| 2010-11-17 09:19:19 |
Heka Treep |
description |
Currently, Python does not reduce the constants in expressions such as:
(+ 3 a 5 b 7 c)
For fixnums this gives:
; A7: 83C203 ADD EDX, 3
; AA: 83C205 ADD EDX, 5
; AD: C1FF02 SAR EDI, 2
; B0: 01FA ADD EDX, EDI
; B2: 83C207 ADD EDX, 7
; B5: C1FE02 SAR ESI, 2
; B8: 8D0432 LEA EAX, [EDX+ESI]
; BB: 6BD004 IMUL EDX, EAX, 4
; BE: 7107 JNO L0
; C0: 8BD0 MOV EDX, EAX
and for generic numbers this generate five calls to GENERIC-+.
It would be nice to collect all numbers at compile-time, doing the following transformation:
(+ 3 a 5 b 7 c) -> (+ 15 a b c)
schematically:
(+ list) -> `(+ ,(fold-left '+ identity (filter const-p list)) ,@(filter not-const-p list)) |
Currently, Python does not reduce the constants in expressions such as:
(+ 3 a 5 b 7 c)
For fixnums this gives:
; A7: 83C203 ADD EDX, 3
; AA: 83C205 ADD EDX, 5
; AD: C1FF02 SAR EDI, 2
; B0: 01FA ADD EDX, EDI
; B2: 83C207 ADD EDX, 7
; B5: C1FE02 SAR ESI, 2
; B8: 8D0432 LEA EAX, [EDX+ESI]
; BB: 6BD004 IMUL EDX, EAX, 4
; BE: 7107 JNO L0
; C0: 8BD0 MOV EDX, EAX
and for generic numbers this generate five calls to GENERIC-+.
It would be nice to collect all numbers at compile-time, doing the following transformation:
(+ 3 a 5 b 7 c) -> (+ 15 a b c)
schematically:
(+ list) -> `(+ ,(fold-left '+ identity (filter const-p list))
,@(filter not-const-p list))
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