1 //===-- Implementation of the tan function for x86_64 ---------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "src/math/tan.h" 10 #include "src/__support/common.h" 11 12 namespace LIBC_NAMESPACE { 13 14 LLVM_LIBC_FUNCTION(double, tan, (double x)) { 15 double result; 16 // The fptan instruction pushes the number 1 on to the FP stack after 17 // computing tan. So, we read out the one before popping the actual result. 18 __asm__ __volatile__("fptan" : "+t"(x)); 19 __asm__ __volatile__("fstpl %0" : "=m"(result)); 20 return result; 21 } 22 23 } // namespace LIBC_NAMESPACE 24