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This commit is contained in:
nub31
@@ -1,14 +1,14 @@
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global gc_init, gc_alloc
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extern alloc, free, printint, printstr, endl
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extern printint, printstr, endl
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section .bss
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alloc_list_head: resq 1
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free_list_head: resq 1
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alloc_list_head: resq 1 ; metadata size: 24
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free_list_head: resq 1 ; metadata size: 16
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stack_start: resq 1
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section .data
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gc_bytes_allocated: dq 0 ; bytes allocated since the last gc cycle
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gc_trigger_threshold: dq 1024 * 1024 * 8 ; initial gc trigger threshold in bytes (adjusts dynamically)
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gc_bytes_allocated: dq 0 ; bytes allocated since the last gc cycle
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gc_trigger_threshold: dq 1024 * 1024 * 8 ; initial gc trigger threshold in bytes (adjusts dynamically)
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gc_start_text: db "Running gc after ", 0
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gc_sweep_done_text: db " Sweep done. We no have ", 0
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gc_next_threshold: db " The next threshold is ", 0
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@@ -21,24 +21,66 @@ gc_init:
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ret
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gc_alloc:
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add rdi, 24
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add rdi, 24 ; adjust for metadata size
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mov rdx, [gc_bytes_allocated]
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cmp rdx, [gc_trigger_threshold]
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jb .skip_collect ; if allocated bytes since last collect has exceeded threshold, trigger collect
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jbe .alloc ; if allocated bytes since last collect has exceeded threshold, trigger collect
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push rdi
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call gc_collect
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pop rdi
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.skip_collect:
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add [gc_bytes_allocated], rdi
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.alloc:
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add [gc_bytes_allocated], rdi ; adjust allocated bytes list
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mov rsi, [free_list_head]
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xor r8, r8
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.loop:
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test rsi, rsi
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jz .new_block ; allocate new block if at end of list
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mov rdx, [rsi]
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cmp rdi, rdx
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jbe .use_block ; use block if object fits within block
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mov r8, rsi ; load r8 with current node
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mov rsi, [rsi + 8] ; load next node
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jmp .loop
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.new_block:
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push rdi
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call alloc ; allocate size + metadata
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push r8
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mov rsi, 4096
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call max ; calculate size of allocation (max(input, 4096))
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mov rdi, rax
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push rdi
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call sys_mmap
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pop rsi
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sub rsi, 16
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mov qword [rax], rsi ; update metadata to page size - metadata
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push rax
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mov rdi, rax
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call insert_into_free
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pop rsi
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pop r8
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pop rdi
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mov byte [rax], 0 ; set mark to 0
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mov qword [rax + 8], rdi ; set total size of object (including metadata)
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mov rsi, [alloc_list_head] ; load first item in allocation list
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mov qword [rax + 16], rsi ; make current head of allocation list the next item in this object
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mov [alloc_list_head], rax ; update head of allocation list so it points to this object
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add rax, 24 ; skip metadata for return value
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.use_block:
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cmp [rsi], rdi ; check if the block will be empty after allocation
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ja .unlink_done ; if not, do not unlink
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test r8, r8 ; r8 is null if node is also head
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jz .unlink_head
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mov rdx, [rsi + 8] ; load next node
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mov [r8 + 8], rdx ; link next node to last node's next
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jmp .unlink_done
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.unlink_head:
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mov rdx, [free_list_head] ; load head
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mov rdx, [rdx + 8] ; load head.next
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mov [free_list_head], rdx ; mov head.next into head
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.unlink_done:
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sub [rsi], rdi ; reduce available space of block by the allocated space
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mov rdx, [rsi] ; load the available space excluding the newly allocated space
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lea rax, [rsi + rdx + 16] ; load the address of the newly allocated space
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mov byte [rax], 0 ; update mark to 0
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sub rdi, 24
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mov [rax + 8], rdi ; update metadata size to allocation size - metadata
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mov rdx, [alloc_list_head]
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mov [rax + 16], rdx
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mov [alloc_list_head], rax ; append this allocation to the head of allocation list
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lea rax, [rax + 24] ; skip past metadata for return value
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ret
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gc_collect:
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@@ -96,67 +138,123 @@ gc_mark_stack:
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ret
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gc_mark:
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test rdi, rdi ; is input null?
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jz .done ; yes? return
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test rdi, rdi ; is input null?
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jz .done ; yes? return
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mov rsi, [alloc_list_head] ; load start of allocation list
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.loop:
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test rsi, rsi ; reached end of list?
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jz .done ; yes? return
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test rsi, rsi ; reached end of list?
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jz .done ; yes? return
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lea rdx, [rsi + 24]
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cmp rdx, rdi ; no? is this the input object?
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je .mark_object ; yes? mark it
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mov rsi, [rsi + 16] ; no? next item
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cmp rdx, rdi ; no? is this the input object?
