| blob | 5c1152a9ed680ab9b022b76c68b5376fb5d85c43 |
1 ;;;; function call for the x86 VM
3 ;;;; This software is part of the SBCL system. See the README file for
4 ;;;; more information.
5 ;;;;
6 ;;;; This software is derived from the CMU CL system, which was
7 ;;;; written at Carnegie Mellon University and released into the
8 ;;;; public domain. The software is in the public domain and is
9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
10 ;;;; files for more information.
13 \f
14 ;;;; interfaces to IR2 conversion
16 ;;; Return a wired TN describing the N'th full call argument passing
17 ;;; location.
25 ;;; Make a passing location TN for a local call return PC.
26 ;;;
27 ;;; Always wire the return PC location to the stack in its standard
28 ;;; location.
32 sap-stack-sc-number return-pc-save-offset))
34 ;;; This is similar to MAKE-RETURN-PC-PASSING-LOCATION, but makes a
35 ;;; location to pass OLD-FP in.
36 ;;;
37 ;;; This is wired in both the standard and the local-call conventions,
38 ;;; because we want to be able to assume it's always there. Besides,
39 ;;; the x86 doesn't have enough registers to really make it profitable
40 ;;; to pass it in a register.
44 ocfp-save-offset))
46 ;;; Make the TNs used to hold OLD-FP and RETURN-PC within the current
47 ;;; function. We treat these specially so that the debugger can find
48 ;;; them at a known location.
49 ;;;
50 ;;; Without using a save-tn - which does not make much sense if it is
51 ;;; wired to the stack?
54 control-stack-sc-number
55 ocfp-save-offset)
56 physenv))
60 sap-stack-sc-number return-pc-save-offset)
61 physenv))
63 ;;; Make a TN for the standard argument count passing location. We only
64 ;;; need to make the standard location, since a count is never passed when we
65 ;;; are using non-standard conventions.
69 ;;; Make a TN to hold the number-stack frame pointer. This is allocated
70 ;;; once per component, and is component-live.
80 ;;; Return a list of TNs that can be used to represent an unknown-values
81 ;;; continuation within a function.
86 ;;; This function is called by the ENTRY-ANALYZE phase, allowing
87 ;;; VM-dependent initialization of the IR2-COMPONENT structure. We
88 ;;; push placeholder entries in the CONSTANTS to leave room for
89 ;;; additional noise in the code object header.
92 ;; The 1+ here is because for the x86 the first constant is a
93 ;; pointer to a list of fixups, or NIL if the code object has none.
94 ;; (If I understand correctly, the fixups are needed at GC copy
95 ;; time because the X86 code isn't relocatable.)
96 ;;
97 ;; KLUDGE: It'd be cleaner to have the fixups entry be a named
98 ;; element of the CODE (aka component) primitive object. However,
99 ;; it's currently a large, tricky, error-prone chore to change
100 ;; the layout of any primitive object, so for the foreseeable future
101 ;; we'll just live with this ugliness. -- WHN 2002-01-02
106 \f
107 ;;;; frame hackery
109 ;;; This is used for setting up the Old-FP in local call.
115 ;;; We don't have a separate NFP, so we don't need to do anything here.
120 nil))
129 ;; Skip space for the function header.
134 ;; The start of the actual code.
135 ;; Save the return-pc.
138 ;; If copy-more-arg follows it will allocate the correct stack
139 ;; size. The stack is not allocated first here as this may expose
140 ;; args on the stack if they take up more space than the frame!
142 ;; The args fit within the frame so just allocate the frame.
150 ;;; This is emitted directly before either a known-call-local, call-local,
151 ;;; or a multiple-call-local. All it does is allocate stack space for the
152 ;;; callee (who has the same size stack as us).
162 ;;; Allocate a partial frame for passing stack arguments in a full
163 ;;; call. NARGS is the number of arguments passed. We allocate at
164 ;;; least 3 slots, because the XEP noise is going to want to use them
165 ;;; before it can extend the stack.
172 \f
173 ;;; Emit code needed at the return-point from an unknown-values call
174 ;;; for a fixed number of values. Values is the head of the TN-REF
175 ;;; list for the locations that the values are to be received into.
176 ;;; Nvals is the number of values that are to be received (should
177 ;;; equal the length of Values).
178 ;;;
179 ;;; MOVE-TEMP is a DESCRIPTOR-REG TN used as a temporary.
