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author | Paolo Bonzini <pbonzini@redhat.com> | 2012-10-06 00:18:55 +0200 |
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committer | Richard Henderson <rth@twiddle.net> | 2013-02-18 15:03:55 -0800 |
commit | 0ff6addd92979b9759efa1c0945526e6ac78ce5b (patch) | |
tree | 01324c611e3a3a99774dc193b813bc37934766c7 /target-i386/translate.c | |
parent | 52320e15dbb0c2531501a924972e63cdb59742a7 (diff) | |
download | hqemu-0ff6addd92979b9759efa1c0945526e6ac78ce5b.zip hqemu-0ff6addd92979b9759efa1c0945526e6ac78ce5b.tar.gz |
target-i386: move eflags computation closer to gen_op_set_cc_op
This ensures the invariant that cpu_cc_op matches s->cc_op when calling
the helpers. The next patches need this because gen_compute_eflags and
gen_compute_eflags_c will take care of setting cpu_cc_op.
Always compute EFLAGS first since it is needed whenever the shift is
non-zero, i.e. most of the time. This makes it possible to remove some
writes of CC_OP_EFLAGS to cpu_cc_op and more importantly removes cases
where s->cc_op becomes CC_OP_DYNAMIC. These are slow and we want to
avoid them: CC_OP_EFLAGS is quite efficient once we paid the initial
cost of computing the flags.
Finally, always follow gen_compute_eflags(cpu_cc_src) by setting s->cc_op
and discarding cpu_cc_dst.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'target-i386/translate.c')
-rw-r--r-- | target-i386/translate.c | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/target-i386/translate.c b/target-i386/translate.c index ed373c3..0970954 100644 --- a/target-i386/translate.c +++ b/target-i386/translate.c @@ -1597,14 +1597,16 @@ static void gen_rot_rm_T1(DisasContext *s, int ot, int op1, gen_op_mov_reg_v(ot, op1, t0); } - /* update eflags */ + /* update eflags. It is needed anyway most of the time, do it always. */ if (s->cc_op != CC_OP_DYNAMIC) gen_op_set_cc_op(s->cc_op); + gen_compute_eflags(cpu_cc_src); + tcg_gen_discard_tl(cpu_cc_dst); + s->cc_op = CC_OP_EFLAGS; label2 = gen_new_label(); tcg_gen_brcondi_tl(TCG_COND_EQ, t1, 0, label2); - gen_compute_eflags(cpu_cc_src); tcg_gen_andi_tl(cpu_cc_src, cpu_cc_src, ~(CC_O | CC_C)); tcg_gen_xor_tl(cpu_tmp0, t2, t0); tcg_gen_lshift(cpu_tmp0, cpu_tmp0, 11 - (data_bits - 1)); @@ -1615,12 +1617,8 @@ static void gen_rot_rm_T1(DisasContext *s, int ot, int op1, } tcg_gen_andi_tl(t0, t0, CC_C); tcg_gen_or_tl(cpu_cc_src, cpu_cc_src, t0); - - tcg_gen_discard_tl(cpu_cc_dst); - tcg_gen_movi_i32(cpu_cc_op, CC_OP_EFLAGS); - + gen_set_label(label2); - s->cc_op = CC_OP_DYNAMIC; /* cannot predict flags after */ tcg_temp_free(t0); tcg_temp_free(t1); @@ -1684,6 +1682,9 @@ static void gen_rot_rm_im(DisasContext *s, int ot, int op1, int op2, gen_op_set_cc_op(s->cc_op); gen_compute_eflags(cpu_cc_src); + tcg_gen_discard_tl(cpu_cc_dst); + s->cc_op = CC_OP_EFLAGS; + tcg_gen_andi_tl(cpu_cc_src, cpu_cc_src, ~(CC_O | CC_C)); tcg_gen_xor_tl(cpu_tmp0, t1, t0); tcg_gen_lshift(cpu_tmp0, cpu_tmp0, 11 - (data_bits - 1)); @@ -1694,10 +1695,6 @@ static void gen_rot_rm_im(DisasContext *s, int ot, int op1, int op2, } tcg_gen_andi_tl(t0, t0, CC_C); tcg_gen_or_tl(cpu_cc_src, cpu_cc_src, t0); - - tcg_gen_discard_tl(cpu_cc_dst); - tcg_gen_movi_i32(cpu_cc_op, CC_OP_EFLAGS); - s->cc_op = CC_OP_EFLAGS; } tcg_temp_free(t0); |