tcg/i386: convert add/sub of 128 to sub/add of -128

Extend the existing conditional that generates INC/DEC, to also swap an
ADD for a SUB and vice versa when the immediate is 128.  This facilitates
using OPC_ARITH_EvIb instead of OPC_ARITH_EvIz.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20231228120514.70205-1-pbonzini@redhat.com>
[rth: Use a switch on C]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
1 file changed