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target-arm: A64: add support for conditional select

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This patch adds support for the instruction group "C3.5.6
Conditional select": CSEL, CSINC, CSINV, CSNEG.

Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
[PMM: Improved code generated in the nomatch case as per RTH suggestions]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Claudio Fontana 2013-12-17 19:42:33 +00:00 committed by Peter Maydell
parent 60e5338831
commit e952d8c77a
1 changed files with 65 additions and 2 deletions
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67
target-arm/translate-a64.c
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@ -724,10 +724,73 @@ static void disas_cc_reg(DisasContext *s, uint32_t insn)
unsupported_encoding(s, insn);
}
/* Conditional select */
/* C3.5.6 Conditional select
* 31 30 29 28 21 20 16 15 12 11 10 9 5 4 0
* +----+----+---+-----------------+------+------+-----+------+------+
* | sf | op | S | 1 1 0 1 0 1 0 0 | Rm | cond | op2 | Rn | Rd |
* +----+----+---+-----------------+------+------+-----+------+------+
*/
static void disas_cond_select(DisasContext *s, uint32_t insn)
{
unsupported_encoding(s, insn);
unsigned int sf, else_inv, rm, cond, else_inc, rn, rd;
TCGv_i64 tcg_rd, tcg_src;
if (extract32(insn, 29, 1) || extract32(insn, 11, 1)) {
/* S == 1 or op2<1> == 1 */
unallocated_encoding(s);
return;
}
sf = extract32(insn, 31, 1);
else_inv = extract32(insn, 30, 1);
rm = extract32(insn, 16, 5);
cond = extract32(insn, 12, 4);
else_inc = extract32(insn, 10, 1);
rn = extract32(insn, 5, 5);
rd = extract32(insn, 0, 5);
if (rd == 31) {
/* silly no-op write; until we use movcond we must special-case
* this to avoid a dead temporary across basic blocks.
*/
return;
}
tcg_rd = cpu_reg(s, rd);
if (cond >= 0x0e) { /* condition "always" */
tcg_src = read_cpu_reg(s, rn, sf);
tcg_gen_mov_i64(tcg_rd, tcg_src);
} else {
/* OPTME: we could use movcond here, at the cost of duplicating
* a lot of the arm_gen_test_cc() logic.
*/
int label_match = gen_new_label();
int label_continue = gen_new_label();
arm_gen_test_cc(cond, label_match);
/* nomatch: */
tcg_src = cpu_reg(s, rm);
if (else_inv && else_inc) {
tcg_gen_neg_i64(tcg_rd, tcg_src);
} else if (else_inv) {
tcg_gen_not_i64(tcg_rd, tcg_src);
} else if (else_inc) {
tcg_gen_addi_i64(tcg_rd, tcg_src, 1);
} else {
tcg_gen_mov_i64(tcg_rd, tcg_src);
}
if (!sf) {
tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
}
tcg_gen_br(label_continue);
/* match: */
gen_set_label(label_match);
tcg_src = read_cpu_reg(s, rn, sf);
tcg_gen_mov_i64(tcg_rd, tcg_src);
/* continue: */
gen_set_label(label_continue);
}
}
/* Data-processing (1 source) */