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target-arm: Fix sbc_CC carry 

While T0+~T1+CF = T0-T1+CF-1 is true for the low 32-bits,
it does not produce the correct carry-out to bit 33.  Do
exactly what the manual says.

Using the ~T1 makes the add and subtract code paths nearly
identical, so have sbc_CC use adc_CC.

Cc: Peter Maydell <peter.maydell@linaro.org>
Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Richard Henderson 2013-02-25 11:41:39 -08:00 committed by Anthony Liguori
parent 8c3ac601bd
commit e77f083292
1 changed files with 4 additions and 24 deletions
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28
target-arm/translate.c
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@ -464,33 +464,13 @@ static void gen_sub_CC(TCGv dest, TCGv t0, TCGv t1)
tcg_gen_mov_i32(dest, cpu_NF);
}
/* dest = T0 + ~T1 + CF = T0 - T1 + CF - 1. Compute C, N, V and Z flags */
/* dest = T0 + ~T1 + CF. Compute C, N, V and Z flags */
static void gen_sbc_CC(TCGv dest, TCGv t0, TCGv t1)
{
TCGv tmp = tcg_temp_new_i32();
tcg_gen_subi_i32(cpu_CF, cpu_CF, 1);
if (TCG_TARGET_HAS_add2_i32) {
tcg_gen_movi_i32(tmp, 0);
tcg_gen_add2_i32(cpu_NF, cpu_CF, t0, tmp, cpu_CF, tmp);
tcg_gen_sub2_i32(cpu_NF, cpu_CF, cpu_NF, cpu_CF, t1, tmp);
} else {
TCGv_i64 q0 = tcg_temp_new_i64();
TCGv_i64 q1 = tcg_temp_new_i64();
tcg_gen_extu_i32_i64(q0, t0);
tcg_gen_extu_i32_i64(q1, t1);
tcg_gen_sub_i64(q0, q0, q1);
tcg_gen_extu_i32_i64(q1, cpu_CF);
tcg_gen_add_i64(q0, q0, q1);
tcg_gen_extr_i64_i32(cpu_NF, cpu_CF, q0);
tcg_temp_free_i64(q0);
tcg_temp_free_i64(q1);
}
tcg_gen_mov_i32(cpu_ZF, cpu_NF);
tcg_gen_xor_i32(cpu_VF, cpu_NF, t0);
tcg_gen_xor_i32(tmp, t0, t1);
tcg_gen_and_i32(cpu_VF, cpu_VF, tmp);
tcg_temp_free_i32(tmp);
tcg_gen_mov_i32(dest, cpu_NF);
tcg_gen_not_i32(tmp, t1);
gen_adc_CC(dest, t0, tmp);
tcg_temp_free(tmp);
}
#define GEN_SHIFT(name) \