From: "Emilio G. Cota" <cota@braap.org>
To: qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Peter Crosthwaite <crosthwaite.peter@gmail.com>,
Richard Henderson <rth@twiddle.net>,
Peter Maydell <peter.maydell@linaro.org>,
Eduardo Habkost <ehabkost@redhat.com>,
Andrzej Zaborowski <balrogg@gmail.com>,
Aurelien Jarno <aurelien@aurel32.net>,
Alexander Graf <agraf@suse.de>, Stefan Weil <sw@weilnetz.de>,
qemu-arm@nongnu.org, alex.bennee@linaro.org,
Pranith Kumar <bobby.prani+qemu@gmail.com>
Subject: [Qemu-devel] [PATCH v2 12/13] target/i386: optimize indirect branches
Date: Tue, 25 Apr 2017 03:53:58 -0400 [thread overview]
Message-ID: <1493106839-10438-13-git-send-email-cota@braap.org> (raw)
In-Reply-To: <1493106839-10438-1-git-send-email-cota@braap.org>
The appended minimizes exits to the exec loop for indirect branches.
By using the gen_jr helper, we can remain in TCG mode as long as
the indirect branch target is found in tb_jmp_cache.
This should improve performance for workloads that have a high
hit rate in tb_jmp_cache.
Softmmu Measurements: (see user-mode measurements in later commit)
Note: baseline (i.e. speedup == 1x) is QEMU v2.9.0.
- SPECint06 (test set), x86_64-softmmu (Ubuntu 16.04 guest). Host: Intel i7-4790K @ 4.00GHz
2.2x +-+--------------------------------------------------------------------------------------------------------------+-+
| +++ |
| cross+inline | |
2x +cross+jr+inline................................................................+++.|............................+-+
| | | |
| | | |
| | | |
1.8x +-+..............................................................................|..|............................+-+
| |#### |
| |# |# |
1.6x +-+............................................................................****.|#...........................+-+
| * |* |# |
| * |* |# |
| * |* |# |
1.4x +-+.......................................................................+++..*.|*.|#...........................+-+
| +++ | * |*++# +++ |
| +++ | #### * |* # +++ | |
1.2x +-+......................###.............+++............|.+++.............#++#.*++*..#...........|..|............+-+
| +++# # +++ | | | ++# # * * # +++ ****## #### |
| ++#### **** # +++#### #### *** | **** # * * # ++#### *| *|# ****++# |
| ****++# ++#### * * # **** # ++#| # ++#### *|*### ****## * * # * * # *** |# *++*+# *++* # |
1x +-++-*++*++#++***+-#++*++*+#++*+-*++#+****++#++***++#+-*+*++#-+*++*+#++*++*-+#+*++*-+#++*+*++#++*-+*+#++*++*++#-++-+
| * * # * * # * * # * * # *++* # * * # *+* |# * * # * * # * * # * * # * * # * * # |
| * * # * * # * * # * * # * * # * * # * *++# * * # * * # * * # * * # * * # * * # |
0.8x +-+--****###--***###--****##--****###-****###--***###--***###--****##--****###-****###--***###--****##--****###--+-+
astar bzip2 gcc gobmk h264ref hmmlibquantum mcf omnetpperlbench sjengxalancbmk hmean
png: http://imgur.com/aSXm0qh
NB. 'cross' represents the previous commit.
