X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fassem.lisp;h=d052886519df0d9370dfa62bf936c318075689f0;hb=54da325f13fb41669869aea688ae195426c0e231;hp=7cdc688c13b89676275e33189583ec571d140898;hpb=a7a4ca961ef0f587a2549bd9433eef7ddb845ab7;p=sbcl.git diff --git a/src/compiler/assem.lisp b/src/compiler/assem.lisp index 7cdc688..d052886 100644 --- a/src/compiler/assem.lisp +++ b/src/compiler/assem.lisp @@ -703,14 +703,16 @@ (def!struct (alignment-note (:include annotation) (:conc-name alignment-) (:predicate alignment-p) - (:constructor make-alignment (bits size fill-byte)) + (:constructor make-alignment (bits size pattern)) (:copier nil)) ;; the minimum number of low-order bits that must be zero (bits 0 :type alignment) ;; the amount of filler we are assuming this alignment op will take (size 0 :type (integer 0 #.(1- (ash 1 max-alignment)))) - ;; the byte used as filling - (fill-byte 0 :type (or assembly-unit (signed-byte #.assembly-unit-bits)))) + ;; the byte used as filling or :LONG-NOP, indicating to call EMIT-LONG-NOP + ;; to emit a filling pattern + (pattern 0 :type (or possibly-signed-assembly-unit + (member :long-nop)))) ;;; a reference to someplace that needs to be back-patched when ;;; we actually know what label positions, etc. are @@ -765,12 +767,18 @@ (incf (segment-current-posn segment)) (values)) -;;; interface: Output AMOUNT copies of FILL-BYTE to SEGMENT. -(defun emit-skip (segment amount &optional (fill-byte 0)) +;;; interface: Output AMOUNT bytes to SEGMENT, either copies of +;;; PATTERN (if that is an integer), or by calling EMIT-LONG-NOP +;;; (if PATTERN is :LONG-NOP). +(defun emit-skip (segment amount &optional (pattern 0)) (declare (type segment segment) (type index amount)) - (dotimes (i amount) - (emit-byte segment fill-byte)) + (etypecase pattern + (integer + (dotimes (i amount) + (emit-byte segment pattern))) + ((eql :long-nop) + (sb!vm:emit-long-nop segment amount))) (values)) ;;; This is used to handle the common parts of annotation emission. We @@ -851,10 +859,23 @@ ;;; This is used internally whenever a chooser or alignment decides it ;;; doesn't need as much space as it originally thought. +;;; This function used to extend an existing filler instead of creating +;;; a new one when the previous segment annotation was a filler. Now +;;; this is only done if the previous filler is immediately adjacent +;;; to the new one in the segment, too. To see why this restriction is +;;; necessary, consider a jump followed by an alignment made of +;;; multi-byte NOPs when both are shrunk: The shortened alignment is +;;; reemitted at its original _start_ position but the joined filler +;;; would extend over this position and instead leave a subsequence of +;;; the segment up to the alignment's original _end_ position visible. (defun emit-filler (segment n-bytes) (declare (type index n-bytes)) (let ((last (segment-last-annotation segment))) - (cond ((and last (filler-p (car last))) + (cond ((and last + (filler-p (car last)) + (= (+ (filler-index (car last)) + (filler-bytes (car last))) + (segment-current-index segment))) (incf (filler-bytes (car last)) n-bytes)) (t (emit-annotation segment (make-filler n-bytes))))) @@ -879,7 +900,7 @@ ;;; see if we can guarantee the alignment restriction by just outputting a ;;; fixed number of bytes. If so, we do so. Otherwise, we create and emit an ;;; alignment note. -(defun %emit-alignment (segment vop bits &optional (fill-byte 0)) +(defun %emit-alignment (segment vop bits &optional (pattern 0)) (when (segment-run-scheduler segment) (schedule-pending-instructions segment)) (let ((hook (segment-inst-hook segment))) @@ -889,29 +910,29 @@ (offset (- (segment-current-posn segment) (segment-sync-posn segment)))) (cond ((> bits alignment) - ;; We need more bits of alignment. First emit enough noise - ;; to get back in sync with alignment, and then emit an - ;; alignment note to cover the rest. - (let ((slop (logand offset (1- (ash 1 alignment))))) - (unless (zerop slop) - (emit-skip segment (- (ash 1 alignment) slop) fill-byte))) - (let ((size (logand (1- (ash 1 bits)) - (lognot (1- (ash 1 alignment)))))) + ;; We need more bits of alignment. Emit an alignment note. + ;; The ALIGNMENT many least significant bits of (- OFFSET) + ;; give the amount of bytes to skip to get back in sync with + ;; ALIGNMENT, and one-bits to the left of that up to position + ;; BITS provide the remaining amount. + (let ((size (deposit-field (- offset) + (byte 0 alignment) + (1- (ash 1 bits))))) (aver (> size 0)) - (emit-annotation segment (make-alignment bits size fill-byte)) - (emit-skip segment size fill-byte)) + (emit-annotation segment (make-alignment bits size pattern)) + (emit-skip segment size pattern)) (setf (segment-alignment segment) bits) (setf (segment-sync-posn segment) (segment-current-posn segment))) (t - ;; The last alignment was more restrictive then this one. + ;; The last alignment was more restrictive than this one. ;; So we can just figure out how much noise to emit ;; assuming the last alignment was met. (let* ((mask (1- (ash 1 bits))) (new-offset (logand (+ offset mask) (lognot mask)))) - (emit-skip segment (- new-offset offset) fill-byte)) + (emit-skip segment (- new-offset