From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: david@redhat.com
Subject: [PATCH v3 4/4] target/s390x: Improve SUB LOGICAL WITH BORROW
Date: Mon, 14 Dec 2020 16:13:56 -0600 [thread overview]
Message-ID: <20201214221356.68039-5-richard.henderson@linaro.org> (raw)
In-Reply-To: <20201214221356.68039-1-richard.henderson@linaro.org>
Now that SUB LOGICAL outputs borrow, we can use that as input directly.
It also means we can re-use CC_OP_SUBU and produce an output borrow
directly from SUB LOGICAL WITH BORROW.
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
target/s390x/internal.h | 2 -
target/s390x/cc_helper.c | 32 ----------------
target/s390x/helper.c | 2 -
target/s390x/translate.c | 76 +++++++++++++++++++++-----------------
target/s390x/insn-data.def | 8 ++--
5 files changed, 46 insertions(+), 74 deletions(-)
diff --git a/target/s390x/internal.h b/target/s390x/internal.h
index 4077047494..11515bb617 100644
--- a/target/s390x/internal.h
+++ b/target/s390x/internal.h
@@ -172,14 +172,12 @@ enum cc_op {
CC_OP_ADD_64, /* overflow on add (64bit) */
CC_OP_SUB_64, /* overflow on subtraction (64bit) */
- CC_OP_SUBB_64, /* overflow on unsigned sub-borrow (64bit) */
CC_OP_ABS_64, /* sign eval on abs (64bit) */
CC_OP_NABS_64, /* sign eval on nabs (64bit) */
CC_OP_MULS_64, /* overflow on signed multiply (64bit) */
CC_OP_ADD_32, /* overflow on add (32bit) */
CC_OP_SUB_32, /* overflow on subtraction (32bit) */
- CC_OP_SUBB_32, /* overflow on unsigned sub-borrow (32bit) */
CC_OP_ABS_32, /* sign eval on abs (64bit) */
CC_OP_NABS_32, /* sign eval on nabs (64bit) */
CC_OP_MULS_32, /* overflow on signed multiply (32bit) */
diff --git a/target/s390x/cc_helper.c b/target/s390x/cc_helper.c
index c7728d1225..e7039d0d18 100644
--- a/target/s390x/cc_helper.c
+++ b/target/s390x/cc_helper.c
@@ -164,19 +164,6 @@ static uint32_t cc_calc_sub_64(int64_t a1, int64_t a2, int64_t ar)
}
}
-static uint32_t cc_calc_subb_64(uint64_t a1, uint64_t a2, uint64_t ar)
-{
- int borrow_out;
-
- if (ar != a1 - a2) { /* difference means borrow-in */
- borrow_out = (a2 >= a1);
- } else {
- borrow_out = (a2 > a1);
- }
-
- return (ar != 0) + 2 * !borrow_out;
-}
-
static uint32_t cc_calc_abs_64(int64_t dst)
{
if ((uint64_t)dst == 0x8000000000000000ULL) {
@@ -237,19 +224,6 @@ static uint32_t cc_calc_sub_32(int32_t a1, int32_t a2, int32_t ar)
}
}
-static uint32_t cc_calc_subb_32(uint32_t a1, uint32_t a2, uint32_t ar)
-{
- int borrow_out;
-
- if (ar != a1 - a2) { /* difference means borrow-in */
- borrow_out = (a2 >= a1);
- } else {
- borrow_out = (a2 > a1);
- }
-
- return (ar != 0) + 2 * !borrow_out;
-}
-
static uint32_t cc_calc_abs_32(int32_t dst)
{
if ((uint32_t)dst == 0x80000000UL) {
@@ -450,9 +424,6 @@ static uint32_t do_calc_cc(CPUS390XState *env, uint32_t cc_op,
case CC_OP_SUB_64:
r = cc_calc_sub_64(src, dst, vr);
break;
- case CC_OP_SUBB_64:
- r = cc_calc_subb_64(src, dst, vr);
- break;
case CC_OP_ABS_64:
r = cc_calc_abs_64(dst);
break;
@@ -472,9 +443,6 @@ static uint32_t do_calc_cc(CPUS390XState *env, uint32_t cc_op,
case CC_OP_SUB_32:
r = cc_calc_sub_32(src, dst, vr);
break;
- case CC_OP_SUBB_32:
- r = cc_calc_subb_32(src, dst, vr);
