Submitted by: Xi Ruoyao Date: 2026-08-06 Initial Package Version: 2.44 Upstream Status: Committed for master (master and 2.44 branch). Origin: Upstream repository (see the "From" line for revision) Description: Fix an issue causing tanh to crash on "old" x86_64 processors (without FMA). From 0b58f5d80d24cf83cfde9d8381aafb11fef0e152 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Thu, 30 Jul 2026 08:55:54 -0300 Subject: [PATCH] math: Fix x86_64 tanh _FloatN aliases binding to the FMA variant [BZ 34465] The generic implementation emits libm_alias_double unconditionally, so tanhf32x and tanhf64 bind directly to __tanh_fma. Guard the alias with '#ifndef __tanh' and emit it from the dispatcher, as sin. Also remove the stale __expm1 defines, unused since tanh moved to CORE-MATH. Checked on x86_64-linux-gnu, and with 'qemu-x86_64 -cpu Nehalem'. Reported-by: Michael Brunnbauer (cherry picked from commit b01abba04a954cbd6b2834c0643a08685a915fe5) --- NEWS | 1 + sysdeps/ieee754/dbl-64/s_tanh.c | 2 ++ sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c | 6 ------ sysdeps/x86_64/fpu/multiarch/s_tanh.c | 5 ++--- 4 files changed, 5 insertions(+), 9 deletions(-) diff --git a/NEWS b/NEWS index fe2b1d7f79..43667c1963 100644 --- a/NEWS +++ b/NEWS @@ -11,6 +11,7 @@ The following bugs are resolved with this release: [34441] math: math: sinh() returns wrong results for some inputs with |x| > 36.736801 + [34465] math: math: x86_64 tanh ifunc selection wrong Version 2.44 diff --git a/sysdeps/ieee754/dbl-64/s_tanh.c b/sysdeps/ieee754/dbl-64/s_tanh.c index 2029de8fa5..ef80b9edb6 100644 --- a/sysdeps/ieee754/dbl-64/s_tanh.c +++ b/sysdeps/ieee754/dbl-64/s_tanh.c @@ -283,4 +283,6 @@ __tanh (double x) return as_tanh_database (x, res); return res; } +#ifndef __tanh libm_alias_double (__tanh, tanh) +#endif diff --git a/sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c b/sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c index 1b808b1227..1e6b33740a 100644 --- a/sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c +++ b/sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c @@ -1,10 +1,4 @@ #define __tanh __tanh_fma -#define __expm1 __expm1_fma - -/* NB: __expm1 may be expanded to __expm1_fma in the following - prototypes. */ -extern long double __expm1l (long double); -extern long double __expm1f128 (long double); #define SECTION __attribute__ ((section (".text.fma"))) diff --git a/sysdeps/x86_64/fpu/multiarch/s_tanh.c b/sysdeps/x86_64/fpu/multiarch/s_tanh.c index ec8826f634..9048c977c1 100644 --- a/sysdeps/x86_64/fpu/multiarch/s_tanh.c +++ b/sysdeps/x86_64/fpu/multiarch/s_tanh.c @@ -25,10 +25,9 @@ extern double __redirect_tanh (double); # define SYMBOL_NAME tanh # include "ifunc-fma.h" -libc_ifunc_redirected (__redirect_tanh, tanh, IFUNC_SELECTOR ()); +libc_ifunc_redirected (__redirect_tanh, __tanh, IFUNC_SELECTOR ()); +libm_alias_double (__tanh, tanh) # define __tanh __tanh_sse2 -# undef libm_alias_double -# define libm_alias_double(a, b) #endif #include -- 2.55.0