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[PATCH 06/11] RISC-V: Adding T-Head multiply-accumulate instructions


From: Christoph Muellner
Subject: [PATCH 06/11] RISC-V: Adding T-Head multiply-accumulate instructions
Date: Tue, 6 Sep 2022 14:22:38 +0200

From: Christoph Müllner <christoph.muellner@vrull.eu>

This patch adds support for the T-Head MAC instructions.
The patch uses the T-Head specific decoder and translation.

Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
---
 target/riscv/cpu.c                         |  1 +
 target/riscv/cpu.h                         |  1 +
 target/riscv/insn_trans/trans_xthead.c.inc | 67 ++++++++++++++++++++++
 target/riscv/meson.build                   |  1 +
 target/riscv/translate.c                   |  3 +
 target/riscv/xtheadmac.decode              | 30 ++++++++++
 6 files changed, 103 insertions(+)
 create mode 100644 target/riscv/xtheadmac.decode

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index b7d6dbd28e..e2d74fa701 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -925,6 +925,7 @@ static Property riscv_cpu_extensions[] = {
     DEFINE_PROP_BOOL("xtheadbs", RISCVCPU, cfg.ext_xtheadbs, false),
     DEFINE_PROP_BOOL("xtheadcmo", RISCVCPU, cfg.ext_xtheadcmo, false),
     DEFINE_PROP_BOOL("xtheadcondmov", RISCVCPU, cfg.ext_xtheadcondmov, false),
+    DEFINE_PROP_BOOL("xtheadmac", RISCVCPU, cfg.ext_xtheadmac, false),
     DEFINE_PROP_BOOL("xtheadsync", RISCVCPU, cfg.ext_xtheadsync, false),
     DEFINE_PROP_BOOL("xventanacondops", RISCVCPU, cfg.ext_XVentanaCondOps, 
false),
 
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 0b58b38335..d0dc4ab031 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -445,6 +445,7 @@ struct RISCVCPUConfig {
     bool ext_xtheadbs;
     bool ext_xtheadcmo;
     bool ext_xtheadcondmov;
+    bool ext_xtheadmac;
     bool ext_xtheadsync;
     bool ext_XVentanaCondOps;
 
diff --git a/target/riscv/insn_trans/trans_xthead.c.inc 
b/target/riscv/insn_trans/trans_xthead.c.inc
index da3a538400..fc8307b113 100644
--- a/target/riscv/insn_trans/trans_xthead.c.inc
+++ b/target/riscv/insn_trans/trans_xthead.c.inc
@@ -217,3 +217,70 @@ static bool trans_th_mvnez(DisasContext *ctx, arg_th_mveqz 
*a)
 {
     return gen_th_condmove(ctx, a, TCG_COND_NE);
 }
+
+static bool gen_th_mac(DisasContext *ctx, arg_r *a,
+                       void (*accumulate_func)(TCGv, TCGv, TCGv),
+                       void (*extend_operand_func)(TCGv, TCGv))
+{
+    TCGv dest = dest_gpr(ctx, a->rd);
+    TCGv src0 = get_gpr(ctx, a->rd, EXT_NONE);
+    TCGv src1 = get_gpr(ctx, a->rs1, EXT_NONE);
+    TCGv src2 = get_gpr(ctx, a->rs2, EXT_NONE);
+    TCGv tmp = tcg_temp_new();
+
+    if (extend_operand_func) {
+        TCGv tmp2 = tcg_temp_new();
+        extend_operand_func(tmp, src1);
+        extend_operand_func(tmp2, src2);
+        tcg_gen_mul_tl(tmp, tmp, tmp2);
+        tcg_temp_free(tmp2);
+    } else {
+        tcg_gen_mul_tl(tmp, src1, src2);
+    }
+
+    accumulate_func(dest, src0, tmp);
+    gen_set_gpr(ctx, a->rd, dest);
+    tcg_temp_free(tmp);
+
+    return true;
+}
+
+/* th.mula: "rd = rd + rs1 * rs2" */
+static bool trans_th_mula(DisasContext *ctx, arg_th_mula *a)
+{
+    return gen_th_mac(ctx, a, tcg_gen_add_tl, NULL);
+}
+
+/* th.mulah: "rd = sext.w(rd + sext.w(rs1[15:0]) * sext.w(rs2[15:0]))" */
+static bool trans_th_mulah(DisasContext *ctx, arg_th_mulah *a)
+{
+    ctx->ol = MXL_RV32;
+    return gen_th_mac(ctx, a, tcg_gen_add_tl, tcg_gen_ext16s_tl);
+}
+
+/* th.mulaw: "rd = sext.w(rd + rs1 * rs2)" */
+static bool trans_th_mulaw(DisasContext *ctx, arg_th_mulaw *a)
+{
+    ctx->ol = MXL_RV32;
+    return gen_th_mac(ctx, a, tcg_gen_add_tl, NULL);
+}
+
+/* th.muls: "rd = rd - rs1 * rs2" */
+static bool trans_th_muls(DisasContext *ctx, arg_th_muls *a)
+{
+    return gen_th_mac(ctx, a, tcg_gen_sub_tl, NULL);
+}
+
+/* th.mulsh: "rd = sext.w(rd - sext.w(rs1[15:0]) * sext.w(rs2[15:0]))" */
+static bool trans_th_mulsh(DisasContext *ctx, arg_th_mulsh *a)
+{
+    ctx->ol = MXL_RV32;
+    return gen_th_mac(ctx, a, tcg_gen_sub_tl, tcg_gen_ext16s_tl);
+}
+
+/* th.mulsw: "rd = sext.w(rd - rs1 * rs2)" */
+static bool trans_th_mulsw(DisasContext *ctx, arg_th_mulsw *a)
+{
+    ctx->ol = MXL_RV32;
+    return gen_th_mac(ctx, a, tcg_gen_sub_tl, NULL);
+}
diff --git a/target/riscv/meson.build b/target/riscv/meson.build
index 496ae37f26..55c019e55b 100644
--- a/target/riscv/meson.build
+++ b/target/riscv/meson.build
@@ -7,6 +7,7 @@ gen = [
   decodetree.process('xtheadbs.decode', extra_args: 
'--static-decode=decode_xtheadbs'),
   decodetree.process('xtheadcmo.decode', extra_args: 
'--static-decode=decode_xtheadcmo'),
   decodetree.process('xtheadcondmov.decode', extra_args: 
'--static-decode=decode_xtheadcondmov'),
+  decodetree.process('xtheadmac.decode', extra_args: 
'--static-decode=decode_xtheadmac'),
   decodetree.process('xtheadsync.decode', extra_args: 
'--static-decode=decode_xtheadsync'),
   decodetree.process('XVentanaCondOps.decode', extra_args: 
'--static-decode=decode_XVentanaCodeOps'),
 ]
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 986243df99..56cc89ce4a 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -137,6 +137,7 @@ MATERIALISE_EXT_PREDICATE(xtheadbb)
 MATERIALISE_EXT_PREDICATE(xtheadbs)
 MATERIALISE_EXT_PREDICATE(xtheadcmo)
 MATERIALISE_EXT_PREDICATE(xtheadcondmov);
+MATERIALISE_EXT_PREDICATE(xtheadmac);
 MATERIALISE_EXT_PREDICATE(xtheadsync)
 MATERIALISE_EXT_PREDICATE(XVentanaCondOps)
 
