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target-ppc: Fix SUBFE carry

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While ~T0+T1+CF = T1-T0+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.

Cc: Alexander Graf <agraf@suse.de>
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 11:41:40 -08:00 committed by Anthony Liguori
parent e77f083292
commit 08f4a0f7ee
1 changed files with 5 additions and 4 deletions
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9
target-ppc/translate.c
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@ -1120,14 +1120,15 @@ static inline void gen_op_arith_subf(DisasContext *ctx, TCGv ret, TCGv arg1,
}
if (add_ca) {
/* dest = ~arg1 + arg2 + ca = arg2 - arg1 + ca - 1. */
/* dest = ~arg1 + arg2 + ca. */
if (compute_ca) {
TCGv zero;
tcg_gen_subi_tl(cpu_ca, cpu_ca, 1);
TCGv zero, inv1 = tcg_temp_new();
tcg_gen_not_tl(inv1, arg1);
zero = tcg_const_tl(0);
tcg_gen_add2_tl(t0, cpu_ca, arg2, zero, cpu_ca, zero);
tcg_gen_sub2_tl(t0, cpu_ca, t0, cpu_ca, arg1, zero);
tcg_gen_add2_tl(t0, cpu_ca, t0, cpu_ca, inv1, zero);
tcg_temp_free(zero);
tcg_temp_free(inv1);
} else {
tcg_gen_sub_tl(t0, arg2, arg1);
tcg_gen_add_tl(t0, t0, cpu_ca);