180 ;;;
181 ;;; This code exploits the fact that in the unknown-values convention,
182 ;;; a single value return returns at the return PC + 2, whereas a
183 ;;; return of other than one value returns directly at the return PC.
184 ;;;
185 ;;; If 0 or 1 values are expected, then we just emit an instruction to
186 ;;; reset the SP (which will only be executed when other than 1 value
187 ;;; is returned.)
188 ;;;
189 ;;; In the general case we have to do three things:
190 ;;; -- Default unsupplied register values. This need only be done
191 ;;; when a single value is returned, since register values are
192 ;;; defaulted by the called in the non-single case.
193 ;;; -- Default unsupplied stack values. This needs to be done whenever
194 ;;; there are stack values.
195 ;;; -- Reset SP. This must be done whenever other than 1 value is
196 ;;; returned, regardless of the number of values desired.
215 ;; Default the unsuppled registers.
223 for count from 2 below register-arg-count
229 ;; The number of bytes depends on the relative jump instructions.
230 ;; Best case is 31+(n-3)*14, worst case is 35+(n-3)*18. For
231 ;; NVALS=6 that is 73/89 bytes, and for NVALS=7 that is 87/107
232 ;; bytes which is likely better than using the blt below.
237 ;; Branch off to the MV case.
239 ;; Do the single value case.
240 ;; Default the register args
247 ;; Fake other registers so it looks like we returned with all the
248 ;; registers filled in.
288 ;; 91 bytes for this branch.
295 ;; Branch off to the MV case.
298 ;; Default the register args, and set up the stack as if we
299 ;; entered the MV return point.
305 ;; Compute a pointer to where to put the [defaulted] stack values.
310 ;; Load EAX with NIL so we can quickly store it, and set up
311 ;; stuff for the loop.
315 ;; Jump into the default loop.
318 ;; The regs are defaulted. We need to copy any stack arguments,
319 ;; and then default the remaining stack arguments.
321 ;; Save EDI.
323 ;; Compute the number of stack arguments, and if it's zero or
324 ;; less, don't copy any stack arguments.
328 ;; Throw away any unwanted args.
333 ;; Save the number of stack values.
335 ;; Compute a pointer to where the stack args go.
339 ;; Save ESI, and compute a pointer to where the args come from.
344 ;; Do the copy.
349 ;; Restore ESI.
351 ;; Now we have to default the remaining args. Find out how many.
354 ;; If none, then just blow out of here.
358 ;; Load EAX with NIL for fast storing.
360 ;; Do the store.
364 ;; Restore EDI, and reset the stack.
370 \f
371 ;;;; unknown values receiving
373 ;;; Emit code needed at the return point for an unknown-values call
374 ;;; for an arbitrary number of values.
375 ;;;
376 ;;; We do the single and non-single cases with no shared code: there
377 ;;; doesn't seem to be any potential overlap, and receiving a single
378 ;;; value is more important efficiency-wise.
379 ;;;
380 ;;; When there is a single value, we just push it on the stack,
381 ;;; returning the old SP and 1.
382 ;;;
383 ;;; When there is a variable number of values, we move all of the
384 ;;; argument registers onto the stack, and return ARGS and NARGS.
385 ;;;
386 ;;; ARGS and NARGS are TNs wired to the named locations. We must
387 ;;; explicitly allocate these TNs, since their lifetimes overlap with
388 ;;; the results start and count. (Also, it's nice to be able to target
389 ;;; them.)
405 ;; dtc: this writes the registers onto the stack even if they are
406 ;; not needed, only the number specified in ecx are used and have
407 ;; stack allocated to them. No harm is done.
410 for i downfrom -1
418 ;;; VOP that can be inherited by unknown values receivers. The main thing this
419 ;;; handles is allocation of the result temporaries.
423 values-start)
426 nvals)
429 \f
430 ;;;; local call with unknown values convention return
432 ;;; Non-TR local call for a fixed number of values passed according to
433 ;;; the unknown values convention.
434 ;;;
435 ;;; FP is the frame pointer in install before doing the call.
436 ;;;
437 ;;; NFP would be the number-stack frame pointer if we had a separate
438 ;;; number stack.
439 ;;;
440 ;;; Args are the argument passing locations, which are specified only
441 ;;; to terminate their lifetimes in the caller.
442 ;;;
443 ;;; VALUES are the return value locations (wired to the standard
444 ;;; passing locations). NVALS is the number of values received.
