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Sketch out gc glue.

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This commit is contained in:
Graydon Hoare 2010-06-25 01:29:51 -07:00
parent 85a701c8f6
commit 287d69ddac
1 changed files with 112 additions and 13 deletions
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125
src/boot/be/x86.ml
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@ -738,10 +738,10 @@ let emit_native_call_in_thunk
mov (word_at (h edx)) (ro eax)
;;
let unwind_glue
let crawl_stack_calling_glue
(e:Il.emitter)
(nabi:nabi)
(exit_task_fixup:fixup)
(glue_field:int)
: unit =
let fp_n = word_n (Il.Hreg ebp) in
@ -753,7 +753,6 @@ let unwind_glue
let add x y = emit (Il.binary Il.ADD (rc x) (ro x) (ro y)) in
let codefix fix = Il.CodePtr (Il.ImmPtr (fix, Il.CodeTy)) in
let mark fix = Il.emit_full e (Some fix) [] Il.Dead in
let glue_field = Abi.frame_glue_fns_field_drop in
let repeat_jmp_fix = new_fixup "repeat jump" in
let skip_jmp_fix = new_fixup "skip jump" in
@ -764,6 +763,8 @@ let unwind_glue
(rc esp)
(c (edx_n Abi.task_field_rust_sp));
push (ro ebp); (* save ebp at entry *)
mark repeat_jmp_fix;
mov (rc esi) (c (fp_n (-1))); (* esi <- crate ptr *)
@ -776,14 +777,14 @@ let unwind_glue
add edx esi; (* add crate ptr to disp. *)
mov
(rc ecx)
(c (edx_n glue_field)); (* ecx <- drop glue *)
(c (edx_n glue_field)); (* ecx <- glue *)
emit (Il.cmp (ro ecx) (immi 0L));
emit
(Il.jmp Il.JE
(codefix skip_jmp_fix)); (* if glue-fn is nonzero *)
add ecx esi; (* add crate ptr to disp. *)
push (ro ebp); (* frame-to-drop *)
push (ro ebp); (* frame-arg *)
push (c task_ptr); (* form usual call to glue *)
push (immi 0L); (* outptr *)
emit (Il.call (rc eax)
@ -803,15 +804,113 @@ let unwind_glue
(* exit path. *)
mark exit_jmp_fix;
let callee =
Abi.load_fixup_codeptr
e (h eax) exit_task_fixup false nabi.nabi_indirect
in
emit_c_call
e (rc eax) (h edx) (h ecx) nabi false callee [| (c task_ptr) |];
pop (rc ebp); (* restore ebp *)
;;
let gc_glue
(e:Il.emitter)
: unit =
(* Mark pass. *)
crawl_stack_calling_glue e Abi.frame_glue_fns_field_mark;
(* Sweep pass. *)
let emit = Il.emit e in
let mov dst src = emit (Il.umov dst src) in
let push x = emit (Il.Push x) in
let pop x = emit (Il.Pop x) in
let band x y = emit (Il.binary Il.AND x (c x) y) in
let add x y = emit (Il.binary Il.ADD (rc x) (ro x) (ro y)) in
let edx_n = word_n (Il.Hreg edx) in
let ecx_n = word_n (Il.Hreg ecx) in
let codefix fix = Il.CodePtr (Il.ImmPtr (fix, Il.CodeTy)) in
let mark fix = Il.emit_full e (Some fix) [] Il.Dead in
let repeat_jmp_fix = new_fixup "repeat jump" in
let skip_jmp_fix = new_fixup "skip jump" in
let exit_jmp_fix = new_fixup "exit jump" in
mov (rc edx) (c task_ptr);
mov (rc edx) (c (edx_n Abi.task_field_gc_alloc_chain));
mark repeat_jmp_fix;
emit (Il.cmp (ro edx) (immi 0L));
emit (Il.jmp Il.JE
(codefix exit_jmp_fix)); (* if nonzero *)
mov (rc ecx) (* Load GC ctrl word *)
(c (edx_n Abi.exterior_gc_slot_field_ctrl));
band (* Clear in-memory mark. *)
(edx_n Abi.exterior_gc_slot_field_ctrl)
(immi 0xfffffffffffffffeL);
band (rc ecx) (immi 1L); (* Check in-reg mark. *)
emit (Il.cmp (ro edx) (immi 0L));
emit
(Il.jmp Il.JNE
(codefix skip_jmp_fix)); (* if unmarked (garbage) *)
(* NB: ecx is a type descriptor now. *)
mov (rc eax) (* Load glue tydesc-off. *)
(c (ecx_n Abi.tydesc_field_free_glue));
add eax ecx; (* Add to tydesc* *)
(* FIXME: this path is all wrong, for three reasons.
*
* First, it needs to unlink the values that it frees from the gc
* chain. Currently it's going to leave dead pointers on it.
*
* Second, the *normal* gc-drop path actually has to do that as well;
* it's not, and that's a problem.
*
* Third, it actually needs to walk in two full passes over the chain:
*
* - In pass #1, it goes through and disposes of all mutable exterior
* slots in each record. That is, rc-- the referent, and then
* null-out. If the rc-- gets to zero, that just means the mutable
* is part of the garbage set currently being collected. But a
* mutable may be live-and-outside; this detaches the garbage set
* from the non-garbage set within the mutable heap.
*
* - In pass #2, run the normal free-glue. This winds up doing the
* immutables only, since all the mutables were nulled out in pass
* #1. This is where you do the unlinking from the double-linked
* chain mentioned above.
*
* So .. this will still take a little more doing.
*
*)
push (ro edx); (* gc_val to drop *)
push (c task_ptr); (* form usual call to glue *)
push (immi 0L); (* outptr *)
emit (Il.call (rc eax)
(reg_codeptr (h eax))); (* call glue_fn, trashing eax. *)
pop (rc eax);
pop (rc eax);
pop (rc eax);
mark skip_jmp_fix;
mov (rc ecx) (* Advance down chain *)
(c (edx_n Abi.exterior_gc_slot_field_next));
emit (Il.jmp Il.JMP
(codefix repeat_jmp_fix)); (* loop *)
mark exit_jmp_fix;
;;
let unwind_glue
(e:Il.emitter)
(nabi:nabi)
(exit_task_fixup:fixup)
: unit =
crawl_stack_calling_glue e Abi.frame_glue_fns_field_drop;
let callee =
Abi.load_fixup_codeptr
e (h eax) exit_task_fixup false nabi.nabi_indirect
in
emit_c_call
e (rc eax) (h edx) (h ecx) nabi false callee [| (c task_ptr) |];
;;
(* Puts result in eax; clobbers ecx, edx in the process. *)
let rec calculate_sz (e:Il.emitter) (size:size) : unit =
let emit = Il.emit e in