(in-package "SB!VM")
-;;; FIXME: It's clever using :SUFFIX -TYPE for these things, but it's
-;;; a pain for people just learning to find their way around the code
-;;; who want to use lexical search to figure out where things like
-;;; EVEN-FIXNUM-LOWTAG are defined. Remove the :SUFFIXes and just expand
-;;; out the full names. Or even define them in DEF-FROB EVEN-FIXNUM-LOWTAG
-;;; style so searches like 'def.*even-fixnum-lowtag' can find them.
-
-;;; tags for the main low-level types, to be stored in the low three
-;;; bits to identify the type of a machine word
+;;; Tags for the main low-level types are stored in the low n (usually three)
+;;; bits to identify the type of a machine word. Certain constraints
+;;; apply:
+;;; * EVEN-FIXNUM-LOWTAG and ODD-FIXNUM-LOWTAG must be 0 and 4: code
+;;; which shifts left two places to convert raw integers to tagged
+;;; fixnums is ubiquitous.
+;;; * LIST-POINTER-LOWTAG + N-WORD-BYTES = OTHER-POINTER-LOWTAG: NIL
+;;; is both a cons and a symbol (at the same address) and depends on this.
+;;; See the definition of SYMBOL in objdef.lisp
+;;; * OTHER-POINTER-LOWTAG > 4: Some code in the SPARC backend,
+;;; which uses bit 2 of the ALLOC register to indicate that
+;;; PSEUDO-ATOMIC is on, doesn't strip the low bits of reg_ALLOC
+;;; before ORing in OTHER-POINTER-LOWTAG within a PSEUDO-ATOMIC
+;;; section.
+;;; * OTHER-IMMEDIATE-0-LOWTAG are spaced 4 apart: various code wants to
+;;; iterate through these
+;;; * Allocation code on Alpha wants lowtags for heap-allocated
+;;; objects to be odd.
+;;; (These are just the ones we know about as of sbcl-0.7.1.22. There
+;;; might easily be more, since these values have stayed highly
+;;; constrained for more than a decade, an inviting target for
+;;; inventive abstraction-phobic maintainers.:-)
+;;;
+;;; Another way to look at lowtags is that there is no one lowtag
+;;; length. On 32-bit platforms, fixnums and other-immediates have a
+;;; lowtag length of two bits, and pointers have a lowtag length of
+;;; three bits. On 64-bit platforms, fixnums and pointers gain an
+;;; extra bit, and six "pad" lowtags waste the extra encoding space so
+;;; obtained.
+;;;
+;;; x00 -- fixnum
+;;; x10 -- other-immediate
+;;; 001 -- instance-pointer
+;;; 011 -- list-pointer
+;;; 101 -- fun-pointer
+;;; 111 -- other-pointer
+;;;
+;;; If you change the tag layout, check the various functions in
+;;; src/runtime/runtime.h to see if they need to be updated, along
+;;; with print_obj() in src/runtime/print.c, possibly gc_init_tables()
+;;; in src/runtime/gc-common-c and possibly the code in src/code/room.
(eval-when (:compile-toplevel :load-toplevel :execute)
;; The EVAL-WHEN is necessary (at least for Lispworks), because the
;; second DEFENUM uses the value of OTHER-IMMEDIATE-0-LOWTAG, which is
;; defined in the first DEFENUM. -- AL 20000216
- (defenum (:suffix -lowtag)
- even-fixnum
- ;; Note: CMU CL, and SBCL < 0.pre7.39, had FUN-POINTER-LOWTAG
- ;; here. We swapped FUN-POINTER-LOWTAG and
- ;; INSTANCE-POINTER-LOWTAG in sbcl-0.pre7.39 in order to help with a
- ;; low-level pun in the function call sequence on the PPC port.