445 ;;;
446 ;;; Save is the save info, which we can ignore since saving has been
447 ;;; done.
448 ;;;
449 ;;; TARGET is a continuation pointing to the start of the called
450 ;;; function.
466 #+nil
471 ;; Is the return-pc on the stack or in a register?
483 RETURN
487 ;;; Non-TR local call for a variable number of return values passed according
488 ;;; to the unknown values convention. The results are the start of the values
489 ;;; glob and the number of values received.
504 #+nil
509 ;; Is the return-pc on the stack or in a register?
514 ;; Stack
518 ;; Register
523 RETURN
527 \f
528 ;;;; local call with known values return
530 ;;; Non-TR local call with known return locations. Known-value return
531 ;;; works just like argument passing in local call.
532 ;;;
533 ;;; Note: we can't use normal load-tn allocation for the fixed args,
534 ;;; since all registers may be tied up by the more operand. Instead,
535 ;;; we use MAYBE-LOAD-STACK-TN.
552 #+nil
557 ;; Is the return-pc on the stack or in a register?
562 ;; Stack
566 ;; Register
571 RETURN
574 \f
575 ;;; Return from known values call. We receive the return locations as
576 ;;; arguments to terminate their lifetimes in the returning function. We
577 ;;; restore FP and CSP and jump to the Return-PC.
578 ;;;
579 ;;; We can assume we know exactly where old-fp and return-pc are because
580 ;;; make-old-fp-save-location and make-return-pc-save-location always
581 ;;; return the same place.
582 #+nil
594 ;; Save the return-pc in a register 'cause the frame-pointer is
595 ;; going away. Note this not in the usual stack location so we
596 ;; can't use RET
598 ;; Restore the stack.
600 ;; Restore the old fp. We know OLD-FP is going to be in its stack
601 ;; save slot, which is a different frame that than this one,
602 ;; so we don't have to worry about having just cleared
603 ;; most of the stack.
607 \f
608 ;;; From Douglas Crosher
609 ;;; Return from known values call. We receive the return locations as
610 ;;; arguments to terminate their lifetimes in the returning function. We
611 ;;; restore FP and CSP and jump to the Return-PC.
612 ;;;
613 ;;; The old-fp may be either in a register or on the stack in its
614 ;;; standard save locations - slot 0.
615 ;;;
616 ;;; The return-pc may be in a register or on the stack in any slot.
637 ;; return-pc may be either in a register or on the stack.
647 ;; Zot all of the stack except for the old-fp.
650 ;; Restore the old fp from its save location on the stack,
651 ;; and zot the stack.
656 "VOP return-local doesn't work if old-fp (in slot ~
657 ~S) is not in slot 0"
661 ;; Zot all the stack.
663 ;; Restore the old-fp.
666 ;; Return; return-pc is in a register.
674 ;; Zot all of the stack except for the old-fp and return-pc.
678 ;; Restore the old fp. old-fp may be either on the stack in its
679 ;; save location or in a register, in either case this restores it.
681 ;; The return pops the return address (4 bytes), then we need
682 ;; to pop all the slots before the return-pc which includes the
683 ;; 4 bytes for the old-fp.
687 \f
688 ;;;; full call
689 ;;;
690 ;;; There is something of a cross-product effect with full calls.
691 ;;; Different versions are used depending on whether we know the
692 ;;; number of arguments or the name of the called function, and
693 ;;; whether we want fixed values, unknown values, or a tail call.
694 ;;;
695 ;;; In full call, the arguments are passed creating a partial frame on
696 ;;; the stack top and storing stack arguments into that frame. On
697 ;;; entry to the callee, this partial frame is pointed to by FP.
699 ;;; This macro helps in the definition of full call VOPs by avoiding
700 ;;; code replication in defining the cross-product VOPs.
701 ;;;
702 ;;; NAME is the name of the VOP to define.
703 ;;;
704 ;;; NAMED is true if the first argument is an fdefinition object whose
705 ;;; definition is to be called.
706 ;;;
707 ;;; RETURN is either :FIXED, :UNKNOWN or :TAIL:
708 ;;; -- If :FIXED, then the call is for a fixed number of values, returned in
709 ;;; the standard passing locations (passed as result operands).
710 ;;; -- If :UNKNOWN, then the result values are pushed on the stack, and the
711 ;;; result values are specified by the Start and Count as in the
712 ;;; unknown-values continuation representation.
