From 2e2485ce05bce85bf092ba0752854afa14b92dad Mon Sep 17 00:00:00 2001
From: Xiaolin Tang <tangxiaolin@loongson.cn>
Date: Wed, 23 Nov 2022 11:45:00 +0800
Subject: Use GCC builtins for logb functions if desired.

This patch is using the corresponding GCC builtin for logbf, logb,
logbl and logbf128 if the USE_FUNCTION_BUILTIN macros are defined to one
in math-use-builtins-function.h.

Co-Authored-By: Xi Ruoyao <xry111@xry111.site>
---
 sysdeps/ieee754/dbl-64/s_logb.c | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'sysdeps/ieee754/dbl-64')

diff --git a/sysdeps/ieee754/dbl-64/s_logb.c b/sysdeps/ieee754/dbl-64/s_logb.c
index 82cabd206a..dd74d5f08c 100644
--- a/sysdeps/ieee754/dbl-64/s_logb.c
+++ b/sysdeps/ieee754/dbl-64/s_logb.c
@@ -21,10 +21,14 @@
 #include <math_private.h>
 #include <libm-alias-double.h>
 #include <fix-int-fp-convert-zero.h>
+#include <math-use-builtins.h>
 
 double
 __logb (double x)
 {
+#if USE_LOGB_BUILTIN
+  return __builtin_logb (x);
+#else
   int64_t ix, ex;
 
   EXTRACT_WORDS64 (ix, x);
@@ -42,6 +46,7 @@ __logb (double x)
   if (FIX_INT_FP_CONVERT_ZERO && ex == 1023)
     return 0.0;
   return (double) (ex - 1023);
+#endif /* !USE_LOGB_BUILTIN  */
 }
 #ifndef __logb
 libm_alias_double (__logb, logb)
-- 
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