[Git][cmucl/cmucl][rtoy-setexception-inexact] Use setexception to raise the inexact exception for tanh.

[Raymond Toy]

Raymond Toy pushed to branch rtoy-setexception-inexact at cmucl / cmucl


Commits:
b9e3a511 by Raymond Toy at 2015-12-24T09:29:08Z
Use setexception to raise the inexact exception for tanh.

Note that original code didn't actually signal inexact probably
because the compiler constant-folded one - tiny to one.

- - - - -


2 changed files:

- src/lisp/s_tanh.c
- tests/fdlibm.lisp


Changes:

=====================================
src/lisp/s_tanh.c
=====================================
--- a/src/lisp/s_tanh.c
+++ b/src/lisp/s_tanh.c
@@ -78,7 +78,9 @@ static double one=1.0, two=2.0, tiny = 1.0e-300;
 	    }
     /* |x| > 22, return +-1 */
 	} else {
-	    z = one - tiny;		/* raised inexact flag */
+	    /* Always raise inexact flag */
+	    fdlibm_setexception(x, FDLIBM_INEXACT);
+	    z = one - tiny;
 	}
 	return (jx>=0)? z: -z;
 }


=====================================
tests/fdlibm.lisp
=====================================
--- a/tests/fdlibm.lisp
+++ b/tests/fdlibm.lisp
@@ -88,7 +88,14 @@
   (assert-error 'floating-point-invalid-operation
 		(kernel:%tanh *snan*))
   (kernel::with-float-traps-masked (:invalid)
-    (assert-true (ext:float-nan-p (kernel:%tanh *snan*)))))
+    (assert-true (ext:float-nan-p (kernel:%tanh *snan*))))
+  ;; tanh(x) = +/- 1 for |x| > 22, raising inexact, always.
+  (let ((x 22.1d0))
+    (with-inexact-exception-enabled
+	;; This must throw an inexact exception for non-zero x even
+	;; though the result is exactly x.
+	(assert-error 'floating-point-inexact
+		      (kernel:%tanh x)))))
 
 (define-test %acosh.exceptions
   (:tag :fdlibm)



View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/commit/b9e3a5113c1c08e5785fc36866a8e4553a96300e
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