Signed-off-by: Emilio G. Cota <cota@braap.org>
---
target/i386/translate.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/target/i386/translate.c b/target/i386/translate.c
index 9982a2d..0b4e1e1 100644
--- a/target/i386/translate.c
+++ b/target/i386/translate.c
@@ -4991,7 +4991,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
gen_push_v(s, cpu_T1);
gen_op_jmp_v(cpu_T0);
gen_bnd_jmp(s);
- gen_eob(s);
+ gen_jr(s, cpu_T0);
break;
case 3: /* lcall Ev */
gen_op_ld_v(s, ot, cpu_T1, cpu_A0);
@@ -5009,7 +5009,8 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
tcg_const_i32(dflag - 1),
tcg_const_i32(s->pc - s->cs_base));
}
- gen_eob(s);
+ tcg_gen_ld_tl(cpu_tmp4, cpu_env, offsetof(CPUX86State, eip));
+ gen_jr(s, cpu_tmp4);
break;
case 4: /* jmp Ev */
if (dflag == MO_16) {
@@ -5017,7 +5018,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
}
gen_op_jmp_v(cpu_T0);
gen_bnd_jmp(s);
- gen_eob(s);
+ gen_jr(s, cpu_T0);
break;
case 5: /* ljmp Ev */
gen_op_ld_v(s, ot, cpu_T1, cpu_A0);
@@ -5032,7 +5033,8 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
gen_op_movl_seg_T0_vm(R_CS);
gen_op_jmp_v(cpu_T1);
}
- gen_eob(s);
+ tcg_gen_ld_tl(cpu_tmp4, cpu_env, offsetof(CPUX86State, eip));
+ gen_jr(s, cpu_tmp4);
break;
case 6: /* push Ev */
gen_push_v(s, cpu_T0);
@@ -6412,7 +6414,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
/* Note that gen_pop_T0 uses a zero-extending load. */
gen_op_jmp_v(cpu_T0);
gen_bnd_jmp(s);
- gen_eob(s);
+ gen_jr(s, cpu_T0);
break;
case 0xc3: /* ret */
ot = gen_pop_T0(s);
@@ -6420,7 +6422,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
/* Note that gen_pop_T0 uses a zero-extending load. */
gen_op_jmp_v(cpu_T0);
gen_bnd_jmp(s);
- gen_eob(s);
+ gen_jr(s, cpu_T0);
break;
case 0xca: /* lret im */
val = cpu_ldsw_code(env, s->pc);
--
2.7.4
next prev parent reply other threads:[~2017-04-25 7:54 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 7:53 [Qemu-devel] [PATCH v2 00/13] TCG optimizations for 2.10 Emilio G. Cota
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 01/13] exec-all: add tb_from_jmp_cache Emilio G. Cota
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 02/13] exec-all: inline tb_from_jmp_cache Emilio G. Cota
2017-04-25 11:00 ` Richard Henderson
2017-04-25 11:15 ` Richard Henderson
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 03/13] tcg: enforce 64-byte alignment of TCGContext Emilio G. Cota
2017-04-25 11:01 ` Richard Henderson
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 04/13] tcg: keep TCGContext's read-mostly fields in a separate cache line Emilio G. Cota
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 05/13] tcg-runtime: add lookup_tb_ptr helper Emilio G. Cota
2017-04-25 11:02 ` Richard Henderson
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 06/13] tcg: add goto_ptr opcode Emilio G. Cota
2017-04-25 11:05 ` Richard Henderson
2017-04-25 12:09 ` Richard Henderson
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 07/13] tcg/i386: implement goto_ptr op Emilio G. Cota
2017-04-25 11:24 ` Richard Henderson
2017-04-25 11:32 ` Richard Henderson
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 08/13] target/arm: optimize cross-page block chaining in softmmu Emilio G. Cota
2017-04-25 11:11 ` Richard Henderson
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 09/13] target/arm: optimize indirect branches with TCG's goto_ptr Emilio G. Cota
2017-04-25 11:12 ` Richard Henderson
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 10/13] target/i386: introduce gen_jr() helper to jump to register Emilio G. Cota
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 11/13] target/i386: optimize cross-page direct jumps in softmmu Emilio G. Cota
2017-04-25 7:53 ` Emilio G. Cota [this message]
2017-04-25 7:53 ` [Qemu-devel] [PATCH v2 13/13] tb-hash: improve tb_jmp_cache hash function in user mode Emilio G. Cota
2017-04-25 11:19 ` Richard Henderson
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