The existing flag, x86_64_hregs, does not accurately describe
its setting. It is true if and only if a REX prefix has been
seen. Yes, that affects the "h" regs, but that's secondary.
Add PREFIX_REX and include this bit in s->prefix. Add REX_PREFIX
so that the check folds away when x86_64 is compiled out.
Fold away the reg >= 8 check, because bit 3 of the register
number comes from the REX prefix in the first place.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210514151342.384376-16-richard.henderson@linaro.org>
1e92b7275c