From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48577) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wgacy-0001Xo-Im for qemu-devel@nongnu.org; Sat, 03 May 2014 10:09:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wgacq-000731-Du for qemu-devel@nongnu.org; Sat, 03 May 2014 10:09:20 -0400 Received: from mail-pa0-x22e.google.com ([2607:f8b0:400e:c03::22e]:42994) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wgacq-00072q-2Q for qemu-devel@nongnu.org; Sat, 03 May 2014 10:09:12 -0400 Received: by mail-pa0-f46.google.com with SMTP id kx10so4161978pab.19 for ; Sat, 03 May 2014 07:09:11 -0700 (PDT) Received: from pike.twiddle.home (50-194-63-110-static.hfc.comcastbusiness.net. [50.194.63.110]) by mx.google.com with ESMTPSA id ry8sm19985030pac.29.2014.05.03.07.09.09 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 03 May 2014 07:09:10 -0700 (PDT) Sender: Richard Henderson From: Richard Henderson Date: Sat, 3 May 2014 07:08:54 -0700 Message-Id: <1399126135-14560-9-git-send-email-rth@twiddle.net> In-Reply-To: <1399126135-14560-1-git-send-email-rth@twiddle.net> References: <1399126135-14560-1-git-send-email-rth@twiddle.net> Subject: [Qemu-devel] [PATCH 8/9] tcg-s390: Improve setcond List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org There are a variety of common cases for which we can use carry tricks to avoid a conditional branch. On very new hardware, use LOAD ON CONDITION instead of a conditional branch. Signed-off-by: Richard Henderson --- tcg/s390/tcg-target.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 91 insertions(+), 6 deletions(-) diff --git a/tcg/s390/tcg-target.c b/tcg/s390/tcg-target.c index 54d6dc1..132f71a 100644 --- a/tcg/s390/tcg-target.c +++ b/tcg/s390/tcg-target.c @@ -1135,15 +1135,100 @@ static int tgen_cmp(TCGContext *s, TCGType type, TCGCond c, TCGReg r1, return tcg_cond_to_s390_cond[c]; } -static void tgen_setcond(TCGContext *s, TCGType type, TCGCond c, +static void tgen_setcond(TCGContext *s, TCGType type, TCGCond cond, TCGReg dest, TCGReg c1, TCGArg c2, int c2const) { - int cc = tgen_cmp(s, type, c, c1, c2, c2const); + int cc; + + switch (cond) { + case TCG_COND_GTU: + case TCG_COND_GT: + do_greater: + /* The result of a compare has CC=2 for GT and CC=3 unused. + ADD LOGICAL WITH CARRY considers (CC & 2) the carry bit. */ + tgen_cmp(s, type, cond, c1, c2, c2const); + tcg_out_movi(s, type, dest, 0); + tcg_out_insn(s, RRE, ALCGR, dest, dest); + return; + + case TCG_COND_GEU: + do_geu: + /* We need "real" carry semantics, so use SUBTRACT LOGICAL + instead of COMPARE LOGICAL. This needs an extra move. */ + tcg_out_mov(s, type, TCG_TMP0, c1); + if (c2const) { + tcg_out_movi(s, TCG_TYPE_I64, dest, 0); + if (type == TCG_TYPE_I32) { + tcg_out_insn(s, RIL, SLFI, TCG_TMP0, c2); + } else { + tcg_out_insn(s, RIL, SLGFI, TCG_TMP0, c2); + } + } else { + if (type == TCG_TYPE_I32) { + tcg_out_insn(s, RR, SLR, TCG_TMP0, c2); + } else { + tcg_out_insn(s, RRE, SLGR, TCG_TMP0, c2); + } + tcg_out_movi(s, TCG_TYPE_I64, dest, 0); + } + tcg_out_insn(s, RRE, ALCGR, dest, dest); + return; + + case TCG_COND_LEU: + case TCG_COND_LTU: + case TCG_COND_LT: + /* Swap operands so that we can use GEU/GTU/GT. */ + if (c2const) { + tcg_out_movi(s, type, TCG_TMP0, c2); + c2 = c1; + c2const = 0; + c1 = TCG_TMP0; + } else { + TCGReg t = c1; + c1 = c2; + c2 = t; + } + if (cond == TCG_COND_LEU) { + goto do_geu; + } + cond = tcg_swap_cond(cond); + goto do_greater; + + case TCG_COND_NE: + /* X != 0 is X > 0. */ + if (c2const && c2 == 0) { + cond = TCG_COND_GTU; + goto do_greater; + } + break; - /* Emit: r1 = 1; if (cc) goto over; r1 = 0; over: */ - tcg_out_movi(s, type, dest, 1); - tcg_out_insn(s, RI, BRC, cc, (4 + 4) >> 1); - tcg_out_movi(s, type, dest, 0); + case TCG_COND_EQ: + /* X == 0 is X <= 0 is 0 >= X. */ + if (c2const && c2 == 0) { + tcg_out_movi(s, TCG_TYPE_I64, TCG_TMP0, 0); + c2 = c1; + c2const = 0; + c1 = TCG_TMP0; + goto do_geu; + } + break; + + default: + break; + } + + cc = tgen_cmp(s, type, cond, c1, c2, c2const); + if (facilities & FACILITY_LOAD_ON_COND) { + /* Emit: d = 0, t = 1, d = (cc ? t : d). */ + tcg_out_movi(s, TCG_TYPE_I64, dest, 0); + tcg_out_movi(s, TCG_TYPE_I64, TCG_TMP0, 1); + tcg_out_insn(s, RRF, LOCGR, dest, TCG_TMP0, cc); + } else { + /* Emit: d = 1; if (cc) goto over; d = 0; over: */ + tcg_out_movi(s, type, dest, 1); + tcg_out_insn(s, RI, BRC, cc, (4 + 4) >> 1); + tcg_out_movi(s, type, dest, 0); + } } static void tgen_movcond(TCGContext *s, TCGType type, TCGCond c, TCGReg dest, -- 1.9.0