A nice alternative than trying to do it throughout the JIT.
While the unused bits in the GQR SPR are probably not supposed to be set, some games set them anyways (e.g. Dirt 2), which broke the JIT code.
1<<31 is not 2^31 because 1 is a signed int in C; this bug affected both the JIT and interpreter quantized store implementations, though I don't know if any games were actually affected.
Fiora