Le 09/11/2016 à 14:46, Richard Henderson a écrit :
> diff --git a/target-m68k/translate.c b/target-m68k/translate.c
> index 4f224d7..1b3765f 100644
> --- a/target-m68k/translate.c
> +++ b/target-m68k/translate.c
> +static inline void shift_reg(DisasContext *s, uint16_t insn, int opsize)
> +{
> + int logical = insn & 8;
> + int left = insn & 0x100;
> + int bits = opsize_bytes(opsize) * 8;
> + TCGv reg = gen_extend(DREG(insn, 0), opsize, !logical);
> + TCGv s32;
> + TCGv_i64 t64, s64;
> +
> + t64 = tcg_temp_new_i64();
> + s64 = tcg_temp_new_i64();
> + s32 = tcg_temp_new();
> +
> + /* Note that m68k truncates the shift count modulo 64, not 32.
> + In addition, a 64-bit shift makes it easy to find "the last
> + bit shifted out", for the carry flag. */
> + tcg_gen_andi_i32(s32, DREG(insn, 9), 63);
> + tcg_gen_extu_i32_i64(s64, s32);
> + tcg_gen_extu_i32_i64(t64, reg);
> +
> + /* Optimistically set V=0. Also used as a zero source below. */
> + tcg_gen_movi_i32(QREG_CC_V, 0);
> + if (left) {
> + tcg_gen_shl_i64(t64, t64, s64);
> +
> + tcg_gen_extr_i64_i32(QREG_CC_N, QREG_CC_C, t64);
This does not extract correctly the C flag when the opsize is word or byte.
I think we should use a shift instead:
- tcg_gen_extr_i64_i32(QREG_CC_N, QREG_CC_C, t64);
-
- /* Note that C=0 if shift count is 0, and we get that for free. */
+ if (opsize == OS_LONG) {
+ tcg_gen_extr_i64_i32(QREG_CC_N, QREG_CC_C, t64);
+ /* Note that C=0 if shift count is 0, and we get that for
free. */
+ } else {
+ TCGv zero = tcg_const_i32(0);
+ tcg_gen_extrl_i64_i32(QREG_CC_N, t64);
+ tcg_gen_shri_i64(t64, t64, bits);
+ tcg_gen_extrl_i64_i32(QREG_CC_C, t64);
+ tcg_gen_movcond_i32(TCG_COND_EQ, QREG_CC_C,
+ s32, zero, zero, QREG_CC_C);
+ tcg_temp_free(zero);
+ }
Do you have a better idea?
thanks,
Laurent
