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wip-rtl, non-immediate constants like lists and arrays does not have a 6


From: Stefan Israelsson Tampe
Subject: wip-rtl, non-immediate constants like lists and arrays does not have a 64bit aligned address!
Date: Sat, 8 Sep 2012 13:49:41 +0200


Hi,

I was a bit surprised when I coded the native versions of rtl-sinstruction, make-non-immediate I just
assumed that alignement meant 64bit on 64bit platforms. It doesen't in for example,

(define const
  (assemble-program
   `((begin-program test-bind-rest)
     (assert-nargs-ee/locals 0 2)
     (load-constant 0 '(1 2))
     (load-constant 1 #(1))
     (cons 0 0 1)
     (return 0)
     (end-program))))

-->
??dissassembles into

;;; ((assert-nargs-ee/locals (op : 20) (expected : 0) (nlocals : 2)))

;;; ((inst))

;;; ((make-non-immediate (op : 52) (dst : 0) (offset : -7) (ip : 20677408)))

;;; ((inst))

;;; ((make-non-immediate (op : 52) (dst : 1) (offset : -31) (ip : 20677320)))

;;; ((inst))

;;; ((cons (op : 74) (dst : 0) (x : 0) (y : 1)))

;;; ((inst))

;;; ((return (op : 5) (src : 0)))

And we see that 20677320 & 8 == 8, hence not 64 bit aligned. Assuming alignment meant 32bit
the native code works very well!

But would I dear to suggest that we try to keep all non immediates aligned on 64bit boundaries?

/Stefan

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