- break;
case CC_OP_ABS_32:
r = cc_calc_abs_32(dst);
break;
diff --git a/target/s390x/helper.c b/target/s390x/helper.c
index fa3aa500e5..7678994feb 100644
--- a/target/s390x/helper.c
+++ b/target/s390x/helper.c
@@ -405,12 +405,10 @@ const char *cc_name(enum cc_op cc_op)
[CC_OP_LTGT0_64] = "CC_OP_LTGT0_64",
[CC_OP_ADD_64] = "CC_OP_ADD_64",
[CC_OP_SUB_64] = "CC_OP_SUB_64",
- [CC_OP_SUBB_64] = "CC_OP_SUBB_64",
[CC_OP_ABS_64] = "CC_OP_ABS_64",
[CC_OP_NABS_64] = "CC_OP_NABS_64",
[CC_OP_ADD_32] = "CC_OP_ADD_32",
[CC_OP_SUB_32] = "CC_OP_SUB_32",
- [CC_OP_SUBB_32] = "CC_OP_SUBB_32",
[CC_OP_ABS_32] = "CC_OP_ABS_32",
[CC_OP_NABS_32] = "CC_OP_NABS_32",
[CC_OP_COMP_32] = "CC_OP_COMP_32",
diff --git a/target/s390x/translate.c b/target/s390x/translate.c
index 40add1df1f..3d5c0d6106 100644
--- a/target/s390x/translate.c
+++ b/target/s390x/translate.c
@@ -601,10 +601,8 @@ static void gen_op_calc_cc(DisasContext *s)
/* FALLTHRU */
case CC_OP_ADD_64:
case CC_OP_SUB_64:
- case CC_OP_SUBB_64:
case CC_OP_ADD_32:
case CC_OP_SUB_32:
- case CC_OP_SUBB_32:
local_cc_op = tcg_const_i32(s->cc_op);
break;
case CC_OP_CONST0:
@@ -663,10 +661,8 @@ static void gen_op_calc_cc(DisasContext *s)
break;
case CC_OP_ADD_64:
case CC_OP_SUB_64:
- case CC_OP_SUBB_64:
case CC_OP_ADD_32:
case CC_OP_SUB_32:
- case CC_OP_SUBB_32:
/* 3 arguments */
gen_helper_calc_cc(cc_op, cpu_env, local_cc_op, cc_src, cc_dst, cc_vr);
break;
@@ -4746,29 +4742,51 @@ static DisasJumpType op_subu64(DisasContext *s, DisasOps *o)
return DISAS_NEXT;
}
-static DisasJumpType op_subb(DisasContext *s, DisasOps *o)
+/* Compute borrow (0, -1) into cc_src. */
+static void compute_borrow(DisasContext *s)
{
- DisasCompare cmp;
- TCGv_i64 borrow;
-
- tcg_gen_sub_i64(o->out, o->in1, o->in2);
-
- /* The !borrow flag is the msb of CC. Since we want the inverse of
- that, we ask for a comparison of CC=0 | CC=1 -> mask of 8 | 4. */
- disas_jcc(s, &cmp, 8 | 4);
- borrow = tcg_temp_new_i64();
- if (cmp.is_64) {
- tcg_gen_setcond_i64(cmp.cond, borrow, cmp.u.s64.a, cmp.u.s64.b);
- } else {
- TCGv_i32 t = tcg_temp_new_i32();
- tcg_gen_setcond_i32(cmp.cond, t, cmp.u.s32.a, cmp.u.s32.b);
- tcg_gen_extu_i32_i64(borrow, t);
- tcg_temp_free_i32(t);
+ switch (s->cc_op) {
+ case CC_OP_SUBU:
+ /* The borrow value is already in cc_src (0,-1). */
+ break;
+ default:
+ gen_op_calc_cc(s);
+ /* fall through */
+ case CC_OP_STATIC:
+ /* The carry flag is the msb of CC; compute into cc_src. */
+ tcg_gen_extu_i32_i64(cc_src, cc_op);
+ tcg_gen_shri_i64(cc_src, cc_src, 1);
+ /* fall through */
+ case CC_OP_ADDU:
+ /* Convert carry (1,0) to borrow (0,-1). */
+ tcg_gen_subi_i64(cc_src, cc_src, 1);
+ break;
}
- free_compare(&cmp);
+}
+
+static DisasJumpType op_subb32(DisasContext *s, DisasOps *o)
+{
+ compute_borrow(s);
+
+ /* Borrow is {0, -1}, so add to subtract. */
+ tcg_gen_add_i64(o->out, o->in1, cc_src);
+ tcg_gen_sub_i64(o->out, o->out, o->in2);
+ return DISAS_NEXT;
+}
+
+static DisasJumpType op_subb64(DisasContext *s, DisasOps *o)
+{
+ compute_borrow(s);
+
+ /*
+ * Borrow is {0, -1}, so add to subtract; replicate the
+ * borrow input to produce 128-bit -1 for the addition.
