X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fgeneric%2Fearly-objdef.lisp;h=ef6563c42057e7d11a7660a38833c5e560d8243a;hb=cd875f8c1fb306067521330fbf84411713b7c20d;hp=25c1e0f70fb51252438b90b1c5e1e76909249edb;hpb=fc999187f3f80dfcf170348df676386b8403e261;p=sbcl.git

diff --git a/src/compiler/generic/early-objdef.lisp b/src/compiler/generic/early-objdef.lisp
index 25c1e0f..ef6563c 100644
--- a/src/compiler/generic/early-objdef.lisp
+++ b/src/compiler/generic/early-objdef.lisp
@@ -58,6 +58,41 @@
 ;;; 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)
+;;;
+;;; 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 (:suffix -widetag
 	  :start (+ (ash 1 n-lowtag-bits) other-immediate-0-lowtag)
 	  :step (ash 1 (1- n-lowtag-bits)))
@@ -71,17 +106,47 @@
   complex-double-float
   #!+long-float complex-long-float
 
-  simple-array
-  simple-array-nil
-  simple-base-string
-  simple-bit-vector
-  simple-vector
+  code-header
+  simple-fun-header
+  closure-header
+  funcallable-instance-header
+
+  return-pc-header
+  value-cell-header
+  symbol-header
+  base-char
+  sap
+  unbound-marker
+  weak-pointer
+  instance-header
+  fdefn
+
+  unused00
+  unused01
+  unused02
+  unused03
+  unused04
+  unused05
+  unused06
+  unused07
+  #!-long-float unused08
+  #!-long-float unused09
+  
+  #!+long-float simple-array-long-float
+  #!+long-float simple-array-complex-long-float
+  #!-long-float unused10
+  #!-long-float unused11
+
   simple-array-unsigned-byte-2
   simple-array-unsigned-byte-4
   simple-array-unsigned-byte-7
   simple-array-unsigned-byte-8
   simple-array-unsigned-byte-15
   simple-array-unsigned-byte-16
+  simple-array-nil
+  simple-base-string
+  simple-bit-vector
+  simple-vector
   simple-array-unsigned-byte-29
   simple-array-unsigned-byte-31
   simple-array-unsigned-byte-32
@@ -91,31 +156,15 @@
   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-base-string
+  simple-array
   complex-vector-nil
+  complex-base-string
   complex-bit-vector
   complex-vector
   complex-array
-
-  code-header
-  simple-fun-header
-  closure-header
-  funcallable-instance-header
-  closure-fun-header
-
-  return-pc-header
-  value-cell-header
-  symbol-header
-  base-char
-  sap
-  unbound-marker
-  weak-pointer
-  instance-header
-  fdefn)
+)
 
 ;;; the different vector subtypes
 (defenum (:prefix vector- :suffix -subtype)