1 ;;;; function call for the x86 VM
3 ;;;; This software is part of the SBCL system. See the README file for
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.
14 ;;;; interfaces to IR2 conversion
16 ;;; Return a wired TN describing the N'th full call argument passing
18 (!def-vm-support-routine standard-arg-location (n)
19 (declare (type unsigned-byte n))
20 (if (< n register-arg-count)
21 (make-wired-tn *backend-t-primitive-type* descriptor-reg-sc-number
22 (nth n *register-arg-offsets*))
23 (make-wired-tn *backend-t-primitive-type* control-stack-sc-number n)))
25 ;;; Make a passing location TN for a local call return PC.
27 ;;; Always wire the return PC location to the stack in its standard
29 (!def-vm-support-routine make-return-pc-passing-location (standard)
30 (declare (ignore standard))
31 (make-wired-tn (primitive-type-or-lose 'system-area-pointer)
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.
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.
41 (!def-vm-support-routine make-old-fp-passing-location (standard)
42 (declare (ignore standard))
43 (make-wired-tn *fixnum-primitive-type* control-stack-sc-number
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.
50 ;;; Without using a save-tn - which does not make much sense if it is
51 ;;; wired to the stack?
52 (!def-vm-support-routine make-old-fp-save-location (physenv)
53 (physenv-debug-live-tn (make-wired-tn *fixnum-primitive-type*
54 control-stack-sc-number
57 (!def-vm-support-routine make-return-pc-save-location (physenv)
58 (physenv-debug-live-tn
59 (make-wired-tn (primitive-type-or-lose 'system-area-pointer)
60 sap-stack-sc-number return-pc-save-offset)
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.
66 (!def-vm-support-routine make-arg-count-location ()
67 (make-wired-tn *fixnum-primitive-type* any-reg-sc-number ecx-offset))
69 ;;; Make a TN to hold the number-stack frame pointer. This is allocated
70 ;;; once per component, and is component-live.
71 (!def-vm-support-routine make-nfp-tn ()
72 (make-restricted-tn *fixnum-primitive-type* ignore-me-sc-number))
74 (!def-vm-support-routine make-stack-pointer-tn ()
75 (make-normal-tn *fixnum-primitive-type*))
77 (!def-vm-support-routine make-number-stack-pointer-tn ()
78 (make-restricted-tn *fixnum-primitive-type* ignore-me-sc-number))
80 ;;; Return a list of TNs that can be used to represent an unknown-values
81 ;;; continuation within a function.
82 (!def-vm-support-routine make-unknown-values-locations ()
83 (list (make-stack-pointer-tn)
84 (make-normal-tn *fixnum-primitive-type*)))
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.
90 (!def-vm-support-routine select-component-format (component)
91 (declare (type component component))
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.)
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
102 (dotimes (i (1+ code-constants-offset))
103 (vector-push-extend nil
104 (ir2-component-constants (component-info component))))
109 ;;; This is used for setting up the Old-FP in local call.
110 (define-vop (current-fp)
111 (:results (val :scs (any-reg control-stack)))
115 ;;; We don't have a separate NFP, so we don't need to do anything here.
116 (define-vop (compute-old-nfp)
122 (define-vop (xep-allocate-frame)
123 (:info start-lab copy-more-arg-follows)
126 (emit-alignment n-lowtag-bits)
127 (trace-table-entry trace-table-fun-prologue)
128 (emit-label start-lab)
129 ;; Skip space for the function header.
130 (inst simple-fun-header-word)
131 (dotimes (i (1- simple-fun-code-offset))
134 ;; The start of the actual code.
135 ;; Save the return-pc.
136 (popw ebp-tn (frame-word-offset return-pc-save-offset))
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!
141 (unless copy-more-arg-follows
142 ;; The args fit within the frame so just allocate the frame.
144 (make-ea :dword :base ebp-tn
145 :disp (- (* n-word-bytes
146 (max 3 (sb-allocated-size 'stack)))))))
148 (trace-table-entry trace-table-normal)))
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).
153 (define-vop (allocate-frame)
154 (:results (res :scs (any-reg control-stack))
160 (inst sub esp-tn (* n-word-bytes (sb-allocated-size 'stack)))))
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.
166 (define-vop (allocate-full-call-frame)
168 (:results (res :scs (any-reg control-stack)))
171 (inst sub esp-tn (* (max nargs 3) n-word-bytes))))
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).
179 ;;; MOVE-TEMP is a DESCRIPTOR-REG TN used as a temporary.
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.
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
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.
197 (defun default-unknown-values (vop values nvals)
198 (declare (type (or tn-ref null) values)
199 (type unsigned-byte nvals))
202 (note-this-location vop :single-value-return)
203 (let ((single-value (gen-label)))
205 ((member :cmov *backend-subfeatures*)
206 (inst cmov :c esp-tn ebx-tn))
208 (inst jmp :nc single-value)
209 (inst mov esp-tn ebx-tn)
210 (emit-label single-value)))))
211 ((<= nvals register-arg-count)
212 (let ((regs-defaulted (gen-label)))
213 (note-this-location vop :unknown-return)
214 (inst jmp :c regs-defaulted)
215 ;; Default the unsupplied registers.
216 (let* ((2nd-tn-ref (tn-ref-across values))
217 (2nd-tn (tn-ref-tn 2nd-tn-ref)))
218 (inst mov 2nd-tn nil-value)
221 for tn-ref = (tn-ref-across 2nd-tn-ref)
222 then (tn-ref-across tn-ref)
223 for count from 2 below register-arg-count
224 do (inst mov (tn-ref-tn tn-ref) 2nd-tn))))
225 (inst mov ebx-tn esp-tn)
226 (emit-label regs-defaulted)
227 (inst mov esp-tn ebx-tn)))
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.