+ */
+ TCGv_i64 zero = tcg_const_i64(0);
+ tcg_gen_add2_i64(o->out, cc_src, o->in1, zero, cc_src, cc_src);
+ tcg_gen_sub2_i64(o->out, cc_src, o->out, cc_src, o->in2, zero);
+ tcg_temp_free_i64(zero);
- tcg_gen_sub_i64(o->out, o->out, borrow);
- tcg_temp_free_i64(borrow);
return DISAS_NEXT;
}
@@ -5307,16 +5325,6 @@ static void cout_subu64(DisasContext *s, DisasOps *o)
gen_op_update2_cc_i64(s, CC_OP_SUBU, cc_src, o->out);
}
-static void cout_subb32(DisasContext *s, DisasOps *o)
-{
- gen_op_update3_cc_i64(s, CC_OP_SUBB_32, o->in1, o->in2, o->out);
-}
-
-static void cout_subb64(DisasContext *s, DisasOps *o)
-{
- gen_op_update3_cc_i64(s, CC_OP_SUBB_64, o->in1, o->in2, o->out);
-}
-
static void cout_tm32(DisasContext *s, DisasOps *o)
{
gen_op_update2_cc_i64(s, CC_OP_TM_32, o->in1, o->in2);
diff --git a/target/s390x/insn-data.def b/target/s390x/insn-data.def
index 7ff3e7e517..26badb663a 100644
--- a/target/s390x/insn-data.def
+++ b/target/s390x/insn-data.def
@@ -916,10 +916,10 @@
C(0xc205, SLFI, RIL_a, EI, r1_32u, i2_32u, new, r1_32, sub, subu32)
C(0xc204, SLGFI, RIL_a, EI, r1, i2_32u, r1, 0, subu64, subu64)
/* SUBTRACT LOGICAL WITH BORROW */
- C(0xb999, SLBR, RRE, Z, r1, r2, new, r1_32, subb, subb32)
- C(0xb989, SLBGR, RRE, Z, r1, r2, r1, 0, subb, subb64)
- C(0xe399, SLB, RXY_a, Z, r1, m2_32u, new, r1_32, subb, subb32)
- C(0xe389, SLBG, RXY_a, Z, r1, m2_64, r1, 0, subb, subb64)
+ C(0xb999, SLBR, RRE, Z, r1_32u, r2_32u, new, r1_32, subb32, subu32)
+ C(0xb989, SLBGR, RRE, Z, r1, r2, r1, 0, subb64, subu64)
+ C(0xe399, SLB, RXY_a, Z, r1_32u, m2_32u, new, r1_32, subb32, subu32)
+ C(0xe389, SLBG, RXY_a, Z, r1, m2_64, r1, 0, subb64, subu64)
/* SUPERVISOR CALL */
C(0x0a00, SVC, I, Z, 0, 0, 0, 0, svc, 0)
--
2.25.1
next prev parent reply other threads:[~2020-12-14 22:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-14 22:13 [PATCH v3 0/4] target/s390x: Improve carry computation Richard Henderson
2020-12-14 22:13 ` [PATCH v3 1/4] target/s390x: Improve cc computation for ADD LOGICAL Richard Henderson
2020-12-14 22:13 ` [PATCH v3 2/4] target/s390x: Improve ADD LOGICAL WITH CARRY Richard Henderson
2020-12-14 22:13 ` [PATCH v3 3/4] target/s390x: Improve cc computation for SUBTRACT LOGICAL Richard Henderson
2020-12-14 22:13 ` Richard Henderson [this message]
2020-12-16 14:44 ` [PATCH v3 0/4] target/s390x: Improve carry computation David Hildenbrand
2020-12-16 17:09 ` Cornelia Huck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201214221356.68039-5-richard.henderson@linaro.org \
--to=richard.henderson@linaro.org \
--cc=david@redhat.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.