Reproducible floating point arithmetic in LuaJIT 2

[Erik Lindroos <gliptic@...>]

Hello,

I'm trying to patch in reproducible (strictly IEEE 754) floating point arithmetic in LuaJIT 2. Only the interpreter is really affected as far as I can tell, since the JIT uses SSE2 exclusively.
To patch the interpreter, I need to store some constants to scale down and up x87 floating point regs before/after multiplication and division.
However, while patching lj_vm_foldarith, I noticed DynASM doesn't seem to relocate loads from globals correctly, e.g.:

|  ->x87_scaledown:
|  .byte 0,0,0,0,0,0,0,128,255,3

|  fld tword [->x87_scaledown]

This turns into a load from a bogus address, while calls to global labels are clearly relocated correctly.

How would I solve this without e.g. writing the constant to the stack and load it from there every time?

Sincerely,
Erik Lindroos