tcg/i386: Special case addci r, 0, 0

Using addci with two zeros as input in order to capture the value
of the carry-in bit is common.  Special case this with sbb+neg so
that we do not have to load 0 into a register first.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2 files changed