patches/glibc/2_9/180-math-tests.patch
branchnewlib
changeset 1365 c4d124ed9f8e
parent 1364 9227d2a2c080
child 1366 5e5d1e6f55d3
     1.1 --- a/patches/glibc/2_9/180-math-tests.patch	Sat Apr 11 19:03:02 2009 +0000
     1.2 +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.3 @@ -1,72 +0,0 @@
     1.4 -Original patch from: gentoo/src/patchsets/glibc/2.9/0090_all_glibc-math-tests.patch
     1.5 -
     1.6 --= BEGIN original header =-
     1.7 -From: "Joseph S. Myers" <joseph at codesourcery dot com>
     1.8 -To: libc-alpha at sourceware dot org
     1.9 -Date: Tue, 15 Jul 2008 14:43:04 +0000 (UTC)
    1.10 -Subject: expm1 ulps
    1.11 -
    1.12 -If you test glibc on i686 with GCC 4.3, you get a test-ildoubl failure:
    1.13 -
    1.14 -Failure: Test: expm1 (1) == M_El - 1.0
    1.15 -Result:
    1.16 - is:          1.71828182845904523532e+00   0xd.bf0a8b14576953500000p-3
    1.17 - should be:   1.71828182845904523543e+00   0xd.bf0a8b14576953600000p-3
    1.18 - difference:  1.08420217248550443401e-19   0x8.00000000000000000000p-66
    1.19 - ulp       :  1.0000
    1.20 - max.ulp   :  0.0000
    1.21 -Maximal error of `expm1'
    1.22 - is      : 1 ulp
    1.23 - accepted: 0 ulp
    1.24 -
    1.25 -What happens is that the inline expansion of expm1l uses __builtin_expm1l,
    1.26 -and GCC 4.3 optimizes calls to __builtin_expm1l with constant argument to
    1.27 -a correctly rounded result using MPFR.  The result returned is thus the
    1.28 -value of e-1 rounded once to long double precision.  However, the test
    1.29 -expects M_El - 1.0, and the result of rounding e to long double precision,
    1.30 -then subtracting 1, differs in the last place from the result of rounding
    1.31 -e-1 to long double precision (the latter has smaller exponent, and the
    1.32 -last bit is 1).
    1.33 -
    1.34 -There are two obvious approaches possible to fixing this.  The first patch
    1.35 -below changes the expectation to a decimal expansion for e-1 (taken from
    1.36 -that of M_El) rather than doing arithmetic in the expected value.  This in
    1.37 -turn requires ulps to be set for the out-of-line version of expm1.  It
    1.38 -might also need ulps to be set for the inline version for older compilers
    1.39 -if they should continue to pass the test, and possibly for other targets.
    1.40 -The second patch below takes the alternative approach of keeping the
    1.41 -existing expectation (which has the wrong bit in the last place) and
    1.42 -setting ulps for the inline expansion of expm1, which avoids the risk of
    1.43 -breaking the test for other targets.
    1.44 -
    1.45 -2008-07-15  Joseph Myers  <joseph@codesourcery.com>
    1.46 -
    1.47 -        * sysdeps/i386/fpu/libm-test-ulps: Add inline long double ulps for
    1.48 -        expm1.
    1.49 -
    1.50 --= END original header =-
    1.51 -
    1.52 -diff -durN glibc-2_9.orig/sysdeps/i386/fpu/libm-test-ulps glibc-2_9/sysdeps/i386/fpu/libm-test-ulps
    1.53 ---- glibc-2_9.orig/sysdeps/i386/fpu/libm-test-ulps	2006-01-15 18:59:37.000000000 +0100
    1.54 -+++ glibc-2_9/sysdeps/i386/fpu/libm-test-ulps	2009-02-02 22:00:47.000000000 +0100
    1.55 -@@ -453,6 +453,10 @@
    1.56 - ildouble: 8
    1.57 - ldouble: 8
    1.58 - 
    1.59 -+# expm1
    1.60 -+Test "expm1 (1) == M_El - 1.0":
    1.61 -+ildouble: 1
    1.62 -+
    1.63 - # gamma
    1.64 - Test "gamma (-0.5) == log(2*sqrt(pi))":
    1.65 - double: 1
    1.66 -@@ -1134,6 +1138,9 @@
    1.67 - ildouble: 8
    1.68 - ldouble: 8
    1.69 - 
    1.70 -+Function: "expm1":
    1.71 -+ildouble: 1
    1.72 -+
    1.73 - Function: "gamma":
    1.74 - double: 1
    1.75 - idouble: 1