From f7be737659813220e1f29c8850c386a9654d549a Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 21 Mar 2014 18:13:58 +0000 Subject: Fix log (1) in round-downward mode (bug 16731). According to ISO C Annex F, log (1) should be +0 in all rounding modes, but some implementations in glibc wrongly return -0 in round-downward mode (mapping to log1p (x - 1) is problematic because 1 - 1 is -0 in round-downward mode, and log1p (-0) is -0). This patch fixes this. (It helps with some implementations of other functions such as acosh, log2 and log10 that call out to log, but not enough to enable all-rounding-modes testing for those functions without further fixes to other implementations of them.) Tested x86_64 and x86 and ulps updated accordingly, and did spot tests for mips64 for the ldbl-128 fix, and i586 for the sysdeps/i386/fpu implementations shadowed by those in sysdeps/i386/i686/fpu. [BZ #16731] * sysdeps/i386/fpu/e_log.S (__ieee754_log): Take absolute value when x - 1 is zero. * sysdeps/i386/fpu/e_logf.S (__ieee754_logf): Likewise. * sysdeps/i386/fpu/e_logl.S (__ieee754_logl): Likewise. * sysdeps/i386/i686/fpu/e_logl.S (__ieee754_logl): Likewise. * sysdeps/ieee754/dbl-64/e_log.c (__ieee754_log): Return +0 when argument is 1. * sysdeps/ieee754/ldbl-128/e_logl.c (__ieee754_logl): Likewise. * sysdeps/x86_64/fpu/e_logl.S: Take absolute value when x - 1 is zero. * math/libm-test.inc (log_test): Use ALL_RM_TEST. * sysdeps/i386/fpu/libm-test-ulps: Update. * sysdeps/x86_64/fpu/libm-test-ulps: Likewise. --- sysdeps/x86_64/fpu/libm-test-ulps | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'sysdeps/x86_64/fpu/libm-test-ulps') diff --git a/sysdeps/x86_64/fpu/libm-test-ulps b/sysdeps/x86_64/fpu/libm-test-ulps index 5f4ab06050..301eaa6542 100644 --- a/sysdeps/x86_64/fpu/libm-test-ulps +++ b/sysdeps/x86_64/fpu/libm-test-ulps @@ -1170,6 +1170,22 @@ ifloat: 1 ildouble: 1 ldouble: 1 +Function: "log_downward": +float: 1 +ifloat: 1 +ildouble: 1 +ldouble: 1 + +Function: "log_towardzero": +ildouble: 1 +ldouble: 1 + +Function: "log_upward": +float: 1 +ifloat: 1 +ildouble: 1 +ldouble: 1 + Function: "pow": float: 1 ifloat: 1 -- cgit 1.4.1