713 ;;; -- If :TAIL, then do a tail-recursive call. No values are returned.
714 ;;; The Old-Fp and Return-PC are passed as the second and third arguments.
715 ;;;
716 ;;; In non-tail calls, the pointer to the stack arguments is passed as
717 ;;; the last fixed argument. If Variable is false, then the passing
718 ;;; locations are passed as a more arg. Variable is true if there are
719 ;;; a variable number of arguments passed on the stack. Variable
720 ;;; cannot be specified with :TAIL return. TR variable argument call
721 ;;; is implemented separately.
722 ;;;
723 ;;; In tail call with fixed arguments, the passing locations are
724 ;;; passed as a more arg, but there is no new-FP, since the arguments
725 ;;; have been set up in the current frame.
731 (:args
753 (:info
757 step-instrumenting)
759 (:ignore
763 ;; We pass either the fdefn object (for named call) or
764 ;; the actual function object (for unnamed call) in
765 ;; EAX. With named call, closure-tramp will replace it
766 ;; with the real function and invoke the real function
767 ;; for closures. Non-closures do not need this value,
768 ;; so don't care what shows up in it.
769 (:temporary
770 (:sc descriptor-reg
771 :offset eax-offset
774 eax)
776 ;; We pass the number of arguments in ECX.
779 ;; With variable call, we have to load the
780 ;; register-args out of the (new) stack frame before
781 ;; doing the call. Therefore, we have to tell the
782 ;; lifetime stuff that we need to use them.
796 old-fp-tmp)))
801 15
805 ;; This has to be done before the frame pointer is
806 ;; changed! EAX stores the 'lexical environment' needed
807 ;; for closures.
812 ;; For variable call, compute the number of
813 ;; arguments and move some of the arguments to
814 ;; registers.
816 ;; Compute the number of arguments.
819 ;; Move the necessary args to registers,
820 ;; this moves them all even if they are
821 ;; not all needed.
824 for index downfrom -1
832 ;; return to so might as well use that clue.
833 ;; This seems really important to the
834 ;; implementation of things like
835 ;; (without-interrupts ...)
836 ;;
837 ;; dtc; Could be doing a tail call from a
838 ;; known-local-call etc in which the old-fp
839 ;; or ret-pc are in regs or in non-standard
840 ;; places. If the passing location were
841 ;; wired to the stack in standard locations
842 ;; then these moves will be un-necessary;
843 ;; this is probably best for the x86.
848 ;; FIXME: FORMAT T for stale
849 ;; diagnostic output (several of
850 ;; them around here), ick
854 ebp-tn
859 ebp-tn
862 ;; For tail call, we have to push the
863 ;; return-pc so that it looks like we CALLed
864 ;; despite the fact that we are going to JMP.
866 ))
868 ;; For non-tail call, we have to save our
869 ;; frame pointer and install the new frame
870 ;; pointer. We can't load stack tns after this
871 ;; point.
873 ;; here which doesn't leave room for the
874 ;; ofp/ret stuff.
876 ;; The variable args are on the stack and
877 ;; become the frame, but there may be <3
878 ;; args and 3 stack slots are assumed
879 ;; allocate on the call. So need to ensure
880 ;; there are at least 3 slots. This hack
881 ;; just adds 3 more.
885 ;; Save the fp
889 )))
895 DONE
902 other-pointer-lowtag)
904 fun-pointer-lowtag)))
906 (:fixed
908 (:unknown
924 ;;; This is defined separately, since it needs special code that BLT's
925 ;;; the arguments down. All the real work is done in the assembly
926 ;;; routine. We just set things up so that it can find what it needs.
934 ; (:ignore ret-addr old-fp)
936 ;; Move these into the passing locations if they are not already there.
940 ;; The following assumes that the return-pc and old-fp are on the
941 ;; stack in their standard save locations - Check this.
950 ;; And jump to the assembly routine.
952 \f
953 ;;;; unknown values return
955 ;;; Return a single-value using the Unknown-Values convention. Specifically,
956 ;;; we jump to clear the stack and jump to return-pc+2.
957 ;;;
958 ;;; We require old-fp to be in a register, because we want to reset ESP before
959 ;;; restoring EBP. If old-fp were still on the stack, it could get clobbered
960 ;;; by a signal.
961 ;;;
962 ;;; pfw--get wired-tn conflicts sometimes if register sc specd for args
963 ;;; having problems targeting args to regs -- using temps instead.
