Sketch out gc glue.
This commit is contained in:
Graydon Hoare
parent
85a701c8f6
commit
287d69ddac
@ -738,10 +738,10 @@ let emit_native_call_in_thunk
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mov (word_at (h edx)) (ro eax)
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;;
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let unwind_glue
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let crawl_stack_calling_glue
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(e:Il.emitter)
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(nabi:nabi)
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(exit_task_fixup:fixup)
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(glue_field:int)
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: unit =
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let fp_n = word_n (Il.Hreg ebp) in
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@ -753,7 +753,6 @@ let unwind_glue
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let add x y = emit (Il.binary Il.ADD (rc x) (ro x) (ro y)) in
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let codefix fix = Il.CodePtr (Il.ImmPtr (fix, Il.CodeTy)) in
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let mark fix = Il.emit_full e (Some fix) [] Il.Dead in
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let glue_field = Abi.frame_glue_fns_field_drop in
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let repeat_jmp_fix = new_fixup "repeat jump" in
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let skip_jmp_fix = new_fixup "skip jump" in
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@ -764,6 +763,8 @@ let unwind_glue
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(rc esp)
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(c (edx_n Abi.task_field_rust_sp));
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push (ro ebp); (* save ebp at entry *)
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mark repeat_jmp_fix;
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mov (rc esi) (c (fp_n (-1))); (* esi <- crate ptr *)
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@ -776,14 +777,14 @@ let unwind_glue
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add edx esi; (* add crate ptr to disp. *)
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mov
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(rc ecx)
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(c (edx_n glue_field)); (* ecx <- drop glue *)
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(c (edx_n glue_field)); (* ecx <- glue *)
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emit (Il.cmp (ro ecx) (immi 0L));
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emit
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(Il.jmp Il.JE
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(codefix skip_jmp_fix)); (* if glue-fn is nonzero *)
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add ecx esi; (* add crate ptr to disp. *)
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push (ro ebp); (* frame-to-drop *)
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push (ro ebp); (* frame-arg *)
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push (c task_ptr); (* form usual call to glue *)
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push (immi 0L); (* outptr *)
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emit (Il.call (rc eax)
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@ -803,7 +804,104 @@ let unwind_glue
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(* exit path. *)
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mark exit_jmp_fix;
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pop (rc ebp); (* restore ebp *)
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;;
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let gc_glue
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(e:Il.emitter)
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: unit =
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(* Mark pass. *)
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crawl_stack_calling_glue e Abi.frame_glue_fns_field_mark;
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(* Sweep pass. *)
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let emit = Il.emit e in
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let mov dst src = emit (Il.umov dst src) in
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let push x = emit (Il.Push x) in
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let pop x = emit (Il.Pop x) in
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let band x y = emit (Il.binary Il.AND x (c x) y) in
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let add x y = emit (Il.binary Il.ADD (rc x) (ro x) (ro y)) in
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let edx_n = word_n (Il.Hreg edx) in
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let ecx_n = word_n (Il.Hreg ecx) in
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let codefix fix = Il.CodePtr (Il.ImmPtr (fix, Il.CodeTy)) in
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let mark fix = Il.emit_full e (Some fix) [] Il.Dead in
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let repeat_jmp_fix = new_fixup "repeat jump" in
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let skip_jmp_fix = new_fixup "skip jump" in
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let exit_jmp_fix = new_fixup "exit jump" in
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mov (rc edx) (c task_ptr);
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mov (rc edx) (c (edx_n Abi.task_field_gc_alloc_chain));
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mark repeat_jmp_fix;
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emit (Il.cmp (ro edx) (immi 0L));
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emit (Il.jmp Il.JE
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(codefix exit_jmp_fix)); (* if nonzero *)
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mov (rc ecx) (* Load GC ctrl word *)
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(c (edx_n Abi.exterior_gc_slot_field_ctrl));
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band (* Clear in-memory mark. *)
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(edx_n Abi.exterior_gc_slot_field_ctrl)
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(immi 0xfffffffffffffffeL);
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band (rc ecx) (immi 1L); (* Check in-reg mark. *)
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emit (Il.cmp (ro edx) (immi 0L));
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emit
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(Il.jmp Il.JNE
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(codefix skip_jmp_fix)); (* if unmarked (garbage) *)
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(* NB: ecx is a type descriptor now. *)
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mov (rc eax) (* Load glue tydesc-off. *)
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(c (ecx_n Abi.tydesc_field_free_glue));
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add eax ecx; (* Add to tydesc* *)
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(* FIXME: this path is all wrong, for three reasons.
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*
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* First, it needs to unlink the values that it frees from the gc
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* chain. Currently it's going to leave dead pointers on it.
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*
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* Second, the *normal* gc-drop path actually has to do that as well;
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* it's not, and that's a problem.
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*
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* Third, it actually needs to walk in two full passes over the chain:
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*
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* - In pass #1, it goes through and disposes of all mutable exterior
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* slots in each record. That is, rc-- the referent, and then
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* null-out. If the rc-- gets to zero, that just means the mutable
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* is part of the garbage set currently being collected. But a
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* mutable may be live-and-outside; this detaches the garbage set
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* from the non-garbage set within the mutable heap.
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*
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* - In pass #2, run the normal free-glue. This winds up doing the
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* immutables only, since all the mutables were nulled out in pass
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* #1. This is where you do the unlinking from the double-linked
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* chain mentioned above.
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*
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* So .. this will still take a little more doing.
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*
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*)
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push (ro edx); (* gc_val to drop *)
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push (c task_ptr); (* form usual call to glue *)
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push (immi 0L); (* outptr *)
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emit (Il.call (rc eax)
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(reg_codeptr (h eax))); (* call glue_fn, trashing eax. *)
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pop (rc eax);
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pop (rc eax);
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pop (rc eax);
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mark skip_jmp_fix;
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mov (rc ecx) (* Advance down chain *)
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(c (edx_n Abi.exterior_gc_slot_field_next));
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emit (Il.jmp Il.JMP
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(codefix repeat_jmp_fix)); (* loop *)
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mark exit_jmp_fix;
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;;
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let unwind_glue
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(e:Il.emitter)
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(nabi:nabi)
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(exit_task_fixup:fixup)
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: unit =
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crawl_stack_calling_glue e Abi.frame_glue_fns_field_drop;
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let callee =
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Abi.load_fixup_codeptr
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e (h eax) exit_task_fixup false nabi.nabi_indirect
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@ -812,6 +910,7 @@ let unwind_glue
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e (rc eax) (h edx) (h ecx) nabi false callee [| (c task_ptr) |];
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;;
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(* Puts result in eax; clobbers ecx, edx in the process. *)
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let rec calculate_sz (e:Il.emitter) (size:size) : unit =
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let emit = Il.emit e in
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