Hi Eliot,if i look at spur64src/vm/cointerp.c generated from VMMaker.oscog-eem.2277i see something wrong in primitiveAdd:static voidprimitiveAdd(void){ DECL_MAYBE_SQ_GLOBAL_STRUCT sqInt integerResult; char *sp; /* begin pop2AndPushIntegerIfOK: */======================================See below: we test if primitive failed before we tried...====================================== if (!GIV(primFailCode)) { integerResult = (stackIntegerValue(1)) + (stackIntegerValue(0)); if ((((((usqInt) integerResult) >> 60) + 1) & 15) <= 1) { /* begin pop:thenPush: */ longAtput((sp = GIV(stackPointer) + ((2 - 1) * BytesPerWord)), (((usqInt)integerResult << 3) | 1)); GIV(stackPointer) = sp; } else { /* begin success: */ /* Don't overwrite an error code that has already been set. */ if (!GIV(primFailCode)) { GIV(primFailCode) = 1; } } }}Note that I could comment the commit in github API.Unfortunately, diff are too big, and comments uneasy to find/view/scan.