From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53198) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YOYRJ-0000ZP-Om for qemu-devel@nongnu.org; Thu, 19 Feb 2015 16:15:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YOYRI-0007Lt-I1 for qemu-devel@nongnu.org; Thu, 19 Feb 2015 16:15:17 -0500 Received: from mail-qa0-x231.google.com ([2607:f8b0:400d:c00::231]:44550) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YOYRI-0007Lp-E0 for qemu-devel@nongnu.org; Thu, 19 Feb 2015 16:15:16 -0500 Received: by mail-qa0-f49.google.com with SMTP id w8so8453197qac.8 for ; Thu, 19 Feb 2015 13:15:16 -0800 (PST) Sender: Richard Henderson From: Richard Henderson Date: Thu, 19 Feb 2015 13:14:27 -0800 Message-Id: <1424380469-20138-10-git-send-email-rth@twiddle.net> In-Reply-To: <1424380469-20138-1-git-send-email-rth@twiddle.net> References: <1424380469-20138-1-git-send-email-rth@twiddle.net> Subject: [Qemu-devel] [PATCH 09/11] target-arm: Implement ccmp branchless List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: peter.maydell@linaro.org This can allow much of a ccmp to be elided when particular flags are subsequently dead. Signed-off-by: Richard Henderson --- target-arm/translate-a64.c | 62 ++++++++++++++++++++++++++++++---------------- 1 file changed, 41 insertions(+), 21 deletions(-) diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c index 7549267..8171a1f 100644 --- a/target-arm/translate-a64.c +++ b/target-arm/translate-a64.c @@ -3641,8 +3641,8 @@ static void disas_adc_sbc(DisasContext *s, uint32_t insn) static void disas_cc(DisasContext *s, uint32_t insn) { unsigned int sf, op, y, cond, rn, nzcv, is_imm; - TCGLabel *label_continue = NULL; - TCGv_i64 tcg_tmp, tcg_y, tcg_rn; + TCGv_i64 tcg_t0, tcg_t1, tcg_t2, tcg_y, tcg_rn; + DisasCompare c; if (!extract32(insn, 29, 1)) { unallocated_encoding(s); @@ -3660,19 +3660,13 @@ static void disas_cc(DisasContext *s, uint32_t insn) rn = extract32(insn, 5, 5); nzcv = extract32(insn, 0, 4); - if (cond < 0x0e) { /* not always */ - TCGLabel *label_match = gen_new_label(); - label_continue = gen_new_label(); - arm_gen_test_cc(cond, label_match); - /* nomatch: */ - tcg_tmp = tcg_temp_new_i64(); - tcg_gen_movi_i64(tcg_tmp, nzcv << 28); - gen_set_nzcv(tcg_tmp); - tcg_temp_free_i64(tcg_tmp); - tcg_gen_br(label_continue); - gen_set_label(label_match); - } - /* match, or condition is always */ + /* Set T0 = !COND. */ + tcg_t0 = tcg_temp_new_i64(); + arm_test_cc(&c, cond); + tcg_gen_setcondi_i64(tcg_invert_cond(c.cond), tcg_t0, c.value, 0); + arm_free_cc(&c); + + /* Load the arguments for the new comparison. */ if (is_imm) { tcg_y = new_tmp_a64(s); tcg_gen_movi_i64(tcg_y, y); @@ -3681,17 +3675,43 @@ static void disas_cc(DisasContext *s, uint32_t insn) } tcg_rn = cpu_reg(s, rn); - tcg_tmp = tcg_temp_new_i64(); + /* Set the flags for the new comparison. */ + tcg_t1 = tcg_temp_new_i64(); if (op) { - gen_sub_CC(sf, tcg_tmp, tcg_rn, tcg_y); + gen_sub_CC(sf, tcg_t1, tcg_rn, tcg_y); } else { - gen_add_CC(sf, tcg_tmp, tcg_rn, tcg_y); + gen_add_CC(sf, tcg_t1, tcg_rn, tcg_y); } - tcg_temp_free_i64(tcg_tmp); - if (cond < 0x0e) { /* continue */ - gen_set_label(label_continue); + /* If COND was false, force the flags to #nzcv. + Note that T1 = (COND ? 0 : -1), T2 = (COND ? -1 : 0). */ + tcg_t2 = tcg_temp_new_i64(); + tcg_gen_neg_i64(tcg_t1, tcg_t0); + tcg_gen_subi_i64(tcg_t2, tcg_t0, 1); + + if (nzcv & 8) { /* N */ + tcg_gen_or_i64(cpu_NF, cpu_NF, tcg_t1); + } else { + tcg_gen_and_i64(cpu_NF, cpu_NF, tcg_t2); + } + if (nzcv & 4) { /* Z */ + tcg_gen_and_i64(cpu_ZF, cpu_ZF, tcg_t2); + } else { + tcg_gen_or_i64(cpu_ZF, cpu_ZF, tcg_t0); + } + if (nzcv & 2) { /* C */ + tcg_gen_or_i64(cpu_CF, cpu_CF, tcg_t0); + } else { + tcg_gen_and_i64(cpu_CF, cpu_CF, tcg_t2); + } + if (nzcv & 1) { /* V */ + tcg_gen_or_i64(cpu_VF, cpu_VF, tcg_t1); + } else { + tcg_gen_and_i64(cpu_VF, cpu_VF, tcg_t2); } + tcg_temp_free_i64(tcg_t0); + tcg_temp_free_i64(tcg_t1); + tcg_temp_free_i64(tcg_t2); } /* C3.5.6 Conditional select -- 2.1.0