[PATCH 10/11] RISC-V: Adding T-Head FMemIdx extension

[Christoph Muellner]

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

This patch adds support for the T-Head FMemIdx 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 | 121 +++++++++++++++++++++
 target/riscv/meson.build                   |   1 +
 target/riscv/translate.c                   |   3 +
 target/riscv/xtheadfmemidx.decode          |  34 ++++++
 6 files changed, 161 insertions(+)
 create mode 100644 target/riscv/xtheadfmemidx.decode

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 0af9cc7bec..01d85f0f96 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("xtheadfmemidx", RISCVCPU, cfg.ext_xtheadfmemidx, false),
     DEFINE_PROP_BOOL("xtheadmac", RISCVCPU, cfg.ext_xtheadmac, false),
     DEFINE_PROP_BOOL("xtheadmemidx", RISCVCPU, cfg.ext_xtheadmemidx, false),
     DEFINE_PROP_BOOL("xtheadmempair", RISCVCPU, cfg.ext_xtheadmempair, false),
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 590a597f39..8b02f530a6 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_xtheadfmemidx;
     bool ext_xtheadmac;
     bool ext_xtheadmemidx;
     bool ext_xtheadmempair;
diff --git a/target/riscv/insn_trans/trans_xthead.c.inc 
b/target/riscv/insn_trans/trans_xthead.c.inc
index 95c6b10d77..1a91371318 100644
--- a/target/riscv/insn_trans/trans_xthead.c.inc
+++ b/target/riscv/insn_trans/trans_xthead.c.inc
@@ -751,3 +751,124 @@ static bool trans_th_surb(DisasContext *ctx, 
arg_th_memidx *a)
     return gen_store_idx(ctx, a, MO_SB, true);
 }
 
