limit DYNAMIC_BMI2 to gcc >= 4.8

attribute bmi2 not supported by gcc 4.4

diff --git a/lib/common/compiler.h b/lib/common/compiler.h
index 24f353280ec1250a12e1c3059f47c5adf66336fc..63d32258a36f58b60184109510cbc23e2b9b4cd6 100644 (file)
--- 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