- ;; For more information, see the PPC port code. -- WHN 2001-10-03
- instance-pointer
- other-immediate-0
- list-pointer
- odd-fixnum
- fun-pointer
- other-immediate-1
- other-pointer))
+ #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
+ (defenum ()
+ even-fixnum-lowtag
+ other-immediate-0-lowtag
+ pad0-lowtag
+ instance-pointer-lowtag
+ pad1-lowtag
+ other-immediate-1-lowtag
+ pad2-lowtag
+ list-pointer-lowtag
+ odd-fixnum-lowtag
+ other-immediate-2-lowtag
+ pad3-lowtag
+ fun-pointer-lowtag
+ pad4-lowtag
+ other-immediate-3-lowtag
+ pad5-lowtag
+ other-pointer-lowtag)
+ #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ (defenum ()
+ even-fixnum-lowtag
+ instance-pointer-lowtag
+ other-immediate-0-lowtag
+ list-pointer-lowtag
+ odd-fixnum-lowtag
+ fun-pointer-lowtag
+ other-immediate-1-lowtag
+ other-pointer-lowtag))
+
+(def!constant nil-value
+ (+ static-space-start n-word-bytes other-pointer-lowtag))
+
+(defconstant-eqx fixnum-lowtags
+ #.(let ((fixtags nil))
+ (do-external-symbols (sym "SB!VM")
+ (let* ((name (symbol-name sym))
+ (len (length name)))
+ (when (and (boundp sym)
+ (integerp (symbol-value sym))
+ (> len 7)
+ (string= name "-LOWTAG" :start1 (- len 7))
+ (zerop (logand (symbol-value sym) fixnum-tag-mask)))
+ (push sym fixtags))))
+ `',(sort fixtags #'string< :key #'symbol-name))
+ #'equal)
;;; the heap types, stored in 8 bits of the header of an object on the
;;; heap, to identify the type of the heap object (which'll be at
;;; least two machine words, often more)
-(defenum (:suffix -widetag
- :start (+ (ash 1 n-lowtag-bits) other-immediate-0-lowtag)
- :step (ash 1 (1- n-lowtag-bits)))
- bignum
- ratio
- single-float
- double-float
- #!+long-float long-float
- complex
- complex-single-float
- complex-double-float
- #!+long-float complex-long-float
+;;;
+;;; Note: the order specified here is not critical for correctness,
+;;; but (FIXME) with %TEST-HEADERS as currently defined, BIGNUM must
+;;; be first, and COMPLEX-ARRAY must be last.
+;;;
+;;; However, for efficiency, we prefer contiguous sets of widetags for
+;;; "similar" objects, so that type checking can be done with a range
+;;; check, rather than several individual checks.
+;;;
+;;; * BIGNUM + RATIO (+ FIXNUM) = RATIONAL
+;;;
+;;; * SINGLE-FLOAT + DOUBLE-FLOAT + LONG-FLOAT = FLOAT
+;;;
+;;; * RATIONAL + FLOAT = REAL
+;;;
+;;; * (FIXME: COMPLEX example, which needs fixing anyway -- see
+;;; UPGRADED-COMPLEX-PART-TYPE)
+;;;
+;;; * SIMPLE-ARRAY-* = (SIMPLE-ARRAY * (*))
+;;;
+;;; * SIMPLE-ARRAY-NIL + SIMPLE-BASE-STRING = SIMPLE-STRING
+;;;
+;;; * SIMPLE-ARRAY + COMPLEX-ARRAYOID = (SATISFIES ARRAY-HEADER-P)
+;;;
+;;; In addition, with
+;;; sufficient care we can cause extra combinations to appear with
+;;; differences in only one bit, permitting a more efficient type
+;;; test. As an example, if SIMPLE-BASE-STRING = 0xA6 and
+;;; COMPLEX-BASE-STRING = 0xE6, then the type test for BASE-STRING is
+;;;
+;;; AND tag, ~0x40, tag
+;;; ANDcc tag, 0xA6, tag
+;;; JNE tag, label
+;;;
+;;; rather than two separate tests and jumps
+(defenum (;; The first widetag must be greater than SB!VM:LOWTAG-LIMIT
+ ;; otherwise code in generic/early-type-vops will suffer
+ ;; a long, horrible death. --njf, 2004-08-09
+ :start (+ (ash 1 n-lowtag-bits) other-immediate-0-lowtag)
+ :step 4)
+ ;; NOTE: the binary numbers off to the side are only valid for 32-bit
+ ;; ports; add #b1000 if you want to know the values for 64-bit ports.
+ ;; And note that the numbers get a little scrambled further down.
