Disable spilling into MMX registers

hphp/runtime/base/runtime_option.h

@@ -424,7 +424,7 @@ public:
   F(bool, HHIREnableCalleeSavedOpt,    true) \
   F(bool, HHIREnablePreColoring,       true) \
   F(bool, HHIREnableCoalescing,        true) \
-  F(bool, HHIREnableMmx,               true) \
+  F(bool, HHIREnableMmx,               false) \
   F(bool, HHIREnableRefCountOpt,       true) \
   F(bool, HHIREnableSinking,           true) \
   F(bool, HHIRGenerateAsserts,         debug) \

hphp/runtime/vm/translator/hopt/vectortranslator.cpp

@@ -397,7 +397,7 @@ SSATmp* HhbcTranslator::VectorTranslator::getInput(unsigned i) {
       // as what Transl::Translator came up with.
       auto t = Type::fromRuntimeType(dl.rtt);
       if (!val->isA(t)) {
-        FTRACE(0, "{}: hhir stack has a {} where Translator had a {}\n",
+        FTRACE(1, "{}: hhir stack has a {} where Translator had a {}\n",
                __func__, val->getType().toString(), t.toString());
         // They'd better not be completely unrelated types...
         assert(t.subtypeOf(val->getType()));