+/*
+ * Load 64-bit float from indexed address.
+ * If !zero_extend_offset, then address is rs1 + (rs2 << imm2).
+ * If  zero_extend_offset, then address is rs1 + (zext(rs2[31:0]) << imm2).
+ */
+static bool gen_fload_idx(DisasContext *ctx, arg_th_fmemidx *a, MemOp memop,
+                          bool zero_extend_offset)
+{
+    TCGv_i64 rd = cpu_fpr[a->rd];
+    TCGv base = get_gpr(ctx, a->rs1, EXT_NONE);
+    TCGv offs = get_gpr(ctx, a->rs2, EXT_NONE);
+    TCGv addr = tcg_temp_new();
+
+    if (zero_extend_offset) {
+        tcg_gen_extract_tl(addr, offs, 0, 32);
+    } else {
+        tcg_gen_mov_tl(addr, offs);
+    }
+    tcg_gen_shli_tl(addr, addr, a->imm2);
+    tcg_gen_add_tl(addr, base, addr);
+
+    if (get_xl(ctx) == MXL_RV32) {
+        tcg_gen_ext32u_tl(addr, addr);
+    }
+
+    tcg_gen_qemu_ld_i64(rd, addr, ctx->mem_idx, memop);
+    if ((memop & MO_SIZE) == MO_32) {
+        gen_nanbox_s(rd, rd);
+    }
+
+    mark_fs_dirty(ctx);
+    tcg_temp_free(addr);
+    return true;
+}
+
+/*
+ * Store 64-bit float to indexed address.
+ * If !zero_extend_offset, then address is rs1 + (rs2 << imm2).
+ * If  zero_extend_offset, then address is rs1 + (zext(rs2[31:0]) << imm2).
+ */
+static bool gen_fstore_idx(DisasContext *ctx, arg_th_fmemidx *a, MemOp memop,
+                           bool zero_extend_offset)
+{
+    TCGv_i64 rd = cpu_fpr[a->rd];
+    TCGv base = get_gpr(ctx, a->rs1, EXT_NONE);
+    TCGv offs = get_gpr(ctx, a->rs2, EXT_NONE);
+    TCGv addr = tcg_temp_new();
+
+    if (zero_extend_offset) {
+        tcg_gen_extract_tl(addr, offs, 0, 32);
+    } else {
+        tcg_gen_mov_tl(addr, offs);
+    }
+    tcg_gen_shli_tl(addr, addr, a->imm2);
+    tcg_gen_add_tl(addr, base, addr);
+
+    if (get_xl(ctx) == MXL_RV32) {
+        tcg_gen_ext32u_tl(addr, addr);
+    }
+
+    tcg_gen_qemu_st_i64(rd, addr, ctx->mem_idx, memop);
+
+    tcg_temp_free(addr);
+    return true;
+}
+
+static bool trans_th_flrd(DisasContext *ctx, arg_th_fmemidx *a)
+{
+    REQUIRE_FPU;
+    REQUIRE_EXT(ctx, RVD);
+    return gen_fload_idx(ctx, a, MO_TEUQ, false);
+}
+
+static bool trans_th_flrw(DisasContext *ctx, arg_th_fmemidx *a)
+{
+    REQUIRE_FPU;
+    REQUIRE_EXT(ctx, RVF);
+    return gen_fload_idx(ctx, a, MO_TEUL, false);
+}
+
+static bool trans_th_flurd(DisasContext *ctx, arg_th_fmemidx *a)
+{
+    REQUIRE_FPU;
+    REQUIRE_EXT(ctx, RVD);
+    return gen_fload_idx(ctx, a, MO_TEUQ, true);
+}
+
+static bool trans_th_flurw(DisasContext *ctx, arg_th_fmemidx *a)
+{
+    REQUIRE_FPU;
+    REQUIRE_EXT(ctx, RVF);
+    return gen_fload_idx(ctx, a, MO_TEUL, true);
+}
+
+static bool trans_th_fsrd(DisasContext *ctx, arg_th_fmemidx *a)
+{
+    REQUIRE_FPU;
+    REQUIRE_EXT(ctx, RVD);
+    return gen_fstore_idx(ctx, a, MO_TEUQ, false);
+}
+
+static bool trans_th_fsrw(DisasContext *ctx, arg_th_fmemidx *a)
+{
+    REQUIRE_FPU;
+    REQUIRE_EXT(ctx, RVF);
+    return gen_fstore_idx(ctx, a, MO_TEUL, false);
+}
+
+static bool trans_th_fsurd(DisasContext *ctx, arg_th_fmemidx *a)
+{
+    REQUIRE_FPU;
+    REQUIRE_EXT(ctx, RVD);
+    return gen_fstore_idx(ctx, a, MO_TEUQ, true);
+}
+
+static bool trans_th_fsurw(DisasContext *ctx, arg_th_fmemidx *a)
+{
+    REQUIRE_FPU;
+    REQUIRE_EXT(ctx, RVF);
+    return gen_fstore_idx(ctx, a, MO_TEUL, true);
+}
diff --git a/target/riscv/meson.build b/target/riscv/meson.build
index 30bb4c5bab..81175b67ce 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('xtheadfmemidx.decode', extra_args: 
'--static-decode=decode_xtheadfmemidx'),
   decodetree.process('xtheadmac.decode', extra_args: 
'--static-decode=decode_xtheadmac'),
   decodetree.process('xtheadmemidx.decode', extra_args: 
'--static-decode=decode_xtheadmemidx'),
   decodetree.process('xtheadmempair.decode', extra_args: 
'--static-decode=decode_xtheadmempair'),
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 1cb0d885b8..915ac11d3b 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(xtheadfmemidx);
 MATERIALISE_EXT_PREDICATE(xtheadmac);
 MATERIALISE_EXT_PREDICATE(xtheadmemidx);
 MATERIALISE_EXT_PREDICATE(xtheadmempair);
@@ -732,6 +733,7 @@ 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-xtheadfmemidx.c.inc"
 #include "decode-xtheadmac.c.inc"
 #include "decode-xtheadmemidx.c.inc"
 #include "decode-xtheadmempair.c.inc"
@@ -1061,6 +1063,7 @@ 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_xtheadfmemidx_p, decode_xtheadfmemidx },
         { has_xtheadmac_p, decode_xtheadmac },
         { has_xtheadmemidx_p, decode_xtheadmemidx },
         { has_xtheadmempair_p, decode_xtheadmempair },
diff --git a/target/riscv/xtheadfmemidx.decode 
b/target/riscv/xtheadfmemidx.decode
new file mode 100644
index 0000000000..43e0f80df8
--- /dev/null
+++ b/target/riscv/xtheadfmemidx.decode
@@ -0,0 +1,34 @@
+#
+# RISC-V instruction decode for the XTheadMemIdx extension
+#
+# Copyright (c) 2022 Christoph Muellner, christoph.muellner@vrull.eu
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+# The XTheadFMemIdx extension provides floating-point memory operations.
+#
+# 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
+%imm2       25:2
+%rs2        20:5
+%rs1        15:5
+%rd          7:5
+
+# Argument sets
+&th_fmemidx rd rs1 rs2 imm2
+
+# Formats
+@th_fmemidx ..... .. ..... ..... ... ..... ....... &th_fmemidx %rd %rs1 %rs2 
%imm2
+
+# Instructions
+th_flrd     01100 .. ..... ..... 110 ..... 0001011 @th_fmemidx
+th_flrw     01000 .. ..... ..... 110 ..... 0001011 @th_fmemidx
+th_flurd    01110 .. ..... ..... 110 ..... 0001011 @th_fmemidx
+th_flurw    01010 .. ..... ..... 110 ..... 0001011 @th_fmemidx
+
+th_fsrd     01100 .. ..... ..... 111 ..... 0001011 @th_fmemidx
+th_fsrw     01000 .. ..... ..... 111 ..... 0001011 @th_fmemidx
+th_fsurd    01110 .. ..... ..... 111 ..... 0001011 @th_fmemidx
+th_fsurw    01010 .. ..... ..... 111 ..... 0001011 @th_fmemidx
-- 
2.37.2