+ ;; --njf, 2004-08-09
+ bignum-widetag ; 00001010
+ ratio-widetag ; 00001110
+ single-float-widetag ; 00010010
+ double-float-widetag ; 00010110
+ complex-widetag ; 00011010
+ complex-single-float-widetag ; 00011110
+ complex-double-float-widetag ; 00100010
+
+ code-header-widetag ; 00100110
+
+ simple-fun-header-widetag ; 00101010
+ closure-header-widetag ; 00101110
+ funcallable-instance-header-widetag ; 00110010
+
+ return-pc-header-widetag ; 00110110
+ value-cell-header-widetag ; 00111010
+ symbol-header-widetag ; 00111110
+ character-widetag ; 01000010
+ sap-widetag ; 01000110
+ unbound-marker-widetag ; 01001010
+ weak-pointer-widetag ; 01001110
+ instance-header-widetag ; 01010010
+ fdefn-widetag ; 01010110
+
+ no-tls-value-marker-widetag ; 01011010
+ #!-sb-simd-pack
+ unused01-widetag
+ #!+sb-simd-pack
+ simd-pack-widetag ; 01011110
+ unused02-widetag ; 01100010
+ unused03-widetag ; 01100110
+ unused04-widetag ; 01101010
+ unused05-widetag ; 01101110
+ unused06-widetag ; 01110010
+ unused07-widetag ; 01110110
+ #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ unused08-widetag ; 01111010
+ #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ unused09-widetag ; 01111110
- simple-array
- simple-string
- simple-bit-vector
- simple-vector
- simple-array-unsigned-byte-2
- simple-array-unsigned-byte-4
- simple-array-unsigned-byte-8
- simple-array-unsigned-byte-16
- simple-array-unsigned-byte-32
- simple-array-signed-byte-8
- simple-array-signed-byte-16
- simple-array-signed-byte-30
- simple-array-signed-byte-32
- simple-array-single-float
- simple-array-double-float
- #!+long-float simple-array-long-float
- simple-array-complex-single-float
- simple-array-complex-double-float
- #!+long-float simple-array-complex-long-float
- complex-string
- complex-bit-vector
- complex-vector
- complex-array
+ #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ unused10-widetag ; 10000010
+ #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ unused11-widetag ; 10000110
- code-header
- simple-fun-header
- closure-header
- funcallable-instance-header
- closure-fun-header
+ simple-array-unsigned-byte-2-widetag ; 10001010
+ simple-array-unsigned-byte-4-widetag ; 10001110
+ simple-array-unsigned-byte-7-widetag ; 10010010
+ simple-array-unsigned-byte-8-widetag ; 10010110
+ simple-array-unsigned-byte-15-widetag ; 10011010
+ simple-array-unsigned-byte-16-widetag ; 10011110
+ simple-array-nil-widetag ; 10100010
+ simple-base-string-widetag ; 10100110
+ #!+sb-unicode simple-character-string-widetag
+ simple-bit-vector-widetag ; 10101010
+ simple-vector-widetag ; 10101110
+ #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ simple-array-unsigned-fixnum-widetag ; 10110010
+ simple-array-unsigned-byte-31-widetag ; 10110110
+ simple-array-unsigned-byte-32-widetag ; 10111010
+ #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
+ simple-array-unsigned-fixnum-widetag
+ #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
+ simple-array-unsigned-byte-63-widetag
+ #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
+ simple-array-unsigned-byte-64-widetag
+ simple-array-signed-byte-8-widetag ; 10111110
+ simple-array-signed-byte-16-widetag ; 11000010
+ #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ simple-array-fixnum-widetag ; 11000110
+ simple-array-signed-byte-32-widetag ; 11001010
+ #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
+ simple-array-fixnum-widetag
+ #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
+ simple-array-signed-byte-64-widetag
+ simple-array-single-float-widetag ; 11001110
+ simple-array-double-float-widetag ; 11010010
+ simple-array-complex-single-float-widetag ; 11010110
+ simple-array-complex-double-float-widetag ; 11011010
+ simple-array-widetag ; 11011110
+ complex-vector-nil-widetag ; 11100010
+ complex-base-string-widetag ; 11100110
+ #!+sb-unicode complex-character-string-widetag
+ complex-bit-vector-widetag ; 11101010
+ complex-vector-widetag ; 11101110
+ complex-array-widetag ; 11110010
- return-pc-header
- value-cell-header
- symbol-header
- base-char
- sap
- unbound-marker
- weak-pointer
- instance-header
- fdefn)
+ #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ unused12-widetag ; 11110110
+ #!+(and #.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ (not sb-unicode))
+ unused13-widetag ; 11111010
+ #!+(and #.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
+ (not sb-unicode))
+ unused14-widetag ; 11111110
+)
;;; the different vector subtypes
-(defenum (:prefix vector- :suffix -subtype)
- normal
- unused
- valid-hashing
- must-rehash)
+(defenum ()
+ vector-normal-subtype
+ vector-unused-subtype
+ vector-valid-hashing-subtype)
projects / sbcl.git / blobdiff