[cmucl-commit] [git] CMU Common Lisp branch master updated. snapshot-2014-08-35-ge38211a

[Raymond Toy]

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- Log -----------------------------------------------------------------
commit e38211a12ceccae3b59938fd4815ab9055d6d5b8
Author: Raymond Toy <toy.raymond at gmail.com>
Date:   Tue Aug 26 20:33:54 2014 -0700

    Implement a simpler (and faster?) algorithm to convert a double to an
    int.

diff --git a/src/compiler/sparc/float.lisp b/src/compiler/sparc/float.lisp
index 013f184..74f279d 100644
--- a/src/compiler/sparc/float.lisp
+++ b/src/compiler/sparc/float.lisp
@@ -1252,17 +1252,13 @@
     (inst fdtox r x)
     (inst fxtod r r)))
 
+;; See Listing 2.2: Conversion from FP to int in in "CR-LIBM: A
+;; library of correctly rounded elementary functions in
+;; double-precision".
 #+sun4
 (deftransform %unary-round ((x) (float) (signed-byte 32))
-  '(let* ((trunc (truly-the (signed-byte 32) (%unary-truncate x)))
-	  (extra (- x trunc))
-	  (absx (abs extra))
-	  (one-half (float 1/2 x)))
-     (if (if (oddp trunc)
-	     (>= absx one-half)
-	     (> absx one-half))
-	 (truly-the (signed-byte 32) (%unary-truncate (+ x extra)))
-	 trunc)))
+   '(kernel:double-float-low-bits (+ x (+ (scale-float 1d0 52)
+					  (scale-float 1d0 51)))))
 
 (define-vop (make-single-float)
   (:args (bits :scs (signed-reg) :target res

-----------------------------------------------------------------------

Summary of changes:
 src/compiler/sparc/float.lisp |   14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)


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