Bug 1523015 - Enable Ion on ARM64, but disable in-browser by pref. r=nbp

js/src/jit-test/lib/jitopts.js

@@ -9,13 +9,6 @@ function jitTogglesMatch(opts) {
     if (k.indexOf(".enable") > 0 && opts[k] != currentOpts[k])
       return false;
   }
-
-  // ARM64 does not yet have an Ion code generator, so return false if
-  // ion.enable is requested.
-  var conf = getBuildConfiguration();
-  if (conf['arm64'] && opts['ion.enable'])
-    return false;
-
   return true;
 }
 

js/src/jit/Ion.h

@@ -160,8 +160,7 @@ void LinkIonScript(JSContext* cx, HandleScript calleescript);
 uint8_t* LazyLinkTopActivation(JSContext* cx, LazyLinkExitFrameLayout* frame);
 
 static inline bool IsIonEnabled(JSContext* cx) {
-  // The ARM64 Ion engine is not yet implemented.
-#if defined(JS_CODEGEN_NONE) || defined(JS_CODEGEN_ARM64)
+#if defined(JS_CODEGEN_NONE)
   return false;
 #else
   return cx->options().ion() && cx->options().baseline() &&

modules/libpref/init/all.js

@@ -1469,7 +1469,11 @@ pref("javascript.options.strict.debug",     false);
 pref("javascript.options.baselinejit",      true);
 //Duplicated in JitOptions - ensure both match.
 pref("javascript.options.baselinejit.threshold", 10);
+#ifdef _ARM64_
+pref("javascript.options.ion",              false);
+#else
 pref("javascript.options.ion",              true);
+#endif
 //Duplicated in JitOptions - ensure both match.
 pref("javascript.options.ion.threshold",    1000);
 //Duplicated in JitOptions - ensure both match.