233 (let ((regs-defaulted (gen-label))
234 (defaulting-done (gen-label))
235 (default-stack-slots (gen-label)))
236 (note-this-location vop :unknown-return)
237 ;; Branch off to the MV case.
238 (inst jmp :c regs-defaulted)
239 ;; Do the single value case.
240 ;; Default the register args
241 (inst mov eax-tn nil-value)
243 (val (tn-ref-across values) (tn-ref-across val)))
244 ((= i (min nvals register-arg-count)))
245 (inst mov (tn-ref-tn val) eax-tn))
247 ;; Fake other registers so it looks like we returned with all the
248 ;; registers filled in.
251 (inst jmp default-stack-slots)
253 (emit-label regs-defaulted)
255 (inst mov eax-tn nil-value)
256 (storew edx-tn ebx-tn -1)
257 (collect ((defaults))
258 (do ((i register-arg-count (1+ i))
259 (val (do ((i 0 (1+ i))
260 (val values (tn-ref-across val)))
261 ((= i register-arg-count) val))
262 (tn-ref-across val)))
264 (let ((default-lab (gen-label))
265 (tn (tn-ref-tn val)))
266 (defaults (cons default-lab tn))
268 (inst cmp ecx-tn (fixnumize i))
269 (inst jmp :be default-lab)
270 (loadw edx-tn ebx-tn (frame-word-offset i))
271 (inst mov tn edx-tn)))
273 (emit-label defaulting-done)
274 (loadw edx-tn ebx-tn -1)
277 (let ((defaults (defaults)))
279 (assemble (*elsewhere*)
280 (trace-table-entry trace-table-fun-prologue)
281 (emit-label default-stack-slots)
282 (dolist (default defaults)
283 (emit-label (car default))
284 (inst mov (cdr default) eax-tn))
285 (inst jmp defaulting-done)
286 (trace-table-entry trace-table-normal)))))))
288 ;; 91 bytes for this branch.
289 (let ((regs-defaulted (gen-label))
290 (restore-edi (gen-label))
291 (no-stack-args (gen-label))
292 (default-stack-vals (gen-label))
293 (count-okay (gen-label)))
294 (note-this-location vop :unknown-return)
295 ;; Branch off to the MV case.
296 (inst jmp :c regs-defaulted)
298 ;; Default the register args, and set up the stack as if we
299 ;; entered the MV return point.
300 (inst mov ebx-tn esp-tn)
302 (inst mov edi-tn nil-value)
304 (inst mov esi-tn edi-tn)
305 ;; Compute a pointer to where to put the [defaulted] stack values.
306 (emit-label no-stack-args)
308 (make-ea :dword :base ebp-tn
309 :disp (frame-byte-offset register-arg-count)))
310 ;; Load EAX with NIL so we can quickly store it, and set up
311 ;; stuff for the loop.
312 (inst mov eax-tn nil-value)
314 (inst mov ecx-tn (- nvals register-arg-count))
315 ;; Jump into the default loop.
316 (inst jmp default-stack-vals)
318 ;; The regs are defaulted. We need to copy any stack arguments,
319 ;; and then default the remaining stack arguments.
320 (emit-label regs-defaulted)
322 (storew edi-tn ebx-tn (frame-word-offset 1))
323 ;; Compute the number of stack arguments, and if it's zero or
324 ;; less, don't copy any stack arguments.
325 (inst sub ecx-tn (fixnumize register-arg-count))
326 (inst jmp :le no-stack-args)
328 ;; Throw away any unwanted args.
329 (inst cmp ecx-tn (fixnumize (- nvals register-arg-count)))
330 (inst jmp :be count-okay)
331 (inst mov ecx-tn (fixnumize (- nvals register-arg-count)))
332 (emit-label count-okay)
333 ;; Save the number of stack values.
334 (inst mov eax-tn ecx-tn)
335 ;; Compute a pointer to where the stack args go.
337 (make-ea :dword :base ebp-tn
338 :disp (frame-byte-offset register-arg-count)))
339 ;; Save ESI, and compute a pointer to where the args come from.
340 (storew esi-tn ebx-tn (frame-word-offset 2))
342 (make-ea :dword :base ebx-tn
343 :disp (frame-byte-offset register-arg-count)))
345 (inst shr ecx-tn word-shift) ; make word count
350 (loadw esi-tn ebx-tn (frame-word-offset 2))
351 ;; Now we have to default the remaining args. Find out how many.
352 (inst sub eax-tn (fixnumize (- nvals register-arg-count)))
354 ;; If none, then just blow out of here.
355 (inst jmp :le restore-edi)
356 (inst mov ecx-tn eax-tn)
357 (inst shr ecx-tn word-shift) ; word count
358 ;; Load EAX with NIL for fast storing.
359 (inst mov eax-tn nil-value)
361 (emit-label default-stack-vals)
364 ;; Restore EDI, and reset the stack.
365 (emit-label restore-edi)
366 (loadw edi-tn ebx-tn (frame-word-offset 1))
367 (inst mov esp-tn ebx-tn)
371 ;;;; unknown values receiving
373 ;;; Emit code needed at the return point for an unknown-values call
374 ;;; for an arbitrary number of values.
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.
380 ;;; When there is a single value, we just push it on the stack,
381 ;;; returning the old SP and 1.
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.
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
390 (defun receive-unknown-values (args nargs start count)
391 (declare (type tn args nargs start count))
392 (let ((variable-values (gen-label))
394 (inst jmp :c variable-values)
396 (cond ((location= start (first *register-arg-tns*))
397 (inst push (first *register-arg-tns*))
398 (inst lea start (make-ea :dword :base esp-tn :disp n-word-bytes)))
399 (t (inst mov start esp-tn)
400 (inst push (first *register-arg-tns*))))
401 (inst mov count (fixnumize 1))
404 (emit-label variable-values)
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.
