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mlugg
611c38e6da
The memory operand might use one of the extended GPRs R8 through R15 and hence require a REX prefix, but having a REX prefix makes the high-byte register AH unencodeable as the src operand. This latent bug was exposed by this branch, presumably because `select` now happens to be putting something in an extended GPR instead of a legacy GPR. In theory this could be fixed with minimal cost by introducing a way to communicate to `select` that neither the destination memory nor the other temporary can be in an extended GPR. However, I just went for the simple solution which comes at a cost of one trivial instruction: copy the remainder from AH to AL, and *then* copy AL to the destination.