From abc040f26cb13b17ac52ea8579dc0d0d894f8bfc Mon Sep 17 00:00:00 2001
From: Brecht Van Lommel <brecht@blender.org>
Date: Thu, 27 Feb 2020 12:46:37 +0100
Subject: Build: change libc compatibility code to only be used for new glibc

This way we can still use fast math functions.
---
 intern/libc_compat/CMakeLists.txt | 2 ++
 intern/libc_compat/libc_compat.c  | 9 ++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

(limited to 'intern/libc_compat')

diff --git a/intern/libc_compat/CMakeLists.txt b/intern/libc_compat/CMakeLists.txt
index 21d252806d4..f8fede5673b 100644
--- a/intern/libc_compat/CMakeLists.txt
+++ b/intern/libc_compat/CMakeLists.txt
@@ -32,4 +32,6 @@ set(SRC
 set(LIB
 )
 
+add_c_flag(-ffast-math)
+
 blender_add_lib(bf_intern_libc_compat "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
diff --git a/intern/libc_compat/libc_compat.c b/intern/libc_compat/libc_compat.c
index bc1a43c6fb1..8da3ca218af 100644
--- a/intern/libc_compat/libc_compat.c
+++ b/intern/libc_compat/libc_compat.c
@@ -21,7 +21,11 @@
  * incompatible with the system libraries that Blender is built on. To solve
  * this we add a few -ffast-math symbols that can be missing. */
 
-#include <math.h>
+#ifdef __linux__
+#  include <features.h>
+#  include <math.h>
+
+#  if defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 31)
 
 double __exp_finite(double x);
 double __acos_finite(double x);
@@ -107,3 +111,6 @@ float __powf_finite(float x, float y)
 {
   return powf(x, y);
 }
+
+#  endif /* __GLIBC_PREREQ */
+#endif   /* __linux__ */
-- 
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