0.9.15.7:

	More OPTIMIZATIONS.

diff --git a/OPTIMIZATIONS b/OPTIMIZATIONS
index 69f4447..cb963ea 100644 (file)
--- a/OPTIMIZATIONS
+++ b/OPTIMIZATIONS
@@ -347,4 +347,59 @@ arguments:
 
 Notice that '(MOD 46) has two entries in the constant vector.  Having
 one would be preferable.
 
 Notice that '(MOD 46) has two entries in the constant vector.  Having
 one would be preferable.

+--------------------------------------------------------------------------------
+#35
+Compiling
+
+(defun foo (a i)
+  (declare (type simple-vector a))
+  (aref a i))
+
+results in the following x86 code:
+
+; 115886E9:       F7C703000000     TEST EDI, 3                ; no-arg-parsing entry point
+;      6EF:       7510             JNE L0
+;      6F1:       8BC7             MOV EAX, EDI
+;      6F3:       83F800           CMP EAX, 0
+;      6F6:       7C09             JL L0
+;      6F8:       8BC7             MOV EAX, EDI
+;      6FA:       3DF8FFFF7F       CMP EAX, 2147483640
+;      6FF:       7E0F             JLE L1
+;      701: L0:   8B057C865811     MOV EAX, [#x1158867C]      ; '(MOD
+                                                              ;   536870911)
+;      707:       0F0B0A           BREAK 10                   ; error trap
+;      70A:       05               BYTE #X05
+;      70B:       1F               BYTE #X1F                  ; OBJECT-NOT-TYPE-ERROR
+;      70C:       FECE01           BYTE #XFE, #XCE, #X01      ; EDI
+;      70F:       0E               BYTE #X0E                  ; EAX
+;      710: L1:   8B42FD           MOV EAX, [EDX-3]
+;      713:       8BCF             MOV ECX, EDI
+;      715:       39C8             CMP EAX, ECX
+;      717:       7620             JBE L2
+;      719:       8B540A01         MOV EDX, [EDX+ECX+1]
+
+... plus the standard return sequence and some error blocks.  The
+`TEST EDI, 3' and associated comparisons are to ensure that `I' is a
+positive fixnum.  The associated comparisons are unnecessary, as the
+%CHECK-BOUND VOP only requires its tested index to be a fixnum and takes
+care of the negative fixnum case itself.
+
+{HAIRY-,}DATA-VECTOR-REF are DEFKNOWN'd with EXPLICIT-CHECK, which would
+seem to take care of this, but EXPLICIT-CHECK only seems to be used when
+compiling calls to unknown functions or similar.  Furthermore,
+EXPLICIT-CHECK, as NJF understands it, doesn't have the right
+semantics--it suppresses all type checking of arguments, whereas what we
+really want is to ensure that the argument is a fixnum, but not check
+its positiveness.
+--------------------------------------------------------------------------------
+#36
+
+In #35, the CMP EAX, $foo instructions are all preceded by a MOV.  They
+appear to be unnecessary, but are necessary because in IR2, EDI is a
+DESCRIPTOR-REG, whereas EAX is an ANY-REG--and the comparison VOPs only
+accept ANY-REGs.  Therefore, the MOVs are "necessary" to ensure that the
+comparison VOP receives an TN of the appropriate storage class.

 
 

+Obviously, it would be better if a) we only performed one MOV prior to
+all three comparisons or b) eliminated the necessity of the MOV(s)
+altogether.  The former option is probably easier than the latter.

diff --git a/version.lisp-expr b/version.lisp-expr
index 058c510..c3429b0 100644 (file)
--- a/version.lisp-expr
+++ b/version.lisp-expr
@@ -17,4 +17,4 @@
 ;;; checkins which aren't released. (And occasionally for internal
 ;;; versions, especially for internal versions off the main CVS
 ;;; branch, it gets hairier, e.g. "0.pre7.14.flaky4.13".)
 ;;; checkins which aren't released. (And occasionally for internal
 ;;; versions, especially for internal versions off the main CVS
 ;;; branch, it gets hairier, e.g. "0.pre7.14.flaky4.13".)

-"0.9.15.6"
+"0.9.15.7"