409 for arg in *register-arg-tns*
411 do (storew arg args i))
418 ;;; VOP that can be inherited by unknown values receivers. The main thing this
419 ;;; handles is allocation of the result temporaries.
420 (define-vop (unknown-values-receiver)
421 (:temporary (:sc descriptor-reg :offset ebx-offset
422 :from :eval :to (:result 0))
424 (:temporary (:sc any-reg :offset ecx-offset
425 :from :eval :to (:result 1))
427 (:results (start :scs (any-reg control-stack))
428 (count :scs (any-reg control-stack))))
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.
435 ;;; FP is the frame pointer in install before doing the call.
437 ;;; NFP would be the number-stack frame pointer if we had a separate
440 ;;; Args are the argument passing locations, which are specified only
441 ;;; to terminate their lifetimes in the caller.
443 ;;; VALUES are the return value locations (wired to the standard
444 ;;; passing locations). NVALS is the number of values received.
446 ;;; Save is the save info, which we can ignore since saving has been
449 ;;; TARGET is a continuation pointing to the start of the called
451 (define-vop (call-local)
455 (:results (values :more t))
457 (:move-args :local-call)
458 (:info arg-locs callee target nvals)
460 (:ignore nfp arg-locs args #+nil callee)
462 (trace-table-entry trace-table-call-site)
465 (let ((ret-tn (callee-return-pc-tn callee)))
467 (format t "*call-local ~S; tn-kind ~S; tn-save-tn ~S; its tn-kind ~S~%"
468 ret-tn (sb!c::tn-kind ret-tn) (sb!c::tn-save-tn ret-tn)
469 (sb!c::tn-kind (sb!c::tn-save-tn ret-tn)))
471 ;; Is the return-pc on the stack or in a register?
474 (unless (= (tn-offset ret-tn) return-pc-save-offset)
475 (error "ret-tn ~A in wrong stack slot" ret-tn))
476 #+nil (format t "*call-local: ret-tn on stack; offset=~S~%"
478 (storew (make-fixup nil :code-object RETURN)
479 ebp-tn (frame-word-offset (tn-offset ret-tn))))
481 (error "ret-tn ~A in sap-reg" ret-tn))))
483 (note-this-location vop :call-site)
486 (default-unknown-values vop values nvals)
487 (trace-table-entry trace-table-normal)))
489 ;;; Non-TR local call for a variable number of return values passed according
490 ;;; to the unknown values convention. The results are the start of the values
491 ;;; glob and the number of values received.
492 (define-vop (multiple-call-local unknown-values-receiver)
497 (:move-args :local-call)
498 (:info save callee target)
499 (:ignore args save nfp #+nil callee)
502 (trace-table-entry trace-table-call-site)
505 (let ((ret-tn (callee-return-pc-tn callee)))
507 (format t "*multiple-call-local ~S; tn-kind ~S; tn-save-tn ~S; its tn-kind ~S~%"
508 ret-tn (sb!c::tn-kind ret-tn) (sb!c::tn-save-tn ret-tn)
509 (sb!c::tn-kind (sb!c::tn-save-tn ret-tn)))
511 ;; Is the return-pc on the stack or in a register?
514 #+nil (format t "*multiple-call-local: ret-tn on stack; offset=~S~%"
517 (storew (make-fixup nil :code-object RETURN)
518 ebp-tn (frame-word-offset (tn-offset ret-tn))))
520 (error "multiple-call-local: return-pc not on stack."))))
522 (note-this-location vop :call-site)
525 (note-this-location vop :unknown-return)
526 (receive-unknown-values values-start nvals start count)
527 (trace-table-entry trace-table-normal)))
529 ;;;; local call with known values return
531 ;;; Non-TR local call with known return locations. Known-value return
532 ;;; works just like argument passing in local call.
534 ;;; Note: we can't use normal load-tn allocation for the fixed args,
535 ;;; since all registers may be tied up by the more operand. Instead,
536 ;;; we use MAYBE-LOAD-STACK-TN.
537 (define-vop (known-call-local)
541 (:results (res :more t))
542 (:move-args :local-call)
544 (:info save callee target)
545 (:ignore args res save nfp #+nil callee)
548 (trace-table-entry trace-table-call-site)
551 (let ((ret-tn (callee-return-pc-tn callee)))
554 (format t "*known-call-local ~S; tn-kind ~S; tn-save-tn ~S; its tn-kind ~S~%"
555 ret-tn (sb!c::tn-kind ret-tn) (sb!c::tn-save-tn ret-tn)
556 (sb!c::tn-kind (sb!c::tn-save-tn ret-tn)))
558 ;; Is the return-pc on the stack or in a register?
561 #+nil (format t "*known-call-local: ret-tn on stack; offset=~S~%"
564 (storew (make-fixup nil :code-object RETURN)
565 ebp-tn (frame-word-offset (tn-offset ret-tn))))
567 (error "known-call-local: return-pc not on stack."))))
569 (note-this-location vop :call-site)
572 (note-this-location vop :known-return)
573 (trace-table-entry trace-table-normal)))
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.
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.
583 (define-vop (known-return)
585 (return-pc :scs (any-reg immediate-stack) :target rpc)
587 (:move-args :known-return)
589 (:temporary (:sc unsigned-reg :from (:argument 1)) rpc)
590 (:ignore val-locs vals)
593 (trace-table-entry trace-table-fun-epilogue)
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
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.
606 (trace-table-entry trace-table-normal)))
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.
613 ;;; The old-fp may be either in a register or on the stack in its
614 ;;; standard save locations - slot 0.
616 ;;; The return-pc may be in a register or on the stack in any slot.