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je .mark_object ; yes? mark it
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mov rsi, [rsi + 16] ; no? next item
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jmp .loop
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.mark_object:
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mov al, [rdi] ; load mark
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test al, al ; already marked?
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jnz .done ; yes? return
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mov byte [rdi - 24], 1 ; mark object
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mov rcx, [rdi + 8] ; load object size
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mov rdx, rdi ; start of data
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add rcx, rdx ; end of data
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mov al, [rdi] ; load mark
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test al, al ; already marked?
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jnz .done ; yes? return
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mov byte [rdi - 24], 1 ; mark object
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mov rcx, [rdi + 8] ; load object size
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mov rdx, rdi ; start of data
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add rcx, rdx ; end of data
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.scan_object:
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cmp rdx, rcx ; done scanning?
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jae .done ; yes? return
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mov rdi, [rdx] ; load value
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cmp rdx, rcx ; done scanning?
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jae .done ; yes? return
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mov rdi, [rdx] ; load value
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call gc_mark
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add rdx, 8 ; next object
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add rdx, 8 ; next object
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jmp .scan_object
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.done:
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ret
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gc_sweep:
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mov rdi, [alloc_list_head]
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xor rsi, rsi
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xor r8, r8
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.loop:
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test rdi, rdi ; reached end of list?
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jz .done ; yes? return
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mov al, [rdi]
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test al, al ; is object marked?
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jz .unmarked ; no? free it
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mov byte [rdi], 0 ; yes? clear mark for next marking
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mov rsi, rdi
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mov rdi, [rdi + 16] ; load the next object in the list
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jmp .loop ; repeat
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.unmarked:
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mov rdx, [rdi + 16] ; save address of next object in list
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test rsi, rsi
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jz .remove_head
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mov [rsi + 16], rdx ; unlink the current node by setting the previous node's next to the next node's address
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jmp .free
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.remove_head:
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mov [alloc_list_head], rdx ; update head node to be the next node
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.free:
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push rsi ; save previous node since it will also be the previous node for the next item
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push rdx ; save next node
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mov rdx, [rdi + 8] ; load the size of the object
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sub [gc_bytes_allocated], rdx ; adjust allocated bytes
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call free ; free the memory
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pop rdi ; input for next iteration
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pop rsi ; prev node for next iteration
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test al, al
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jz .unmarked ; if unmarked, free object
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mov byte [rdi], 0 ; unmark object
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mov r8, rdi
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mov rdi, [rdi + 16] ; next item
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jmp .loop
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.done:
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ret
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.unmarked:
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mov r9, [rdi + 16] ; save address of next object in list
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test r8, r8
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jz .unlink_head ; if current is head, unlink head
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mov [r8 + 16], r9 ; unlink the current node by setting the previous node's next to the next node's address
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jmp .unlink_done
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.unlink_head:
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mov [alloc_list_head], r9 ; update head node to be the next node
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.unlink_done:
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push r8 ; save previous node since it will also be the previous node for the next item
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push r9 ; save next node
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mov rdx, [rdi + 8] ; load the size of the object
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add rdx, 24 ; adjust for metadata size
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sub [gc_bytes_allocated], rdx ; adjust allocated bytes
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call insert_into_free
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pop rdi ; input for next iteration
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pop r8 ; prev node for next iteration
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jmp .loop
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insert_into_free:
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mov rsi, [free_list_head] ; rsi will track the current node
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test rsi, rsi
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jz .insert_head ; if list is empty, insert at head
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cmp rdi, rsi
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jb .insert_head ; is input is smaller than head, insert at head
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.loop:
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mov r9, [rsi + 8] ; load next node
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test r9, r9
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jz .insert_tail ; if at end of the list, insert at tail
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cmp rdi, r9
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ja .next ; if input > next continue
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mov [rdi + 8], r9
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mov [rsi + 8], rdi ; insert node between current and next
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ret
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.insert_head:
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mov [rdi + 8], rsi ; set old head to input.next
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mov [free_list_head], rdi ; set head to input
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ret
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.insert_tail:
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mov qword [rdi + 8], 0 ; set input.tail to null
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mov [rsi + 8], rdi ; add input to current.next
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ret
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.next:
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mov rsi, r9
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jmp .loop
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sys_mmap:
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mov rax, 9
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mov rsi, rdi
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mov rdi, 0
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mov rdx, 3
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mov r10, 34
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mov r8, -1
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mov r9, 0
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syscall
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cmp rax, -1
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je .error
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ret
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.error:
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mov rax, 60
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mov rdi, 1
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syscall
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sys_munmap:
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mov rax, 11
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syscall
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cmp rax, -1
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je .error
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ret
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.error:
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mov rax, 60
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mov rdi, 1
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syscall
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max:
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cmp rdi, rsi
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