From 01189b083b8ce54fc568fd2ab0dd433d869ede0e Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Thu, 5 Nov 2015 21:56:31 +0000 Subject: Fix i386/x86_64 log* (1) zero sign for -ffinite-math-only (bug 19213). For the -ffinite-math-only versions of various x86_64 and x86 log* functions, a zero result from log* (1) is returned with incorrect sign in round-downward mode. This patch fixes this in a similar way to the previous fixes for the non-*_finite versions of the functions. Tested for x86_64 and x86 (including an i586 build), together with a patch that will be applied separately to enable the main libm-test.inc tests for the finite-math-only functions. [BZ #19213] * sysdeps/i386/fpu/e_log.S (__log_finite): Ensure +0 is always returned for argument 1. * sysdeps/i386/fpu/e_logf.S (__logf_finite): Likewise. * sysdeps/i386/fpu/e_logl.S (__logl_finite): Likewise. * sysdeps/i386/i686/fpu/e_logl.S (__logl_finite): Likewise. * sysdeps/x86_64/fpu/e_log10l.S (__log10l_finite): Likewise. * sysdeps/x86_64/fpu/e_log2l.S (__log2l_finite): Likewise. * sysdeps/x86_64/fpu/e_logl.S (__logl_finite): Likewise. --- sysdeps/x86_64/fpu/e_log2l.S | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'sysdeps/x86_64/fpu/e_log2l.S') diff --git a/sysdeps/x86_64/fpu/e_log2l.S b/sysdeps/x86_64/fpu/e_log2l.S index c12906d456..a063255ddd 100644 --- a/sysdeps/x86_64/fpu/e_log2l.S +++ b/sysdeps/x86_64/fpu/e_log2l.S @@ -78,7 +78,13 @@ ENTRY(__log2l_finite) fnstsw // x-1 : x : 1 andb $0x45, %ah jz 2b - fstp %st(1) // x-1 : 1 + fxam + fnstsw + andb $0x45, %ah + cmpb $0x40, %ah + jne 6f + fabs // log2(1) is +0 in all rounding modes. +6: fstp %st(1) // x-1 : 1 fyl2xp1 // log(x) ret END (__log2l_finite) -- cgit 1.4.1