617 (define-vop (known-return)
621 (:move-args :known-return)
623 (:ignore val-locs vals)
626 (trace-table-entry trace-table-fun-epilogue)
628 #+nil (format t "*known-return: old-fp ~S, tn-kind ~S; ~S ~S~%"
629 old-fp (sb!c::tn-kind old-fp) (sb!c::tn-save-tn old-fp)
630 (sb!c::tn-kind (sb!c::tn-save-tn old-fp)))
632 #+nil (format t "*known-return: return-pc ~S, tn-kind ~S; ~S ~S~%"
633 return-pc (sb!c::tn-kind return-pc)
634 (sb!c::tn-save-tn return-pc)
635 (sb!c::tn-kind (sb!c::tn-save-tn return-pc)))
637 ;; return-pc may be either in a register or on the stack.
640 #+nil (format t "*known-return: return-pc ~S on stack; offset=~S~%"
641 return-pc (tn-offset return-pc))
642 (unless (and (sc-is old-fp control-stack)
643 (= (tn-offset old-fp) ocfp-save-offset))
644 (error "known-return: ocfp not on stack in standard save location?"))
645 (unless (and (sc-is return-pc sap-stack)
646 (= (tn-offset return-pc) return-pc-save-offset))
648 "known-return: return-pc not on stack in standard save location?"))
650 ;; Zot all of the stack except for the old-fp and return-pc.
652 (make-ea :dword :base ebp-tn
653 :disp (frame-byte-offset ocfp-save-offset)))
655 (inst ret (* (tn-offset return-pc) n-word-bytes)))
657 (error "known-return, return-pc not on stack")))
659 (trace-table-entry trace-table-normal)))
663 ;;; There is something of a cross-product effect with full calls.
664 ;;; Different versions are used depending on whether we know the
665 ;;; number of arguments or the name of the called function, and
666 ;;; whether we want fixed values, unknown values, or a tail call.
668 ;;; In full call, the arguments are passed creating a partial frame on
669 ;;; the stack top and storing stack arguments into that frame. On
670 ;;; entry to the callee, this partial frame is pointed to by FP.
672 ;;; This macro helps in the definition of full call VOPs by avoiding
673 ;;; code replication in defining the cross-product VOPs.
675 ;;; NAME is the name of the VOP to define.
677 ;;; NAMED is true if the first argument is an fdefinition object whose
678 ;;; definition is to be called.
680 ;;; RETURN is either :FIXED, :UNKNOWN or :TAIL:
681 ;;; -- If :FIXED, then the call is for a fixed number of values, returned in
682 ;;; the standard passing locations (passed as result operands).
683 ;;; -- If :UNKNOWN, then the result values are pushed on the stack, and the
684 ;;; result values are specified by the Start and Count as in the
685 ;;; unknown-values continuation representation.
686 ;;; -- If :TAIL, then do a tail-recursive call. No values are returned.
687 ;;; The Old-Fp and Return-PC are passed as the second and third arguments.
689 ;;; In non-tail calls, the pointer to the stack arguments is passed as
690 ;;; the last fixed argument. If Variable is false, then the passing
691 ;;; locations are passed as a more arg. Variable is true if there are
692 ;;; a variable number of arguments passed on the stack. Variable
693 ;;; cannot be specified with :TAIL return. TR variable argument call
694 ;;; is implemented separately.
696 ;;; In tail call with fixed arguments, the passing locations are
697 ;;; passed as a more arg, but there is no new-FP, since the arguments
698 ;;; have been set up in the current frame.
699 (macrolet ((define-full-call (name named return variable)
700 (aver (not (and variable (eq return :tail))))
702 ,@(when (eq return :unknown)
703 '(unknown-values-receiver)))
705 ,@(unless (eq return :tail)
706 '((new-fp :scs (any-reg) :to (:argument 1))))
708 (fun :scs (descriptor-reg control-stack)
709 :target eax :to (:argument 0))
711 ,@(when (eq return :tail)
715 ,@(unless variable '((args :more t :scs (descriptor-reg)))))
717 ,@(when (eq return :fixed)
718 '((:results (values :more t))))
720 (:save-p ,(if (eq return :tail) :compute-only t))
722 ,@(unless (or (eq return :tail) variable)
723 '((:move-args :full-call)))
727 ,@(unless (or variable (eq return :tail)) '(arg-locs))
728 ,@(unless variable '(nargs))
729 ,@(when (eq return :fixed) '(nvals))
733 ,@(unless (or variable (eq return :tail)) '(arg-locs))
734 ,@(unless variable '(args)))
736 ;; We pass either the fdefn object (for named call) or
737 ;; the actual function object (for unnamed call) in
738 ;; EAX. With named call, closure-tramp will replace it
739 ;; with the real function and invoke the real function
740 ;; for closures. Non-closures do not need this value,
741 ;; so don't care what shows up in it.
749 ;; We pass the number of arguments in ECX.
750 (:temporary (:sc unsigned-reg :offset ecx-offset :to :eval) ecx)
752 ;; With variable call, we have to load the
753 ;; register-args out of the (new) stack frame before
754 ;; doing the call. Therefore, we have to tell the
755 ;; lifetime stuff that we need to use them.
757 (mapcar (lambda (name offset)
758 `(:temporary (:sc descriptor-reg
763 *register-arg-names* *register-arg-offsets*))
765 ,@(when (eq return :tail)
766 '((:temporary (:sc unsigned-reg
771 (:generator ,(+ (if named 5 0)
773 (if (eq return :tail) 0 10)
775 (if (eq return :unknown) 25 0))
776 (trace-table-entry trace-table-call-site)
778 ;; This has to be done before the frame pointer is
779 ;; changed! EAX stores the 'lexical environment' needed
785 ;; For variable call, compute the number of
786 ;; arguments and move some of the arguments to
789 ;; Compute the number of arguments.
