Fix register-use bugs in sweep pass, factor sweep pass out and call twice for separate sever/free phases.
This commit is contained in:
Graydon Hoare
parent
90eaaf666b
commit
50e96414d2
@ -745,7 +745,7 @@ let crawl_stack_calling_glue
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: unit =
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let fp_n = word_n (Il.Hreg ebp) in
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let edx_n = word_n (Il.Hreg edx) in
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let edi_n = word_n (Il.Hreg edi) in
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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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@ -763,16 +763,16 @@ let crawl_stack_calling_glue
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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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mov (rc edx) (c (fp_n (-2))); (* edx <- frame glue functions. *)
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emit (Il.cmp (ro edx) (immi 0L));
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mov (rc edi) (c (fp_n (-2))); (* edi <- frame glue functions. *)
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emit (Il.cmp (ro edi) (immi 0L));
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emit
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(Il.jmp Il.JE
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(codefix skip_jmp_fix)); (* if struct* is nonzero *)
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add edx esi; (* add crate ptr to disp. *)
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add edi 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 <- glue *)
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(c (edi_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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@ -789,11 +789,11 @@ let crawl_stack_calling_glue
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pop (rc eax);
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mark skip_jmp_fix;
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mov (rc edx) (c (fp_n 3)); (* load next fp (callee-saves[3]) *)
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emit (Il.cmp (ro edx) (immi 0L));
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mov (rc edi) (c (fp_n 3)); (* load next fp (callee-saves[3]) *)
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emit (Il.cmp (ro edi) (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 ebp) (ro edx); (* move to next frame *)
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mov (rc ebp) (ro edi); (* move to next frame *)
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emit (Il.jmp Il.JMP
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(codefix repeat_jmp_fix)); (* loop *)
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@ -802,8 +802,10 @@ let crawl_stack_calling_glue
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pop (rc ebp); (* restore ebp *)
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;;
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let gc_glue
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let sweep_gc_chain
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(e:Il.emitter)
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(glue_field:int)
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(clear_mark:bool)
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: unit =
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let emit = Il.emit e in
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@ -812,7 +814,7 @@ let gc_glue
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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 edi_n = word_n (Il.Hreg edi) 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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@ -820,60 +822,32 @@ let gc_glue
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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); (* switch back to rust stack *)
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mov
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(rc esp)
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(c (edx_n Abi.task_field_rust_sp));
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(* Mark pass. *)
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save_callee_saves e;
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push (ro eax);
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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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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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mov (rc edi) (c task_ptr);
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mov (rc edi) (c (edi_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.cmp (ro edi) (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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(c (edi_n Abi.exterior_gc_slot_field_ctrl));
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mov (rc eax) (ro ecx);
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band (rc eax) (immi 1L); (* Extract mark to eax. *)
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band (* Clear mark in ecx. *)
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(rc ecx)
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(immi 0xfffffffffffffffeL);
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mov
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((edx_n Abi.exterior_gc_slot_field_ctrl)) (* Write-back cleared. *)
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(ro ecx);
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if clear_mark
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then
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mov (* Write-back cleared. *)
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((edi_n Abi.exterior_gc_slot_field_ctrl))
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(ro ecx);
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emit (Il.cmp (ro eax) (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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(* FIXME: this path is all wrong
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*
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* 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); (* Push gc_val to drop. *)
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push (ro edi); (* Push gc_val. *)
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(* NB: ecx is a type descriptor now. *)
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@ -885,21 +859,63 @@ let gc_glue
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push (immi 0L); (* Push null outptr. *)
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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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(c (ecx_n glue_field));
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add eax ecx; (* Add to tydesc* *)
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emit (Il.call (rc eax)
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(reg_codeptr (h eax))); (* Call free glue. *)
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(reg_codeptr (h eax))); (* Call glue. *)
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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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pop (rc eax);
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mark skip_jmp_fix;
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mov (rc edx) (* Advance down chain *)
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(c (edx_n Abi.exterior_gc_slot_field_next));
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mov (rc edi) (* Advance down chain *)
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(c (edi_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 gc_glue
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(e:Il.emitter)
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: unit =
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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 edi_n = word_n (Il.Hreg edi) in
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mov (rc edi) (c task_ptr); (* switch back to rust stack *)
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mov
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(rc esp)
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(c (edi_n Abi.task_field_rust_sp));
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(* Mark pass. *)
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save_callee_saves e;
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push (ro eax);
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crawl_stack_calling_glue e Abi.frame_glue_fns_field_mark;
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(* The sweep pass has two sub-passes over the GC chain:
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*
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* - In pass #1, 'severing', we goes through and disposes of all
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* mutable exterior slots in each record. That is, rc-- the referent,
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* and then null-out. If the rc-- gets to zero, that just means the
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* mutable is part of the garbage set currently being collected. But
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* a 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, 'freeing', we run the normal free-glue. This winds up
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* running drop-glue on the zero-reference-reaching immutables only,
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* since all the mutables were nulled out in pass #1. This is where
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* you do the unlinking from the double-linked chain and call free(),
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* also.
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*
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*)
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sweep_gc_chain e Abi.tydesc_field_sever_glue false;
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sweep_gc_chain e Abi.tydesc_field_free_glue true;
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pop (rc eax);
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restore_callee_saves e;
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@ -915,12 +931,12 @@ let unwind_glue
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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 edx_n = word_n (Il.Hreg edx) in
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let edi_n = word_n (Il.Hreg edi) in
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mov (rc edx) (c task_ptr); (* switch back to rust stack *)
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mov (rc edi) (c task_ptr); (* switch back to rust stack *)
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mov
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(rc esp)
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(c (edx_n Abi.task_field_rust_sp));
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(c (edi_n Abi.task_field_rust_sp));
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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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@ -928,7 +944,7 @@ let unwind_glue
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e (h eax) exit_task_fixup false nabi.nabi_indirect
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in
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emit_c_call
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e (rc eax) (h edx) (h ecx) nabi false callee [| (c task_ptr) |];
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e (rc eax) (h edi) (h ecx) nabi false callee [| (c task_ptr) |];
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;;
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