964 ;;;
965 ;;; First off, modifying the return-pc defeats the branch-prediction
966 ;;; optimizations on modern CPUs quite handily. Second, we can do all
967 ;;; this without needing a temp register. Fixed the latter, at least.
968 ;;; -- AB 2006/Feb/04
976 ;; Code structure lifted from known-return.
979 ;; return PC in register for some reason (local call?)
980 ;; we jmp to the return pc after fixing the stack and frame.
983 ;; ofp on stack must be in slot 0 (the traditional storage place).
984 ;; Drop the stack above it and pop it off.
990 ;; Should this ever happen, we do the same as above, but
991 ;; using (tn-offset old-fp) instead of ocfp-save-offset
992 ;; (which is 0 anyway, see src/compiler/x86/vm.lisp) and
993 ;; then lea esp again against itself with a displacement
994 ;; of (* (tn-offset old-fp) n-word-bytes) to clear the
995 ;; rest of the stack.
999 ;; ofp in reg, drop the stack and load the real fp.
1003 ;; Set single-value-return flag
1005 ;; And return
1009 ;; Note that this will only work right if, when old-fp is on
1010 ;; the stack, it has a lower tn-offset than return-pc. One of
1011 ;; the comments in known-return indicate that this is the case
1012 ;; (in that it will be in its save location), but we may wish
1013 ;; to assert that (in either the weaker or stronger forms).
1014 ;; Should this ever not be the case, we should load old-fp
1015 ;; into a temp reg while we fix the stack.
1016 ;; Drop stack above return-pc
1019 ;; Set single-value return flag
1021 ;; Restore the old frame pointer
1023 ;; And return, dropping the rest of the stack as we go.
1026 ;;; Do unknown-values return of a fixed (other than 1) number of
1027 ;;; values. The VALUES are required to be set up in the standard
1028 ;;; passing locations. NVALS is the number of values returned.
1029 ;;;
1030 ;;; Basically, we just load ECX with the number of values returned and
1031 ;;; EBX with a pointer to the values, set ESP to point to the end of
1032 ;;; the values, and jump directly to return-pc.
1040 ;; In the case of other than one value, we need these registers to
1041 ;; tell the caller where they are and how many there are.
1045 ;; We need to stretch the lifetime of return-pc past the argument
1046 ;; registers so that we can default the argument registers without
1047 ;; trashing return-pc.
1057 ;; Establish the values pointer and values count.
1062 ;; Restore the frame pointer.
1064 ;; Clear as much of the stack as possible, but not past the return
1065 ;; address.
1068 ;; Pre-default any argument register that need it.
1075 ;; Set multi-value return flag.
1077 ;; And away we go. Except that return-pc is still on the
1078 ;; stack and we've changed the stack pointer. So we have to
1079 ;; tell it to index off of EBX instead of EBP.
1081 ;; Return popping the return address and the OCFP.
1084 ;; Return popping the return, leaving 1 slot. Can this
1085 ;; happen, or is a single value return handled elsewhere?
1093 ;;; Do unknown-values return of an arbitrary number of values (passed
1094 ;;; on the stack.) We check for the common case of a single return
1095 ;;; value, and do that inline using the normal single value return
1096 ;;; convention. Otherwise, we branch off to code that calls an
1097 ;;; assembly-routine.
1098 ;;;
1099 ;;; The assembly routine takes the following args:
1100 ;;; EAX -- the return-pc to finally jump to.
1101 ;;; EBX -- pointer to where to put the values.
1102 ;;; ECX -- number of values to find there.
1103 ;;; ESI -- pointer to where to find the values.
1121 ;; Load the return-pc.
1124 ;; Check for the single case.
1129 ;; Return with one value.
1131 ;; Clear the stack. We load old-fp into a register before clearing
1132 ;; the stack.
1136 ;; Set the single-value return flag.
1138 ;; Out of here.
1141 ;; Nope, not the single case. Jump to the assembly routine.
1149 \f
1150 ;;;; XEP hackery
1152 ;;; We don't need to do anything special for regular functions.
1157 ;; Don't bother doing anything.
1158 nil))
1160 ;;; Get the lexical environment from its passing location.
1166 ;; Get result.
1169 ;;; Copy a &MORE arg from the argument area to the end of the current
1170 ;;; frame. FIXED is the number of non-&MORE arguments.