790 (noise '(inst mov ecx new-fp))
791 (noise '(inst sub ecx esp-tn))
792 ;; Move the necessary args to registers,
793 ;; this moves them all even if they are
796 for name in *register-arg-names*
797 for index downfrom -1
798 do (noise `(loadw ,name new-fp ,index)))
802 (inst mov ecx (fixnumize nargs)))))
803 ,@(cond ((eq return :tail)
804 '(;; Python has figured out what frame we should
805 ;; return to so might as well use that clue.
806 ;; This seems really important to the
807 ;; implementation of things like
808 ;; (without-interrupts ...)
810 ;; dtc; Could be doing a tail call from a
811 ;; known-local-call etc in which the old-fp
812 ;; or ret-pc are in regs or in non-standard
813 ;; places. If the passing location were
814 ;; wired to the stack in standard locations
815 ;; then these moves will be un-necessary;
816 ;; this is probably best for the x86.
819 (unless (= ocfp-save-offset
821 ;; FIXME: FORMAT T for stale
822 ;; diagnostic output (several of
823 ;; them around here), ick
824 (error "** tail-call old-fp not S0~%")
825 (move old-fp-tmp old-fp)
828 (frame-word-offset ocfp-save-offset))))
829 ((any-reg descriptor-reg)
830 (error "** tail-call old-fp in reg not S0~%")
833 (frame-word-offset ocfp-save-offset))))
835 ;; For tail call, we have to push the
836 ;; return-pc so that it looks like we CALLed
837 ;; despite the fact that we are going to JMP.
838 (inst push return-pc)
841 ;; For non-tail call, we have to save our
842 ;; frame pointer and install the new frame
843 ;; pointer. We can't load stack tns after this
845 `(;; Python doesn't seem to allocate a frame
846 ;; here which doesn't leave room for the
849 ;; The variable args are on the stack and
850 ;; become the frame, but there may be <3
851 ;; args and 3 stack slots are assumed
852 ;; allocate on the call. So need to ensure
853 ;; there are at least 3 slots. This hack
856 '(inst sub esp-tn (fixnumize 3)))
859 (storew ebp-tn new-fp
860 (frame-word-offset ocfp-save-offset))
862 (move ebp-tn new-fp) ; NB - now on new stack frame.
865 (when step-instrumenting
866 (emit-single-step-test)
868 (inst break single-step-around-trap))
871 (note-this-location vop :call-site)
873 (inst ,(if (eq return :tail) 'jmp 'call)
875 '(make-ea-for-object-slot eax fdefn-raw-addr-slot
876 other-pointer-lowtag)
877 '(make-ea-for-object-slot eax closure-fun-slot
878 fun-pointer-lowtag)))
881 '((default-unknown-values vop values nvals)))
883 '((note-this-location vop :unknown-return)
884 (receive-unknown-values values-start nvals start count)))
886 (trace-table-entry trace-table-normal)))))
888 (define-full-call call nil :fixed nil)
889 (define-full-call call-named t :fixed nil)
890 (define-full-call multiple-call nil :unknown nil)
891 (define-full-call multiple-call-named t :unknown nil)
892 (define-full-call tail-call nil :tail nil)
893 (define-full-call tail-call-named t :tail nil)
895 (define-full-call call-variable nil :fixed t)
896 (define-full-call multiple-call-variable nil :unknown t))
898 ;;; This is defined separately, since it needs special code that BLT's
899 ;;; the arguments down. All the real work is done in the assembly
900 ;;; routine. We just set things up so that it can find what it needs.
901 (define-vop (tail-call-variable)
902 (:args (args :scs (any-reg control-stack) :target esi)
903 (function :scs (descriptor-reg control-stack) :target eax)
906 (:temporary (:sc unsigned-reg :offset esi-offset :from (:argument 0)) esi)
907 (:temporary (:sc unsigned-reg :offset eax-offset :from (:argument 1)) eax)
908 ; (:ignore ret-addr old-fp)
910 ;; Move these into the passing locations if they are not already there.
914 ;; The following assumes that the return-pc and old-fp are on the
915 ;; stack in their standard save locations - Check this.
916 (unless (and (sc-is old-fp control-stack)
917 (= (tn-offset old-fp) ocfp-save-offset))
918 (error "tail-call-variable: ocfp not on stack in standard save location?"))
919 (unless (and (sc-is ret-addr sap-stack)
920 (= (tn-offset ret-addr) return-pc-save-offset))
921 (error "tail-call-variable: ret-addr not on stack in standard save location?"))
924 ;; And jump to the assembly routine.
925 (inst jmp (make-fixup 'tail-call-variable :assembly-routine))))
927 ;;;; unknown values return
929 ;;; Return a single-value using the Unknown-Values convention.
931 ;;; pfw--get wired-tn conflicts sometimes if register sc specd for args
932 ;;; having problems targeting args to regs -- using temps instead.
934 ;;; First off, modifying the return-pc defeats the branch-prediction
935 ;;; optimizations on modern CPUs quite handily. Second, we can do all
936 ;;; this without needing a temp register. Fixed the latter, at least.
937 ;;; -- AB 2006/Feb/04
938 (define-vop (return-single)
944 (trace-table-entry trace-table-fun-epilogue)
945 ;; Code structure lifted from known-return.
948 ;; Note that this will only work right if, when old-fp is on
949 ;; the stack, it has a lower tn-offset than return-pc. One of
950 ;; the comments in known-return indicate that this is the case
951 ;; (in that it will be in its save location), but we may wish
952 ;; to assert that (in either the weaker or stronger forms).
953 ;; Should this ever not be the case, we should load old-fp into
954 ;; a temp reg while we fix the stack.
955 (unless (and (sc-is old-fp control-stack)
956 (= (tn-offset old-fp) ocfp-save-offset))
957 (error "ocfp not on stack in standard save location?"))
958 (unless (and (sc-is return-pc sap-stack)
959 (= (tn-offset return-pc) return-pc-save-offset))
960 (error "return-pc not on stack in standard save location?"))
