i386-options.c (ix86_option_override_internal): Default PARAM_AVOID_FMA_MAX_BITS to 256 for znver2.

	* config/i386/i386-options.c (ix86_option_override_internal): Default
	PARAM_AVOID_FMA_MAX_BITS to 256 for znver2.

From-SVN: r273730

gcc/config/i386/i386-options.c

@@ -2779,7 +2779,11 @@ ix86_option_override_internal (bool main_args_p,
     opts->x_flag_cf_protection
       = (cf_protection_level) (opts->x_flag_cf_protection | CF_SET);
 
-  if (ix86_tune_features [X86_TUNE_AVOID_128FMA_CHAINS])
+  if (ix86_tune_features [X86_TUNE_AVOID_256FMA_CHAINS])
+    maybe_set_param_value (PARAM_AVOID_FMA_MAX_BITS, 256,
+			   opts->x_param_values,
+			   opts_set->x_param_values);
+  else if (ix86_tune_features [X86_TUNE_AVOID_128FMA_CHAINS])
     maybe_set_param_value (PARAM_AVOID_FMA_MAX_BITS, 128,
 			   opts->x_param_values,
 			   opts_set->x_param_values);