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authorRichard Henderson <rth@twiddle.net>2013-02-25 11:41:39 -0800
committerAnthony Liguori <aliguori@us.ibm.com>2013-02-25 14:32:36 -0600
commite77f083292916ba43b940fdacd2fc1001b750d1d (patch)
treeac7fd7f25acb15e0f1d182130d8df59ff417dfd9
parent8c3ac601bdaf8d4d81823a79f2a166b586db7dab (diff)
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>
-rw-r--r--target-arm/translate.c28
1 files changed, 4 insertions, 24 deletions
diff --git a/target-arm/translate.c b/target-arm/translate.c
index 6d91b70aff..f2f649dffd 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -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) \