961 ;; Drop stack above old-fp
962 (inst lea esp-tn (make-ea :dword :base ebp-tn
963 :disp (frame-byte-offset (tn-offset old-fp))))
964 ;; Set single-value return flag
966 ;; Restore the old frame pointer
968 ;; And return, dropping the rest of the stack as we go.
969 (inst ret (* (tn-offset return-pc) n-word-bytes)))
971 (error "return pc not on stack")))))
973 ;;; Do unknown-values return of a fixed (other than 1) number of
974 ;;; values. The VALUES are required to be set up in the standard
975 ;;; passing locations. NVALS is the number of values returned.
977 ;;; Basically, we just load ECX with the number of values returned and
978 ;;; EBX with a pointer to the values, set ESP to point to the end of
979 ;;; the values, and jump directly to return-pc.
982 (return-pc :to (:eval 1))
987 ;; In the case of other than one value, we need these registers to
988 ;; tell the caller where they are and how many there are.
989 (:temporary (:sc unsigned-reg :offset ebx-offset) ebx)
990 (:temporary (:sc unsigned-reg :offset ecx-offset) ecx)
992 ;; We need to stretch the lifetime of return-pc past the argument
993 ;; registers so that we can default the argument registers without
994 ;; trashing return-pc.
995 (:temporary (:sc unsigned-reg :offset (first *register-arg-offsets*)
997 (:temporary (:sc unsigned-reg :offset (second *register-arg-offsets*)
999 (:temporary (:sc unsigned-reg :offset (third *register-arg-offsets*)
1003 (unless (and (sc-is old-fp control-stack)
1004 (= (tn-offset old-fp) ocfp-save-offset))
1005 (error "ocfp not on stack in standard save location?"))
1006 (unless (and (sc-is return-pc sap-stack)
1007 (= (tn-offset return-pc) return-pc-save-offset))
1008 (error "return-pc not on stack in standard save location?"))
1010 (trace-table-entry trace-table-fun-epilogue)
1011 ;; Establish the values pointer and values count.
1014 (inst xor ecx ecx) ; smaller
1015 (inst mov ecx (fixnumize nvals)))
1016 ;; Restore the frame pointer.
1017 (move ebp-tn old-fp)
1018 ;; Clear as much of the stack as possible, but not past the return
1021 (make-ea :dword :base ebx
1022 :disp (frame-byte-offset (max (1- nvals)
1023 return-pc-save-offset))))
1024 ;; Pre-default any argument register that need it.
1025 (when (< nvals register-arg-count)
1026 (let* ((arg-tns (nthcdr nvals (list a0 a1 a2)))
1027 (first (first arg-tns)))
1028 (inst mov first nil-value)
1029 (dolist (tn (cdr arg-tns))
1030 (inst mov tn first))))
1031 ;; Set the multiple value return flag.
1033 ;; And away we go. Except that return-pc is still on the
1034 ;; stack and we've changed the stack pointer. So we have to
1035 ;; tell it to index off of EBX instead of EBP.
1036 (cond ((zerop nvals)
1037 ;; Return popping the return address and what's earlier in
1039 (inst ret (* return-pc-save-offset n-word-bytes)))
1041 ;; This is handled in RETURN-SINGLE.
1042 (error "nvalues is 1"))
1044 ;; Thou shalt not JMP unto thy return address.
1045 (inst push (make-ea :dword :base ebx
1046 :disp (frame-byte-offset (tn-offset return-pc))))
1049 (trace-table-entry trace-table-normal)))
1051 ;;; Do unknown-values return of an arbitrary number of values (passed
1052 ;;; on the stack.) We check for the common case of a single return
1053 ;;; value, and do that inline using the normal single value return
1054 ;;; convention. Otherwise, we branch off to code that calls an
1055 ;;; assembly-routine.
1057 ;;; The assembly routine takes the following args:
1058 ;;; EAX -- the return-pc to finally jump to.
1059 ;;; EBX -- pointer to where to put the values.
1060 ;;; ECX -- number of values to find there.
1061 ;;; ESI -- pointer to where to find the values.
1062 (define-vop (return-multiple)
1063 (:args (old-fp :to (:eval 1) :target old-fp-temp)
1064 (return-pc :target eax)
1065 (vals :scs (any-reg) :target esi)
1066 (nvals :scs (any-reg) :target ecx))
1068 (:temporary (:sc unsigned-reg :offset eax-offset :from (:argument 1)) eax)
1069 (:temporary (:sc unsigned-reg :offset esi-offset :from (:argument 2)) esi)
1070 (:temporary (:sc unsigned-reg :offset ecx-offset :from (:argument 3)) ecx)
1071 (:temporary (:sc unsigned-reg :offset ebx-offset :from (:eval 0)) ebx)
1072 (:temporary (:sc descriptor-reg :offset (first *register-arg-offsets*)
1073 :from (:eval 0)) a0)
1074 (:temporary (:sc unsigned-reg :from (:eval 1)) old-fp-temp)
1078 (trace-table-entry trace-table-fun-epilogue)
1079 ;; Load the return-pc.
1080 (move eax return-pc)
1081 (unless (policy node (> space speed))
1082 ;; Check for the single case.
1083 (let ((not-single (gen-label)))
1084 (inst cmp nvals (fixnumize 1))
1085 (inst jmp :ne not-single)
1087 ;; Return with one value.
1089 ;; Clear the stack. We load old-fp into a register before clearing
1091 (move old-fp-temp old-fp)
1092 (move esp-tn ebp-tn)
1093 (move ebp-tn old-fp-temp)
1094 ;; clear the multiple-value return flag
1099 ;; Nope, not the single case. Jump to the assembly routine.
1100 (emit-label not-single)))
1104 (move ebp-tn old-fp)
1105 (inst jmp (make-fixup 'return-multiple :assembly-routine))
1106 (trace-table-entry trace-table-normal)))
1110 ;;; We don't need to do anything special for regular functions.
