(:res result descriptor-reg a0-offset)
(:temp ndescr non-descriptor-reg nl0-offset)
+ (:temp gc-temp non-descriptor-reg nl1-offset)
(:temp vector descriptor-reg a3-offset))
(pseudo-atomic ()
- (inst or vector alloc-tn other-pointer-lowtag)
;; boxed words == unboxed bytes
(inst add ndescr words (* (1+ vector-data-offset) n-word-bytes))
(inst andn ndescr 7)
- (inst add alloc-tn ndescr)
+ (allocation vector ndescr other-pointer-lowtag :temp-tn gc-temp)
(inst srl ndescr type word-shift)
(storew ndescr vector 0 other-pointer-lowtag)
(storew length vector vector-length-slot other-pointer-lowtag))
;; This makes sure the zero byte at the end of a string is paged in so
;; the kernel doesn't bitch if we pass it the string.
+ ;;
+ ;; RLT comments in CMUCL about changing the following line to
+ ;; store at -1 instead of 0:
+ ;; This used to write to the word after the last allocated word. I
+ ;; (RLT) made it write to the last allocated word, which is where
+ ;; the zero-byte of the string is. Look at the deftransform for
+ ;; make-array in array-tran.lisp. For strings we always allocate
+ ;; enough space to hold the zero-byte.
+ ;; Which is most certainly motivated by the fact that this store (if
+ ;; performed on gencgc) overwrites the first word of the following
+ ;; page -- destroying the first object of an unrelated allocation region!
+ ;;
+ ;; But the CMUCL fix breaks :ELEMENT-TYPE NIL strings, so we'd need a
+ ;; branch to figure out whether to do it. Until and unless someone
+ ;; demonstrates that gencgc actually gives us uncommitted memory, I'm
+ ;; just not doing it at all: -- DFL
+ #!-gencgc
(storew zero-tn alloc-tn 0)
(move result vector))
projects / sbcl.git / blobdiff