[pypy-svn] pypy fast-forward: Skip this test in the same situation as CPython, for the same reason.

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: fast-forward
Changeset: r40508:25d38cc1bbfc
Date: 2011-01-09 11:42 +0100
http://bitbucket.org/pypy/pypy/changeset/25d38cc1bbfc/

Log:	Skip this test in the same situation as CPython, for the same
	reason.

diff --git a/pypy/module/math/test/test_math.py b/pypy/module/math/test/test_math.py
--- a/pypy/module/math/test/test_math.py
+++ b/pypy/module/math/test/test_math.py
@@ -47,6 +47,15 @@
     def test_fsum(self):
         import math
 
+        # detect evidence of double-rounding: fsum is not always correctly
+        # rounded on machines that suffer from double rounding.
+        # It is a known problem with IA32 floating-point arithmetic.
+        # It should work fine e.g. with x86-64.
+        x, y = 1e16, 2.9999 # use temporary values to defeat peephole optimizer
+        HAVE_DOUBLE_ROUNDING = (x + y == 1e16 + 4)
+        if HAVE_DOUBLE_ROUNDING:
+            skip("fsum is not exact on machines with double rounding")
+
         test_values = [
             ([], 0.0),
             ([0.0], 0.0),