1111 (define-vop (setup-environment)
1115 ;; Don't bother doing anything.
1118 ;;; Get the lexical environment from its passing location.
1119 (define-vop (setup-closure-environment)
1120 (:results (closure :scs (descriptor-reg)))
1125 (move closure eax-tn)))
1127 ;;; Copy a &MORE arg from the argument area to the end of the current
1128 ;;; frame. FIXED is the number of non-&MORE arguments.
1130 ;;; The tricky part is doing this without trashing any of the calling
1131 ;;; convention registers that are still needed. This vop is emitted
1132 ;;; directly after the xep-allocate frame. That means the registers
1133 ;;; are in use as follows:
1135 ;;; EAX -- The lexenv.
1136 ;;; EBX -- Available.
1137 ;;; ECX -- The total number of arguments.
1138 ;;; EDX -- The first arg.
1139 ;;; EDI -- The second arg.
1140 ;;; ESI -- The third arg.
1142 ;;; So basically, we have one register available for our use: EBX.
1144 ;;; What we can do is push the other regs onto the stack, and then
1145 ;;; restore their values by looking directly below where we put the
1147 (define-vop (copy-more-arg)
1150 ;; Avoid the copy if there are no more args.
1151 (cond ((zerop fixed)
1152 (inst jecxz JUST-ALLOC-FRAME))
1154 (inst cmp ecx-tn (fixnumize fixed))
1155 (inst jmp :be JUST-ALLOC-FRAME)))
1157 ;; Allocate the space on the stack.
1158 ;; stack = ebp - (max 3 frame-size) - (nargs - fixed)
1160 (make-ea :dword :base ebp-tn
1161 :disp (- (fixnumize fixed)
1163 (max 3 (sb-allocated-size 'stack))))))
1164 (inst sub ebx-tn ecx-tn) ; Got the new stack in ebx
1165 (inst mov esp-tn ebx-tn)
1167 ;; Now: nargs>=1 && nargs>fixed
1169 ;; Save the original count of args.
1170 (inst mov ebx-tn ecx-tn)
1172 (cond ((< fixed register-arg-count)
1173 ;; We must stop when we run out of stack args, not when we
1174 ;; run out of more args.
1175 ;; Number to copy = nargs-3
1176 (inst sub ecx-tn (fixnumize register-arg-count))
1177 ;; Everything of interest in registers.
1178 (inst jmp :be DO-REGS))
1180 ;; Number to copy = nargs-fixed
1181 (inst sub ecx-tn (fixnumize fixed))))
1183 ;; Save edi and esi register args.
1187 ;; Okay, we have pushed the register args. We can trash them
1190 ;; Initialize src to be end of args.
1191 (inst mov esi-tn ebp-tn)
1192 (inst sub esi-tn ebx-tn)
1194 ;; We need to copy from downwards up to avoid overwriting some of
1195 ;; the yet uncopied args. So we need to use EBX as the copy index
1196 ;; and ECX as the loop counter, rather than using ECX for both.
1197 (inst xor ebx-tn ebx-tn)
1199 ;; We used to use REP MOVS here, but on modern x86 it performs
1200 ;; much worse than an explicit loop for small blocks.
1202 (inst mov edi-tn (make-ea :dword :base esi-tn :index ebx-tn))
1203 ;; The :DISP is to account for the registers saved on the stack
1204 (inst mov (make-ea :dword :base esp-tn :disp (* 3 n-word-bytes)
1207 (inst add ebx-tn n-word-bytes)
1208 (inst sub ecx-tn n-word-bytes)
1209 (inst jmp :nz COPY-LOOP)
1211 ;; So now we need to restore EDI and ESI.
1219 (inst mov ecx-tn ebx-tn)
1221 ;; Here: nargs>=1 && nargs>fixed
1222 (when (< fixed register-arg-count)
1223 ;; Now we have to deposit any more args that showed up in
1227 ;; Store it relative to ebp
1228 (inst mov (make-ea :dword :base ebp-tn
1229 :disp (- (* n-word-bytes
1231 (max 3 (sb-allocated-size 'stack))))))
1232 (nth i *register-arg-tns*))
1235 (when (>= i register-arg-count)
1238 ;; Don't deposit any more than there are.
1240 (inst test ecx-tn ecx-tn)
1241 (inst cmp ecx-tn (fixnumize i)))
1242 (inst jmp :eq DONE)))
1248 (make-ea :dword :base ebp-tn
1249 :disp (- (* n-word-bytes
1250 (max 3 (sb-allocated-size 'stack))))))
1254 (define-vop (more-kw-arg)
1255 (:translate sb!c::%more-kw-arg)
1256 (:policy :fast-safe)
1257 (:args (object :scs (descriptor-reg) :to (:result 1))
1258 (index :scs (any-reg immediate) :to (:result 1) :target keyword))
1259 (:arg-types * tagged-num)
1260 (:results (value :scs (descriptor-reg any-reg))
1261 (keyword :scs (descriptor-reg any-reg)))
1266 (inst mov value (make-ea :dword :base object :disp (tn-value index)))
1267 (inst mov keyword (make-ea :dword :base object
1268 :disp (+ (tn-value index) n-word-bytes))))
1270 (inst mov value (make-ea :dword :base object :index index))
1271 (inst mov keyword (make-ea :dword :base object :index index
1272 :disp n-word-bytes))))))
1274 (define-vop (more-arg)
1275 (:translate sb!c::%more-arg)
1276 (:policy :fast-safe)
1277 (:args (object :scs (descriptor-reg) :to (:result 1))
1278 (index :scs (any-reg) :to (:result 1) :target value))
1279 (:arg-types * tagged-num)
1280 (:results (value :scs (descriptor-reg any-reg)))
1285 (inst mov value (make-ea :dword :base object :index value))))
1287 ;;; Turn more arg (context, count) into a list.
