diff --git a/js/src/ctypes/CTypes.cpp b/js/src/ctypes/CTypes.cpp

--- a/js/src/ctypes/CTypes.cpp

+++ b/js/src/ctypes/CTypes.cpp

@@ -1017,6 +1017,25 @@

};

#endif

+#ifdef SPARC

+// Simulate x86 overflow behavior

+template<>

+struct ConvertImpl<JSUint64, jsdouble> {

+ static JS_ALWAYS_INLINE JSUint64 Convert(jsdouble d) {

+ return d >= 0xffffffffffffffff ?

+ 0x8000000000000000 : JSUint64(d);

+ }

+};

+

+template<>

+struct ConvertImpl<JSInt64, jsdouble> {

+ static JS_ALWAYS_INLINE JSInt64 Convert(jsdouble d) {

+ return d >= 0x7fffffffffffffff ?

+ 0x8000000000000000 : JSInt64(d);

+ }

+};

+#endif

+

template<class TargetType, class FromType>

static JS_ALWAYS_INLINE TargetType Convert(FromType d)

{