@@ -729,6 +730,7 @@ static int ex_rvc_shifti(DisasContext *ctx, int imm)
 #include "decode-xtheadbs.c.inc"
 #include "decode-xtheadcmo.c.inc"
 #include "decode-xtheadcondmov.c.inc"
+#include "decode-xtheadmac.c.inc"
 #include "decode-xtheadsync.c.inc"
 #include "decode-XVentanaCondOps.c.inc"
 
@@ -1055,6 +1057,7 @@ static void decode_opc(CPURISCVState *env, DisasContext 
*ctx, uint16_t opcode)
         { has_xtheadbs_p, decode_xtheadbs },
         { has_xtheadcmo_p, decode_xtheadcmo },
         { has_xtheadcondmov_p, decode_xtheadcondmov },
+        { has_xtheadmac_p, decode_xtheadmac },
         { has_xtheadsync_p, decode_xtheadsync },
         { has_XVentanaCondOps_p,  decode_XVentanaCodeOps },
     };
diff --git a/target/riscv/xtheadmac.decode b/target/riscv/xtheadmac.decode
new file mode 100644
index 0000000000..dda1f82334
--- /dev/null
+++ b/target/riscv/xtheadmac.decode
@@ -0,0 +1,30 @@
+#
+# RISC-V instruction decode for the XTheadMac extension
+#
+# Copyright (c) 2022 Christoph Muellner, christoph.muellner@vrull.eu
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+# The XTheadMac extension provides multiply-accumulate instructions.
+#
+# It is documented in
+# 
https://github.com/T-head-Semi/thead-extension-spec/releases/download/2.0.0/xthead-2022-09-05-2.0.0.pdf
+
+# Fields
+%rs2       20:5
+%rs1       15:5
+%rd        7:5
+
+# Argument sets
+&r         rd rs1 rs2          !extern
+
+# Formats:
+@r          ..... .. ..... ..... ... ..... ....... &r %rs2 %rs1 %rd
+
+# T-Head conditional move instructions
+th_mula     00100 00 ..... ..... 001 ..... 0001011 @r
+th_mulah    00101 00 ..... ..... 001 ..... 0001011 @r
+th_mulaw    00100 10 ..... ..... 001 ..... 0001011 @r
+th_muls     00100 01 ..... ..... 001 ..... 0001011 @r
+th_mulsh    00101 01 ..... ..... 001 ..... 0001011 @r
+th_mulsw    00100 11 ..... ..... 001 ..... 0001011 @r
-- 
2.37.2




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