1171 ;;;
1172 ;;; The tricky part is doing this without trashing any of the calling
1173 ;;; convention registers that are still needed. This vop is emitted
1174 ;;; directly after the xep-allocate frame. That means the registers
1175 ;;; are in use as follows:
1176 ;;;
1177 ;;; EAX -- The lexenv.
1178 ;;; EBX -- Available.
1179 ;;; ECX -- The total number of arguments.
1180 ;;; EDX -- The first arg.
1181 ;;; EDI -- The second arg.
1182 ;;; ESI -- The third arg.
1183 ;;;
1184 ;;; So basically, we have one register available for our use: EBX.
1185 ;;;
1186 ;;; What we can do is push the other regs onto the stack, and then
1187 ;;; restore their values by looking directly below where we put the
1188 ;;; more-args.
1192 ;; Avoid the copy if there are no more args.
1199 ;; Allocate the space on the stack.
1200 ;; stack = ebp - (max 3 frame-size) - (nargs - fixed)
1204 (* n-word-bytes
1209 ;; Now: nargs>=1 && nargs>fixed
1211 ;; Save the original count of args.
1215 ;; We must stop when we run out of stack args, not when we
1216 ;; run out of more args.
1217 ;; Number to copy = nargs-3
1219 ;; Everything of interest in registers.
1222 ;; Number to copy = nargs-fixed
1225 ;; Save edi and esi register args.
1229 ;; Okay, we have pushed the register args. We can trash them
1230 ;; now.
1232 ;; Initialize src to be end of args.
1236 ;; We need to copy from downwards up to avoid overwriting some of
1237 ;; the yet uncopied args. So we need to use EBX as the copy index
1238 ;; and ECX as the loop counter, rather than using ECX for both.
1241 ;; We used to use REP MOVS here, but on modern x86 it performs
1242 ;; much worse than an explicit loop for small blocks.
1243 COPY-LOOP
1245 ;; The :DISP is to account for the registers saved on the stack
1248 edi-tn)
1253 ;; So now we need to restore EDI and ESI.
1258 DO-REGS
1260 ;; Restore ECX
1263 ;; Here: nargs>=1 && nargs>fixed
1265 ;; Now we have to deposit any more args that showed up in
1266 ;; registers.
1269 ;; Store it relative to ebp
1280 ;; Don't deposit any more than there are.
1288 JUST-ALLOC-FRAME
1294 DONE))
1329 ;;; Turn more arg (context, count) into a list.
1349 ;; Check to see whether there are no args, and just return NIL if so.
1356 ;; Set decrement mode (successive args at lower addresses)
1358 ;; Set up the result.
1360 ;; Jump into the middle of the loop, 'cause that's were we want
1361 ;; to start.
1364 ;; Compute a pointer to the next cons.
1366 ;; Store a pointer to this cons in the CDR of the previous cons.
1369 ;; Grab one value and stash it in the car of this cons.
1372 ;; Go back for more.
1375 ;; NIL out the last cons.
1380 ;;; Return the location and size of the &MORE arg glob created by
1381 ;;; COPY-MORE-ARG. SUPPLIED is the total number of arguments supplied
1382 ;;; (originally passed in ECX). FIXED is the number of non-rest
1383 ;;; arguments.
1384 ;;;
1385 ;;; We must duplicate some of the work done by COPY-MORE-ARG, since at
1386 ;;; that time the environment is in a pretty brain-damaged state,
1387 ;;; preventing this info from being returned as values. What we do is
1388 ;;; compute supplied - fixed, and return a pointer that many words
1389 ;;; below the current stack top.
1402 ;; SP at this point points at the last arg pushed.
1403 ;; Point to the first more-arg, not above it.
1410 ;;; Signal wrong argument count error if NARGS isn't equal to COUNT.
1427 ;;; Various other error signallers.
1435 args))
1443 object type)
1445 object layout)
1452 ;;; Single-stepping
1455 ;; We use different ways of representing whether stepping is on on
1456 ;; +SB-THREAD / -SB-THREAD: on +SB-THREAD, we use a slot in the
1457 ;; thread structure. On -SB-THREAD we use the value of a static
1458 ;; symbol. Things are done this way, since reading a thread-local
1459 ;; slot from a symbol would require an extra register on +SB-THREAD,
1460 ;; and reading a slot from a thread structure would require an extra
1461 ;; register on -SB-THREAD.
1462 #!+sb-thread
1467 nil-value))
1468 #!-sb-thread
1470 nil-value))
1479 DONE