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target-ppc: implement branch-less divw[o][.] 

While implementing modulo instructions figured out that the
implementation uses many branches. Change the logic to achieve the
branch-less code. Undefined value is set to dividend in case of invalid
input.

Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Nikunj A Dadhania 2016-07-28 23:44:11 +05:30 committed by David Gibson
parent 5817355ed0
commit b07c32dc4b
1 changed files with 23 additions and 25 deletions
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48
target-ppc/translate.c
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@ -1097,41 +1097,39 @@ static void gen_addpcis(DisasContext *ctx)
static inline void gen_op_arith_divw(DisasContext *ctx, TCGv ret, TCGv arg1,
TCGv arg2, int sign, int compute_ov)
{
TCGLabel *l1 = gen_new_label();
TCGLabel *l2 = gen_new_label();
TCGv_i32 t0 = tcg_temp_local_new_i32();
TCGv_i32 t1 = tcg_temp_local_new_i32();
TCGv_i32 t0 = tcg_temp_new_i32();
TCGv_i32 t1 = tcg_temp_new_i32();
TCGv_i32 t2 = tcg_temp_new_i32();
TCGv_i32 t3 = tcg_temp_new_i32();
tcg_gen_trunc_tl_i32(t0, arg1);
tcg_gen_trunc_tl_i32(t1, arg2);
tcg_gen_brcondi_i32(TCG_COND_EQ, t1, 0, l1);
if (sign) {
TCGLabel *l3 = gen_new_label();
tcg_gen_brcondi_i32(TCG_COND_NE, t1, -1, l3);
tcg_gen_brcondi_i32(TCG_COND_EQ, t0, INT32_MIN, l1);
gen_set_label(l3);
tcg_gen_div_i32(t0, t0, t1);
tcg_gen_setcondi_i32(TCG_COND_EQ, t2, t0, INT_MIN);
tcg_gen_setcondi_i32(TCG_COND_EQ, t3, t1, -1);
tcg_gen_and_i32(t2, t2, t3);
tcg_gen_setcondi_i32(TCG_COND_EQ, t3, t1, 0);
tcg_gen_or_i32(t2, t2, t3);
tcg_gen_movi_i32(t3, 0);
tcg_gen_movcond_i32(TCG_COND_NE, t1, t2, t3, t2, t1);
tcg_gen_div_i32(t3, t0, t1);
tcg_gen_extu_i32_tl(ret, t3);
} else {
tcg_gen_divu_i32(t0, t0, t1);
tcg_gen_setcondi_i32(TCG_COND_EQ, t2, t1, 0);
tcg_gen_movi_i32(t3, 0);
tcg_gen_movcond_i32(TCG_COND_NE, t1, t2, t3, t2, t1);
tcg_gen_divu_i32(t3, t0, t1);
tcg_gen_extu_i32_tl(ret, t3);
}
if (compute_ov) {
tcg_gen_movi_tl(cpu_ov, 0);
tcg_gen_extu_i32_tl(cpu_ov, t2);
tcg_gen_or_tl(cpu_so, cpu_so, cpu_ov);
}
tcg_gen_br(l2);
gen_set_label(l1);
if (sign) {
tcg_gen_sari_i32(t0, t0, 31);
} else {
tcg_gen_movi_i32(t0, 0);
}
if (compute_ov) {
tcg_gen_movi_tl(cpu_ov, 1);
tcg_gen_movi_tl(cpu_so, 1);
}
gen_set_label(l2);
tcg_gen_extu_i32_tl(ret, t0);
tcg_temp_free_i32(t0);
tcg_temp_free_i32(t1);
tcg_temp_free_i32(t2);
tcg_temp_free_i32(t3);
if (unlikely(Rc(ctx->opcode) != 0))
gen_set_Rc0(ctx, ret);
}