commit 45b09e7625ae3d121aa8586b65db906a8da3ec93
author Yann Collet <cyan@fb.com> Thu Mar 01 15:02:18 2018 -0800
committer Yann Collet <cyan@fb.com> Thu Mar 01 15:02:18 2018 -0800
tree ad1288a5d3df5ab3af050944a4d5a57b8b971aaa
parent b01552a07ae20b5ed28fdb2084dbe9dadd1a6d9a

limit DYNAMIC_BMI2 to gcc >= 4.8

attribute bmi2 not supported by gcc 4.4

lib/common/compiler.h

diff --git a/lib/common/compiler.h b/lib/common/compiler.h
index 24f3532..63d3225 100644
--- a/lib/common/compiler.h
+++ b/lib/common/compiler.h
@@ -71,10 +71,11 @@
 #endif
 
 /* Enable runtime BMI2 dispatch based on the CPU.
- * Enabled for clang/gcc on x86 when BMI2 isn't enabled by default.
+ * Enabled for clang & gcc >=4.8 on x86 when BMI2 isn't enabled by default.
  */
 #ifndef DYNAMIC_BMI2
-  #if defined(__GNUC__) && (defined(__x86_64__) || defined(_M_X86)) && !defined(__BMI2__)
+  #if defined(__GNUC__) && (__GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)) \
+      && (defined(__x86_64__) || defined(_M_X86)) && !defined(__BMI2__)
   #  define DYNAMIC_BMI2 1
   #else
   #  define DYNAMIC_BMI2 0