offset) pattern)) ;; But we emit an alignment with size=0 so we can verify ;; that everything works. - (emit-annotation segment (make-alignment bits 0 fill-byte))))) + (emit-annotation segment (make-alignment bits 0 pattern))))) (values)) ;;; This is used to find how ``aligned'' different offsets are. @@ -1000,7 +1021,7 @@ (with-modified-segment-index-and-posn (segment index posn) (setf (segment-last-annotation segment) prev) (%emit-alignment segment nil (alignment-bits note) - (alignment-fill-byte note)) + (alignment-pattern note)) (let* ((new-index (segment-current-index segment)) (size (- new-index index)) (old-size (alignment-size note)) @@ -1049,6 +1070,11 @@ (with-modified-segment-index-and-posn (segment (alignment-index note) posn) + (when (eql (alignment-pattern note) :long-nop) + ;; We need to re-emit the alignment because a shorter + ;; multi-byte NOP pattern is most of the time not a + ;; prefix of a longer one. + (emit-skip segment size (alignment-pattern note))) (emit-filler segment additional-delta) (setf prev (segment-last-annotation segment)) (if prev @@ -1093,6 +1119,33 @@ (chooser-size note))) (t (setf prev remaining))))))) + +;;; Replace the SEGMENT-BUFFER of SEGMENT with a vector that contains +;;; only the valid content of the original buffer, that is, the parts +;;; not covered by fillers. Set FINAL-INDEX of SEGMENT to the length +;;; of the new vector and return this length. +(defun compact-segment-buffer (segment) + (let ((buffer (segment-buffer segment)) + (new-buffer (make-array (segment-final-posn segment) + :element-type 'assembly-unit)) + (i0 0) + (index 0)) + (declare (type (simple-array assembly-unit 1) buffer) + (type index index)) + (flet ((frob (i0 i1) + (when (< i0 i1) + (replace new-buffer buffer :start1 index :start2 i0 :end2 i1) + (incf index (- i1 i0))))) + (dolist (note (segment-annotations segment)) + (when (filler-p note) + (let ((i1 (filler-index note))) + (frob i0 i1) + (setf i0 (+ i1 (filler-bytes note)))))) + (frob i0 (segment-final-index segment))) + (aver (= index (segment-final-posn segment))) + (setf (segment-buffer segment) new-buffer) + (setf (segment-final-index segment) (segment-final-posn segment)))) + ;;;; interface to the rest of the compiler @@ -1229,10 +1282,10 @@ ;;; Note: The need to capture SYMBOL-MACROLET bindings of ;;; **CURRENT-SEGMENT* and (%%CURRENT-VOP%%) prevents this from being an ;;; ordinary function. -(defmacro emit-alignment (bits &optional (fill-byte 0)) +(defmacro emit-alignment (bits &optional (pattern 0)) #!+sb-doc "Emit an alignment restriction to the current segment." - `(%emit-alignment (%%current-segment%%) (%%current-vop%%) ,bits ,fill-byte)) + `(%emit-alignment (%%current-segment%%) (%%current-vop%%) ,bits ,pattern)) (defun label-position (label &optional if-after delta) #!+sb-doc @@ -1300,48 +1353,23 @@ (compress-output segment) (finalize-positions segment) (process-back-patches segment) - (segment-final-posn segment)) + (compact-segment-buffer segment)) -;;; Call FUNCTION on all the stuff accumulated in SEGMENT. FUNCTION -;;; should accept a single vector argument. It will be called zero or -;;; more times on vectors of the appropriate byte type. The -;;; concatenation of the vector arguments from all the calls is the -;;; contents of SEGMENT. -;;; -;;; KLUDGE: This implementation is sort of slow and gross, calling -;;; FUNCTION repeatedly and consing a fresh vector for its argument -;;; each time. It might be possible to make a more efficient version -;;; by making FINALIZE-SEGMENT do all the compacting currently done by -;;; this function: then this function could become trivial and fast, -;;; calling FUNCTION once on the entire compacted segment buffer. -- -;;; WHN 19990322 -(defun on-segment-contents-vectorly (segment function) - (declare (type function function)) - (let ((buffer (segment-buffer segment)) - (i0 0)) - (declare (type (simple-array (unsigned-byte 8)) buffer)) - (flet ((frob (i0 i1) - (when (< i0 i1) - (funcall function (subseq buffer i0 i1))))) - (dolist (note (segment-annotations segment)) - (when (filler-p note) - (let ((i1 (filler-index note))) - (frob i0 i1) - (setf i0 (+ i1 (filler-bytes note)))))) - (frob i0 (segment-final-index segment)))) - (values)) +;;; Return the contents of SEGMENT as a vector. We assume SEGMENT has +;;; been finalized so that we can simply return its buffer. +(defun segment-contents-as-vector (segment) + (declare (type segment segment)) + (aver (= (segment-final-index segment) (segment-final-posn segment))) + (segment-buffer segment)) ;;; Write the code accumulated in SEGMENT to STREAM, and return the -;;; number of bytes written. +;;; number of bytes written. We assume that SEGMENT has been finalized. (defun write-segment-contents (segment stream) - (let ((result 0)) - (declare (type index result)) - (on-segment-contents-vectorly segment - (lambda (v) - (declare (type (vector assembly-unit) v)) - (incf result (length v)) - (write-sequence v stream))) - result)) + (declare (type segment segment)) + (let ((v (segment-contents-as-vector segment))) + (declare (type (simple-array assembly-unit 1) v)) + (length (write-sequence v stream)))) + ;;;; interface to the instruction set definition