GC_nursery_size; + GC_next_nursery_block = 0; + if (GC_nursery_start < GC_least_plausible_heap_addr) { + GC_least_plausible_heap_addr = GC_nursery_start; + } + if (GC_nursery_end > GC_greatest_plausible_heap_addr) { + GC_greatest_plausible_heap_addr = GC_nursery_end; + } + if (GC_nursery_start & (NURSERY_BLOCK_SIZE-1)) { + GC_err_printf1("Nursery area is misaligned!!"); + /* This should be impossible, since GET_MEM returns HBLKSIZE */ + /* aligned chunks, and that should be a multiple of */ + /* NURSERY_BLOCK_SIZE */ + ABORT("misaligned nursery"); + } + GC_nursery_map = GET_MEM(GC_nursery_size/NURSERY_WORD_SIZE); + /* Map is cleared a block at a time when we allocate from the block. */ + /* BZERO(GC_nursery_map, GC_nursery_size/NURSERY_WORD_SIZE); */ + GC_nursery_blocks = GC_nursery_size/NURSERY_BLOCK_SIZE; + GC_pinned = GC_scratch_alloc(GC_nursery_blocks * sizeof(unsigned short)); + BZERO(GC_pinned, GC_nursery_blocks); +} + +/* Pin all nursery objects referenced from mark stack. */ +void GC_pin_mark_stack_objects(void) { + for each possible pointer current in a mark stack object + if (current >= GC_nursery_start && current < GC_nursery_end) { + unsigned offset = current - GC_nursery_start; + unsigned word_offset = BYTES_TO_WORDS(offset); + unsigned blockno = (current - GC_nursery_start)/NURSERY_BLOCK_SIZE; + while (GC_nursery_map[word_offset] == NURSERY_MAP_NOT_START) { + --word_offset; + } + if (GC_nursery_map[word_offset] != NURSERY_MAP_PINNED) { + GC_nursery_map[word_offset] = NURSERY_MAP_PINNED; + ++GC_pinned[blockno]; + ??Push object at GC_nursery_start + WORDS_TO_BYTES(word_offset) + ??onto stack. + } + } + } +} + +/* Caller holds allocation lock. */ +void GC_collect_nursery(void) { + int i; + ptr_t scan_ptr = 0; + ?? old_mark_stack_top; + STOP_WORLD; + for (i = 0; i < GC_nursery_blocks; ++i) GC_pinned[i] = 0; + GC_push_all_roots(); + old_mark_stack_top = GC_mark_stack_top(); + GC_pin_mark_stack_objects(); + START_WORLD; +} + +/* Initialize an allocation state so that it can be used for */ +/* allocation. This implicitly reserves a small section of the */ +/* nursery for use with his allocator. */ +void GC_init_copy_alloc_state(GC_copy_alloc_state *) + unsigned next_block; + ptr_t block_addr; + LOCK(); + next_block = GC_next_nursery_block; + while(is_pinned[next_block] && next_block < GC_nursery_blocks) { + ++next_block; + } + if (next_block < GC_nursery_blocks) { + block_addr = GC_nursery_start + NURSERY_BLOCK_SIZE * next_block; + GC_next_nursery_block = next_block + 1; + BZERO(GC_nursery_map + next_block * + (NURSERY_BLOCK_SIZE/NURSERY_WORD_SIZE), + NURSERY_BLOCK_SIZE/NURSERY_WORD_SIZE); + *GC_copy_alloc_state = block_addr; + UNLOCK(); + } else { + GC_collect_nursery(); + GC_next_nursery_block = 0; + UNLOCK(); + get_new_block(s); + } +} + +GC_PTR GC_copying_malloc2(GC_copy_descriptor *d, GC_copy_alloc_state *s) { + size_t sz = GC_SIZE_FROM_DESCRIPTOR(d); + ptrdiff_t offset; + ptr_t result = *s; + ptr_t new = result + sz; + if (new & COPY_BLOCK_MASK <= result & COPY_BLOCK_MASK> { + GC_init_copy_alloc_state(s); + result = *s; + new = result + sz; + GC_ASSERT(new & COPY_BLOCK_MASK > result & COPY_BLOCK_MASK> + } + (struct copy_obj *)result -> descr = d; + (struct copy_obj *)result -> forward = 0; + offset = (result - GC_nursery_start)/NURSERY_WORD_SIZE; + GC_nursery_map[offset] = NURSERY_MAP_NOT_START; +} + +GC_PTR GC_copying_malloc(GC_copy_descriptor *d) { +} |