1288 (define-vop (listify-rest-args)
1289 (:translate %listify-rest-args)
1291 (:args (context :scs (descriptor-reg) :target src)
1292 (count :scs (any-reg) :target ecx))
1293 (:arg-types * tagged-num)
1294 (:temporary (:sc unsigned-reg :offset esi-offset :from (:argument 0)) src)
1295 (:temporary (:sc unsigned-reg :offset ecx-offset :from (:argument 1)) ecx)
1296 (:temporary (:sc unsigned-reg :offset eax-offset) eax)
1297 (:temporary (:sc unsigned-reg) dst)
1298 (:results (result :scs (descriptor-reg)))
1301 (let ((enter (gen-label))
1304 (stack-allocate-p (node-stack-allocate-p node)))
1307 ;; Check to see whether there are no args, and just return NIL if so.
1308 (inst mov result nil-value)
1310 (inst lea dst (make-ea :dword :base ecx :index ecx))
1311 (maybe-pseudo-atomic stack-allocate-p
1312 (allocation dst dst node stack-allocate-p list-pointer-lowtag)
1313 (inst shr ecx (1- n-lowtag-bits))
1314 ;; Set decrement mode (successive args at lower addresses)
1316 ;; Set up the result.
1318 ;; Jump into the middle of the loop, 'cause that's where we want
1322 ;; Compute a pointer to the next cons.
1323 (inst add dst (* cons-size n-word-bytes))
1324 ;; Store a pointer to this cons in the CDR of the previous cons.
1325 (storew dst dst -1 list-pointer-lowtag)
1327 ;; Grab one value and stash it in the car of this cons.
1329 (storew eax dst 0 list-pointer-lowtag)
1330 ;; Go back for more.
1333 ;; NIL out the last cons.
1334 (storew nil-value dst 1 list-pointer-lowtag)
1336 (emit-label done))))
1338 ;;; Return the location and size of the &MORE arg glob created by
1339 ;;; COPY-MORE-ARG. SUPPLIED is the total number of arguments supplied
1340 ;;; (originally passed in ECX). FIXED is the number of non-rest
1343 ;;; We must duplicate some of the work done by COPY-MORE-ARG, since at
1344 ;;; that time the environment is in a pretty brain-damaged state,
1345 ;;; preventing this info from being returned as values. What we do is
1346 ;;; compute supplied - fixed, and return a pointer that many words
1347 ;;; below the current stack top.
1348 (define-vop (more-arg-context)
1349 (:policy :fast-safe)
1350 (:translate sb!c::%more-arg-context)
1351 (:args (supplied :scs (any-reg) :target count))
1352 (:arg-types positive-fixnum (:constant fixnum))
1354 (:results (context :scs (descriptor-reg))
1355 (count :scs (any-reg)))
1356 (:result-types t tagged-num)
1357 (:note "more-arg-context")
1359 (move count supplied)
1360 ;; SP at this point points at the last arg pushed.
1361 ;; Point to the first more-arg, not above it.
1362 (inst lea context (make-ea :dword :base esp-tn
1363 :index count :scale 1
1364 :disp (- (+ (fixnumize fixed) n-word-bytes))))
1365 (unless (zerop fixed)
1366 (inst sub count (fixnumize fixed)))))
1368 ;;; Signal wrong argument count error if NARGS isn't equal to COUNT.
1369 (define-vop (verify-arg-count)
1370 (:policy :fast-safe)
1371 (:translate sb!c::%verify-arg-count)
1372 (:args (nargs :scs (any-reg)))
1373 (:arg-types positive-fixnum (:constant t))
1376 (:save-p :compute-only)
1379 (generate-error-code vop 'invalid-arg-count-error nargs)))
1381 (inst test nargs nargs) ; smaller instruction
1382 (inst cmp nargs (fixnumize count)))
1383 (inst jmp :ne err-lab))))
1385 ;;; Various other error signallers.
1386 (macrolet ((def (name error translate &rest args)
1387 `(define-vop (,name)
1389 `((:policy :fast-safe)
1390 (:translate ,translate)))
1391 (:args ,@(mapcar (lambda (arg)
1392 `(,arg :scs (any-reg descriptor-reg)))
1395 (:save-p :compute-only)
1397 (error-call vop ',error ,@args)))))
1398 (def arg-count-error invalid-arg-count-error
1399 sb!c::%arg-count-error nargs)
1400 (def type-check-error object-not-type-error sb!c::%type-check-error
1402 (def layout-invalid-error layout-invalid-error sb!c::%layout-invalid-error
1404 (def odd-key-args-error odd-key-args-error
1405 sb!c::%odd-key-args-error)
1406 (def unknown-key-arg-error unknown-key-arg-error
1407 sb!c::%unknown-key-arg-error key)
1408 (def nil-fun-returned-error nil-fun-returned-error nil fun))
1412 (defun emit-single-step-test ()
1413 ;; We use different ways of representing whether stepping is on on
1414 ;; +SB-THREAD / -SB-THREAD: on +SB-THREAD, we use a slot in the
1415 ;; thread structure. On -SB-THREAD we use the value of a static
1416 ;; symbol. Things are done this way, since reading a thread-local
1417 ;; slot from a symbol would require an extra register on +SB-THREAD,
1418 ;; and reading a slot from a thread structure would require an extra
1419 ;; register on -SB-THREAD.
1422 (inst cmp (make-ea :dword
1423 :disp (* thread-stepping-slot n-word-bytes))
1426 (inst cmp (make-ea-for-symbol-value sb!impl::*stepping*)
1429 (define-vop (step-instrument-before-vop)
1430 (:policy :fast-safe)
1433 (emit-single-step-test)
1435 (inst break single-step-before-trap)
1437 (note-this-location vop :step-before-vop)))